Team – 3 Amjad Khan
Dinesh Baluraj Karthikeyan Baskaran
Murali Krishna Safiq Ahmad
Varun Prakash
Overview
Introduction Ice protection Types of ice protection
systems
Pneumatic deicing system
Electro-impulsive
deicing system
Eddy current deicing system
SPEED Ultrasonic
deicing system
SMA technologies for deicing
Summary
Types of ice on Aircrafts Clear ice:
Forms in temp. range between 0˚C to -10˚C
It is a homogeneous and transparent ice coating ; difficult to break
When the droplet size is large its known as “Super-cooled Large Droplet” (SLD).
Rime ice
Forms between -15˚C to-20˚C
Rough milky white appearance and a comb-like appearance
Mixed ice/ Conglomerated ice:
It is a combination of Clear and Rime ice
Forms between -10˚C to -15˚C.
Frost ice
It is the result of water freezing on unprotected surfaces, often forming behind deicing boots or heated leading edges.
Types of ice on Aircrafts (contd.)
Ice protection Ice formation on aircrafts can lead to catastrophic
failures
The consequences of neglecting ice formation are: Loss of Lift
Increased drag due flow separation
Unresponsive control surfaces
All the above lead to loss of control of the aircraft
Ice protection can be done by Anti-icing – Preventing ice formation/growth
Deicing – Removal of ice
Effect of icing on Aircraft
Pneumatic Deicing System
Pneumatic Boot Deicing System Basic Principle-Alternate or simultaneous inflations and
deflations of the boot breaks the accreted ice into particles
Aerodynamic and Centrifugal forces on rotating airfoils removes the ice
Deicing system
Boot thickness < 0.075 inch
Pneumatic Boots
Components Span wise / Chord wise pneumatic tubes
Regulated pressure source, Vacuum source and air distribution system (Primary components)
Air filters, Control switches, relief valves (Miscellaneous)
Turbine Powered Pneumatic Boot Deicing system
Reciprocating Engine Powered Pneumatic Boot Deicing System
• Repair, Inspection, Maintenance are well understood
• Simplest and cost effective method
Advantages
• Boot material deteriorates with time
• If accretion of ice is too thin, bridging may be formed
Disadvantages
Pneumatic Impulse Deicing System
Deicer Embodiments
Configuration of Deicer
Skin-Bonded
Recess-Bonded
Integrated Composite
Leading Edge Assembly
Modular Composite
Leading Edge Assembly
Schematics and Working
• Low power requirement
• Aerodynamically non-intrusive and No runback and refreezing
• Thin ice removing capability (0.08-0.2 inch)
Advantages
• Mechanical system-residual ice remains after the cycle
• Noise
• Fatigue of deicer Disadvantages
Electro – Impulsive Deicing System
Electro – impulse deicing system
Electro-Impulse De-icing (EIDI) is classified as a mechanical ice protection method
Ice is shattered, debonded, and expelled from a surface by a hammer-like blow delivered electro dynamically.
Removal of the ice shard is aided by turbulent airflow; thus, relatively low electrical energy is required.
EIDI – Operating concept
Primarily, this system consists of of ribbon-wire coils rigidly supported inside the aircraft surface to be de-iced
It separated from small air gap and the coil under the skin induces the strong eddy currents on surface
The circuit must have low resistance and inductance to permit the discharge to be very rapid, typically less than one-half millisecond in duration
EIDI – Operating concept(cont’d)
The eddy current and coil current fields are mutually repulsive, resulting in a toroidal-shaped pressure on the skin opposite the coil
The peak force on the skin is typically 400-500 pounds, produces sound resembling on metal
Resulting acceleration sheds ice from the surface and can shed ice as thin as 0.05 but acceleration is rapid
EIDI – Operating concept(contd.)
Impulse coils in a leading edge
EIDI – Operating concept(contd.) During EIDI systems operations, a coil receives two or three
successive pulses from the capacitor unit
The span wise extent of wing leading edge that each coil (or coil pair) will deice depends largely on the structural properties of the leading edge
The capacitor is then switched to another coil station, and then to another until it cycles around the aircraft
The time to complete the de-icing cycle must be less than the time for acceptable ice accretion for the protected surfaces
EIDI – Design concept
The EIDI system requires a careful and rather sophisticated design
The current pulse width in the coil resulting from the capacitor discharge must be properly matched to the skin electrical properties and to the leading-edge structural dynamic response
Failure to do this properly severely reduces the coil’s ice expelling performance
Installation of the power supply and control system in the aircraft should be done in a manner that minimizes the distance through which the high-energy electrical pulse must travel
EIDI – Design concept(contd.)
