Experimental Investigation of Particle Lag behind a Shock Wave using a Novel Laser Doppler Accelerometer

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 acceleration and drag, using different types and sizes of seeding material, including standardized microspheres is carried out in the Mâ = 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 agglomeration 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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Aerospace and Ocean Engineering

Department dc:contributor.department

Aerospace and Ocean Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2011

Author dc:creator

• Ecker, Tobias

Chair dc:contributor.committeechair

• Simpson, Roger L.

Committee members dc:contributor.committeemember

• Vlachos, Pavlos P.
• Schetz, Joseph A.
• Lowe, K. Todd

• Acceleration
• Particle Drag
• Multiphase Flow
• Laser Doppler
• Supersonic
• Slip Flow
• Non-Continuum Flow

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-08232011-110638

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/34720