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Experimental investigation of engine dynamics and controls for 48-inch ramjet engine in free jet facility at Mach number 2.76 and altitudes 68,000 to 82,000 feet
A computational analysis of a ramjet engine at Mach 3.5 has been conducted and compared to results obtained experimentally. This study focuses on the behavior of the inlet both with and without combustor backpressure. Increased backpressure results in separation of the body side boundary layer and a resultant static pressure rise in the inlet throat region. The computational results compare well with the experimental data for static pressure distribution through the engine, inlet throat flow profiles, and mass capture. The computational analysis slightly underpredicts the thickness of the engine body surface boundary layer and the extent of the interaction caused by backpressure; however, the interaction is observed at approximately the same level of backpressure both experimentally and computationally. This study demonstrates the ability of two different Navier-Stokes codes, namely RPLUS and PARC, to calculate the flow features of this ramjet engine and to provide more detailed information on the process of inlet interaction and unstart.
Limitations of ramjet engines for spacecraft and launch vehicles
Basic periods in the history of the development of ramjet engine theory are cited. The periods include the first experimental tests as well as the development of basic ideas and theoretical development of the cosmic ramjet engine.
Operational and design characteristics of ramjet engines, and requirements for hypersonic aircraft
Flow field around pylon-mounted dummy ramjet engine of X-15-2 airplane prior to hypersonic ramjet engine flight tests
Flight tests of early ramjet engines
Water cooled tubular leading edge for hypersonic ramjet engine inlets, discussing wind tunnel analysis
Four different combustion efficiencies commonly used for assessing ramjet engines are compared. The mixture ratios cover a range from stoichiometric to an equivalence ratio of 0.2, and the polyethylene/air propellant system is used. The ratio of effective to ideal temperature rise is taken as reference efficiency. As might be expected, major differences can be observed near stoichiometric and down to equilvalence ratios of 0.5. These are quantitatively demonstrated.
Instrumentation for testing hypersonic ramjet engine on X-15A-2 aircraft
Inflight thrust and drag measuring device for hypersonic ramjet engine on X-15A-2 aircraft
Ground and flight tests of ramjet engines in 1942-1944
The full Navier-Stokes solver, RPLUS, has been used to compute the flow field of a ramjet engine in the low supersonic operating regime. Computations have been made for the case where hydrogen is transversely injected and ignited using nine species and eighteen reactions to model the combustion process. The flow fields for two methods of hydrogen injection have been computed and compared to the available experimental data. The purpose of these computations was to assess the mixing effectiveness of the injected hydrogen with the primary supersonic stream. Results indicate significant ignition delay resulting from the poor mixing dynamics in the combustor section.
Approximation of ramjet exhaust plume effects on external pressure of nozzle extension of X-15 aircraft
Combustion instability in ramjets is a complex phenomenon that involve nonlinear interaction between acoustic waves, vortex motion and unsteady heat release in the combustor. To numerically simulate this 3-D, transient phenomenon, enormous computer resources (time, memory and disk storage) are required. Although current generation vector supercomputers are capable of providing adequate resources for simulations of this nature, their high cost and limited availability, makes such machines less than satisfactory for routine use. The primary focus of this study is to assess the feasibility of using highly parallel computer systems as a cost-effective alternative for conducting such unsteady flow simulations. Towards this end, a large-eddy simulation model for combustion instability was implemented on the Intel iPSC/860 and a careful study was conducted to determine the benefits and the problems associated with the use of such machines for transient simulations. Details of this study along with the results obtained from the unsteady combustion simulations carried out on the iPSC/860 are discussed in this paper.
Computer modelling was used with two different designs of an advanced turbofan-ramjet in order to derive performance predictions. The engine would enable an aircraft to take-off, accelerate to Mach 5.0, and climb to 90,000 ft. The two concepts included a turbofan with a ramjet annularly wrapped around it and a side-by-side configuration with the ramjet having a rectangular shape and mounted alongside the turbofan. The studies were performed to model weight, length, fuel efficiency, and the requirements of the thrust/drag ratio to exceed unity over the entire flight path. LH2 would be used for fuel and to regeneratively cool the combustion chamber. Turbofan operation with and without afterburner and with and without the ramjet inlet open were examined, as were variable areas for the burners. A side-by-side configuration displayed the best performance predictions, with a ramjet mass flow being 75 percent that of the turbofan and maximum temperatures being equal.
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