Seven improvement packages for inlet cabin were developed to resolve the problem of engine surge in a helicopter under the hovering flight conditions. Airflow field distribution of inlet cabin/intake was numerically studied for setting circular arc baffle in the inlet cabin and moving downward the lower lip of air inlet.And

unstructured grid and grid self-adaptive technology were applied for regional simulation discretion.The results indicate that local flow separation exists in the inlet cabin/intake for each package under the hovering flight conditions

and the airflow quality can be improved by setting baffle inside the cabin and changing the size of the lower lip of air inlet.Flight-test results show that the engine surge under hovering flight conditions can be prevented to ensure engine performance by using the above-specified methods.