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A shock-induced combustion ramjet engine (abbreviated as shcramjet; also called oblique detonation wave engine; also called standing oblique detonation ramjet (sodramjet); [1] or simply referred to as shock-ramjet engine) is a concept of air-breathing ramjet engine, proposed to be used for hypersonic and/or single-stage-to-orbit propulsion applications. [2]
The shcramjet engine geometry is simple and similar to scramjet, varying only in the combustor design. The engine includes a supersonic inlet followed by a combustion chamber and a nozzle, respectively. The inlet design is similar to a scramjet, in which the whole nose structure is used as inlet. Combustion in a shcramjet can occur in shock-induced combustion or detonation combustion, depending on the strength of the inducing shock. If ignition occurs far enough downstream that the ensuing combustion process does not influence the preceding shock, the combustion is said to be shock-induced. However, for extremely fast reactions, ignition occurs close to the preceding shock wave and the combustion couples with the shock wave and forms a detonation wave. [3] Therefore, detonation wave ramjet, or oblique detonation wave engine, is a particular case of shcramjet.
Though shock and detonation waves are related to high pressure loss during combustion, the theoretical total pressure loss associated with shcramjet combustor approaches that of the scramjet engine at increasing mach numbers.[ citation needed ] This fact, together with the simpler engine geometry with concomitant increase in component efficiencies, results in superior predicted performance at flight Mach numbers beyond 12.[ citation needed ]
This engine funnels a mixture of air and fuel at hypersonic speeds (more than five times the speed of sound) toward a ramp, which creates a shock wave. This shock wave heats the mixture and causes it to detonate, ejecting exhaust gasses. Such an approach burns nearly 100% of the fuel. In theory, vehicle speeds could reach 17 times the speed of sound. [4]
A critical challenge is to confine the detonation in a small area, without allowing it to direct energy upstream towards the fuel source or downstream where it loses force. In 2021 an experimental device maintained a detonation in a fixed location for 3 seconds, far longer than earlier attempts. [4] [5]
A shcramjet engine is similar to a scramjet engine; however, unlike the diffusive mode of combustion in a scramjet engine, shcramjet engine combustion takes place across a thin region of standing oblique shock and/or detonation waves stabilized over a wedge, blunt body, etc. Since combustion is confined to a narrow region across the igniting wave, the combustor length in a shcramjet can be significantly shorter than the scramjet, which requires a lengthy combustor for complete fuel-air mixing and combustion. Also, the shcramjet is believed to have a better overall propulsive performance than the scramjet at higher Mach numbers, especially above Mach 12. Recent researches have stipulated that shcramjet, alongside its other airbreathing variants, can act as an efficient high-speed vehicle propulsion system for SSTO flights. [6] These potential advantages have attracted substantial research on propulsive applications, as well as on the fundamental physical phenomena. [7]
A jet engine is a type of reaction engine, discharging a fast-moving jet of heated gas that generates thrust by jet propulsion. While this broad definition may include rocket, water jet, and hybrid propulsion, the term jet engine typically refers to an internal combustion air-breathing jet engine such as a turbojet, turbofan, ramjet, pulse jet, or scramjet. In general, jet engines are internal combustion engines.
A ramjet is a form of airbreathing jet engine that requires forward motion of the engine to provide air for combustion. Ramjets work most efficiently at supersonic speeds around Mach 3 and can operate up to Mach 6.
A magnetohydrodynamic drive or MHD accelerator is a method for propelling vehicles using only electric and magnetic fields with no moving parts, accelerating an electrically conductive propellant with magnetohydrodynamics. The fluid is directed to the rear and as a reaction, the vehicle accelerates forward.
A pulse detonation engine (PDE) is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture.
A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion, but where as a ramjet decelerates the air to subsonic velocities before combustion using shock cones, a scramjet has no shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone. This allows the scramjet to operate efficiently at extremely high speeds.
The Lightcraft is a space- or air-vehicle driven by beam-powered propulsion, the energy source powering the craft being external. It was conceptualized by aerospace engineering professor Leik Myrabo at Rensselaer Polytechnic Institute in 1976, who developed the concept further with working prototypes, funded in the 1980s by the Strategic Defense Initiative organization, and the decade after by the Advanced Concept Division of the US Air Force AFRL, NASA's MFSC and the Lawrence Livermore National Laboratory.
