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MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1
Galina Ilieva Jos Pscoa Miguel Silvestre
26.05.2014
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Universidade da Beira Interior, Departamento de Engenharia
Electromecnica,
R. Marqus D'vila e Bolama
Covilh, Portugal
WP3, WP4 JBLADE code innovative software - HAP
design. Propulsion system elements efficiency increase.
Transition modeling new turbulence model
WP4, WP5 Aerodynamics, forces and effects affecting
the propulsive system performance
WP4 Propulsive systems for cruiser and feeder design
UBI
2
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
6000
7000
8000
9000
10000
11000
12000
0 1 2 3 4 5 6 7 8 9 10
Dra
g [N
]
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
0 1 2 3 4 5 6 7 8 9 10
Use
ful L
oad
[N
]
x10^5
l/d
Dyneema
PET(mylar)
Vectran
Tedlar PV2001
AluminiumAlloy 2024-
T351
Stainless Steel316Ti
PARAMETRIC STUDY OF HIGH ALTITUDE AIRSHIP
Ph.D. Student Joao Morgado
h=0 m
Ve = 20 000 m3
Ve2/3= 736.81 m2
v = 25 m/s
h=0 m
Ve = 20 000 m3
Ve2/3= 736.81 m2
v = 25 m/s
Fig. 1 The influence of fineness ratio on airships drag. Fig. 2 The influence of fineness ratio on useful load.
A methodology to carry out parametric studies for conceptual design evolution of a high altitude airship was
implemented. This methodology is quite useful to identify key parameters and especially to study the what-if
scenarios.
The implementation of methodology is open ended, so it can be continuously updated with new models found in
literature to provide more accurate results.
This methodology can be adopted to Multidisciplinary Design Optimization of an airship system as a way to
determine the optimum combination of design parameters and options that correspond to highest payload
available.
UBI
3
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
360 Polar Object
-Lift and drag coefficients;
-Reynolds number;
-Full angle of attack range.
Extrapolated Data
Blade Object
-Geometric parameters;
-Number of stations;
-Number of blades;
360 Polar Objects
Propeller Object
-Propeller Parameters;
Blade Object
Propeller Simulation Object
-Simulation Parameters.
Propeller Object
Blade Data Object
Blade Data Object
-Simulation Results Data along
the blade.
-Induction Factors;
-Inflow Angles;
-Circulation;
-Advance Ratio;
-Speed. BEM Simulation
-Advance Ratio;
-Speed Range.
360 Polar
Extrapolation
Airfoil Object
-Airfoil
Coordinates;
-Airfoi l Camber;
-Airfoil Thickness;
Polar Object
-Lift and drag
coefficients;
-Reynolds number;
-Angle of attack range.
Airfoil Object
Simulation Results
Panel
Simulation
- Angle of attack
Range
XFOIL
BEM CODE
JBLADE SOFTWARE - user-friendly, accurate, validated OS code, that can be used to design and optimize a variety of propellers
Ph.D. Student Joao Morgado
Fig. 3 Interaction among different sub-modules of the programm elaborated in UBI
The post stall model plays a
significant role in the low
advance ratio region and may
well be the main source of the
remaining differences relative
to the actual propeller
performance.
UBI
4
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
The long term goal of the JBLADE development is to provide a user-friendly, accurate, and
validated open-source code that can be used to design and optimize a variety of propellers. The code
allows the introduction of the blade geometry as an arbitrary number of sections, characterized by
their radial position, chord, twist, length, airfoil and associated complete angle of attack range
airfoil polar.
JBLADE SOFTWARE
Ph.D. Student Joao Morgado
An airship propeller must be very efficient in thrust/power ratio during hovering conditions as
well as it should maintain the high propulsive efficiency during cruise flight. Knowing that the
MAAT project will operate an airship under stratospheric conditions, it is crucial for us to have a
numerical tool suitable for the optimization needs of airships propellers.
Optimizing the propeller shape and performance is required in order to maximize effectiveness
over the flight envelope. The optimization process is based in the analysis of numerous designs as to
compare their relative merits.
3D Equilibrium shows better results than the classical BEM formulation but could be improved further for
actual axial velocity (the induced one) distribution.
JBLADE seems superior to other available open source codes.
The post stall model plays a significant role in the low advance ratio region and may well be the main
source of the remaining differences relative to the actual propeller performance.
UBI
5
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
The Blade sub-module, contains a 3D tool which allows the user to visualize the blade final shape. In addition it was
also implemented and inverse design methodology for calculation of the blade geometry for only one given
operating point.
The Multi-Parameter Simulation sub-module allows the simulation of the propeller varying the air speed, the
propeller rotational speed and the propeller pitch angle, providing a easy way to evaluate the propeller performance
for further improvements towards optimization.
Fig.5 Simulation environment -Sub-module. Fig.4 Blade Definition process and Inverse Design Sub-
module.
