Design, Optimization, and Analysis of Supersonic Radial Turbines

Abstract

New compact engine architectures such as pressure gain combustion require ad hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the cross section along the flow path, which holds great potential for high turning of supersonic flow with a low stage number and guarantees a compact design. First, the preliminary design space is described. Afterward a differential evolution multi-objective optimization with 12 geometrical design parameters is deducted. With the design tool autoblade 10.1, 768 geometries were generated and hub, shroud, and blade camber line were designed by means of Bezier curves. Outlet radius, passage height, and axial location of the outlet were design variables as well. Structured meshes with around 3.7 × 106 cells per passage were generated. Steady three-dimensional (3D) Reynolds-averaged Navier–Stokes (RANS) simulations, enclosed by the k-omega shear stress transport turbulence model were solved by the commercial solver CFD++. The geometry was optimized toward low entropy and high-power output. To prove the functionality of the new turbine concept and optimization, a full wheel unsteady RANS simulation of the optimized geometry exposed to a nozzled rotating detonation combustor (RDC) has been performed and the advantageous flow patterns of the optimization were also observed during transient operation.

Measurement, Simulation, and 1D-Modeling of Turbocharger Radial Turbines at Design and Extreme Off-Design Conditions

“…The characteristic compressor lines measured, while using the IGV at the inlet, are shown in Figure 3. 9. The IGV has realized the generation of positive compressor power at a rotational speed of 3890 rpm/K 0.5 , which has not been possible before ( Figure 3.9(b)).…”

“…In section 1.2 the importance and problematic of off-design performance for the final power output has been exhaustively illustrated. By means of a supersonic radial outflow turbine as it has been introduced by Inhestern et al [9] this problem might be bypassed in a certain range. Since the designed geometry also works with subsonic inflow the application in the field of compact turbocharging might be possible.…”

“…Hence, the use of heat transfer models or corrections to process the measured turbine power is needed as the results have shown. 9. Using higher inlet pressure on the compressor side can allow measurements at higher rotational speeds.…”

“…Thus, it can be recommended to measure closed positions rather than extrapolating them. 9. The model can easily be modified to fit and extrapolate vaneless turbines, when the equations for calculating the stator outlet condition are skipped.…”