A Simple and Accurate Method of Calibrating X-Probes

Abstract

This paper presents an improved method of calibrating hot-film X-probes in incompressible flow. The yaw response of a hot-film X-probe was investigated for different velocities and found to be strongly velocity dependent at low velocities. A simple relation was developed to correct for the variation of yaw response at low velocities. The method using the yaw correction is compared with the single-velocity yaw calibration method. The correction to the yaw response considerably improves accuracy at low velocities.

Fluid Mechanics for Engineers

“…John and Schobeiri [40] presented a simple method for calibrating the x-wire probes. Using calibration equation, a set of voltage-velocity table is produced that can be spline fitted.…”

“…40) in any arbitrary curvilinear coordinate system, first the coordinate system must be specified. (A.…”

“…40) determine the reaction moment, M 0 . This reaction moment is exerted by the flow on the solid boundary S W of the system with respect to a fixed point such as the coordinate origin shown inFig.…”

Effect of Unsteady Wake Passing Frequency on Boundary Layer Transition, Experimental Investigation and Wavelet Analysis

“…For unsteady boundary layer measurements, a triggering system is implemented for data collection and tracking the number of cycles to later aid in the calculation of the ensemble-averaged quantities of the periodic unsteady wakes. In order to ensure a high level of accuracy, the new calibration method described in John and Schobeiri (1993) was used for all hot-wire calibration. The instantaneous velocity components are calculated from the temperature compensated instantaneous voltages using the calibration coefficients.…”

“…The unsteady data were reduced by the ensemble-averaging method. In order to keep the amount of the produced data and the required data analysis time under control, extensive preliminary frequency study was performed prior to the final data acquisition and analysis (see also Schobeiri et al 1994 andSchobeiri 1993). This study dealt with the variation of the number of samples per each wake generator revolution and the number of total revolutions to determine the optimum settings for convergence of the ensemble averaged quantities.…”