A novel 4-sensor fast-response aerodynamic probe for non-isotropic turbulence measurement in turbomachinery flows

Abstract

In modern computational studies for turbomachinery applications, time, length scales and isotropy of turbulent structures are important for representative modelling. To this end, experimental data are essential to validate the numerical tools. The current article presents the development and application of a newly designed 4-sensor Fast Response Aerodynamic Probe (FRAP-4S) enabling time-resolved measurement of the three-dimensional unsteady flow velocity vector in turbomachines. The miniature multi-sensor probe demonstrates a 4 mm probe-tip. In the first part of this article the design, manufacturing and calibration results of the FRAP-4S are presented in detail. To assess the newly developed probe accuracy, comparison against traditional instrumentation developed at the Laboratory for Energy Conversion is also provided. In the second part of this work, measurements are performed at the rotor exit of a one-and-a-half stage, unshrouded and highly-loaded axial turbine configuration. The results showed increased level of unsteadiness and turbulence levels with peak-to-peak fluctuation from 5 to 35%. More importantly, in some regions stream-wise unsteadiness was found to be ten times higher, compared to the cross-wise components, an indication of the high degree of anisotropy.

A flow field around a cylindrical probe in proximity to stator blades and its effect on the measurements

“…The corrections for probe readings can now be discussed. This can be done in the same sequence as the raw data of three-hole pressure probe readings is processed: first, the yaw angle, then the stagnation pressure and the dynamic head [17].…”

Experimental Investigation of the Unsteady Stator/Rotor Wake Characteristics Downstream of an Axial Air Turbine

“…An example of this type of measurement can be found in the pioneering work reported in [3] and elsewhere. The development of a fast response aerodynamic probe (FRAP) [4] allows us to resolve high frequency pressure fluctuations up to tens of kilohertz [5], similar to hot-wire anemometry, which is another of the promising possibilities characterized by high frequency response up to hundreds of kilohertz, see for example, [6].…”

Numerical study of probe parameters on performance of a transonic axial compressor

“…The pneumatic probes find wide applications in the aerospace industry, because of their low cost, easy implementation and its capability to give reliable and stable measurements. However, the presence of probe enhances the flow-complexity when it is installed at upstream of the cascade that may affect the stability and engine performance [ 1 , 2 ].…”