Abstract
This study proposes a unique approach to convert a voltage signal obtained from a hot-wire anemometry to flow velocity data by making a slight modification to existing temperature-correction methods. The approach was a simplified calibration method for the constant-temperature mode of hot-wire anemometry without knowing exact wire temperature. The necessary data are the freestream temperature and a set of known velocity data which gives reference velocities in addition to the hot-wire signal. The proposed method was applied to various boundary layer velocity profiles with large temperature variations while the wire temperature was unknown. The target flow velocity was ranged between 20 and 80 m/s. By using a best-fit approach between the velocities in the boundary layer obtained by hot-wire anemometry and by the pitot-tube measurement, which provides reference data, the unknown wire temperature was sought. Results showed that the proposed simplified calibration approach was applicable to a velocity range between 20 and 80 m/s and with temperature variations up to 15 °C with an uncertainty level of 2.6% at most for the current datasets.
Highlights
Hot-wire anemometry for flow velocimetry has been widely used in wind tunnel experiments in various flow applications [1]
Other than the hot-wire signals, the necessary data are the freestream temperature and a set of known velocities that gives reference velocities obtained from the pitot-tube measurement
The proposed approach was applied to various boundary layer profiles with large temperature variations while the wire temperature was unknown
Summary
Hot-wire anemometry for flow velocimetry has been widely used in wind tunnel experiments in various flow applications [1]. The primary motivation was to enable a temperature correction for a constant-temperature mode of the hot-wire anemometer that calibrates an output signal to flow velocity in large temperature variation without knowing the wire temperature Another motivation was to identify minimal required datasets of reference velocities for this method. Eight individual cases with different temperature variations were measured with respect to the velocity profile of the boundary layer by the hot-wire anemometry and the pitot-tube measurement, separately. Those datasets included a case with large temperature variation (i.e., greater than 10 ◦ C throughout the operation duration) and a case with negligibly small temperature variation (i.e., less than 1 ◦ C throughout the operation). More details of the experiment are described in Takahashi et al [10]
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