Brian E. Rice

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

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-...

Direct Measurement of Combustion Efficiency of a Dual-Mode Scramjet via TDLAT and SPIV (Invited)

The combustion efficiency of a scramjet is a metric that evaluates the overall performance of the engine. Until recently, combustion efficiency was measured using indirect approaches such as a 1-D control volume calculation or calorimeter and wall pressure tap measurements. A non-intrusive direct approach for the measurement of combustion efficiency is presented which combines the optical diagnostic techniques tunable diode laser absorption tomography (TDLAT) and stereoscopic particle image velocimetry (SPIV). Experimental results are presented for measurements on the University of Virginia’s supersonic combustion facility (UVaSCF) in both the scramand ram-modes of operation. The TDLAT/SPIV method directly measures the flux of water vapor exiting the dual-mode scramjet and compares this to the facility-measured injected H2 fuel flux. A complementary computational fluid dynamics (CFD) study was performed and results were available for only the scram-mode operating condition. The results reported show excellent agreement between the TDLAT/SPIV measured combustion efficiency and the CFD predicted combustion efficiency for the scram-mode of operation, both near 99%. The TDLAT/SPIV measured combustion efficiency for the ram-mode of operation is shown to be lower than that of the scram-mode operation, at 79%.

Characterization of a Dual-Mode Scramjet via Stereoscopic Particle Image Velocimetry

Despite over 50 years of research, the supersonic, turbulent, combusting flow field of a scramjet is not fully understood. This is particularly the case for the dual-mode scramjet (DMSJ) which operates in supersonic, subsonic, and mixed modes of combustion. This gap in knowledge stems from the inability to experimentally measure key flow properties and the resulting absence of validated computational tools. Renewed interest in hypersonic flight and the advancement of optical measurement techniques provide an opportunity to quantify flow properties that were once not accessible. This includes instream velocimetry, which can provide a fundamental understanding of the turbulent transport processes in these engines. The work described here employs the experimental technique of Stereoscopic Particle Image Velocimetry to measure the three-dimensional, instantaneous velocities within a dual-mode scramjet model. Significant design of new DMSJ model hardware was necessary to allow the required optical access with the end goal of building a one-of-a-kind dataset for the development of advanced computational techniques. The work presented herein contributes to this goal by measuring the flow field within the combustor in both dual and scram modes of operation at several axial locations. The measurements reveal the key velocity field differences between modes of operation and show the influence on the velocity field as the combustion process develops axially. The comprehensive data set provides converged turbulence statistics and presents the opportunity for future comparison to numerical models.

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

Hypersonic airbreathing engines rely on scramjet combustion processes, which involve high-speed, compressible, and highly turbulent reacting flows. The combustion environment and the turbulent flam...

Scramjet Combustion Efficiency Measurement via Tomographic Absorption Spectroscopy and Particle Image Velocimetry

The combustion efficiency of a scramjet is a metric that evaluates the overall performance of the engine. Until recently, combustion efficiency was measured using indirect approaches such as a one-dimensional control volume calculation or a calorimeter and wall pressure tap measurements. A novel nonintrusive direct approach for the measurement of combustion efficiency is presented that combines the optical diagnostic techniques tunable diode laser absorption tomography and stereoscopic particle image velocimetry. Experimental results are presented for measurements of the University of Virginia’s Supersonic Combustion Facility in both the scram and ram-modes of operation. The tunable-diode-laser-absorption-tomography/stereoscopic-particle-image-velocimetry method directly measures the converted hydrogen (via water vapor) mass flow rate exiting the dual-mode scramjet and compares this to the facility-measured injected hydrogen fuel mass flow rate. A complementary computational fluid dynamics study was perfo...

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

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 those ends, this paper describes the initial results of a unique, close collaboration of experimental and computational approaches. Detailed computational fluid dynamics (CFD) and finite element thermal-structural analyses (FEA) have been performed throughout the design and implementation of a direct-connect scramjet combustor operating at steady state during long duration testing on the order of an hour or more. The test-section hardware has been designed to provide numerous access points for optical laser diagnostic measurements. Measurement locations include the inflow plane to the scramjet combustor as well as several locations downstream of the fuel injector. In addition, static wall pressures and temperatures are measured at numerous points along the fuel injector side of the scramjet flowpath. Initial CFD calculations were used to generate detailed thermal boundary conditions that were then applied to a non-linear, thermalstructural finite element model of the test-section. The calculated temperatures and thermal deformations are evaluated and validated against experimental measurements. Significant results described in this paper include experimentally measured static wall pressure and temperature data, Stereoscopic Particle Image Velocimetry (SPIV) and focused schlieren imaging. Validated finite element calculations of temperature in the test-section hardware, and temperature maps of the flowpath boundaries are also presented. CFD results are discussed in a separate paper.