Frequency response of hot-film air mass flow sensors

This paper studied the frequency response of hot-film air mass flow sensors by the theoretical analysis and experimental research methods.The expression of the time-constant was derived by analyzing the phenomena of heat-delay in sensor unit under gas unsteady flow.And the all sorts of influence factors for the time-constant and also the compensation methods were discussed.The results indicate that the time-constant with constant temperature measuring method is 2g(R_r-1) times less than that with constant electric current measuring method,and the frequency response with constant temperature measuring method is decided by the feedback efficiency.If feedback process is very quick and effective,the instantaneous compensation can be realized for the heat-delay with constant temperature measuring method.4 figs,6 refs.