RU2084675C1 - Chamber for puls detonation engine - Google Patents

Abstract

FIELD: engine engineering. SUBSTANCE: chamber consists of Laval nozzle and Hartmann resonator axially alined inside the housing. Between the inner side of the housing and outer side of the nozzle is a space. The space is a mixing chamber whose inlet portion is the throat that further goes into the diverging portion. EFFECT: improved design. 1 dwg

Description

 The invention relates to pulsating jet engines with resonant combustion chambers, as well as to devices for burning fuel.

 Known gas-jet generators Hartmann, operating in a pulsating mode of flow of the working fluid and are currently used as powerful acoustic emitters. With the discovery of the effect of increasing the temperature at the bottom of the resonator in a fraction of a second, they began to be used for igniting combustible fuel mixtures, and also when high-temperature heat sources were needed (Lyakhov V.N. Podlubny V.V. Titarenko V.V. Impact of shock waves and jets on structural elements. M. Mechanical Engineering, 1989, 392 pp.). One of the options for the structural embodiment of this effect is the "Pulsating device for burning fuel" according to ed. St. USSR N 687313, 1979, however, this device cannot be used to create traction.

 Closest to the claimed device, both in principle of operation and in technical design, is a ramjet engine (application FRG N 4139338, IPC F 02 K 1/04 and F 02 K 7/10, 1982). It creates traction due to the pulse (pulsating) regime of the expiration of the working fluid resulting from the combustion of the fuel-air mixture. This mode of operation is implemented in a resonant tube, creating a vacuum due to oscillations of the column of the working fluid, and air is supplied through annular slots. Despite the fact that this device has much in common with the claimed, it cannot realize the detonation mode of combustion.

 The objective of the invention is to increase the efficiency of the device.

 This problem can be solved by detonation combustion of a fuel-air mixture.

 The task in the claimed device is achieved by the fact that the principle of operation of the Hartmann generator is the basis for the development of its detonation chamber. In this case, the resonator is made in the form of a tube closed on one side, and a cavity is formed between the inner surface of the housing and the outer surface of the nozzle, which is a displacement chamber, the output part of which is a critical section with a further transition to a supersonic nozzle with an external expansion with a truncated central body.

 The drawing shows a chamber of a pulsating detonation combustion engine, which consists of a resonator 1 and a supersonic nozzle 2 installed in a single housing 3.

 The resonator 1 is designed to create shock waves and to initiate detonation combustion. It is made in the form of a tube of cylindrical (slightly conical) shape, closed at one end and facing the open end towards the nozzle.

 The supersonic nozzle 2 is designed to accelerate the working mixture to speeds with M> 2 and direct it into the interior of the resonator 1, as well as to disperse the gases flowing from the cavity of the resonator.

 The resonator 1 and the supersonic nozzle 2 are installed coaxially in the housing 3 and in such a way that a cavity is formed between the inner surface of the housing and the outer surface of the nozzle, which is the mixing chamber “a” intended to create a working mixture. The output of mixing chamber “a” is a critical section.

 On the end and side surfaces of the housing 3 are evenly placed inlet channels for the oxidizing agent (gas) and fuel (gas or liquid). Moreover, the axis of symmetry of the channels for better mixture formation. The output of the working mixture from the chamber "a" is through the critical section of the external expansion nozzle.

 The engine chamber is tuned to a predetermined mode of its operation by changing the critical section area. This is achieved by selecting the thickness of the gasket 4, installed between the flanges of the housing 3 and the supersonic nozzle 2, which are fastened together by bolts 5.

 The camera is a pulsating detonation combustion engine as follows.

 When the fuel components are fed into the mixing chamber "a", a mixing process takes place in it. The resulting working mixture, flowing out through the critical section, acquires supersonic speed. A characteristic design feature is an external expansion nozzle, the mode of which does not depend on the ambient pressure, i.e. always running in steady state. This is because the pressure in the cavity "a" is equal to the pressure of the environment due to communication with her windows 6.

 Accelerated to a speed of M≥2, the working mixture enters the internal cavity "b" of the resonator 1, in which the oscillatory process is excited with the formation of shock waves (Hartmann effect), which in turn generate detonation waves. When these waves collide with the closed end of the resonator, reflected shock waves form. In this case, there is a sharp increase in temperature and pressure (Springer effect), which leads to the occurrence of a detonation wave in the working mixture and its detonation combustion. The detonation wave, reflected from this part of the resonator 1, rushes to its output, blocking the path of the incoming working mixture. The detonation wave, meeting with the supersonic flow of the working mixture, forms a "gas shutter", which blocks the path of the supersonic flow of the working mixture into the resonator 1. Subsequently, the detonation products, expiring through the annular gap formed between the nozzle 2 and the resonators 1, expand, which leads to pressure reduction. When the pressure of the detonation products and the working mixture are equalized, a “gas lock” is opened at the nozzle exit and the detonation wave rushes out through the “g” cavity. The working mixture rushes into the resonator 1 and the process is repeated again.

 The traction force is created due to the interaction of the detonation wave with the bottom of the resonator (traction wall), as well as due to the reactive force formed by the supersonic gas stream flowing through the nozzle. The total thrust impulse of a pulsating detonation combustion engine is directly proportional to the pulsation frequency and the pressure on the bottom of the resonator. By changing these parameters, it is possible to regulate the thrust vector module.

The pressure pulsation in the resonator 1 depends on the depth of the resonator and is determined only by the number M of the incident jet. In this case, the condition must be met
L> D
where L is the depth of the resonator; D is the inner diameter of the resonator.

 The purity of the oscillations is determined by the depth of the resonator L and the speed of wave propagation in it.

 Thus, increasing the efficiency of the device lies in the fact that during detonation combustion of the fuel mixture, the temperature and pressure are much higher than similar parameters obtained by conventional combustion of the same amount of the working mixture. Therefore, the work done by the detonation products will be more than the work done by the combustion products.

 In addition, this engine chamber does not need a special ignition or initiation system. The proposed design of the chamber allows to obtain the frequency of detonation processes 1.2 orders of magnitude higher than the frequency of existing detonation combustion engines.

Claims (1)

 A chamber of a pulsating detonation combustion engine containing a supersonic nozzle located in the housing and coaxially located with it in the form of a tube facing one open ring towards the expiration of the working fluid, characterized in that the tube is closed at the other end, between the inner surface of the housing and the outer surface of the nozzle a cavity is formed, which is a mixing chamber, the output part of which is a critical section with a further transition to a supersonic nozzle of external expansion with truncated m body.