EXPERIMENTAL RESEARCH ON THE COMPARISON OF LDA AND PIV MEASURING SYSTEMS FOR THE DETERMINATION OF THE AIR VELOCITY INSIDE A SQUARE CHANNEL

Abstract

In this study, the comparison of the accuracy of the results obtained from different fluid velocity measuring systems such as LDA (Laser Doppler Anemometer) and PIV (Particle Image Velocimetry) devices are presented to determine the air velocity profile inside a square channel. These measuring systems are essential and important for the aerodynamic design of vehicles, trains and planes. The paraffin oil was chosen due to their ability of following the air movement inside the channel. The air temperature was around room temperature and it was flowing by means of a compressor in the horizontal Plexiglas channel having 30 x 30 mm square cross section and a length of 1200 mm. Optical laser device was used to illuminate the flow area in the PIV system, and it also has a significant role on the measuring in the LDA system. The detailed description of design and development of the test apparatus, control devices, instrumentation, and the experimental procedure are reported and the study of experimental setups from the available literature survey with the existing one are compared in this paper. Alteration of air velocity at the cross section of the test tube during stable flow at extremely low velocities such as 0-0.08 m/s was measured by these measuring systems sensitively and compared with each other. Characteristics of velocity profile in the test channel are found to be in good agreement with White's results.