Kin-ichi Komiya

Estimating the velocity profile of air flow by means of the ultrasonic translation time computed tomography method

Computed tomography (CT) was used to reconstruct the velocity profile of air flow from the average velocity over some different paths of ultrasonic-wave propagation. The algorithm used reconstructs the function, which is defined on a unit circle and zero outside, by its line integrals over N(N-1)/2 chords connecting any two points of N points equally spaced along the circumference of the circle. An experiment was performed to reconstruct the velocity profile of air flow in a pipe where a motor fan was used as the air source. The number of points N in the experiment was 8. The result was then compared to the value measured by a hot-wire anemometer.<<ETX>>

Ultrasonic tomography for visualizing the velocity profile of air flow

Abstract The computerized tomography technique (CT) is used to reconstruct the velocity profile of air flow in a pipe from its average velocities measured by an ultrasonic velocimeter over a specific set of paths. The data, which is detected by a fan beam arrangement, is rearranged into the form of interlaced parallel data, which is further interpolated in each view to obtain uniformly spaced data. This is then applied in the convolution algorithm for parallel scan data. This is then applied in the convolution algorithm for parallel scan data. This method is tested with experimental data and the reconstructed velocity is compared with the values measured by a hot wire anemometer.

VISUALIZING THE VELOCITY PROFILE OF AIR FLOW BY MEANS OF THE ULTRASONIC TRANSLATION TIME COMPUTED TOMOGRAPHY METHOD

The technique of computed tomography (CT) was used to estimate the velocity profile of axisymmetric flow of air from the average velocity, obtained from ultrasonic (US) flowmeter, over 4 different paths of propagation of ultrasonic wave. 2 experiments, where motor fan and air compressor were used as the air source, were performed and the results are repoered.

Flow Velocity Measurement by Means of Turbulence Correlation

When the turbulence is detected at two points along the flow direction, the fluid transit time may be equal to the delay time which makes the cross-correlation function of the turbulence maximum. Therefore the flow velocity is determined by this transit time and distance between two detecting points. An analytical expression of the cross-correlation function of the turbulence is derived under the following assumptions. The behaviour of the fluid particles is the same as that of a random walk. The displacements of the fluid particles due to diffusion corresponding to the longitudinal and transverse velocity fluctuations are not correlated. The auto-correlation function of turbulence is expressed approximately