RU2157909C1 - Supersonic pulse detonating ramjet engine and method of its functioning - Google Patents

Abstract

FIELD: proposed engine includes supersonic air intake, supersonic mixing chamber, supersonic combustion chamber, supersonic nozzle, engine starting device and fuel feed system. SUBSTANCE: fuel feed system includes pylons with nozzles and valves for change of fuel feed which are connected with sensors recording passage of detonating waves from inlet to outlet of combustion chamber. At the moment of start of engine, fuel is fed and detonating wave is initiated; further operation of engine is ensured due to change of fuel feed forming lean and rich mixtures in combustion chamber and causing change in direction and rate of motion of wave relative to combustion chamber from its outlet to inlet at rich mixture and in opposite direction at lean mixture; in extreme case, by pre air at retained direction of motion of wave against flow. EFFECT: increased specific pulse; reduced calorific intensity of engine passage during flights at high supersonic speeds. 3 cl, 1 dwg

Description

 The invention relates to the class of WFD conventionally referred to as "pulsating detonation engines" (SDA). The main distinguishing feature of these engines is that the combustion of a mixture of air and fuel occurs in unsteady ("pulsating") shock waves.

 All proposed schemes of these engines can be divided into two types - "valve" and "valveless" schemes. The main difference between these types of traffic rules is the way they control the processes of filling the combustion chamber with a fuel-air mixture and freeing it from combustion products. In valveless traffic rules, these processes are associated only with the dynamics of pressure changes in the combustion chamber. In multi-chamber valve circuits, these processes are controlled by rotating valves or other types of valves.

 In most SDA implementations, the combustion of the mixture in each operation cycle is initiated using an external ignition source. Such a source may be, for example, a “detonation tube”. In this case, the ignition of the mixture is carried out by a detonation wave emerging from the specified tube. The tube itself is periodically filled with a mixed air-fuel mixture, and the detonation wave in it is initiated by an electric discharge of the required power for this. If the realization of detonation in the tube does not present a particular problem, then the creation of a detonation wave in the chamber with its help, and the wave propagating through the chamber to the left, is possible only for “initiators,” i.e. Detonation waves of sufficiently high power emerging from the tube. Along with the use of a detonation tube, other methods of initiating a detonation wave (electric discharge in a chamber, laser systems, etc. S. Eidelman and W. Grossman "Pulsed Detonation Engine Experimental and Theoretical Rewiew", 1992, AIAA92-3168; TEBratkovich and TRA Bussing "A Pulse Detonation Engine Performance Model", 1995, AIAA95-3155).

 The invention solves the problem of increasing the specific impulse and reducing the heat stress of the engine path when flying at high supersonic speeds (for a hydrogen-air engine with flight Mach numbers M from 4.5 to 7.5).

 The technical result is achieved in a supersonic pulsating detonation ramjet engine (SPDD) containing a supersonic air intake, a supersonic mixing chamber, a supersonic combustion chamber, a supersonic nozzle, an engine start device, a fuel supply system including pylons with nozzles and valves for changing the fuel supply mode, connected through the fuel supply control system with sensors for detecting the passage of detonation waves of specified distances from the inlet and outlet of the camera with Gorania.

 The technical result is also achieved in the method of operation of a supersonic pulsating detonation ramjet engine (SPDD), which consists in the fact that at the time of starting the engine supply fuel and initiate a detonation wave, further engine operation is provided sequentially-periodically, changing the fuel supply, realizing in the chamber rich and poor air-fuel mixture and causing a change in the direction and velocity of the wave relative to the combustion chamber from its exit to ode on the rich mixture in the opposite direction of lean, in an extreme case - the fresh air, while maintaining the direction of motion of the waves against the flow.

 The invention is a new valveless scheme of a ramjet with a supersonic flow in the combustion chamber and with combustion in a pulsating detonation wave - "supersonic pulsating detonation ramjet engine - SPDD". In SPAPD, a pulsating non-stationary process is initiated by periodic interruptions in fuel supply. In SPDD, a detonation wave in a rich mixture and a detonation wave periodically replacing it in a lean mixture or a “head” shock wave propagate in a supersonic flow, rather than in a stationary gas or in a subsonic flow, as in the SDA of the types discussed above. Secondly, there is no permanent “external ignition source” in this circuit. An external ignition source is needed in the SDDPD only for starting.

 The invention is illustrated in the drawing. The supersonic pulsating detonation ramjet engine (SPDD) contains a supersonic air intake 1, a supersonic mixing chamber 2, a supersonic combustion chamber 3, a supersonic nozzle 4, an engine starting device 5, a fuel supply system 6 including pylons 7 with nozzles 8 and change valves 9 the fuel supply mode, connected through the fuel supply control system 10 with the sensors 11 for detecting the passage of detonation waves of predetermined distances from the input and output of the combustion chamber.

