ON THE RESPONSE OF A TURBULENT-PRESSURE PROBE AND THE MEASUREMENT OF PRESSURE TRANSPORT

Wind-tunnel calibrations of turbulent-pressure sensors usually reveal deviations from ideal response. These deviations are typically reporte d in dimensional form (e.g., in microbars) or as a fraction of the dyn amic pressure. Neither presentation gives a direct indication of the r eliability of pressure statistics measured in a turbulent flow. We der ive a general response equation for a turbulent-pressure probe. The co efficients in the equation are obtainable from standard wind-tunnel ca libration results. The form of the response equation makes it straight forward to relate the errors in measured pressure statistics to the st atistics of the turbulence. We demonstrate this by evaluating the reli ability of measurements of some important pressure covariances, includ ing the pressure-transport term in the turbulent kinetic energy (TKE) budget in the unstable surface layer. The preliminary finding is that the Nishiyama-Bedard sensor is capable of measuring pressure transport of TKE there to within 10-20%.