WEBFM: Post-doctoral position at ISAE-SUPAERO
– WEBFM : Whole Engine Body Force Modeling –
Profile Post-doctorate
Keywords CFD•Turbomachines•Propulsion•Modeling Supervisors Guillaume DufourT05-61-33-89-71
Bguillaume.dufour@isae.fr
Laboratory ISAE Supaero, Departement of Aerodynamics, Energetics and Propulsion (DAEP)
10, Av. Edouard Belin, Toulouse, France
Context and objectives
The architecture of forthcoming propulsion sys- tems is mainly oriented in two directions : increa- sing the bypass ratio (BPR) of turbofan, and integra- ting more closely the propulsion system on the air- craft. The current industrial standard for engine per- formance prediction is a thermodynamic approach at the system level (1D modeling). Given the fo- recast evolutions of propulsive architectures, global approaches have two major shortcomings : (i) the limitations of classical performance map of turbo- machinery components, particularly in off-design re- gimes and (ii) the inability of performance models to account properly for installation effects (such as fan/intake interactions, or distorsions effects as in boundary layer ingestion configurations). Although advanced CFD techniques (such as whole annulus unsteady simulations) can provide the required ac- curacy, this comes at a prohibitive cost for routine design. To adress these problematics, we propose to resort to a source term modeling approach of tur- bomachinery rows, known as Body Force Modeling (BFM). This approach is illustrated on the figures on the side. The main goal of the project is to achieve af- fordable simulations of a complete turbofan engine using body force modeling.
This approach would allow to : (i) overcome performance map limitations in off-design regimes, (ii) account for distorsion effects and (iii) offer a high precision-to-cost ratio method to integrate en- gine effects in aircraft simulations.
The proposed research project relies on funding from the DGA (an in instance of the French Depart- ment of Defense).
Classical CFD approach (fan/intake configuration).
BFM approach (from Tholletet al.[1]).
Scientific problematic
The body force modeling (BFM) approach aims at modeling turbomachinery blade rows by a source term corresponding to a volumic force field that reproduces the flow turning (work exchange) and losses (entropy rise) generated by the blades. The approach selected for the present study is the use of analytical modeling of the source terms (see for example the work of Gong [2]), which can be cali- brated on limited input from standard RANS com- putations.
In the published literature, the existing BFM mo- dels deal with fans and compressors, with a large fo- cus on surge regime. On the application side, short
Post-doctoral position at ISAE-SUPAERO
WEBFM: Post-doctoral position at ISAE-SUPAERO
intake/fan interactions have received considerable attention.
In this context, a significant contribution of the project is to develop and apply the BFM approach to the full flow path (core and bypass flow) of a com- plete turbofan engine. The test case is the DGEN 380 turbofan, which is installed on the ISAE engine test- bed, and for which a large experimental database (both local and global) is available. The main ob- jective is to tackle the prediction of the windmilling (engine out) regime of the turbofan. The nominal
regime (including source-term modeling of combus- tion) will then be studied.
The present study thus aims to contribute to the state of the art on four themes :
— treating the windmilling regime with BFM ;
— develop BFM models for turbines ;
— integrate several BFM models in full engine calculation ;
— account for combustion in the calculation with source terms.
The DGEN 380 : high bypass ratio geared turbofan
Research program
— WP1 : Improvement and validation of the BFM approach for the fan at windmill.
— WP2 : Development and application of BFM to the centrifugal compressor.
— WP3 : Development and application of BFM to the axial turbines.
— WP4 : Whole engine simulation at windmill.
— WP5 : Whole engine simulation at the nominal operating point.
Publication of the results in international journals is expected and participation to international conferences will be encouraged.
Candidate profile
The successful candidate is expected to have :
— A PhD in computational fluid dynamics.
— Good knowledge of turbomachines and propulsion systems.
— Good knowledge of CFD. Experience with a general 3D CFD code.
— Basic programming knowledge (post-processnig withPythonwill be developped).
— Team working capability, initiative and problem solving skills.
The position is for 2 years (with a 1 year additional renewable period).
R´ ef´ erences
[1] W. THOLLET, F. BLANC, G. DUFOUR & X. CARBONNEAU. Body force modeling for aerodynamic analysis of air intake-fan interactions.3AF Conference, 2015.
[2] Y. GONG. A computational model for rotating stall and inlet distortions in multistage compressors.PhD thesis, Massachusetts Institute of Technology, 1999.
[3] N. GARC´IAROSA, G. DUFOUR, R. BAR`ENES& G. LAVERGNE. Experimental Analysis of the Global Performance and the Flow Through a High-Bypass Turbofan in Windmilling Conditions.Journal of Turbomachinery2015.
[4] G. DUFOUR, N. GARC´IAROSA& S. DUPLAA. Validation and flow structure analysis in a turbofan stage at windmill.Journal of Power and Energy2015.
Post-doctoral position at ISAE-SUPAERO