JBLADE SOFTWARE I
Ph.D. Student Joao Morgado
UBI
6
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
4
5
at 0
.75R
30
at 0
.75R
JBLADE SOFTWARE I
Ph.D. Student Joao Morgado
Fig. 6 Validation of
JBLADE code against
NACA TR 594
Propeller C, Martin
Hepperle Code
JAVAPROP and Mark
Drelas code QPROP
The new JBLADE code to propeller design is successfully implemented and its
validation shows promising results. The improvements in the method to extrapolate
the drag coefficient polar besides reducing the errors, introduced by the user, leads
to an improvement in the prediction of all propeller performance coefficients as well
as in its propulsive efficiency prediction.
UBI
7
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Incorporating : blade structure module; electrical motor module in the code such that the thrust per unit
weight for constant power of the complete propulsion set can be optimized as a whole.
JBLADE SOFTWARE I
Ph.D. Student Joao Morgado
FUTURE WORK and list of publications
Refereed Conference Papers Morgado, Joo, Miguel ngelo Rodrigues Silvestre, and Jos Carlos Pscoa. 2012. Parametric Study of a High Altitude Airship
According to the Multi-Body Concept for Advanced Airship Transport - MAAT. Proc. of IV Conferncia Nacional Em Mecnica Dos
Fluidos, Termodinmica e Energia. LNEC, Lisbon - Portugal; 28-29 May 2012.
Morgado, J., Silvestre, M. A. R. and Pascoa, J. C.. 2013. Full Range Airfoil Polars for Propeller Blade Element Momentum Analysis.
Proc. of 2013 International Powered Lift Conference. Los Angeles, California: American Institute of Aeronautics and Astronautics.
DOI:10.2514/6.2013-4379.
Silvestre, M. A. R., Morgado, J. and Pascoa, J. C. 2013. JBLADE: a Propeller Design and Analysis Code. Proc. of 2013 International
Powered Lift Conference. Los Angeles, California; American Institute of Aeronautics and Astronautics. DOI:10.2514/6.2013-4220.
Morgado, J., Silvestre, M. A. R. and Pascoa, J. C.. 2013. Low Reynolds Propeller Design and Analysis with JBLADE Accepted for
Presentation at AVIATION 2014.
Journal Submissions
Morgado, J., Silvestre, M. A. R. and Pascoa, J. C.. 2013. Validation of New Formulations for Propeller Analysis Submitted to
Journal of Propulsion and Power AIAA 1st Revision Completed.
Morgado, J., Silvestre, M. A. R. and Pascoa, J. C.. 2013. A software tool for propeller inverse design and aerodynamic performance
prediction Submitted to Aerospace Science and Technology Elsevier
UBI
8
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Ph.D. Student Rui Oliveira
At high altitude the air flow presents low turbulence intensity. This leads to a late transition to turbulence of the laminar
boundary layers. This fact is very important for all the components of a propulsion system. The correct flow state calculation,
turbulent or laminar, is of extremely important. Failure to provide an accurate determination of the flow state will over -or under -
estimate power requirements. Incorrect determination of flow separation will deliver an incorrect operational envelope of the
propulsion system.
That is why we need of correct determination of the transition region . Nowadays turbulence models lack of specific and
correct term for transition determination. Main goal during the MAAT project research activities was to elaborate turbulence model
for correct and exact prediction of the transition regions over streamed bodies, especially in case of high altitudes.
In our team Rui Oliveira is currently working on the elaboration and implementation of a new turbulence code.
Objectives
Implementation of recently developed transition models in OpenFOAM.
Evaluation of transitional model codes performance.
Accuracy refinement of selected transition model.
Validation of implemented turbulence transition models.
Application of selected transition code to geometries with interest to propulsion.
Development of a new transition model.
Validation of the new transition model over a wide range of turbulence flow
conditions.
Application of transition models over 2D and 3D geometries relevant to MAAT
project.
Research and effects of transition flows in high altitude propulsion
system components
UBI
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MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
The majority of the performed research up to now was done in order to find the correct model description of each of its terms. Through the available literature and knowledge of the transition mechanism simulated by the model, reasonable changes were applied to
the model. After some trial and error, the final version of the corrected model was achieved.
Research and effects of transition flows in high altitude propulsion
system components
Ph.D. Student Rui Oliveira
Fig.7. Skin friction
coefficient
distribution -flat-
plate multiple
boundary
conditions study
prove that the
model behaves
similar to the
commercial one;
(TI, Ekin dis ) .
The model is
validated for classic
geometries against
experiments
UBI
10
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Ph.D. Student Rui Oliveira
Research and effects of transition flows in high altitude
propulsion system components
Fig. 7a. VALIDATION - Flat-plate ERCOFTAC T3A skin friction coefficient distribution
UBI
11
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Our corrected transition model was tested over 3D geometries, the Onera-M6 wing Fig.8 and a Nacelle,
Fig.9. For the wing geometry, the transition model was compared with the Spalart-Allmaras model, Fig. 8. This was
performed through a direct comparison of skin-friction coefficient contour map over the wing for the two models.
Fig.8. Onera-M6 wing -skin friction
coefficient distribution.
