SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 16 - AUGUST 12, 2005

01 AERONAUTICS (GENERAL)
Includes general research topics related to manned and unmanned aircraft and the problems of flight within the Earth’s atmosphere.

Also includes manufacturing, maintenance, and repair of aircraft.

For specific topics in aeronauticssee categories 02 through 09.

For information related to space vehicles see 12 Astronautics.

20050192475 NASA Langley Research Center, Hampton, VA, USA

Doppler Global Velocimetry Measurements for Supersonic Flow Fields

Meyers, James F.; [2005]; 19 pp.; In English; Advanced Measuring Techniques for Supersonic Flows, 28 Feb. - 3 Mar. 2005, Brussels, Belgium Contract(s)/Grant(s): 23-065-10-91; No Copyright; Avail: CASI; A03, Hardcopy

The application of Doppler Global Velocimetry (DGV) to high-speed flows has its origins in the original development of the technology by Komine et al (1991). Komine used a small shop-air driven nozzle to generate a 200 m/s flow. This flow velocity was chosen since it produced a fairly large Doppler shift in the scattered light, resulting in a significant transmission loss as the light passed through the Iodine vapor. This proof-of-concept investigation showed that the technology was capable of measuring flow velocity within a measurement plane defined by a single-frequency laser light sheet. The effort also proved that velocity measurements could be made without resolving individual seed particles as required by other techniques such as Fringe-Type Laser Velocimetry and Particle Image Velocimetry. The promise of making planar velocity measurements with the possibility of using 0.1-micron condensation particles for seeding, Dibble et al (1989), resulted in the investigation of supersonic jet flow fields, Elliott et al (1993) and Smith and Northam (1995) - Mach 2.0 and 1.9 respectively. Meyers (1993) conducted a wind tunnel investigation above an inclined flat plate at Mach 2.5 and above a delta wing at Mach 2.8 and 4.6. Although these measurements were crude from an accuracy viewpoint, they did prove that the technology could be used to study supersonic flows using condensation as the scattering medium. Since then several research groups have studied the technology and developed solutions and methodologies to overcome most of the measurement accuracy limitations: Derived from text

Laser Doppler Velocimeters; Doppler Effect; Supersonic Speed; Supersonic Jet Flow; Flow Velocity; Flow Distribution

Source: NASA.