Experimental modal analysis (EMA) was presented on the 10kg rotor in free constraint state and gas film constraint state.The experimental results were given including rotor translation

conical moving and the first bending natural frequency and modal shape.The effect of gas film constraint on natural frequency of gas bearing-rotor system was analyzed by the experiment.EMA under gas film constraint was closer to the raising speed experimental results.The results provide a basis to determine the natural frequency of the gas shaft and to choose the control parameters.Also

it lays a foundation for vibration controlling of the gas bearing-rotor system.