Publications

This paper describes a simple and efficient physics-based method for designing optimal transonic multistage compressor rotors. The key to this novel method is that the spanwise variation of the parameter which controls the three-dimensional shock structure, the area ratio between the throat and the inlet, ‘Athroat /Ainlet’, is extracted directly from the 3D CFD. The spanwise distribution of the area ratio is then adjusted iteratively to balance the shock structure across the blade span. Because of this, the blade design will be called ‘aerodynamically balanced’. The new designmethod converges in a few iterations and is physically intuitive because it accounts for the real changes in the 3D area ratio that directly controls the shock structure. Specifically, changes in both the spanwise 3D flow and in the rotor’s operating condition; thus aiding designer understanding.

The prevailing view is that high fidelity simulation, particularly DNS (direct numerical simulation), is not something for the practical turbomachinery aerodynamicist — requiring too much computational and personal effort to make it worth it. The aim of the ‘Desktop-DNS’ toolkit described in this paper is to change this by greatly lowering the barrier to entry for running DNS. The paper shows how, using an efficient high-order Navier-Stokes computer code, it is becoming increasingly possible to solve testcases of industry relevance with high fidelity LES and DNS, making use of the latest advances in single compute node performance. This is achievable using both efficient algorithms and GPU acceleration. The paper will use a compressor blade testcase to illustrate how, in some cases, high-fidelity simulations can be performed at relatively low costs on a small number of computer nodes. This raises the possibility of a much more widespread use of DNS to inform early design choices, enhan

This paper investigates the importance of nonequilibrium boundary-layer modeling for three compressor blade geometries, using RANS and high-fidelity simulations. We find that capturing nonequilibrium effects in RANS is crucial to capturing the correct boundary-layer loss. This is because the production of turbulence within the nonequilibrium region affects both the loss generation in the nonequilibrium region, but also the final equilibrium state. We show that capturing the correct nonequilibrium behavior is possible by adapting industry standard models (in this case the k-omega SST model). We show that for the range of cases studied here, nonequilibrium effects can modify the trailing-edge momentum thickness by up to 40% and can change the trailing-edge shape factor from 1.8 to 2.1.