Challenges for high-enthalpy gasdynamics research during the 1990's: Plans for the GALCIT T5 Laboratory (original) (raw)
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Aerospace Science and Technology, 2007
The simulation of high enthalpy flows, both experimentally and numerically, is a topic of international research efforts. It is important to understand and quantitatively describe the aerothermodynamic phenomena of high speed/high enthalpy flows in order to develop more capable reusable space transportation systems. A CFD-method is used here to model several piston driven shock tunnels used around the world to experimentally study re-entry and supersonic combustion phenomena. The results are compared to measured data (pressure and shock speed) of the various tunnels and shows that the approach is valid and is ideal for the development of new tunnel operating conditions and new tunnels. Using the numerical models, test facilities are compared to each other. For the medium enthalpy condition presented here, the tunnels produce similar test conditions, with the bigger ones having greater levels of nozzle supply pressure relative to the diaphragm rupture pressure, and greater test time.
Experimental Investigation of Supersonic Combustion in the HIEST and HEG Free Piston Shock Tunnels
46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2010
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Comparison of Supersonic Combustion Tests with Shock Tunnels, Flight and CFD
42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006
In 2002, the HyShot supersonic flight experiment was successfully launched and allowed to access experimental flight data for supersonic combustion. Ground based testing performed in the High Enthalpy Shock Tunnel (HEG) of the German Aerospace Center (DLR) allowed to reproduce the Mach 7.8 flight conditions. The present numerical work focuses on the computation of the experiments in HEG considering flows with and without combustion and fuel injection. Further, variations of the equivalence ratio and the resulting influence on the flow topology are studied.
Gasdynamical Detectors of Driver Gas Contamination in a High-Enthalpy Shock T\mnel
Simple gasdynamical devices consisting of a duct and a wedge have been applied to the detection of driver gas arrival in the test section of a high-enthalpy shock tunnel. Static pressure in the duct has been measured during a shot, and the time of driver gas arrival has been determined by the onset of the pressure rise, which indicates duct flow choking. The ability to detect driver gas in small concentrations is critical to the satisfactory performance of the device. Duct internal flows for various wedge angles have been numerically simulated to clarify the flow choking mechanism. The simulations give an idea of the improvement of detector sensitivity, and modified configurations of the detector are proposed. Flow visualization in the duct leads to a better understanding of pressure traces obtained, and pressure measurement data show a satisfactory degree of sensitivity. The arrival time of driver gas measured with the detectors is in good agreement with an analytical prediction based on a shock-bifurcation flow model. The useful test time in T5 with uncontaminated freestream is also demonstrated over a wide range of specific reservoir enthalpies. Nomenclature A e = stream-tube area at the entry of the subsonic region A exit = area at the duct exit • Ainiet = area at the duct inlet A t = stream-tube area at the throat of the subsonic region AR = aspect ratio of the duct inlet h = duct height ho = specific reservoir enthalpy M = local Mach number MI = Mach number at the duct inlet MOO = freestream Mach number p duct = static pressure in the duct of the detector Po-nozzle reservoir pressure P4-burst pressure of the main diaphragm w = duct width x = distance from the reference point to the shock wave (see Fig. 10) ft-shock angle y = ratio of specific heats 9 C = cone half-angle Oj = wedge angle at shock detachment #MR = wedge angle at the transition from regular to Mach reflection 6 W = wedge angle 0i = angle of attack of the duct or angle of the shock generator
Characterization of High-Enthalpy Flows
The chapter reports on the diagnostic tools that had been developed, qualified and successfully set in operation during the SFB259. Exemplary results are shown. Moreover a sub-chapter on in-flight instrumentation is provided.
CFD validation for hypersonic flight - Real gas flows
40th AIAA Aerospace Sciences Meeting & Exhibit, 2002
The aerodynamics of future hypersonic air-breathing vehicles will be greatly affected by high-enthalpy or "real gas" effects. It is the purpose of a recent NATO Research and Technology Organization study to assess the readiness of computational fluid dynamics to simulate high-enthalpy flows. This paper summarizes the results of this effort through the discussion of four test cases: a transverse cylinder, shock-shock interactions, blunt double-cones, and a large blunt cone-flare. The contributed CFD results are capable of capturing the main features of these flows, but quantitative comparisons are probably not sufficiently accurate for vehicle design. The study also shows that there are too few reliable high-enthalpy datasets to validate CFD codes.
Real gas flow characterization in the ONERA F4 high enthalpy wind tunnel
ICIASF'97 Record. International Congress on Instrumentation in Aerospace Simulation Facilities, 1997
The ONERA F4 Hot Shot wind tunnel provides hypersonic air flows at high enthalpy and high pressure total conditions. In such a wind tunnel, real gas effects are large yielding experimental difficulties to assess the test section free stream characteristics. Flow contamination was a problem for total enthalpy determination when using the frst arc chamber configuration, made of copper and organic materials. This point has been dramatically improved with the new arc chamber made of carbon materials. Test section fiee stream knowledge is achieved by direct means involving optical techniques and by indirect means, i.e. through the numerical rebuilding of experiments on nozzle and standard model flows. The free stream flow is observed to be close to equilibrium on data like pressure or transational temperature, while nitric oxide (NO) concentration measurement is rather close to a nonequilibrium situation. The possibility to model such results is discussed. Finally, example of force measurements on a capsule model is given to compare real gas with perfect gas results 0-7803-41 67-8
Preliminary On Design Tests of the M12REST Scramjet in the T4 Shock Tunnel
School of Mining and Mechanical Engineering Departmental Report, 2009
A report of the M12REST scramjet ground test program at ‘on - design’ test conditions, conducted from January 1 st to June 24 th , 2009 in the T4 Shock Tunnel Facility at the Centre for Hypersonics, The University of Queensland, is presented. The study was performed to investigate discrepancies between numerical and experimental results of a previous 2007 test program involving the M12REST scramjet engine. Off-design results of the engine in the 2007 study demonstrated good agreement between numerical and experimental results (Suraweera and Smart, 2009). However, on-design experimental results showed a large pressure region on the forward section of the inlet that could not be replicated using a computational fluid dynamics (CFD) code (White and Morrison, 1999). The present study trialled combinations of ten distinct boundary layer trip configurations, in order to investigate whether this large pressure region was the result of local flow separation. A blunt 3 mm radius leading edge and a longer 500 mm forebody were also separately tested. Three new ‘on - design’ flow conditions (four in total) were also tested. Pressure and heat transfer measurements were taken along the engine flowpath. A description of the T4 Shock Tunnel and its operating characteristics has been given. Drawings of the proposed test model and extraneous test articles have also been provided. All 45 test runs executed during the experimental campaign have been listed, along with the corresponding flow properties for four test conditions. Mean pressure and Stanton number distributions for significant tunnel runs, illustrating the effects of various boundary layer trip and engine fuelling configurations, have been presented. The fuel used was gaseous hydrogen. Supersonic and subsonic combustion was measured at a range of fuel equivalence ratios for two of the test conditions (3 and 4). Inlet injection was found to produce separated flow regions within the inlet, and hence the fuelling scheme was discontinued. Step injection was tested successfully at a range of equivalence 3 ratios. In terms of combustion induced increases in pressure, higher levels were seen when engine was run with the M11 enthalpy test condition 4. However, the engine was able to operate in true scramjet mode with the inflow of the M12 enthalpy test condition 3. Furthermore, the engine was found to be more stable at this condition as the combustion induced pressure rise was contained by the isolator.