The flow field and the efficiency of the compressor can be improved and increased by the guide vane in the radial inlet chamber. However, the guide vane generates the wake and results in the rotor–stator interaction, which threatens the safety of the impeller. This paper investigated the guide vane with a self-induced slot (SIS) in a radial inlet, and the self-induced slot was a passive flow control method. Through computational fluid dynamics (CFD) simulation, the radial inlet containing unevenly distributed guide vanes (UGVs) in the hydrogen compressor was studied to clarify the flow phenomenon in the radial inlet and the aerodynamic load on the impellers. The simulation results showed that the self-induced slot did not affect the compressor performance but improved the pure wake style to the weak wake near the shroud region. The aerodynamic load on the impeller leading edge was obtained under different radial inlets through unsteady simulation. The dominant frequency and the pulse amplitude of aerodynamic load were obtained by fast Fourier transforms (FFTs). The SIS model had lower amplitude values at the impeller passing frequency, and the reduction in amplitude was about 18% compared to the UGV model near the impeller shroud region.

The intermediate duct connects high-pressure and low-pressure compressors. It comprises flow channels and struts that fix the relative positions of the hub and shroud. The mechanism of airflow movement around the struts in the downstream intermediate ducts is experimentally investigated based on four cases, including two types of struts and two shapes of meridional flow channels. The measurement parameters of the intermediate duct under the same conditions are measured in the wind tunnel, including the total pressure loss coefficient at the outlet and axial wall pressure distribution. In addition, the flow characteristics near the wall are obtained through the oil flow test, and the frequency of the shedding vortex is captured by the dynamic pressure probes. The results demonstrate that the strut and channel with the modified profile can reduce the total pressure loss and eliminate wake oscillation by changing the flow characteristic. The total pressure losses of the modified profile at 0.2, 0.25, 0.3, 0.35, 0.4, and 0.45 Ma conditions are reduced by 60%, 63%, 83%, 89%, 85%, and 87%, respectively.