Preliminary Study on a Round Tube Jet in a Vertical Water Tunnel

• Main Authors: JHIH -CHAO JHANG, 張智超
• Other Authors: Yi-Jiun Lin
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/30620421160988830127

碩士 === 國立臺灣科技大學 === 機械工程系 === 97 === The purpose of this paper is to establish the round tube jet assembly in a vertical water tunnel, and measure the flow speed by using Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV). Both PIV and PTV measurement approaches do not disturb the flow field. Experiments were illuminated by a green laser light sheet that was formed by cylindrical glass lenses in front of three semiconductor laser generators. Water in the vertical tunnel was seeded by tracer particles, which could scatter the laser light. A high-speed digital camera was recording images of experiments. The flow velocity was estimated by the motion of these particles. The particles have similar density as that of water, so they are regarded as part of the fluid in the water tunnel. Water pump power was adjusted by changing the frequency of the inverter. Three distinct methods, simple visual method, PIV method and PTV method, were used to estimate the flow velocity. Experimental results show that, at low speed (2Hz to 10Hz), the velocity measurements of PIV have a deviation of 8% or less, and measurements of PTV have a deviation of 4% or less. At high speed (11Hz to 30Hz), the measurements of PIV have a deviation of 8% or less, and PTV fails to estimate the flow velocity. For high speed, enhancing intensity of the laser and reducing exposure time of the camera could reduce analysis error.