Research Papers: Techniques and Procedures

Extended Angular Range of a Three-Hole Cobra Pressure Probe for Incompressible Flow

[+] Author and Article Information
Katia María Argüelles Díaz

Fluid Mechanics Group, University of Oviedo, Campus de Viesques, Gijón, 33271 Asturias, Spainarguelleskatia@uniovi.es

Jesús Manuel Fernández Oro, Eduardo Blanco Marigorta

Fluid Mechanics Group, University of Oviedo, Campus de Viesques, Gijón, 33271 Asturias, Spain

J. Fluids Eng 130(10), 101401 (Sep 04, 2008) (6 pages) doi:10.1115/1.2969457 History: Received December 19, 2007; Revised July 02, 2008; Published September 04, 2008

This paper analyzes the operative characteristics of a three-hole cobra type probe especially designed to attain an angular range higher than 180deg for planar turbulent flows. A new calibration and data reduction method are also introduced, discriminating three different zones inside the angular range of the calibration. This methodology improves the probe performance, extending its operative angular range from the typical ±30degto±105deg. In addition, the transmission of the uncertainty—from the pressure measurements to the flow variables—is estimated, showing reasonably low levels for the whole angular range. Furthermore, the sensibility of the probe calibration to the Reynolds number and the pitch angle is considered, and the influence of the turbulence level is outlined. Regarding these factors, the probe precision in the extended angular range is found to be similar to that of the traditional range. Finally, the probe is tested in a flow field with large variations of the incidence angle, and the results obtained with the new method are compared to those given by the traditional calibration.

Copyright © 2008 by American Society of Mechanical Engineers
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Figure 3

Pressure coefficient distributions in the holes of the cobra type probe

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Figure 4

Traditional calibration coefficients and data reduction procedure

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Figure 5

Angular calibration coefficient: zone-based (solid) and traditional methods (dashed line)

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Figure 6

Uncertainty of the flow variables

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Figure 7

Pressure and angular coefficients for different flow Reynolds numbers

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Figure 8

Errors in the estimation of the flow angle using a reference calibration of Re=1.8×104

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Figure 9

Errors in the estimation of the flow angle when interpolating between two calibrations at different Reynolds numbers

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Figure 10

Influence of the pitch angle β on the angular coefficient

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Figure 11

Errors in the yaw angle determination with different pitch angles

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Figure 12

Flow angle measurements obtained with the traditional calibration and with the zone-based data reduction method

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Figure 2

Sketch of the cobra type probe

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Figure 1

Three-hole cobra type probe



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