Measurements of heat transfer to a flat plate in a dissociated high-enthalpy laminar air flow

East, R. A.; Stalker, R. J.; Baird, J. P.

doi:10.1017/s0022112080002753

Cited by 65 publications

(40 citation statements)

References 10 publications

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“…A similar delay after the passage of the starting pulse was observed in the experimental measurements of East et al [24]. For x < 0.3, the delay beyond the flat plate value of G L-3 is significant.…”

Section: (Xt)-diagramssupporting

confidence: 82%

“…From the experimental point of view, it appears that the correlations available in the literature are adequate for predicting the establishment times for the flow features of the model if the inflow conditions are steady and allowance is made for the passage of the starting pulse [24]. For the relaxing flow, there are perturbations outside the 2% error band for a significantly longer time but these perturbations are probably umaller than the measurement uncertainty in the shock tunnel experiment.…”

Section: Resultsmentioning

confidence: 97%

See 1 more Smart Citation

Flow establishment in a generic scramjet combustor

Jacobs¹,

Rogers

Weidner

et al. 1992

Journal of Propulsion and Power

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Section: (Xt)-diagramssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 97%

Flow establishment in a generic scramjet combustor

Jacobs¹,

Rogers

Weidner

et al. 1992

Journal of Propulsion and Power

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“…The values of γ w are however consistent with those found in the literature, which also show a large variation. For example, East, Stalker & Baird (1980) use γ w ≈ 3 × 10 −3 which they regard as typical for oxygen and nitrogen recombination on oxidized metallic surfaces with a wall temperature of 300 K. In contrast, Anderson (1973) determined values of γ w using experimental measurements of stagnation-point heat transfer rates in supersonic flow and gave a value for metallic surfaces, including platinum, of 0.09 for 400 ± 100 K. The standard assumption is that γ w increases with temperature, but Chen & Chandler (1993) state, unusually, that it may also be a function of pressure. The free-stream pressures for cases 1 to 4 are included in table 9, and clearly there is no direct relationship between p and γ w in these flows.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

High-speed flow with discontinuous surface catalysis

2000

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In a reacting gas flow both gas-phase chemical activity and surface catalysis can increase the rate of heat transfer from the gas to a solid surface. In particular, when there is a discontinuous change in the catalytic properties of the surface, there can be a very large increase in the local heat transfer rate. In this study numerical simulations have been performed for the laminar high-speed flow of a high-temperature, non-equilibrium reacting gas mixture over a flat plate. The surface of the plate is partly catalytic, with the leading region non-catalytic, and a discontinuous change in the catalytic properties of the surface at the catalytic junction. The surface is assumed to be isothermal, and cold relative to the free stream. The gas is assumed to be a mixture of molecular and atomic forms of a diatomic gas in an inert gas forming a thermal bath, giving a three-species mixture with dissociation and recombination of the reactive species. The calculations are performed for a gas with atomic and molecular oxygen in an argon bath, but a full range of gas-phase chemical and surface catalytic effects is considered. Kinetic schemes with frozen gas-phase chemistry, and partial or full recombination of atomic oxygen in the boundary layer are investigated. The catalytic nature of the surface material is given by a catalytic recombination rate coefficient, which varies from zero (non-catalytic) to one (fully catalytic), and the effects on the flow and the surface heat transfer of materials which are non-, partially, or fully catalytic are considered. A self-similar thin-layer analytical model of the change in the gas composition downstream of the catalytic junction is developed. For physically realistic (O(10 −2 )) values of the catalytic recombination rate coefficient, the predictions from this model of the surface values of the atomic oxygen mass fraction and the catalytic surface heat transfer rate are excellent when the only change in the composition of the gas comes from the surface catalysis, and reasonable when there is partial recombination of the gas in the boundary layer due to the gas-phase chemistry. In contrast, when the surface is fully catalytic, the streamwise diffusion terms play a significant role, and the model is not valid. These results should apply to other situations with an attached boundary layer with recombination reactions. A comparison is made between the calculated and experimental measurements of the heat transfer rate at the catalytic junction. With a kinetic scheme which allows partial recombination in the boundary layer, good agreement is found between the experimental and predicted values for surface materials which are essentially non-catalytic. For a catalytic material (platinum), the experimental and numerical heat transfer rates are matched to estimate the value of the catalytic recombination rate coefficient. The values obtained show a considerable amount of scatter, but are consistent with those found in the literature.

