Development of an unsteady pressure measurement method

Aerodynamic phenomena such as wakes behind bluff bodies are inherently unsteady. Thus, many aerodynamic experiments require the measurement of unsteady or dynamic flow characteristics such as surface or base pressure on the body. Pressure-measuring instruments (pressure transducers) have a transient response that depends on two factors: (1) the response of the transducer elements that senses the pressure and (2) the response of the pressure-transmitting fluid and the connecting tubing, etc. This latter factor is frequently the one that determines the overall frequency response of a pressure measurement system in unsteady flows. This study presents the development of a technique with which time domain samples of unsteady pressure signals can be corrected to compensate for the influence of the connecting tube. The technique was validated employing single and multiple-frequency periodic pressure fields as well as complex pressure fields generated inside the wind tunnel. The results indicated that the actual pressure field could be measured using this technique with reasonable accuracy.