Applications of EIDI
It is used in the following parts,
Airfoil and leading edges
Engine inlets
Propellers and nose cones
Helicopter rotors and hubs
Radomes and Antennas
Miscellaneous intakes and vents
Comparison
Through this method deicing of wind shield and engine components cannot be done.
Sensors are not applicable in this method.
Capacitors are used since the coil produces the current which is drive through the these capacitors.
It can be easily shed ice as thin as 0.05
Advantages
Weight comparable to other deicing systems.
Nonintrusive in the airstream, hence no aerodynamic penalty.
Ice of all types is expelled, with only light residual ice remaining after the impulses (i.e.) reliable deicing.
Low power required. EIDI system power consumption is less than 1 percent of that required for hot air or electrothermal anti-ice systems.
Limitations It has limited use.
It is not an anti-icing system, so some ice will be present over most of the aircraft leading edges during flight in icing.
Complex design requirements.
Outside the aircraft the discharges may be quite loud, resembling a light gunshot.
Eddy Current Deicing System
Eddy Current Deicing System (ECDS)
ECDS is classified under the electro-mechanical ice protection system.
Uses eddy currents to produce momentary displacement of surface.
The mechanism of ice removal is similar to earlier mentioned electro – impulsive and electro – expulsive systems.
This deicing system is differs in the design that causes the outer surface to accelerate.
ECDS – Operating Principle
Accreted ice expulsed from the blanket protected structures by a strong, rapid outward thrust of blanket surface.
The rapid outward thrust is the reaction to pulsed current passed through flattened planar coils.
These planar coils run span-wise along the LE as shown.
ECDS – Operating Principle contd.
ECDS - Components
ECDS in Smaller Aircrafts
The power supply housing all the
capacitor charging and distribution
ECDS in Larger Aircrafts
ECDS – Design criterions D
eice
r B
lan
ket
Material
Metallic
Good erosion characteristics
Ease of maintenance
Elastomeric Easier to install
(retro-fit)
Installation
Retro-fitting
Flexible adhesives
Hard fasteners
ECDS – Potential Applications
ECDS can be used on:
Wing leading edge
Engine inlet periphery
Its usage is limited in:
Windshields
Radar and antennas
Flight sensors
ECDS – A Summary
Advantages Limitations
Sonic Pulse Electro - Expulsive Deicing System
Introduction
The system was developed in collaboration with NASA
Lewis and ARPA’s SBIR program.
The Sonic Pulse Electro-Expulsive Deicer (SPEED) is an
acceleration based deicer for aircraft ice protection.
SPEED evolved from the Electro-Impulsive deicing
(EIDI) concept with a major improvement in the actuator
coil and electronics.
Fatalities by accident categories,
fatal accidents, worldwide
commercial jet fleet.
Old methods could not remove thick ice formation over the leading edge. An example: • ATR-72 accident, Rose lawn, Indiana, Oct.31,1994, all passengers (72) killed . • Embraer 120, Monroe, Michigan, Jan.9, 1997, 29 passengers & crew members killed.
Sonic pulse Electro expulsive deicing system consists of :
1. Deicing Control Unit (DCU):
a. smart box controller
2. an Energy Storage Bank contains:
a. Capacitors
b. the electromagnetic actuators
c. sensor.
Sonic Pulse Electro Expulsive Deicing System
Mechanism Mounted on the substructure of the
leading edge.
It apply impulsive loads directly to the aircraft skin or outer surface material.
The rapid acceleration debonds and sheds ice into the airstream in a very efficient manner (ice layers can be shed as thin as 12 mm).
Icing Onset Sensor (IOS) can be added to the basic system to provide an autonomous mode of operation
Actuator
Typical sketch of the Sonic Pulse Electro Expulsive Deicing System by Innovative Dynamics.
. • IOS detects and monitors
. • Sensor commands the deicer to fire
. • Feedback if another cycle required or not
.
