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A pulse compression detonation system (PCD-system) is a combination of pulse detonation and compression systems.
A prototype of the PCD-system has been made at the National Technical University Kharkiv Polytechnic Institute in Ukraine in 2017. The measurements of the prototype with the detonation tube diameter of 20 mm and its length of 600 mm were taken. The device was operated using the mixture of atmospheric air and LPG fuel. In 2019 the device started operating on the mixture of atmospheric air and petroleum. The shock wave velocity at the open end of the tube reached 1700 m/s. The frequency of device pulsations was 23-24 Hz. [1] The deflagration-to-detonation transition (DDT) occurred due to the mixture heating and the compression of it.
A cooperation between the National Technical University "Kharkiv Polytechnic Institute" and the University of Warmia and Mazury in Olsztyn started to investigate an efficiency of the PCD-system as a detonation gun for coating technology.
PCD-system includes the piston compressor 1 with the cylinder 2. The crankshaft 4 connected to the external drive is used for the reciprocal motion of the piston 3. The intake valve 7 arranged inside the intake port 6 of the cylinder head. The air supply system 8 is connected to the port 6. The fuel can be supplied both immediately into the cylinder 2 of the compressor and into the inlet port 6. The detonation tube 9 is connected to the cylinder 2 through the exhaust port 10.
PCD-system operates in the following way: The crankshaft 4 starts moving in a circular motion by the external drive. During the motion of the piston 3 from the top dead center (TDC) to the bottom dead center (BDC) the intake valve 7 is opened, and the detonable gas mixture is pumped into the cylinder 2 of the compressor 1 through the intake port 6 using the supply system 8. As soon as the BDC is reached the valve 7 is closed. Due to the further motion of the piston 3 from the BDC to the TDC the compression of combustible mixture occurs in the cylinder 2 and in the detonation tube 9. This results in an increase of the density, the temperature, and the pressure of combustible mixture at a closed end of the detonation tube 9 and inside the tube itself. As the piston approaches the TDC the combustible mixture is self-ignited due to the compression of it. Then, the deflagration to the detonation transition occurs in the detonation tube 9. The output of detonation products from the tube 9 happens in a short period of time, when the piston is near the TDC. Then, the process is repeated.
A pulse compression detonation system has been designed to solve the problem of a high-frequency efficient initiation of a detonation in fuel-air mixtures. Instead of the Shchelkin spiral, U-bend tubes and an electrical treatment of detonable mixture, a technique of an ultra-fast pressurized filling of a detonation tube with a preheated detonable gaseous mixture is applied to reduce a time and a length of DDT in the tube.
PCD-system is applied in techniques of a generation of pulsed high-speed hot gas flows and also the acceleration of solid particles and drop-liquid medium. The PCD-system can be used by pulse detonation engines to initiate the detonation, for the detonation coating, to solve the problems related to crushing of minerals, abrasive or water blasting, to produce aerosols, for gas detonation lasers, and as a vibrator machine.
The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values.
In engineering, the Miller cycle is a thermodynamic cycle used in a type of internal combustion engine. The Miller cycle was patented by Ralph Miller, an American engineer, US patent 2817322 dated Dec 24, 1957. The engine may be two- or four-stroke and may be run on diesel fuel, gases, or dual fuel.
A pulsejet engine is a type of jet engine in which combustion occurs in pulses. A pulsejet engine can be made with few or no moving parts, and is capable of running statically.
A two-strokeengine is a type of internal combustion engine that completes a power cycle with two strokes of the piston during one power cycle, this power cycle being completed in one revolution of the crankshaft. A four-stroke engine requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust functions occurring at the same time.
An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines.
A four-strokeengine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:
Knocking in spark ignition internal combustion engines occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise point in the piston's stroke. Knock occurs when the peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive.
An intercooler is a mechanical device used to cool a gas after compression. Compressing a gas increases its internal energy which in turn raises its temperature. An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. Intercoolers have a variety of applications, and can be found, for instance, in air compressors, air conditioners, refrigeration, gas turbines, and automotive engines. They are widely known as an air-to-air or air-to-liquid cooler for forced induction internal combustion engines, used to improve volumetric efficiency. This is accomplished by increasing intake air density through nearly constant pressure cooling.
A pulse detonation engine (PDE) is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture. The engine is pulsed because the mixture must be renewed in the combustion chamber between each detonation wave and the next. Theoretically, a PDE can operate from subsonic up to a hypersonic flight speed of roughly Mach 5. An ideal PDE design can have a thermodynamic efficiency higher than other designs like turbojets and turbofans because a detonation wave rapidly compresses the mixture and adds heat at constant volume. Consequently, moving parts like compressor spools are not necessarily required in the engine, which could significantly reduce overall weight and cost. PDEs have been considered for propulsion since 1940. Key issues for further development include fast and efficient mixing of the fuel and oxidizer, the prevention of autoignition, and integration with an inlet and nozzle.
Forced induction is the process of delivering compressed air to the intake of an internal combustion engine. A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air. An engine without forced induction is considered a naturally aspirated engine.
A refrigerator designed to reach cryogenic temperatures is often called a cryocooler. The term is most often used for smaller systems, typically table-top size, with input powers less than about 20 kW. Some can have input powers as low as 2–3 W. Large systems, such as those used for cooling the superconducting magnets in particle accelerators are more often called cryogenic refrigerators. Their input powers can be as high as 1 MW. In most cases cryocoolers use a cryogenic fluid as the working substance and employ moving parts to cycle the fluid around a thermodynamic cycle. The fluid is typically compressed at room temperature, precooled in a heat exchanger, then expanded at some low temperature. The returning low-pressure fluid passes through the heat exchanger to precool the high-pressure fluid before entering the compressor intake. The cycle is then repeated.
In a reciprocating engine, the cylinder is the space in which a piston travels.
In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word manifold comes from the Old English word manigfeald and refers to the folding together of multiple inputs and outputs.
In internal combustion engines, water injection, also known as anti-detonant injection (ADI), can spray water into the incoming air or fuel-air mixture, or directly into the combustion chamber to cool certain parts of the induction system where "hot points" could produce premature ignition. In jet engines it increases engine thrust at low speeds and at takeoff.
A valveless pulsejet is the simplest known jet propulsion device. Valveless pulsejets are low in cost, light weight, powerful and easy to operate. They have all the advantages of conventional valved pulsejets, but without the reed valves that need frequent replacement - a valveless pulsejet can operate for its entire useful life with practically zero maintenance. They have been used to power model aircraft, experimental go-karts, and unmanned military aircraft such as cruise missiles and target drones.
In a spark ignition internal combustion engine, Ignition timing refers to the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.
The term six-stroke engine has been applied to a number of alternative internal combustion engine designs that attempt to improve on traditional two-stroke and four-stroke engines. Claimed advantages may include increased fuel efficiency, reduced mechanical complexity, and/or reduced emissions. These engines can be divided into two groups based on the number of pistons that contribute to the six strokes.
A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.
A two-stroke diesel engine is an internal combustion engine that uses compression ignition, with a two-stroke combustion cycle. It was invented by Hugo Güldner in 1899.
An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is applied typically to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into useful kinetic energy and is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where weight or size of the engine is important.