VELOCITY MEASUREMENTS IN A HIGH-SPEED FLOW THROUGH A SQUARE DUCT CONTAINING A $90^circ$ BEND
Open Access
- Author:
- Sheth, Preyank R.
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Dr Kendra Sharp, Thesis Advisor/Co-Advisor
Kendra V Sharp, Thesis Advisor/Co-Advisor - Keywords:
- square duct
experimental
90 degree bend
turbulent flow
Particle image velocimetry - Abstract:
- This study is aimed at better understanding the nature of bend effects in a high Reynolds number duct flow. Bend effects have been previously studied using laser Doppler velocimetry and hot wire anemometry, but these are point measurement techniques, which limits the amount and type of data that can be obtained. The current work employs particle image velocimetry to present detailed field measurements of the flow velocity throughout the bend, including upstream and downstream sections. Additionally, velocity measurements have been carried out at three different Reynolds numbers to establish the dependence or independence of the bend effects on the flowrate. Associated turbulence quantities have also been calculated and presented in an intuitive, graphical manner. The test section is a square cross-sectioned duct, containing a 90 degree bend preceded by an 5Dh upstream section and a 10Dh downstream straight section, where Dh is the hydraulic diameter. Turbulent flow entering the upstream section is fully-developed to allow the isolation of the bend effects. At Re ~ 2.76X10^5, detailed velocity measurements are acquired at 12 streamwise locations in three streamwise-radial planes at different heights (top, middle and bottom). Complementary data are obtained in a more limited set of locations at Re~1.76X10^5 and Re~3.20X10^5 to allow comparison of the bend effects at different flowrates. Turbulence intensities and the Reynolds shear stress components are calculated and presented for all three Reynolds numbers. One of the major aims of this work is to provide a benchmark for computational codes developed to study bend effects in a turbulent pipe flow. To allow easy comparison of these codes to the results of the current study, all the measured and calculated quantities are plotted in a curvilinear coordinate system in addition to the native cartesian (global) coordinate system.