Fig. 9. Nacelle B.C.1 and B.C.2 skin
friction coefficient distribution.
Research and effects of transition flows in high altitude propulsion system components
Ph.D. Student Rui Oliveira
12
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Re=6.5x10^6
U=45 m/s
Tu=0.1%
AoA=15
Fig. 11. Prolate Spheroid 6:1 low turbulence intensity case
skin friction coefficient distribution- obtained from the mid
section-plane normal to the spheroid minor axis.
.
Fig. 10. Prolate Spheroid 6:1 model validation against
other specific turbulence models for transition modeling
Transition pattern similar to the experimental data.
The used geometry has the same length size of 2.4 meters
13
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Research and effects of transition flows in high altitude propulsion
system components
Ph.D. Student Rui Oliveira
Conclusions
The proposed objectives have been accomplished.
The selected transitional model is able to compute transition over a diverse set of
flow geometries and boundary conditions.
The turbulence transition model was successfully corrected, behaving very similarly
to the commercial version of it.
The corrected model is able to predict transition over a diverse range of geometries.
The newly developed model is able to predict transition over a flat-plate with varying
turbulence intensity.
The new transition model is able to predict transition onset under several pressure
gradient and turbulence conditions.
Future planning
The new transition model will be tested in curved geometries, both bi-dimensional
and three-dimensional. Also the model will require supersonic and transonic
validation in order to assure that it behaves accordingly under the influence of
pressure shock waves interacting with the boundary layer. Considerations regarding
the coupling of the transition model to an already known turbulence model or the
addition of a transport equation for specific turbulence dissipation rate or turbulence
dissipation in order to enable the model to calculate turbulent state will be considered.
UBI
14
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Publications:
R. Vizinho, J. Pascoa, and M. Silvestre. High altitude transitional flow computation for a
propulsion system nacelle of maat airship. SAE International Journal of Aerospace, 6(2):7,
2013.
Conferences:
R. Vizinho, J. Pascoa, and M. Silvestre. By-pass transition effects in propulsion components
of high-altitude airships. 5th European Conference for Aeronautics and Space Sciences
(EUCASS), Munich, Germany, 2013.
R. Vizinho, J. Pascoa, and M. Silvestre. Preliminary assessment of transitional flow
modeling using low-re turbulence closures. IV Conferncia Nacional em Mecnica dos
Fludos, Termodinmica e Energia (MEFTE), Lisboa, Portugal, 2012.
Submissions:
R. Vizinho, J. Pascoa, and M. Silvestre. Development and validation of a transition model
based on a mechanical approximation. Flow Turbulence and Combustion, (Pre-Print), 2014.
R. Vizinho, J. Pascoa, and M. Silvestre. A refurbishing of the k-kl-omega laminar kinetic
energy transition model for improved accuracy. Engineering Applications of Computational
Fluid Mechanics, (Pre-Print), 2014.
Research and effects of transition flows in high altitude propulsion
system components
Ph.D. Student Rui Oliveira
UBI
15
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Efficiency increase in high altitude propulsion systems
using plasma actuators
Task - to apply the concept of Plasma Actuators to
improve the efficiency of the PS for air-vehicles. The specific
plasma actuator which is considered for this study is the single-
dielectric barrier-discharge (SDBD).
Airflow control by DBD actuators is based on the
generation of the ionic wind at the wall which adds momentum
to the boundary layer. At low flow velocities, those actuators
have proven to be effective for a wide range of applications.
Exposed Electrode
Encapsulated Electrode
Dielectric Layerplasma
Ionic Wind
Objectives:
Development and improvement of a model for simulation the detail of the plasma discharge.
Development of phenomenological model for modeling the macroscopic effect of plasma actuators.
Implementation of the plasma actuators with sinosoidal and nano-second voltage shape for controlling the flow
(Stall over airfoil) in steady and unsteady mode.
Implementation of the plasma actuators with nano-second pulsed voltage for modification of the shock wave
structure.
The plasma actuators are formed by a pair of electrodes
separated by a dielectric material(Fig 12).. The ionized air in
the presence of the electric field gradient, produced by the
electrodes, results in a body force vector on the external flow
shift for the separation point.
Ph. D. Student M.Abdoullahzadeh
Fig. 12.
UBI
16
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Efficiency increase in high altitude propulsion systems
using plasma actuators
26.05.2014 26.05.2014
Single Dielectric Barrier Discharge (SDBD) actuator (plasma actuators)
Present study Suzan et. al
[10]
Bouchmal
[17]
Maximum velocity 1.054 0.934
Maximum Body force 1315 1250 1440
100100
200
300
400
500
X
Y
-0.002 -0.001 0 0.001 0.002 0.003-0.001
0
0.001
0.002
0.003100 200 300 400 500 600 700 800 900 1000 1100 1200
X
Y
-0.002 -0.001 0 0.001 0.002 0.003-0.001
0
0.001
0.002
0.003
velocity vectors body force
magnitude vector plot of
body force
X
Y
-0.002 -0.001 0 0.001 0.002 0.003-0.001
0
0.001
0.002
0.003
Ph. D. Student M.Abdoullahzadeh
Fig. 13(a,b,c).
