Total and Static Quantity Measurements in Unsteady Flow — Effect of Unsteadiness

Abstract

The effects of unsteadiness both on high-response dynamic measurements and on time-averaged measurements with slow-response probes are analytically investigated separately from the response characteristics of the measuring system. The approach is based on physical similarity and dimensional analysis. The potential errors from flow unsteadiness and the major parameters which influence the measurement results are discussed. In the case of five sensor spherical probes a quantitative investigation for inviscid, incompressible, irrotational flow is carried out with the help of potential theory.

Enhanced performance of fast-response 3-hole wedge probes for transonic flows in axial turbomachinery

“…This problem is usually mitigated by placing the lateral holes downstream of the recirculation bubble. An extensive investigation of the respective effects of sensor location and wedge apex angle was conducted by Humm et al, 1994, andAinsworth, 1995. The frequency range of the probe is limited by the characteristic size of the probe (Lou et al, 1998), as well as the geometry and sensor implementation due to cavity resonances and sensor cut-off frequencies. Obtaining a high angular resolution typically requires to minimize the probe size; this can mean having holes in separated regions, which is detrimental on the probe frequency response.…”