scholarly journals A Miniature Four-Hole Probe for Measurement of Three-Dimensional Flow with Large Gradients

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Ravirai Jangir ◽  
Nekkanti Sitaram ◽  
Ct Gajanan
Keyword(s):  
Measurement Errors ◽  
Three Dimensional ◽  
Lookup Table ◽  
Three Dimensional Flow ◽  
Velocity Gradients ◽  
Good Spatial Resolution ◽  
Large Pressure ◽  
Flow Gradient ◽  
Maximum Absolute Errors ◽  
Calibration Coefficients

A miniature four-hole probe with a sensing area of 1.284 mm2to minimise the measurement errors due to the large pressure and velocity gradients that occur in highly three-dimensional turbomachinery flows is designed, fabricated, calibrated, and validated. The probe has good spatial resolution in two directions, thus minimising spatial and flow gradient errors. The probe is calibrated in an open jet calibration tunnel at a velocity of 50 m/s in yaw and pitch angles range of ±40 degrees with an interval of 5 degrees. The calibration coefficients are defined, determined, and presented. Sensitivity coefficients are also calculated and presented. A lookup table method is used to determine the four unknown quantities, namely, total and static pressures and flow angles. The maximum absolute errors in yaw and pitch angles are 2.4 and 1.3 deg., respectively. The maximum absolute errors in total, static, and dynamic pressures are 3.4, 3.9, and 4.9% of the dynamic pressures, respectively. Measurements made with this probe, a conventional five-hole probe and a miniature Pitot probe across a calibration section, demonstrated that the errors due to gradient and surface proximity for this probe are considerably reduced compared to the five-hole probe.

scholarly journals Extended Calibration Technique of a Four-Hole Probe for Three-Dimensional Flow Measurements

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Suresh Munivenkatareddy ◽  
Nekkanti Sitaram
Keyword(s):  
Three Dimensional ◽  
Lower Sensitivity ◽  
Angular Range ◽  
Calibration Technique ◽  
Zonal Method ◽  
Three Dimensional Flow ◽  
Flow Measurements ◽  
Reduction Program ◽  
Left And Right ◽  
Calibration Coefficients

The present paper reports the development and nonnulling calibration technique to calibrate a cantilever type cylindrical four-hole probe of 2.54 mm diameter to measure three-dimensional flows. The probe is calibrated at a probe Reynolds number of 9525. The probe operative angular range is extended using a zonal method by dividing into three zones, namely, center, left, and right zone. Different calibration coefficients are defined for each zone. The attainable angular range achieved using the zonal method is ±60 degrees in the yaw plane and −50 to +30 degrees in the pitch plane. Sensitivity analysis of all the four calibration coefficients shows that probe pitch sensitivity is lower than the yaw sensitivity in the center zone, and extended left and right zones have lower sensitivity than the center zone. In addition, errors due to the data reduction program for the probe are presented. The errors are found to be reasonably small in all the three zones. However, the errors in the extended left and right zones have slightly larger magnitudes compared to those in the center zone.

scholarly journals Error analyses of a multistatic meteor radar system to obtain a three-dimensional spatial-resolution distribution

2021 ◽  
Vol 14 (5) ◽  
pp. 3973-3988
Author(s):  
Wei Zhong ◽  
Xianghui Xue ◽  
Wen Yi ◽  
Iain M. Reid ◽  
Tingdi Chen ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Measurement Errors ◽  
Dimensional Space ◽  
Lower Thermosphere ◽  
Three Dimensional ◽  
Radar System ◽  
Meteor Radar ◽  
Radar Systems ◽  
Good Spatial Resolution ◽  
First Time

Abstract. In recent years, the concept of multistatic meteor radar systems has attracted the attention of the atmospheric radar community, focusing on the mesosphere and lower thermosphere (MLT) region. Recently, there have been some notable experiments using such multistatic meteor radar systems. Good spatial resolution is vital for meteor radars because nearly all parameter inversion processes rely on the accurate location of the meteor trail specular point. It is timely then for a careful discussion focused on the error distribution of multistatic meteor radar systems. In this study, we discuss the measurement errors that affect the spatial resolution and obtain the spatial-resolution distribution in three-dimensional space for the first time. The spatial-resolution distribution can both help design a multistatic meteor radar system and improve the performance of existing radar systems. Moreover, the spatial-resolution distribution allows the accuracy of retrieved parameters such as the wind field to be determined.

A Probe for the Measurement of the Velocity Field

1979 ◽  
Vol 101 (1) ◽  
pp. 143-146 ◽  
Author(s):  
A. K. Raghava ◽  
K. L. Kumar ◽  
R. C. Malhotra ◽  
D. P. Agrawal
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Convenient Method ◽  
Velocity Vector ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
Pressure Probe ◽  
Three Dimensional Flow ◽  
Velocity Gradients ◽  
Total Head

A convenient method for the measurement of the complete velocity vector in subsonic three-dimensional flow using a simple three-tube off set-geometry pressure probe is presented. Basically, this probe is a combination of a total head tube and a Conrad probe. In order to use this probe to determine both the magnitude of the velocity vector at a point in the flow field and the two angles which determine the orientation of this velocity vector it is only necessary to rotate the probe about its longitudinal axis. Measurements obtained with the present probe compare very favorably with those obtained using other techniques. The probe will be specially suited for measuring velocity in flows with steep velocity gradients.

Passive Control of Vortex Shedding Induced Vibration of a Five-Hole Probe

1993 ◽  
Author(s):  
Neil B. Kimerer
Keyword(s):  
Vortex Shedding ◽  
Coherent Structure ◽  
Measurement Errors ◽  
Passive Control ◽  
Vibration Reduction ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Structural Fatigue ◽  
Dimensional Flow ◽  
Wire Coil

Abstract Vortex shedding in flow over a five-hole probe, used to measure three dimensional flow, excites the probe into vibration which causes measurement errors and acoustically induced structural fatigue of the probe stem. One method of reducing the coherent structure of the shed vortices and thereby reduce the vibration is to place a fin on the probe shaft with the fin free to rotate around the shaft. In a particular five-hole probe application there was no room for a fin so an alternate method of breaking up the coherent structure in the vortices was required. Coiling a wire around the probe was a technique tried using several wire diameters and coil spacings. Vibration levels were measured and analyzed for several wire coil configurations and compared to the vibration reduction achieved by the fin.

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