Method for the determination of frequency response and signal to noise ratio for constant-temperature hot-wire anemometers

Determination of the frequency response of constant-temperature hot-wire an emometers is needed for measurements of high frequency turbulent fluctuatio ns or when the bridge cannot be well adjusted because of too short a testin g time. A method is proposed to determine the complete transfer function of a constant-temperature anemometer bridge in several milliseconds by means of an electrical test. The frequency response is used to perform postcorrec tion of the data, which enables the measurement of turbulent quantities at frequencies higher than the cut-off frequency of the system, when the bridg e adjustment is not optimum. The technique, which is tested in the free str eam of a supersonic wind tunnel at M=2.5, also enables a accurate estimatio n of the signal to noise ratio. (C) 2001 American Institute of Physics.