Hypersonic Laminar Boundary Layer Velocimetry with Discrete Roughness on a Flat Plate

Abstract

Laminar boundary layer velocity measurements are made on a 10-degree half-angle wedge in a Mach 10 flow. Two types of discrete boundary layer trips were used to perturb the boundary layer gas. The first was a 2-mm tall, 4-mm diameter cylindrical trip. To study the precision of the measurement technique, the angle of attack was varied during one run. Nitric-oxide (NO) molecular tagging velocimetry (MTV) was used to obtain averaged axial velocity values and associated uncertainties. These uncertainties are as low as 20 m/s. An interline, progressive scan CCD camera was used to obtain separate images of the initial reference and shifted NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond sequential acquisition of both images. The maximum planar spatial resolution achieved for the side-view velocity measurements was 0.07-mm in the wall-normal direction by 1.45-mm in the streamwise direction with a spatial depth of 0.5-mm. For the plan-view measurements, the maximum planar spatial resolution in the spanwise and streamwise directions was 0.69-mm by 1.28-mm, respectively, with a

Trip-induced Transition Measurements in a Hypersonic Boundary Layer Using Molecular Tagging Velocimetry

“…This is opposed to data acquired at lower Reynolds numbers but similar k/δ L values, such as the measurements of ̅ in Ref. 16, Fig. 1(c).…”

“…Also in Ref. 16, the ̅ profiles in Fig. 1(c) between the region immediately behind the tripping element at x = 81 mm and approximately x = 120 mm exhibit two inflection points similar to those shown in Fig.…”

PLIF Study of Mars Science Laboratory Capsule Reaction Control System Jets

“…The timing sequence used for the velocity measurement was similar to that used in Ref. 23, with the effective 1 st exposure and 2 nd exposure being 15 ns and 100 ns in duration, respectively. As with the flow visualization experiment, a Layertec GmbH filter (<1% transmission at 226 nm and >80% transmission at 235-280 nm) was used to block the laser scatter occurring along the model surface and pass the fluorescence emitted from the tagged lines.…”

Review of Fluorescence-Based Velocimetry Techniques to Study High-Speed Compressible Flows

“…For example, quantitative measurements of laminar and laminar-unsteady hypersonic boundary layer behavior, [5][6][7] reaction control system (RCS) jet behavior in wake flows, 5,6,8,9 and facility characterization 10 were of particular interest. Since these types of experiments were to be made in flows with both a steady and unsteady nature, the quantitative measurements to be used required the ability to probe the flowfield with relatively high spatial and temporal accuracy and precision.…”

“…Based on analysis of the side-view velocity profiles in Ref. 7, it was estimated that the closest a measurement of streamwise velocity could be made to the plate surface was 0.38-mm.…”