A Flow Velocity Measurement Method Based on Turbulent Pressure Fluctuation Characteristics

Abstract

In order to perform flow velocity measurements without interfering in the flow field itself, a flow velocity measurement method based on the characteristics (the rule by which the power spectrum varies with the flow velocity) of turbulent pressure fluctuations is proposed. This method is based on the characteristics of turbulent pressure fluctuations in the turbulent boundary layer (TBL) and uses a polyvinylidene fluoride (PVDF) sensor to convert pressure fluctuations into voltage outputs. First, TBL pressure fluctuation characteristics are studied. Second, the piezoelectric characteristics of PVDF piezoelectric sensors are studied and a sensor array signal processing method that can improve the signal-to-noise ratio is provided. Then, numerical simulations are performed to verify the characteristics of turbulent pressure fluctuations in the TBL. Finally, a PVDF sensor is made and flow velocity measurement experiments are performed. The results show that the power spectrum of the PVDF sensor response to excitation by turbulent pressure fluctuations is proportional to the fourth power of the flow velocity. It is feasible to use this characteristic to measure the flow velocity.