INVESTIGATION OF FLOW AROUND A CIRCULAR CYLINDER THROUGH HOT WIRE ANEMOMETRY

INVESTIGATION OF - INVESTIGATION OF FLOW AROUND A CIRCULAR CYLINDER THROUGH HOT WIRE ANEMOMETRY Aero Engineering Laboratory AOE 4154 Lab Instructor

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INVESTIGATION OF FLOW AROUND A CIRCULAR CYLINDER THROUGH HOT WIRE ANEMOMETRY Aero Engineering Laboratory AOE 4154 Lab Instructor: Dr. Roger Simpson Lab TA: Scott Burger Lab Section: Friday 3:55 – 5:20 Date Performed: October 16, 2009 Student Name: Craig Sossi Student Number: 904512344 Honor Pledge: By submitting this document I pledge that I have neither given nor received unauthorized aid. Craig Sossi Page | 1
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The purpose of this experiment is to utilize a wind tunnel to observe flow velocity profiles and turbulence intensity downstream of a circular cylinder at subcritical and supercritical Reynolds numbers. The Virginia Tech Stability Wind Tunnel is used in conjunction with LabVIEW and a hot- wire anemometer to gather data about the flow at different locations behind the cylinder. This data is then reduced and put into plots depicting the flow at the various points tested. It is observed that the flow behind the cylinder for supercritical Reynolds numbers is less turbulent and has smaller turbulence fluctuations than for the subcritical Reynolds numbers. INTRODUCTION Hot-wire anemometry is a technique used to measure certain properties in a flow, usually velocity, temperature, or composition changes. [1] Hot-wire (and hot-film) anemometers are available in a range of shapes and sizes, each offering distinct advantages for different applications. For instance, if the flow medium is water, a thin wire would easily break due to the forces exerted on the wire by the water, so a hot-film anemometer would be chosen because of its robust build. Hot-wire and hot-film anemometers are typically made of tungsten, platinum or a platinum-iridium alloy, with tungsten being the most popular. The tungsten offers good strength and a high temperature coefficient of resistance, while the platinum offers excellent oxidation resistance, and the alloy offering a combination of the properties. Hot-film anemometers consist of a conductive film on some insulated material. Hot-film sensors offer better frequency response as well as lower heat conduction. They are also available in a wide variety of shapes which can be applicable to many flow types and locations, although their larger size may not be desired for some applications. Hot-wire anemometers use temperature and resistance to determine flow properties. The probe is heated to some temperature electronically once placed in the flow. The flow medium (i.e. air) rushing past the wire has a cooling effect on the wire. This in turn changes the resistance of the wire, which can be related to the change in the desired property (such as flow velocity). Some properties that the hot-wire anemometer can measure include velocity, turbulence levels in wind tunnels, flow patters around models and blade wakes in compressors. [1] For the experiment, the Virginia Tech Stability Wind tunnel will be used in conjunction with a hot-wire anemometer to determine the flow characteristics behind a circular cylinder at various velocities.
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This note was uploaded on 01/23/2012 for the course AOE 4154 taught by Professor Simpson,r during the Fall '08 term at Virginia Tech.

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INVESTIGATION OF - INVESTIGATION OF FLOW AROUND A CIRCULAR CYLINDER THROUGH HOT WIRE ANEMOMETRY Aero Engineering Laboratory AOE 4154 Lab Instructor

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