CIMNE

Fluid-Structure Interaction for Combustion Systems

36-Months Progress MeetingQueen's University of Belfast

Belfast UKJan 24

Pavel Ryzhakov: activities

1. Development of an updated lagrangian formulation of a fluidelement

2. The structural part of the multi-physics code KRATOS, develeoped at CIMNE was utilized in order to perform the analysis of the structural response of the thin part of the liner (Twente test rig)

3. Smart interpolation tool in order to couple structural code of CIMNE with the fluid code of CERFACS (in progress)

Training and mobility

4-weeks stay at CERFACS, Toulouse, France.

Computation of the structural response to the oscillating flame in the thin part of the liner. Work performed in cooperation with Mauro Porta

Interaction between unsteady flow and the elastic liner

To be analyzed:

The thin part of the liner of a research combustion chamber was analyzed. The experiments were performed at Twente University (The Nederlands)

Thin liner

Interaction between unsteady flow and the elastic liner

Input data:

Pressure fluctuations on the inner surface of the liner(results of the Large Eddy Scale Simulation, doneby CERFACS)

Non-pulsating, unsteady flow (pressure fluctuations at 430 Hz), with steady inlet and outlet boundary conditions

values up to 104 Pa

Interaction between unsteady flow and the elastic liner

Model:

The thin part of the liner (400x150 mm, wall thickness 15mm)was modelled and discretized by the mesh of ca. 17000 lineartetrahedras (6000 nodes).

Boundary conditions: displecaments are fixed on both ends.

Fixed displacements on both ends

Interaction between unsteady flow and the elastic liner

Coupling:

The locations of the nodes of the structural mesh was tranferedto the fluid simulation, and the data of interest (pressure)was read at those locations. The structure was loaded by thesepressures.

Fixed displacements on both ends

Interaction between unsteady flow and the elastic liner

Structural solver: Multiphysics software KRATOS, developed at CIMNE.Direct temporal approach. Total simulation time=15 ms

Here following options were used:

-Bossak scheme for time integraion

-Biconjugate gradient linear solver

-Time step for the structural computation: 0.05 ms

Interaction between unsteady flow and the elastic liner

Results:Displacement profile (of the node located 50 mm away from the edge of the upper wall)

Interaction between unsteady flow and the elastic liner

Results:Velocity profile (of the node located 50 mm away from the edge of the upper wall)

Interaction between unsteady flow and the elastic liner

Comparison:Results presented by Rob Huls (velocity evolution)

Interaction between unsteady flow and the elastic liner

Results:Deflection of the structure at 4 time instances: 2 ms, 5 ms, 10 ms, 15 ms

Interaction between unsteady flow and the elastic liner

Results:Deflection of the structure (x400 000)

Interaction between unsteady flow and the elastic liner

Results:Deflection of the structure (x400 000)

Interaction between unsteady flow and the elastic liner

Results:Principal stress:

Interaction between unsteady flow and the elastic liner

Results:Analysis:

Principal stress values of range of few MPa. (Material strength=400MPa)

Period of oscillation of the structure: ~2ms

Strcuture responds mostly to the accoustic modeof ~400 Hz

Interaction between unsteady flow and the elastic liner

Conclusions:

feasability of the fluid structure interaction for combustion chamber

good comparison with experimental data

temporal approach taking into account inertial effects (dynamic computation) necessary

Interaction between unsteady flow and the elastic liner

Conclusions:

displacements of structure of magnitude less than 1mm

principal stress (<1 MPa) values much less than materials strength

due to the small obtained displacements, two-way couplingmay not be necessary

Interaction between unsteady flow and the elastic liner

To be done:

◦Take into account the effect of the temperature

◦Develop a better tool for data transfer between the AVBP and KRATOS

◦Try different numerical scheme for LES

◦Try different element type for structural simulation (e.g. hexahedra)

Thank you for attention!