The shape of the centrifugal compressor scroll for turbocharger was optimized by adjoint method. In this method, the sensitivity of the performance improvement to shape changes is calculated, and the shape is morphed based on the obtained sensitivity. As the result of optimization, the recirculation flow rate was reduced by the triangulated cross-sectional shape at winding start, and the separation of the recirculation flow was suppressed by the convex cross-sectional shape at winding end. In addition, in the performance test of the optimized scroll, a large efficiency improvement (approx.+1.5%) was achieved without any demerit against base scroll, and therefore the effectiveness of the shape optimization of centrifugal compressor scroll using adjoint method was confirmed.

The contra-rotating rotors are applied to UAVs because of the counter balance of the torque. High thrust can be obtained for the contra-rotating rotors, and its thrust can be increased by adopting a duct with a bellmouse. Therefore, we started the research of the large scale ducted fan having the contra-rotating rotors. The numerical analysis result is validated by the experimental result using a thrust measurement apparatus in this paper. Furthermore, research and development results of the contra-rotating ducted fan based on the numerical analysis are presented.

Recently to improve thermal efficiency of an automobile engine, downsizing of turbochargers attracts more and more attention. An actual turbocharger operates under pulsating flow because of repeating operation of the engine valves. The turbine performance may decrease in such conditions. In this study, experimental and Computational Fluid Dynamics (CFD) investigation were carried out under a pulsating flow to clarify the loss mechanisms of the turbocharger turbine. Performance tests and Particle Image Velocimetry (PIV) were performed as an experimental approach to confirm the unsteady loss. CFD results have good agreement with the experimented results. The losses in the wheel and the exhaust diffuser under pulsating flow were larger than under steady flow.