UBI
17
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
X( m)
Y(m
)
0.005 0.01 0.015
-0.002
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.2 0.6 1 1.4 1.8 2.2 2.6 3 3.4 3.8 4.2 4.6
X(m)0 0.005 0.01 0.015
Ux( m/s)y
(mm
)0 1 2 3 4 5
0
1
2
3
4
5
Present Study
Experimntal results [36]
U/Umax
Y(m
m)
0 0.2 0.4 0.6 0.8 1
0.5
1
1.5
2
2.5
3
A
B
C
D
Fig.15 and Fig. 16 - The comparison of the present
modeling approach with exist model is shown. The
results of present modeling (dashed line) are the
closest to the experimental result.
Ionic wind
formation due to
the effect of
plasma actuator.
The developed
model captures
with acceptable
accuracy the
experimental
results
Results New
phenomenological model
Ph. D. Student M.Abdoullahzadeh
Fig. 14.
Fig. 15.
Fig. 16.
18
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
P(atm)
Nor
mal
ized
Th
rust
Nor
mal
ized
Bod
yF
orce
0 0.2 0.4 0.6 0.8 10.7
0.75
0.8
0.85
0.9
0.95
1
1.05
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
p=0.6 atm
p=0.710526 atm
p=0.592105 atm
Ux (m/s)
Y(m
m)
0 0.5 1 1.5 2 2.5 3 3.5
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Expermental results [42], x=5 mm
Expermental results [42], x=10mm
Expermental results [42] x=20 mm
Present study,x=5mm
Present study,x=10mm
Present study,x=20mm
Effect of operating pressure (altitude) was
included in the model. The results show that
the model can provide good results for both
above/below atmospheric pressure level
p( kPa)
T(m
N/m
)
50 100 150 200 250 300 350 400 450-5
0
5
10
15
20
25
30
35
40
45
Experimental results [46]
Present study,
Present study,
Fig. 17.
Fig. 18.
Fig. 19.
19
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Successfully validated!!!
NS DBD was used for controling a transonic flow over a profile NACA0012. The induced micro show wave
was shown by isolines of density gradiant and in accordane with experintsal results
X(m)
Y(m
)
0 0.02 0.04 0.06 0.08
0
0.01
0.02
Current Study
contour lines
Peschke et al. [26]
Efficiency increase in high altitude propulsion systems
using plasma actuators
Ph. D. student M.Abdoullahzadeh
Fig. 20 (a, b).
20
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Efficiency increase in high altitude propulsion systems
using plasma actuators
Ph. D. Student M.Abdoullahzadeh
M. Abdollahzadeh, J.C. Pscoa, P.J. Oliveira, Two-dimensional numerical modeling of interaction of
micro-shock wave generated by nanosecond plasma actuators and transonic flow, Journal of
Computational and Applied Mathematics, 2014, (Accepted article in press)
M. Abdollahzadeh, J.C. Pscoa, P.J. Oliveira ,Modified Split-Potential Model for Modeling the Effect of
DBD Plasma Actuators in High Altitude Flow Control , 2014, Current Applied Physics ( Submitted).
Abdollahzadeh M., Pscoa J.C., Oliveira P.J. (2013), "Two dimensional numerical Modeling of
nanosecond plasma Actuators, a preliminary study of application in propulsion systems", in Proc.
EUCASS 2013 5th European Conference for Aeronautics and Space Sciences Munich, Germany, 1-5
July 2013.
Abdollahzadeh M., Pscoa J. C. , Oliveira P.J. (2012), "Numerical investigation on efficiency increase in
high altitude propulsion systems using plasma actuators", in Proc. European Congress on
Computational Methods in Applied Sciences and Engineering, ECCOMAS 2012.
M. Abdollahzadeh, J.C. Pscoa, P.J. Oliveira, Numerical Modeling of Boundary Layer Control Using
Dielectric Barrier Discharge, in: Conferncia Nac. Em Mecnica Dos Fluidos, Termodinmica e Energ.
MEFTE, 2012: p. Paper No 61, pp. 110.
UBI
21
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
*Objectives:
To obtain CG positioning and changes in velocity, due to the acting
aerodynamic forces and pressure distribution around the airships body.
IMPORTANCE - determine propulsion requirements strong winds and
instabilities; power budget for the docking/undocking procedures; restoring
moment; power needed to maintain the position Identify problems related to
the propulsion system behavior and to assess the stability and control during
this flight phases
CG MOTION AND VELOCITY CHANGES DUE TO FORCES
ACTING ON THE AIRSHIP. EFFECTS ON THE PROPULSION
POWER AND VEHICLES STABILITY
In our case having the final shape need to perform a research on CG,
Munk moment, separation moment, other forces and moments causing
disturbing movements, exerting the propulsion system and leading to
stability problems.
This will help to achieve better propulsion system performance, control
on the airship and see where is the best position for stabilizers. Also, what
should be their profile, dimensions, design
IMPORTANT
!!!