The NASA X-43 was an experimental unmanned hypersonic aircraft with multiple planned scale variations meant to test various aspects of hypersonic flight. It was part of the X-plane series and specifically of NASA's Hyper-X program developed in the late 1990s. It set several airspeed records for jet aircraft. The X-43 is the fastest jet-powered aircraft on record at approximately Mach 9.6.
A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, burner can, combustion chamber or flame holder. In a gas turbine engine, the combustor or combustion chamber is fed high-pressure air by the compression system. The combustor then heats this air at constant pressure as the fuel/air mix burns. As it burns the fuel/air mix heats and rapidly expands. The burned mix is exhausted from the combustor through the nozzle guide vanes to the turbine. In the case of a ramjet or scramjet engines, the exhaust is directly fed out through the nozzle.
A jet engine performs by converting fuel into thrust. How well it performs is an indication of what proportion of its fuel goes to waste. It transfers heat from burning fuel to air passing through the engine. In doing so it produces thrust work when propelling a vehicle but a lot of the fuel is wasted and only appears as heat. Propulsion engineers aim to minimize the degradation of fuel energy into unusable thermal energy. Increased emphasis on performance improvements for commercial airliners came in the 1970s from the rising cost of fuel.
The Boeing X-51 Waverider is an unmanned research scramjet experimental aircraft for hypersonic flight at Mach 5 and an altitude of 70,000 feet (21,000 m). The aircraft was designated X-51 in 2005. It completed its first powered hypersonic flight on 26 May 2010. After two unsuccessful test flights, the X-51 completed a flight of over six minutes and reached speeds of over Mach 5 for 210 seconds on 1 May 2013 for the longest duration powered hypersonic flight.
Scramjet programs refers to research and testing programs for the development of supersonic combustion ramjets, known as scramjets. This list provides a short overview of national and international collaborations, and civilian and military programs. The USA, Russia, India, and China (2014), have succeeded at developing scramjet technologies.
The air turborocket is a form of combined-cycle jet engine. The basic layout includes a gas generator, which produces high pressure gas, that drives a turbine/compressor assembly which compresses atmospheric air into a combustion chamber. This mixture is then combusted before leaving the device through a nozzle and creating thrust.
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This article briefly describes the components and systems found in jet engines.
Frederick Stucky Billig was an American aerospace engineer who was a pioneer in the development of scramjet propulsion.
An airbreathing jet engine is a jet engine in which the exhaust gas which supplies jet propulsion is atmospheric air, which is taken in, compressed, heated, and expanded back to atmospheric pressure through a propelling nozzle. Compression may be provided by a gas turbine, as in the original turbojet and newer turbofan, or arise solely from the ram pressure of the vehicle's velocity, as with the ramjet and pulsejet.
Space Engine Systems Inc. (SES) is a Canadian aerospace company and is located in Edmonton, Alberta, Canada. The main focus of the company is the development of a light multi-fuel propulsion system to power a reusable spaceplane and hypersonic cruise vehicle. Pumps, compressors, gear boxes, and other related technologies being developed are integrated into SES's major R&D projects. SES has collaborated with the University of Calgary to study and develop technologies in key technical areas of nanotechnology and high-speed aerodynamics.
Kholod (Холод) is an experimental Russian rocket project. The hypersonic rocket uses a scramjet engine and was created to exceed Mach 6+ The prototype consists of a Soyuz TMKB with liquid hydrogen and modified fillings from the SA-5 Gammon missiles. The entire rocket, including the four booster rockets, is 12 metres (39 ft) long and 750 millimetres (30 in) in diameter. The project led to other Russian hypersonic rockets like the Igla rocket craft and the Yu-71 boost-glide warhead.
A rotating detonation engine (RDE) uses a form of pressure gain combustion, where one or more detonations continuously travel around an annular channel. Computational simulations and experimental results have shown that the RDE has potential in transport and other applications.
Pressure gain combustion (PGC) is the unsteady state process used in gas turbines in which gas expansion caused by heat release is constrained. First developed in the early 20th century as one of the earliest gas turbine designs, the concept was mostly abandoned following the advent of isobaric jet engines in WWII.
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