Title page for ETD etd-08232011-110638


Type of Document Master's Thesis
Author Ecker, Tobias
Author's Email Address ecker@vt.edu
URN etd-08232011-110638
Title Experimental Investigation of Particle Lag behind a Shock Wave using a Novel Laser Doppler Accelerometer
Degree Master of Science
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Simpson, Roger L. Committee Chair
Lowe, Kevin Todd Committee Member
Schetz, Joseph A. Committee Member
Vlachos, Pavlos P. Committee Member
Keywords
  • Acceleration
  • Particle Drag
  • Multiphase Flow
  • Laser Doppler
  • Supersonic
  • Slip Flow
  • Non-Continuum Flow
Date of Defense 2011-08-03
Availability unrestricted
Abstract
Determination of particle slip is a major concern for particle based measurements in un- heated supersonic facilities, as it is a limiting factor for the instruments’ frequency response. For the purpose of determining the particle deceleration through a stationary shock wave in a super sonic windtunnel, a novel 1-D Laser Doppler probe with an unique spatial range (~1.5 mm) is presented. The study first gives a short review of the physics of particle motion with respect to different drag models and flow regime encountered in super sonic flows. In the second part, the focus lies on the development of a new Laser Doppler probe using non Gaussian beams to obtain a prolonged measurement volume. This volume covers a major part of the particle lag after a shock wave. An experimental investigation on particle accel- eration and drag, using different types and sizes of seeding material, including standardized microspheres is carried out in the M∞ = 2.0 super sonic facility. Three different types of particles with four different sizes are experimentally investigated. The experimental data provides mean velocity as a function of distance from the shock and reveals significant ag- glomeration and evaporation problems with Titanium Oxide and Polystyrene Latex spheres. Particle acceleration measurements are presented, proving the unique concept of the new Laser Doppler probe. Mean and instantaneous acceleration data is extracted from high SNR signals. The acceleration data obtained is consistent in magnitude and trend with the physical phenomena expected and shows the feasibility of the new instrument.
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