UBI
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1
22
GEOMETRY AND NUMERICAL MODLEING
26.05.2014
Geometry modeling GAMBIT, final concept for feeder - UNIMORE
Domain discretization Hexahedral mesh 2 482 167 grid elements
BOUNDARY ZONES far-field, walls, fluid
BOUNDARY LAYER-first row elements h=0.01 m
CG MOTION AND VELOCITY CHANGES DUE TO FORCES
ACTING ON THE AIRSHIP. EFFECTS ON THE PROPULSION
POWER AND VEHICLES STABILITY
Fig. 21.
UBI
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1
23
*Approach to access the main task:
Dynamic mesh, code with activated 6 DOF, function - forces and moments acting on the airships
hull
Spring-based smoothing, connectivity remains unchanged; local re-mesh, performed every time step .
. .
*UDF Macro to Govern the Dynamic Mesh:
Coupled Mesh Motion via the 6 DOF UDF DEFINE_SDOF_PROPERTIES !!! (ch)
Controlling Rigid Body Motion using DEFINE_CG_MOTION !!!
CG MOTION AND VELOCITY CHANGES DUE TO FORCES ACTING ON THE
AIRSHIP. EFFECTS ON THE PROPULSION POWER AND VEHICLES
STABILITY
26.05.2014
GEOMETRY AND NUMERICAL MODLEING
Very important function for reading obtained results over the feeders walls,
extract results, insert in a file and then integrate for CG motion is:
*Compute_Forces_And_Moments (domain, tf1, x_cg, f_glob, m_glob, TRUE).
HOW THESE CHANGES IN CG, position EXERT PROP.SYSTEM???
UBI
24
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
CG MOTION AND VELOCITY CHANGES DUE TO FORCES ACTING ON
THE AIRSHIP. EFFECTS ON THE PROPULSION POWER AND VEHICLES
STABILITY
FLOWCHART -HOW WORKS THE CODE - CFD ANALYSIS AND RIGID BODY
MOTION
1. STEADY SOLUTION 2. UNSTEADY WITH ACTIVATED UDF MACRO
Fig. 22.
UBI
25
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
CG MOTION AND VELOCITY CHANGES DUE TO FORCES ACTING ON
THE AIRSHIP. EFFECTS ON THE PROPULSION POWER AND VEHICLES
STABILITY
The motion of airship can be splitted into two motions, the desired motion which are the values on the equilibrium, and the disturbing
motion which are the values away from the equilibrium.
+Propulsion vector with prop. forces and moments!!!
+Gravity and buoyancy effects !!!
-mass matrix
-aerodynamic vector with total aerodynamic forces and moments
-dynamic terms associated with inertial linear and angular velocities
6-DOF non-linear mathematical model of the airship flight for computer simulation
Math model in FLUENT (shown below) must be updated in order to follow the model already presented!!!
UBI
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MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Altitude/
imposed
paramete
rs/conditi
ons
Density
[kg/m3]
Viscosity
[kg/m.s]
Static
pressure
Pst [Pa]
Static
temperatur
e
Tst [K]
Mach
number
M [-]
Turb.
Intensity
Tu [%]
Turbulent
viscosity
ratio
[-]
15km 0.19476 0.0000142 12112 216.65 0.169 2 5
Numerical simulation FLUENT
Altitude: 15 km
LATERAL WIND VELOCITY 92 km/h ; VERTICAL VELOCITY 15 km/h
RANS equations; Realizable k- turbulence model with non-equilibrium functions
Working fluid: air; physical properties in function of the altitude
BOUNDARY ZONES: static pressure, static temperature, turbulence parameters, Mach number, flow direction
RELAXATION FACTORS: 0.5 for each DOF ; CONVERGENCE APPROACHES
CG MOTION AND VELOCITY CHANGES DUE TO FORCES
ACTING ON THE AIRSHIP. EFFECTS ON THE PROPULSION
POWER AND VEHICLES STABILITY
UBI
27
MAAT Multibody Advanced Airship for Transport Project ID 285602 / FP7-AAT-2011-RTD-1 26.05.2014
Fig.23. Static pressure distribution Fig.24. Velocity flow field distribution
Assymetric pressure distribution around the streamed airships hull, boundary layer
separation and vortex structures, leading to aerodynamic problems, power budget increase, stability
problems and need of strong control. NOT included inertial effects, pressure forces, 6 dof., forces
and moments ...
RESULTS UNIMORE concept
Case without air-jets, 50 m/s velocity of the incoming air-flow.
Altitude 15 km
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TI in zones of separated b.l.
interacting with the incoming flow and
formed vortex structures.
The area of max TI will affect the
working air-jets and lead to worse
aerodynamic behaviour.
Drag coefficient 0.35535
Total force 179 987.73 [N]
Thrust 179 987.73 [N]
Power 8.999 [MW]
Lift coefficient - 0.2679
Total force in vertical direction
-135 702.06[N] !!! Prove - 03.2012. Covilha meeting
NEED ADDITIONAL THRUST
during VERTICAL TAKe-OFF!!!
