Accession Number : ADA137019

Title :   A Study of Annular Diffuser Flow Using A Photon-Correlating Laser Doppler Anemometer.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Dierksen,J M

PDF Url : ADA137019

Report Date : Dec 1983

Pagination or Media Count : 134

Abstract : An experimental investigation of air flow in an annular inlet and diffuser was conducted using a photon-correlating laser doppler anemometer. The inlet has an inside wall radius of 22.9 cm (9.0 in.) and a cross-sectional area of 0.0426 sq m (0.4583 sq ft). The diffuser walls have a divergence half-angle of seven deg. Flow rates in the vicinity of 0.25 kg/sec (0.55 lbm/sec) were studied. The Reynolds number in the annular inlet was 18300. Flow in the annulus was turbulent and boundary layer growth was approximately 20% less than that predicted using flat plate boundary layer assumptions. The laser anemometer measurements are compared to hot film anemometer measurements. Good comparison was obtained except in the annular inlet. The difference is probably due to the differing boundary layer growth rates between the laser and hot film anemometer tests since they were conducted with different mass flow rates. The photon-correlating laser doppler anemometer is evaluated in this application. The flexibility of a laser anemometer system in measuring 3-dimensional, internal flow is determined by two factors: the system's frequency shifting capability and the geometry of its optics. Reflected background light is inherent in measuring internal flows. Without a means of reducing the signal caused by this light, long measurement times are necessary for each data point.

Descriptors :   *Boundary layer, *Air flow, *Diffusers, *Laser anemometers, Doppler systems, Turbulence, Velocity, Photons, Correlation, Inlets, Internal, Fluid dynamics, Walls, Frequency shift, Mass flow, Estimates, Flat plate models, Turbulent boundary layer, Thickness, Three dimensional flow, Laser velocimeters, Films, Anemometers, Theses

Subject Categories : Lasers and Masers
      Test Facilities, Equipment and Methods
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE