Modares Mechanical Engineering

Modares Mechanical Engineering

Experimental Investigation on Parameters Affecting the Directional Sensitivity of Hot Wire Anemometer

Authors
Saeed Farsad 1
Mohammed Ali Ardekani 1
Foad Farhani 2
1 Department of Mechanical Engineering, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran
2 Faculty member and Head of Department of Mechanical Engineering, Iranian Research Organization for Science and Technology (IROST)
Abstract
measurement accuracy. The angular response of the sensor describes the relationship between flow velocity vector and heat transfer from the sensor, which is determined by a sensitivity function. In this paper, two sensitivity functions, namely cosine law and Hinze equation, have been studied using wind tunnel experiments to evaluate the effect of various parameters such as flow conditions (velocity and direction), probe aspect ratio (l/d) and probe operational condition (sensor temperature) on the range of applicability of cosine law and magnitude of the sensitivity coefficient, k. Results show that the angular range of applicability of cosine law depends on flow and probe conditions. At 1% measurement error, the range of applicability of cosine law for flow measurements of velocities exceeding 10 m/s was found to be in the range of ±30º. Moreover, at geometrical ratios higher than 600, two-dimensional flow measurements using the cosine law presents results with acceptable accuracy. In addition, the sensitivity coefficient is completely dependent on flow condition and probe aspect ratio, and its value decreases with increase in flow angle and velocity and reduction in probe aspect ratio. The results of this research can be used in the selection and proper design of probes for two-dimensional flow measurements using hot wire anemometers.
Keywords
Cosine law
Directional sensitivity
Hot wire anemometer
Probe aspect ratio
Sensitivity coefficient

Subjects

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Modares Mechanical Engineering
Volume 18, Issue 4
August 2018
Pages 110-116