Collaborative Experimental and Computational Study of a Dual-Mode Scramjet Combustor

Abstract

Advanced computational models of hypersonic air-breathing combustion processes are being developed to better understand and predict the complex flows within a dual-mode scramjet combustor. However, the accuracy of these models can only be quantified through comparison to experimental databases. Moreover, the quality of computational results is dependent on accurate and detailed knowledge of the combustor inflow and boundary conditions. Toward these ends, this paper describes results from a collaboration of experimental and computational investigators. Detailed computational fluid dynamics and finite element analyses were performed throughout the design and implementation of experiments involving a direct-connect scramjet combustor operating at steady state during long duration testing. The test section hardware was designed to provide substantial access for optical laser diagnostics. Measurement locations included the inflow plane and several locations downstream of fuel injection. A suite of advanced in-stream diagnostics were applied, many of which are described in companion papers. Significant results in this paper include measured static wall pressures and temperatures, stereoscopic particle image velocimetry, and focused schlieren imaging. Validated thermal finite element calculations in the scramjet hardware and temperature maps of the flow path boundaries are also presented. Comparison of experimental results with computational fluid dynamics predictions are discussed in a separate paper. Nomenclature H = fuel injector normal ramp height h = convective heat transfer coefficient k = thermal conductivity P ref = measured static pressure immediately downstream of facility nozzle P o = flow stagnation pressure _ q = rate of heat transfer T o = flow stagnation temperature T r = recovery or adiabatic wall temperature T w = wall surface temperature x = axial coordinate γ = specific heat ratio φ = fuel equivalence ratio

A Priori Analysis of Flamelet-based Modeling for a Dual-Mode Scramjet Combustor

“…Some of these experiments include the HyShot flight experiment, 1,2 the X-43 flight program, 3,4 the HIFiRE experiments, 5,6 and the National Center for Hypersonic Combined Cycle Propulsion (NCHCCP) experiments. 7 Several research efforts have also subsequently been directed at computationally investigating these experiments via both Reynolds-averaged simulations (RAS) 8,9 and large eddy simulations (LES). [10][11][12] The computational efforts have focused primarily on hydrogen combustion experiments and utilized either flamelet models or reduced finite-rate kinetics to model combustion.…”

Velocimetry Using Graphite Tracer Particles in a Scramjet Flowpath (Invited)

“…The 10 Hz system has been applied successfully to the UVaSCF when configured with a ramp fuel injector and hydrogen fueling, 1,14,24 and the present study represents the initial application to the UVaSCF for the 1 kHz system. Both systems can be used to acquire either two-dimensional or stereoscopic PIV measurements.…”

“…5 Optical diagnostics applied to scramjet flows have included planar laser-induced fluorescence (PLIF), 6 coherent antiStokes Raman spectroscopy (CARS), 7 tunable diode laser absorption spectroscopy (TDLAS), 8 tunable diode laser absorption tomography (TDLAT), 9 laser Doppler velocimetry (LDV), 10 hydroxyl-tagging velocimetry (HTV), 11 and particle image velocimetry (PIV). 1,[12][13][14][15][16] Of the velocimetry techniques, both PIV and LDV are dependent on proper seeding of the flowfield with tracer particles. 17 These particles must be sufficiently large to scatter enough light to enable photographic detection, yet small enough to faithfully track the flow.…”

Development of a Premixed Combustion Capability for Dual-Mode Scramjet Experiments (Invited)

“…Specifically, the experiments employ a direct connect scramjet combustor that is operated at Mach 5 enthalpy (total temperature of 1200 K) using the University of Virginia Supersonic Combustion Facility (UVaSCF). The test-section hardware has been designed to accommodate the application of multiple advanced flow diagnostic techniques [13]. In particular, the combustor section incorporates a modular construction approach that provides substantial access for optical laser diagnostics.…”