RESULTS UNIMORE concept
Case without air-jets, 50 m/s velocity of the incoming air-flow.
Altitude 15 km
Fig.25. Turbulence intensity
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RESULTS UNIMORE concept
Case without air-jets, dynamic mesh UDF. Altitude 15 km
Incoming air flow 50m/s, imposed 5m/s feeders speed,
Mass and inertia - 28 people on board 2 pilots, 26 passengers
CG motion: (x/y/z) (0.9365/ -0.60576/-0.00311) m
(x y z) (0.006239/-6.035.10-6/-1.0014) deg
(x y x) (0.0004356 /-4.213.10-7/ -0.6991) rad
Drag coefficient 0.3642 Drag force 184 510.804 N Power budget 9.225 W
Fig.26(a,b,c). Static pressure, velocity flow field, turbulence
intensity unsteady T=0.5sec
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RESULTS UNIMORE concept
Case without air-jets, 50 m/s velocity of the incoming air-
flow. Altitude 15 km
CG motion: (x/y/z) (4.821/ -3.88032/-0.004822) m
(x y z) (0.03346/0.00102/-14.483) deg
(x y x) (0.000403 /-3.55.10-5/ -0.17611 rad
Drag coefficient 0.833 Drag force 468368.804 N (4)
Significant restoring moments, additional forces to maintain the trajectory,
provide additional thrust to overcome the increased drag, .
Fig.27. Static pressure, velocity flow field, turbulence intensity
unsteady T=2.25sec
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RESULTS UNIMORE concept
Case without air-jets, 50 m/s velocity of the incoming air-
flow. Altitude 15 km
Fig. 28. CG motion in X direction Fig. 31. CG position change in Z direction
Maximum angle of rotation (oZ) is -34.473 deg (!!!)
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RESULTS UNIMORE concept
Case without air-jets, 50 m/s velocity of the incoming air-
flow. Altitude 15 km
Fig.30. Drag coeficient values
Drag force: ( 179988 168326 165561 234225.91 245084.76 347823.353 236492.27 622593.25 543417.408 541865.23 609198.59 539035.51 558348.12 544798.92 553347.839 ) [N]
Fig. 31. Power budget changes during one time
period
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Fig.32. Velocity flow field and streamlines
realized around the feeder
Fig.33. Static pressure distribution
RESULTS flight in vertical direction, 5m/s velocity
UNIMORE concept
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Fig.34. Turbulence intencity
Drag coefficient - 0.445
Total force -34023.907 [N]
Thrust -34023.907 [N]
Power 0.17[MW]
Positive lift (!)
RESULTS flight in vertical direction, 5m/s velocity
UNIMORE concept
TI in zones of separated b.l.
interacting with the incoming flow and
formed vortex structures with small
intensity
Coupling vortices due to edge
streaming and vortices due to air-jets
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RESULTS previous UNIMORE concept (!!!)
Case without air-jets, 30 m/s velocity for the incoming air-flow.
Altitude 15 km
Fig.35. Static pressure distribution Fig.36. Velocity flow field distribution
Assymetric pressure distribution around the streamed airships hull, boundary layer
separation and vortex structures, leading to aerodynamic problems, power budget increase, stability
problems and need of strong control. NOT included inertial effects, pressure forces, 6 dof....
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RESULTS UNIMORE concept
Case without air-jets, 30 m/s velocity for the incoming air-flow.
Altitude 15 km
Fig.37. Turbulence intensity
TI in zones of separated b.l.
interacting with the incoming flow and
formed vortex structures.
**The area of max TI will affect the
working air-jets and lead to worse
aerodynamic behaviour.
Drag coefficient 0.24569
Total force 150 867.87 [N]
Thrust 150 867.87 [N]
Power 4.526 [MW]
Lift coefficient -0.3427
Total force in vertical direction
- 210 430 [N]
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RESULTS UNIMORE concept
Case with air-jets, 30 m/s velocity for the incoming air-flow at altitude
15 km. Non-vectorized air-jets case
Air-jets parameters - mass-flow rate ; velocity components X=1 Y=Z=0
Drag coefficient 0.3241 (24%) Thrust 199062 [N] Power budget 5.97
[MW]
Fig.38(a,b). Velocity flow field and turbulence intensity
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RESULTS UNIMORE concept
Case with air-jets, 30 m/s velocity for the incoming air-flow at altitude
15 km
Vectorized air-jets in the case 10 deg
Drag coefficient - 0.2752 Thrust -1680929 [N]
Power budget 5.067[MW]
Fig.39. Velocity flow field in case of
vectorized air-jets.
Coanda effect
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RESULTS UNIMORE concept DYNAMIC MESH
COMPARISON for two cases of T=0.05sec and T=1.0sec (slice Z=0)
Due to the movement and aerodyn. features pressure after the vehicle is decreasing and differences in the pressure flow field around the airship increases, for different time steps. It will tend to move toward the low-pressure zone-
affect on the propulsion system. There is an increase in the max turbulence intensity.
