Bleeding air has been well-known as one of the effective methods of boundary layer control technique to enhance turbomachine efficiency and stability in the automotive and aeronautical industries. This study proposed a novel concept of bleeding airflow technique called a Bleeding Channel with a Dual Discharge Port (BC-DDP), which was applied to a single-stage transonic axial compressor, NASA Stage 37, to improve its adiabatic efficiency and stall margin. The compressor model with a new design casing treatment used 3D Reynolds-Averages Navier-Stokes with the k-ε turbulence model to simulate and evaluate its aerodynamic performance and stability. Adiabatic efficiency (EFF), total pressure ratio (PR), stall margin (SM), and stable range extension (SRE) of the compressor using the bleeding casing handling were better than the original design model. In the parametric studies, the numerical results with the BC-DDP showed that the largest EFF was 84.37%, the maximum SM got a value of 13.09%, and the SRE had a price of 33.35%.

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Comprehending bubble movement is crucial in cavitation research. In this study, a numerical analysis method is used to investigate the hydrodynamic behavior of a single void, and the relationship between the velocity, force, impact load, and wall shear rate of the void with time and infinite wall distance is illustrated. The results reveal that the pressure generated by the cavitation collapse is associated with the wall distance. At a later stage of cavitation collapse, the flow field is significantly disturbed, which may induce a secondary flow of fluid near the cavitation and result in an unstable flow. The numerical results are consistent with the theoretical calculation results obtained for the free-field cavitation movement process using the Keller–Miksis model.

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Figure 20 on page 360 is replaced, and the corresponding explanation is corrected.

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