Free-Jet Testing of a REST Scramjet at Off-Design Conditions

Smart, Michael K.; Ruf, Edward G.

doi:10.2514/6.2006-2955

Cited by 28 publications

(16 citation statements)

References 7 publications

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“…Stalker et al (2005) provide an detailed summary covering the period up to 2005. Furthermore, results from the HyShot II flight experiment were found to match results from experiments conducted in the t4 Stalker Tube (Smart, 2006), providing further evidence of the validity and usefulness of shock tunnel testing for the development of scramjet engines.…”

Section: Forebody Flow Conditionssupporting

confidence: 59%

“…A six-component force balance was also used but facility-model interactions in the larc chstf prevented net force data from being measured; only the force increment due to combustion could be quantified. Furthermore, Smart and Ruf (2006) did not provide any details concerning the geometry of the isolator, combustor, nozzle or fuel injection station and all plots were shown in the paper without axis limits.…”

Section: Rest Engine Design and Testingmentioning

confidence: 99%

“…In this configuration, the inlet self-started with a mass capture ratio of 79.7 % and compression ratio 12.6. Following on from the successful off-design tests, Smart and Ruf (2006) mated the m7(v2)rest with an isolator, divergent combustor and thrust nozzle, thus forming the first complete rest scramjet engine. Shown in Figure 2.3c, the complete engine was tested in the nasa larc Combustion Heated Scramjet Test Facility (chstf) at Mach 4.5.…”

Section: Rest Engine Design and Testingmentioning

confidence: 99%

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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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Section: Forebody Flow Conditionssupporting

confidence: 59%

Section: Rest Engine Design and Testingmentioning

confidence: 99%

Section: Rest Engine Design and Testingmentioning

confidence: 99%

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

Doherty¹

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“…The engine was found to be self-starting, even under mechanically induced engine unstart conditions, and remained started with back-pressure ratios as high as 5.7. Further testing with the injection and combustion of hydrogen fuel under Mach 5.3 flight conditions showed that the engine maintained robust combustion for fuel equivalence ratios between 0.5 and 1.5 (Smart and Ruf, 2006). The engine remained self-started under a variety of adverse conditions, though at the lower range of Mach numbers (i.e.…”

Section: Experimental Investigationsmentioning

confidence: 99%

Mixing and combustion enhancement in a Mach 12 shape-transitioning scramjet engine

Barth¹

118

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are to investigate and characterize the flow physics behind the Mach 12 REST engine's current performance, and then attempt to improve its combustion performance by tailoring the engine's fuel injection to its internal flow field without otherwise modifying the engine geometry. To meet these aims, the engine was studied both numerically and experimentally.The first-ever combusting simulations of a REST scramjet operating at Mach 12 conditions were performed for the Mach 12 REST engine using the CFD research code US3D. The simulations covered a range of conditions, including: unfuelled engine flow, inlet-fuelled flow, and various combined inlet/combustor fuelling configurations. The simulations were found to match well with the experiments they were designed to reproduce and be compared against. A comparison of simulations with experimental inflow conditions and their equivalent flight conditions on an otherwise identical engine showed that experiments in the T4 Stalker tube reproduce engine pressure and heat flux distributions well. The tunnel condition tends to capture less incoming flow than the engine at flight conditions, which leads to the ground-tested engine over-predicting the engine equivalence ratio.The Mach 12 REST inlet was found to produce a thick "bubble-shaped" boundary layer along its bodyside compression surface, due to the compression effects of the inlet sidewalls acting on a thick turbulent boundary layer ingested from the vehicle forebody. This thick boundary layer forces the majority of inlet-captured air into a high-density, high Mach number flow region along the engine cowlside wall . The inlet also produces a symmetric pair of high-temperature swept separations that enter the engine isolator along the sidewalls of the engine. When fuel is injected from the bodyside surface of the inlet, it remains trapped inside the thick, turbulent boundary layer, where it becomes well-mixed and begins to burn just upstream of the inlet throat.i As much as 50% of this fuel is burned by the time it enters the engine isolator, while its injection and burning increases the inlet's drag by less than 5%. This burning bodyside flow region thermally compresses the remaining air flow within the engine isolator, and provides a source of heat and combustion radicals for the ignition of fuel injected further downstream. Overall combustion efficiency of inlet-injected fuel at the engine exhaust plane was found to be nearly 80% at high equivalence ratios.Flow within the Mach 12 REST combustor is strongly shock-dominated. This is caused by both the cowl closure shock train transmitted from the inlet, and a strong recompression shock generated at the start of the combustor. This recompression shock is generated by the flow passing over a backward step at the entrance to the combustor, and is reinforced on the cowlside of the engine by compression caused by the engine flow path turning to realign with the nominal direction of flight. Fuel injected from the face of the combustor step was combined with inlet injection in...

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“…This fixed-geometry mixed-compression configuration transitions smoothly from a quasirectangular capture shape to an elliptical throat. In combination with a divergent elliptical combustion chamber, REST inlets have been shown to produce a useful flowpath for hypersonic applications [20]. The current configuration is an exploratory Mach 8.1 design-point flowpath which has been explicitly adapted to be used in conjunction with inlet injection and radical farming.…”

mentioning

confidence: 99%

Application of Inlet Injection to a Three-Dimensional Scramjet at Mach 8

Turner

Smart

2010

AIAA Journal

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An investigation of inlet injection in a scramjet having a three-dimensional inlet and an elliptical combustion was undertaken. Experiments were conducted using a test flow simulating a Mach 8.1 flight condition with an altitude of 32 km. The objective was to determine the feasibility of reducing the combustion-chamber length by injection of hydrogen fuel in the inlet. The study involved a self-starting three-dimensional inlet with an overall geometric contraction ratio of 5.80, of which 2.08 was internal. The fuel was injected through multiple portholes in the forward portion of the inlet to allow significant mixing upstream of the combustion chamber. The divergent elliptical combustion chamber had a length sized for fuel ignition and combustion only and used a fluid-dynamic ignition scheme requiring no physical obstructions to the flowpath. Results indicated that inlet injection produced robust combustion at good combustion efficiency over a large fueling range up to an equivalence ratio of 0.92. A further key result was that no evidence of combustion was observed in the inlet. These experiments suggest that fuel injection in the inlet is a promising concept for higher-speed scramjet applications.

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Free-Jet Testing of a REST Scramjet at Off-Design Conditions

Cited by 28 publications

References 7 publications

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

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

Mixing and combustion enhancement in a Mach 12 shape-transitioning scramjet engine

Application of Inlet Injection to a Three-Dimensional Scramjet at Mach 8

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