SPAPA operates as follows:
1. The oncoming air flow (for hydrogen-air SPDD with the number M ≈ 4.5–7.5 of Fig. 1, section 0) is inhibited in oblique jumps of the supersonic air intake 1 to M ≈ 2.5 –4.5 (section 1).

 2. In section 2, the air flow is additionally (slightly) slowed down in the oblique jumps that occur during the flow around the pylons 7 installed in this section for fuel supply.

3. After passing the fuel pylons 7, the air enters the mixing chamber 2, the length of which is L _m much greater than the caliber of the fuel pylons 7 and sufficient to form a homogeneous air-fuel mixture with a given coefficient of excess air (a ≥ 1). Depending on the phase of the engine cycle, different amounts of fuel are supplied from the fuel pylons. Thus, the control of the engine's operating cycle is carried out by controlling the fuel supply.

 3.1. In the case when the fuel from the pylons is supplied in a "larger" quantity, an air-fuel mixture close to a homogeneous air-fuel mixture with a given coefficient of excess air (α ≈ 1 "rich" mixture) and a supersonic flow rate is formed at the exit from the mixing chamber 2.

 3.2. In the case when the fuel is supplied in a "small" amount (or not supplied at all), a close to homogeneous air-fuel mixture with an excess air coefficient α> 1 (in the limit of "clean" air) ("poor" mixture) is formed at the outlet of the mixing chamber 2 and supersonic flow velocity.

 4. The cycle of the engine is as follows.

 4.1. The rich air-fuel mixture coming from the mixing chamber 2 into the combustion chamber 3, against the flow, propagates a detonation wave in which the combustion of the air-fuel mixture occurs. The combustion products enter the nozzle 4 and, expanding, provide engine thrust. The speed of propagation of the detonation wave exceeds the flow rate of the air-fuel mixture, therefore, the detonation wave moves towards the entrance to the combustion chamber 3 relative to the engine.

 4.2. At the moment when the detonation wave reaches a predetermined point near the entrance to the combustion chamber 3 mode, the fuel supply is changed. The detonation wave continues to move towards the entrance to the combustion chamber 3 until the remainder of the rich air-fuel mixture continues to enter the combustion chamber 3.

 4.3. After the rich air-fuel mixture at the entrance to the combustion chamber 3 is replaced by a flow of lean mixture or "clean" air and the detonation wave enters this flow, the detonation wave either becomes less intense (in the case of entering the lean mixture), or passes into a shock wave . In both cases, the detonation or shock wave continues to propagate upstream. But the propagation velocity of these waves is less than the speed of the incident flow and, therefore, the waves are carried by the flow in the direction of exit from the combustion chamber 3.

 4.4. At the moment when the wave reaches a predetermined point near the exit of the combustion chamber 3 from the fuel pylons 7, a "large" amount of fuel begins to be supplied. The fuel supply mode changes at the moment of passage of the detonation or shock wave of a given section near the exit of the combustion chamber 3.

 4.5. After the detonation wave enters the rich air-fuel mixture, an increase in the intensity of the detonation wave occurs. If a shock wave enters a rich air-fuel mixture, the air-fuel mixture ignites behind the shock wave (due to the sufficiently high temperature of the flow behind the shock wave of ~ 1100 K). The released energy of fuel combustion behind the shock wave leads to an increase in the intensity of the latter and its transition to the detonation wave.

 4.6. Formed detonation wave begins to move towards the entrance to the combustion chamber 3 and the engine cycle is repeated.

 The invention can be used as an engine for aircraft for various purposes), and the method of functioning of its fuel supply system, mixing and combustion chambers in magneto-gas-dynamic generators operating in batch mode.

Claims (2)

 1. Supersonic pulsating detonation ramjet engine (SPDD), containing a supersonic air intake, a supersonic mixing chamber, a supersonic combustion chamber, a supersonic nozzle, an engine start device, a fuel supply system including pylons with nozzles and valves for changing the fuel supply mode, connected through fuel supply control system with detectors for detecting passage of detonation waves of predetermined distances from the input and output of the combustion chamber.  2. The method of functioning of a supersonic pulsating detonation ramjet engine (SPDD), which consists in the fact that at the time of engine start, fuel is supplied and a detonation wave is initiated, further engine operation is provided sequentially from time to time, changing the fuel supply, realizing a rich and poor air-fuel mixture and causing a change in the direction and speed of the wave relative to the combustion chamber from its exit to the entrance along the rich mixture and in the opposite direction In the extreme case - in clean air, while maintaining the direction of motion of the wave against the flow.