Single shot spatially and spectrally resolved laser-induced predissociation fluorescence (LIPF) and standard laser-induced fluorescence (LIF) of oxygen (O2) and nitric oxide (NO) measurements, produced along a line inside the shock layer, have been extensively analysed in preparation of Mr Sutton's PhD thesis which was submitted in early 1995.
Measurement of rotational and vibrational temperatures using CARS in the
freestream and shock layer of a pulsed hypervelocity blunt body flow and
comparisons with CFD calculations
Pulford, Boyce, Houwing
Broadband single pulse coherent anti-Stokes Raman scattering (CARS) experiments employing a folded box phase matching geometry in a pulsed hypervelocity blunt body completed in previous years of this project have been extensively analysed. Rovibrational spectra of molecular nitrogen, have produced in the free stream and within the shock layer at moderately high enthalpy (~7.5 MJ/kg) have been compared with theoretically calculated values for temperatures based upon algorithms used to determine freestream and shock layer conditions. Good agreement was achieved between theory and experiment. The measurements indicate that thermal nonequilibrium conditions exist within the freestream, and that thermal equilibrium exists at the point of measurement within the shock layer.
CFD validation using multiple interferometric views of three dimensional
shock layer flows over a blunt body
Boyce, Houwing, Morton
Experimental work has been undertaken to provide a data base for the tomographic deconvolution of three-dimensional density distributions in the shock layer around a body at nonzero incidence in a supersonic flow. In particular, a hyperboloid was placed at 15[[ring]] incidence to a supersonic perfect gas argon flow, and a supersonic nonequilibrium gas air flow. A total of 7 different viewing angles were produced by rotating the axis of the test body around the axis of the shock tunnel. Comparisons have been made between: (i) the interferometric results obtained from the perfect gas and real gas experiments, and (ii) CFD-produced phase maps for each of the different lines-of-sight. Excellent agreement between theory and experiment was achieved for the perfect gas flow, whereas some discrepancies observed in the real gas air flows are explainable from the fact that severe under-tailoring existed in those cases.
Tomographic reconstruction of density in a hypersonic flow over a blunt body
Morton, Boyce, Houwing, Bone
During the first few months of 1994 phase map data obtained in experiments in 1993, using hypersonic flow over a hyperboloid model, were used for tomographic reconstruction of the three-dimensional density field. The iterative forms of the tomographic algorithm were fully implemented and tested. From June 1994 until December 1994 final data analysis was undertaken and a first draft of the PhD thesis was written.
PLIF imaging of shock tunnel flow development and thermometry in a shock
layer flow on a cylinder in a supersonic jet
Houwing, Palmer, Boyce, Thurber, Wehe and Hanson
This work is part of a collaborative research program with the experimental work having been done at the High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, under the direction of Prof. Ron Hanson. The work, which was done in late 1993 and early 1994, involved planar laser induced fluorescence (PLIF) experiments in shock tunnel flows, to study firstly transient shock phenomena during flow development (using PLIF imaging), and secondly the temperature distribution in a shock layer flow on a bluff body in a quasi-steady supersonic jet (using PLIF thermometry). Fluorescence was produced through the excitation of rovibronic transitions in nitric oxide, which was present at extremely low levels (500 ppm) in an argon test gas. Both the imaging and thermometry experiments were highly successful, with good agreement being achieved between theory and experiment for most of the imaged field, except for the region near the shock vertex where flow non-uniformities localised around the centre-line perturb the shock from the shape expected for a uniform incident flow.
Investigations into the effects of surface catalysity and boundary layer
reactions on surface heat flux
Gai, Mudford, Mallinson, Sandeman
The object of this investigation was to study the role of chemical reactions in enhancing or inhibiting surface heat flux to bodies exposed to high enthalpy hypersonic flows. Attention was directed to both gas phase atomic recombination in the boundary layer and to surface catalysed atomic recombination at the surface. The intention was to test long standing but experimentally unconfirmed theories concerning the extent of the departure of the reactions from chemical equilibrium and the consequent effects on heat flux. In the first phase of the project, a series of experiments using a sharp nosed flat plate was conducted. In the first series, the flat plate, consisting of two surfaces (one aluminium and the other copper) was exposed to the flow. A direct comparison of heat transfer rates on aluminium and copper surfaces simultaneously under identical flows has therefore been obtained. In the second series of experiments, two sharp nosed flat plates, one consisting of an aluminium/quartz and the other a copper/quartz surface, were exposed to the shock tunnel flow. In these experiments, the intention was to study effects on heat transfer of discontinuity in catalytic surfaces. This has important implications for practical designs of spacecraft. In both series, both air and nitrogen were used as test gases. In the second phase of the project, the tests were repeated at various angles of attack to induce chemical reactions in the shock layer outside the boundary layer. Secondly, a series of bluff bodies of simple geometry was studied. Once again, both air and nitrogen test gases were used and surface coatings varied to alter the extent of surface catalysed recombination. This work was completed in 1994, with Mr Mallinson (of ADFA) submitting his thesis in that year.