15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

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Main Topic:

Axial Compressors



Thomas Gianoli  - Safran Aircraft Engines; CERFACS; M2P2 Aix Marseille Univ, Centrale Marseille
Jean-François Boussuge - CERFACS
Pierre Sagaut - M2P2 Aix Marseille Univ, Centrale Marseille
Jérôme de Laborderie - Safran Aircraft Engines


Considering the complexity of the flow, and despite the intense research conducted in recent years, it remains a challenge to simulate the flow developing in modern aero-engines. Even though the formalism has shown a lack of accuracy, the most widespread method applied in the industry is still the Reynolds-Averaged Navier-Stokes (RANS) method due to its low computational cost. However, considering the continuous increase in computing power, Large Eddy Simulation (LES) applied to the Navier-Stokes equations rises as an alternative technique to investigate the complex physics of such flows. The Lattice Boltzmann approach (LBM) has risen in the fluid dynamics community as a viable LES method to solve the Navier-Stokes equations. The LBM has demonstrated its capability to handle complex geometries by the use of Cartesian grids, thanks to immersed boundary conditions. These different properties have attracted intensive research in aerodynamics, aero-acoustics, and its extension to weakly compressible thermal flows, compressible flows and turbulent applications. Finally, the algorithm of the method is well adapted to High-Performance Computing thanks to an easy parallelization.\ In this paper, the scope of the study is placed on a component called the S-duct, which role is to redirect the flow from the Low-Pressure Compressor (LPC) to the High-Pressure Compressor (HPC) situated at two different radial positions. Increasing the accuracy of the losses prediction with a high-fidelity method is indeed of the most importance as they directly impact the aerodynamic performances of the whole compressor (LPC and HPC). This paper describes the unsteady computations performed on the CAM1 inter-stage S-duct configuration designed and tested within the framework of the European project AIDA. The configuration consists of a strutted S-duct, placed between an LPC and HPC. The Mach number is 0.25 with a Reynolds number based on the chord of 125 000. Despite a relatively low Mach number, this configuration is representative of a modern engine in terms of aerodynamic loading. The test rig was instrumented using 5-holes probes traversing at several radial planes as well as casing pressure taps. These measurements are used to perform comparisons with the LBM results as well as available RANS and URANS computations.\ The simulations are performed using the ProLB solver. For an accurate simulation, the computational domain represents the 360 degrees of the machine and will gradually incorporate the different rows to evaluate their influence on the flow field and on the loss level. This is the first turbomachinery simulation of this complexity performed with this solver.\ Preliminary results were presented at the last 3AF conference. Radial profiles, 2D contour maps and loss levels were compared to experimental measurements as well as RANS simulations. These results were since improved by adjusting the meshing strategy on the first stator row S1, limiting a corner separation. On the two geometries presented, the LBM allows retrieving results in good agreement while maintaining a competitive computational time. In the full paper, the different rows will be gradually added and a physical analysis of the flow development will be performed to study their relative influence on the performance.\


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