Fig.40(a-f). Static pressure, velocity flow field and turbulence intensity in case of vectorized
air-jets.
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RESULTS DYNAMIC MESH UNIMORE concept
GRAPHIC RESULTS for CG position change along x,y,z axis and
rotation angle
For unsteady calculations were observed periodic changes in both the drag
coefficient and power budget values. Variations in drag values lead to a
strong change in power required for propulsion needs during one time
period.=> design, performance of the airship??? THINK ABOUT ContrS,
ContrDevices, prop system specifics.!!!
Power needed for
propulsion 4.526 [MW] to
5.82 [MW] smaller mass
and inertia
Important calculate the restoring moment!!!
Fig.42
Fig.43
Fig.44
Fig.45
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RESULTS DYNAMIC MESH UNIMORE concept
Case with air-jets, 30 m/s velocity for the incoming air-flow at altitude
15 km
Vectorized air-jets at 10 deg, without UDF macro
Power needed for propulsion varies in the range of 5.067 [MW] to 5.49 [MW]
Fig.46(a,b,c). Velocity flow
field and turbulence intensity
in case of vectorised air-jets
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RESULTS DYNAMIC MESH UNIMORE concept
Case with air-jets, 30 m/s velocity incoming air-flow, altitude 15 km
Vectorized air-jets at 10 deg (T=0.05 sec up and down, y const
sections) The zone at the bottom as
previously appeared with high turb.
intensity cause problems for the air-
jets.
As the speed increases, due to
additional movements according
acting moments and 6 dof, air-jets are
also working the pitch- incidence
oscillation mode and the side slip
(yaw angle) shifting mode of the
airship could become more unstable.
This is because of the already
mentioned unstable moment(!), which
could dominate, even over the
stabilizing moment generated by fins
or other stabilizers (last case is
explained in some papers). It is possible for other cases and modes to
become more stable as the speed increases, due to
the increasing of the aerodynamic damping and
some vortex shedding effects, but the last could be
true only for specific shapes
Fig.47a
Fig.47b
Fig.48a
Fig.48b
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RESULTS DYNAMIC MESH UNIMORE concept Case with air-jets, 30 m/s velocity incoming air-flow, altitude 15 km
Vectorized air-jets at 10 deg (tree control sections at the rare part perpendicular to the incoming flow)
Increase a circulation zone around the airship, due to the interaction between the acting air-jets, air stream flow, and the
separated boundary layer. This will cause significant losses in momentum and can involve pressure increase. The pressure
differences are a reason for vortex structures to appear
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RESULTS DYNAMIC MESH UNIMORE concept
Unsteady computations have shown that the stability and related to the prop system
problems (due to inertia, added masses, pressure forces on the vehicles body) lead to CG
additional movement differences, development of vortex structures and the increase of
vortices.
It is also observed that were introduced strong changes in both the drag coefficients
and required power budget.
The change of vorticity during the disturbing movements of the CG lead to
irregularity in pressure distribution around the hull and will introduce stability problems.
Also, a change in vorticity means that there is additional force acting on the body under
study.
The additional vortex structures provoke less aerodynamic performance and stability
problems. The results obtained for this research can be used as a basis for a study on the
frequency of vortex shedding, stability problems and how they exert the propulsion
system performance.
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PROPULSION SYSTEM FOR CRUISER
CRUISERS PROPULSIVE SYSTEM
INITIAL DATA
Altitude 16 km
Air density 0.16647 kg/m3
Velocity v = 28 m/s
Mach number M = 0.6
Local sound speed A = 295.0695 m/s
Disc loading for high-altitude vehicles DL = 300
N/m2
!!!
Table 1. Disc loading (F/A) values for different high-altitude vehicles.
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Table 2. Aerodynamic data of cruiser at different angles of attack
Table 3. Aerodynamic data of cruiser at different sideslip angles
Numerical simulations cruiser with 2 feeders (University of Hertfordshire)
Focus on the case without AoA - thrust 202 601 N (min) and on the case with
12 deg AoA - thrust 339 654 N ( 68.14% increase of P)
Drag coefficient
Cd = 0.171;
Drag force
Fd = 172 658.349 N
Power budget
P = 4 834 433.765 W
Drag coefficient
Cd = 0.185;
Drag force
Fd = 290 317.321 N
Power budget
P = 8 128 884.980 W
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FINAL SOLUTION
Number of propellers 40
Diameter of each propeller: 5.552 [m]
RPM = 601.564 [1/min]
Thrust for each propeller: T = 7258 [N]
Efficiency: 0.65 0.70 / as a result of modeling in JBLADE - in function of velocity, advance ratio ./
Minimum power for one propeller (in function of the induced velocity Vind [m/s]) Pmin = 0.342.106 [W]
Maximum power for one propeller (in function of the induced velocity Vind [m/s] and included profile losses)
Pmax = 0.3933.106 [W]
Estimated weight for one propulsion unit: (assumed weight/power
ratio is 0.136 kg/1kW)
is 53.4888 [kg]. For 40 units: 2.14 [tons]
PROPULSION SYSTEM FOR CRUISER
JBLADE results in function of blade design, material Al, ..
