Flow Visualization Lab

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Lab 1: Flow Visualization
Jintark Kim
Purdue University
ME309 lab Section 009 Abstract The purpose of this experiment is to visualize and analyze the flow patterns formed by objects in different conditions: cylinders in different diameter at different flow rate, and airfoils with different angle of attack at a constant flow rate. Properties of water at measured temperature and flow conditions for each trial were used to compute the Reynolds number. Red-dye ejector was used to traces the flow field around experiment objects. The cylinders with 2 different diameters (6.35mm and 25.4mm) at different water channel speed (1.25 in/sec and 3.00 in/sec) were used to observe flow patterns in 4 different Reynolds numbers. In addition, an
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The Von Karman vortex street becomes more turbulent with increasing Reynolds number. In the airfoil experiment, the airfoil with 0° angle of attack shows the laminar and smooth flow pattern while the airfoil with 20° shows the turbulent flow pattern. The result of this experiment strongly supports the validity of using Reynolds number to predict the flow pattern. Predicting rough conjecture of flow pattern without experiments can reduce the time consumption for design projects related to flow. Accordingly, the flow pattern analysis from this experiment contributes to engineering development. Introduction Flow visualization is a classic technique that visualizes flow patterns by using colored dye, or other tracking material. The visualized flow pattern is recorded by camera subsequently. Flow visualization is needed when designing and testing any components related to fluid flow such as car body, jet engine, aircraft, etc. Many fields of industry are related to analyze how an object is affected by surrounding flow field. The Reynolds number is used to predict the flow patterns. Reynolds number is given in Equation 1 (Fox, Pritchard, & McDonald, 2009). Re=ρ VL/μ (Eq.1) …show more content…
Airfoil is placed approximately 1 inch away from the tip of the nozzle. The height of the nozzle is then adjusted so that dye is injected on the middle of the front of airfoil. After 30 seconds, red dye is released and the pattern is recorded by cell phone camera (School of Mechanical Engineering, 2016).

Results The measured temperature and kinematic viscosity of the water are listed in Table 1. Temperature of the water tunnel is measured by thermocouple at the beginning of the experiment. The kinematic viscosity of the water is retrieved from the table of properties of water in Appendix A. Interpolation was used to approximate the most accurate value of the viscosity. Calculation of interpolation is shown in Appendix A.

Water Temperature (°C) 16.6 ±0.1
Kinematic Viscosity (m2/sec) 1.10×〖10〗^(-6)

Reynolds number for each test case shown in Table 2 is calculated using interpolated kinematic viscosity value, diameter of the cylinders, and water flow rate. Detailed calculation is shown in Appendix

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