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“…In previous studies the model establishment time after the passing of the starting pulse of gas has been correlated with the required number of flow lengths based on a characteristic length and velocity (see, for example, Davies and Bernstein, 1969;East et al, 1980;Jacobs et al, 1992;Lee and Lewis, 1993). For the current work an additional constraint was the requirement that 24 Height restictions imposed by the force balance prevented the model from being raised higher than shown in Figure 3.18.…”

Section: Test Time Determinationmentioning

confidence: 94%

An experimental investigation of an airframe integrated three-dimensional scramjet engine at a Mach 10 flight condition

Doherty¹

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The University of Queensland in 2014 school of mechanical and mining engineering centre for hypersonics abstract Realisation of the dream of airbreathing access-to-space requires the development of a scramjet engine that produces sufficient net thrust to enable acceleration over a wide Mach number range. With engines that are highly integrated with the airframe, the net performance of a scramjet powered vehicle is closely coupled with the vehicle attitude and is difficult to determine only from component level studies. This work investigates the influence of airframe integration on the performance of an airframe integrated scramjet through the measurement of internal pressure distribution and the direct measurement of the net lift, thrust and pitching moment using a three-component stress wave force balance. The engine chosen as the basis for this study was the Mach 12 rectangularto-elliptical shape-transition (m12rest) scramjet that was developed by Suraweera and Smart (2009) as a research engine for access-to-space applications. The inlet and combustor flowpath were integrated with a slender 6°wedge forebody, streamlined external geometry and three dimensional thrust nozzle. The scale of the engine was chosen so that the entire engine would fit within the core-flow diamond (bi-conic) produced by a Mach 10 facility nozzle. The Mach 10b facility nozzle was chosen because it is the largest nozzle current in use with the t4 Stalker Tube and because the offdesign performance of a scramjet engine is of interest for access-to-space vehicles that must accelerate over a range of Mach numbers.Freejet experiments were conducted within the t4 Stalker Tube. Two trueflight Mach 10 test conditions were used: a high pressure test condition that replicated flight at a dynamic pressure of 48 kPa and a low pressure test condition that replicated flight at a dynamic pressure of 28 kPa. Scaling of the test conditions according to the established binary scaling law was not completed due to facility operational limits.The engine featured two fuel injection stations from which gaseous hydrogen was injected. The first injection station was partway along the length of the inlet while the second injection station was at the start of the combustor behind a rearward facing circumferential step. In addition to investigating inlet-only and step-only injection, a combined scheme where 68 % of the fuel was injected from the step station and 32 % from the inlet station was also investigated.To support the analysis of the experimental results, numerical simulations of the engine with no fuel injection were conducted using the nasa code vulcan. Analysis of the simulations show that the mass capture ratio with respect to the projected inlet area is approximately 60 % at each test condition. The simulations also show that spillage of flow from the slender forebody accounts for just 12 % of the flow through the projected iii inlet area, a small but non-negligible fraction. By integrating the engine surface forces, the drag coefficient with respect ...

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Measurements of heat transfer to a flat plate in a dissociated high-enthalpy laminar air flow

Cited by 65 publications

References 10 publications

Flow establishment in a generic scramjet combustor

Flow establishment in a generic scramjet combustor

High-speed flow with discontinuous surface catalysis

An experimental investigation of an airframe integrated three-dimensional scramjet engine at a Mach 10 flight condition

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