Weight for one propulsion unit: 5blades X 418kg = 2090 kg
For 40 units: 83.6 [tons]
In our report 03.2013 around 72 tons (!) with imposed
weight/power ratio 3kg/1kW!!
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Figure 50*. Blades shape comparison for DL 1000 N/m2 (a), and DL 300 N/m2 4 blades (B), five blades (C)
and 6 blades (D), (author -Joao Morgado, Ph.D. student).
PROPULSION SYSTEM FOR CRUISER
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L = 400 m (20 propellers each side)
PROPULSION SYSTEM FOR CRUISER
VECTORIZED THRUST
4 PROPELLERS - MOMENT CONTROL
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PROPULSION SYSTEM FOR FEEDER
Numerical simulations feeder at zero and cruise altitudes (University of Hertfordshire)
Table 4. Aerodynamic data at zero altitude, VTO (author UoH).
Table 5. Aerodynamic data at 15 km altitude, vertical flight (author UoH).
At zero altitude the
maximum drag force Fd = -104
386 N 0degrees.
Minimum drag force
Fd = -14 228 N is realized at
15 km altitude and at angle
of attack 12 degrees.
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Table 6. Aerodynamic data at zero altitude, horizontal flight (author UoH).
Table 7. Aerodynamic data at 15 km altitude, horizontal flight (author UoH).
Maximum drag force Fd = 266 672 N is realized at 15 km altitude and at
angle of attack 12 degrees.
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PROPULSION SYSTEM FOR FEEDER
It is preferable for airships with VTOL and horizontal cruise flight capability to have vectorized thrust. Thrusters
must have high efficiency and possibility to fast change for thrust according to the flight needs. A HAA airship needs to be
light and have an efficient propulsion system that can operate with little or no oxygen. This is important when an airship
operates, in the thin atmosphere, at very high altitudes and for extended periods of time. - > covered by AIR-JETS concept
Fig. 51 Air-jets propulsion concept (a) and main air channels (b) .
Fig. 52. Air-jets working principle.
For higher efficiency, jets must operate at a high mass flow rate and low velocity. The application of higher mass flow
rates, at low speeds, is linked to the dimensions of air inlets, and outlets with large cross sectional area.
Less velocity of air-jets generates insufficient thrust. In order to achieve the required thrust, with less air-jets velocity more air mass is
needed. This fact reflects on the overall concept for distribution of weights, buoyancy and required propulsion needs. In order to
overcome these problems, an additional study for impact of air-jet working parameters (mass flow rate and velocity) on the dimensions
distribution was performed. The research is very helpful in order to arrive to a final solution for dimensions of air-jets channels, their
working parameters,
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PROPULSION SYSTEM FOR FEEDER
Table 8. The impact of air-jets
working parameters on the
dimensions distribution
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PROPULSION SYSTEM FOR FEEDER
Fig. 54. Velocity magnitude and static pressure distribution in a section
along the axis of air-jets outlet area.
Fig.53. Velocity field distribution realized by the working air-jets.
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Vortex structures, which are formed because of the interaction between the two central air-jets and the incoming flow, at the bottom part of airship hull, have higher
vorticity than those raised due to the sideward air-jets. The vorticity change lead to irregularity in pressure distribution around the hull and will introduce stability problems. A
change in vorticity means that there will arise additional force acting on the body under consideration. This analysis helped us to attain power changes due to vortex shedding
effects
(a) (b)
(c) (d)
(e) (f)
Fig. 13(a-f). Streamlines and vortex structures (t=T), obtained due to interaction between the working air-jets and the incoming air flow: section 1-top (a) and bottom side (b), section 2-top (c) and bottom side (d), section 3-top (e) and bottom side (f).
(c) (d)
(e) (f)
Fig. 56(a-f). Streamlines and vortex structures (t=T), obtained due
to interaction between the working air-jets and the incoming air
flow: section 1-top (a) and bottom side (b), section 2-top (c) and
bottom side (d), section 3-top (e) and bottom side (f).
(e) (f)
Fig. 10 (a-f). Streamlines and vortex structures (t=0 s), obtained due to interaction between the working air-jets and the incoming air flow: section 1-top (a) and bottom side (b), section 2-top (c) and bottom side (d), section 3-top (e) and bottom side (f).
(a) (b)
(c) (d)
Fig. 55(a-f). Streamlines and vortex structures (t=0), obtained due to
interaction between the working air-jets and the incoming air flow:
section 1-top (a) and bottom side (b), section 2-top (c) and bottom side
(d), section 3-top (e) and bottom side (f).
(e) (f)
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PROPULSION SYSTEM FOR FEEDER
Top air-jets: distributed air suppliers !!!
T - to avoid pitching moments!
Bottom air-jets: Zone 2 - for VTO purposes.
Zone 1 - horizontal flight;
control issues
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DEFINE_CG_MOTION
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