Browse Topic: Scramjet engines
What if the future of space travel were to look less like Space-X’s rocket-based Starship and more like NASA’s “Hyper-X,” the hypersonic jet plane that, 20 years ago this year, flew faster than any other aircraft before or since?
Hypersonic flight vehicles have potential applications in strategic defence, space missions, and future civilian high-speed transportation systems. However, structural integration has significant challenges due to extreme aero-thermo-mechanical coupled effects. Scramjet-powered air-breathing hypersonic vehicles experience extreme heat loads induced by combustion, shock waves and viscous heat dissipation. An active cooling thermal protection system for scramjet applications has the highest potential for thermal load management, especially for long-duration flights, considering the weight penalty associated with the heavier passive thermal insulation structures. We consider the case of active cooling of scramjet engine structural walls with endothermic hydrocarbon fuel. We have developed a semi-analytical quasi-2D heat transfer model considering a prismatic core single cooling channel segment as a representative volume element (RVE) to analyse larger-scale problems. The model includes various mechanisms of heat transfer as well as the coolant’s energy transport (non-cracking fuel). Using this model, we aim to study the effect of active cooling on the system's thermal behaviour and heat transfer characteristics. The model predicts the temperature distribution in the channel and the interfaces. Parametric analysis is undertaken to assess the active cooling system design parameters which affect the heat transfer characteristics of the system. Such semi-analytical models help investigate the effect of the cooling channel geometry and flow parameters, which can be a decisive prerequisite to the configuration design of a scramjet engine.
The development of hypersonic missiles represents the most significant advancement of defense weaponry since the 1960s. However, they also pose unique challenges for both design and technology. The term “hypersonic” refers to any speed faster than five times the speed of sound, or above Mach 5. Modern hypersonic missile systems require extensive communications interconnects within a highly confined space. This space requirement creates a demand for solutions combining small form factor with reduced weight and rugged construction to withstand high vibration and impact conditions from deployment to target. Currently there are two types of hypersonic weapons. Hypersonic glide vehicles (HGVs), also known as boost-glide vehicles, typically launch from ballistic missiles and are released at a specific altitude, speed, and with the flight path tailored to a target without being powered. Hypersonic cruise missiles (HCMs) are powered all the way to their targets, flying at lower altitudes than HGVs and launched from rockets or jet aircraft. Power for HCMs comes from air-breathing scramjet engines, which have been in development since the 1950s and most successful since the 2000s.
Taking measurements in a scramjet engine is particularly challenging because of the harsh testing environment. Any probe inserted in the flow would generate shock waves, strongly perturbing the flow. Coherent Anti-Stokes Raman spectroscopy (CARS) is a non-intrusive laser-based measurement technique that has been implemented successfully to measure temperature and species concentrations in ducted scramjet engines.
Molecular-based optical diagnostics techniques capable of obtaining simultaneous measurements of multiple fluid properties are critically important for characterizing hypersonic air-breathing engines, such as scramjet engines and scramjet-rocket combined cycle engines. Correlations between those properties lead to a more detailed understanding of complex flow behavior, and aid in the development of multiparameter turbulence models required for supersonic combustion engine flow path predictions.
A capability for real-time computational simulation of aeroheating has been developed in support of the Hyper-X program, which is directed toward demonstrating the feasibility of operating an air-breathing ramjet/scramjet engine at mach 5, mach 7, and mach 10. The simulation software will serve as a valuable design tool for initial trajectory studies in which aerodynamic heating is expected to exert a major influence in the design of the Hyper-X airplane; this tool will aid in the selection of materials, sizing of structural skin thicknesses, and selection of components of a thermal-protection system (TPS) for structures that must be insulated against aeroheating.
From Summary: The ramjet, propelled YHJ-1 Hiller Helicopter and 8RJ22 ramjets were u ed as test equipment for a general study of the problem of rotor tip-mounted jet, engines. Air flow through the helicopter rotor, and particularly in the neighborhood of the tipjet engines, has been visualized by using smoke filaments. Notion pictures were taken at speeds ranging from 64 to 1000 pictures per second, both on the whirlstand and the YHJ-1 helicopter. The pictures reveal details of the flow in the region of'he tipjet engine, as well as overall flow through the helicopter rotor in flight.
When we were first invited to participate in this panel discussion, it was suggested that since McDonnell has had some experience with pulse jet, ram jet, pressure jet, gas turbine, and reciprocating engines we might comment upon the application of these various propulsion systems to the helicopter.
From Summary: The problem of supplying additional power to a helicopter rotor for take-off or hovering under overload, hot-day, or altitude conditions is discussed briefly, and the boost system requirements are defined qualitatively. The Marquardt Aircraft Co. is in the process of developing a novel ramjet engine to meet these requirements under the sponsorship of the United States Air Force, The progress to date is reviewed, and the eventual application of this engine is discussed.
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