• Smart box controller identifies the electrical leaks and short circuit
Process
Various uses in aircrafts:
Propeller leading edge
Helicopter rotor blade
Wing leading edge
Tail leading edge
Also used in military applications
SPEED vs. Pneumatic Deicing boots. Parameter Modern Technology:
SPEED Traditional Technology: Pneumatic boots
1. Surface life
2. Drag increment
3. Cost
4. Weight
5. Electric power from 12m span
Life of aircraft No increase Equivalent Equivalent 0.7kw
Months rather not years depending on service Measurable increase Baseline Baseline Zero
Merits
Electrically operated
Very low power consumption
Erosion resistant
Reliable and maintenance-free
Fault-tolerant operation
Graceful degradation (of aircraft performance)
Superior Performance
Competitively Priced
Enhanced Maintainability
Maintenance and cost: Maintenance: No periodic inspection required Life time- 15 years Capacitors must be replaced that it reaches 1 million cycles Cuffs have been tested at over 250,000 firings and have not
failed. Cost: 10m wing span Aircraft about 50,000$-75,000$ System power requirements 300-700w RMS. Power consumption is about 450w for an entire aircraft for
one pulse.
Ultrasonic Deicing System
Principle
The ultrasonic de-icing system creates transverse shear stresses at the ice/airfoil interface that exceed the ice adhesion strength of ice, promoting delamination of ice.
It is done by launching ultrasonic shear-horizontal waves at the ice-substrate interface.
The goal is to induce sufficiently large shear strains at the ice-substrate interface so as to weaken or break the interfacial bond.
To demonstrate instantaneous ice delamination due to ultrasonic excitation, a suitable actuator, able to provide transverse shear stresses exceeding the adhesion strength of ice to steel, has to be selected.
Deicing Mechanism
Target adhesive shear strength of the ice aluminum interface bond
dynamic shear stress generated by the actuator at the interface increases the stress concentration
stress concentrations result in crack patterns
The mechanical, dielectric and piezoelectric losses in the actuator combined with the mechanical losses in the ice layer are converted into heat energy
Deicing Mechanism (contd.)
Design Requirements Power consumption of less than 2 kW with minimal current
consumption.
Produce a shear stress of 1.42MPa at the ice – Aluminum interface
Withstand centrifugal forces due to blade rotation
Withstand ambient temperatures from -50°C to 100°C
Not disturb the blade aerodynamics
Overview of Available Actuators
Piezo Electric Actuator
The direct piezoelectric effect
is the property of piezoelectric crystals to produce a charge when stressed
Inverse piezoelectric effect
is the ability of piezoelectric crystals to strain under an applied electric field. Thus piezoelectric materials can be used as electro-mechanical actuators and sensors.
The goal of the actuator is
to launch guided shear horizontal waves through the rotor blade erosion shield (substrate) so as to overcome the adhesive strength of the ice-substrate bond.
Have the capability of producing the required maximum stresses
Available in various sizes and shapes as well as various modes of vibration (thickness extension, length extension and thickness shear)
Consume low electrical power compared to thermal heating systems as well as other electro-mechanical actuation technologies
Can produce bi-directional strain
Piezo Electric Actuator (contd.)
SMA Ice deicing system
SHAPE MEMORY ALLOY DE-ICING TECHNOLOGY Shape Memory Alloys can be
plastically deformed at some relatively low temperature (Martensite phase)
Upon exposure to some higher temperature (Austenite phase), will return to their original shape.
Advantage: Low size & weight
Less energy consumption
Resistance to corrosion, abrasion
One Way SMA in Leading Edge
Types: One Way SMA (Cannot return
unassisted)
Two Way SMA (Use Temperature to return to original form)
Actuation methods:
Self actuation using latent heat of fusion, increase surface temperature by 25°
External resistance heating system
NiTi is used:
highly durable
4% elastic deformation Memory strain 8% Permanent deformation > 5%
after million cycle
SMA– heated by electric heater
Reverse Transformation
occurs
Shearing action developed
Ice deposit peel off into the air
Forward Transformation
Debonding Action
• 0.1-0.3% shear strain sufficient to debond ice deposits
• Once ice removed, SMA is cooled by ambient air
Span wise Positioning
Chord wise Positioning
Positioning Shape Memory Alloy in the Leading edge
Block Diagram of Current Pulse generator
Block Diagram of Active State Sheet
Questions are welcome !!!