RU2315193C1 - Ramjet engine with lengthwise heat-mass distribution - Google Patents

Abstract

FIELD: rocketry.

SUBSTANCE: proposed ramjet engine contains air intake, generator with propellant combustion chamber with fuel unit and exit nozzle. Propellant carrying sections with nozzles for efflux of propellant jets from inner spaces of sections into inner space of combustion chamber are installed in combustion chamber and connected to control unit. Nozzles in each propellant carrying section are distributed over perimeter of combustion chamber, and their axes are pointed at angle of 90°>β>0° to axis of combustion chamber. Propellant charges differing in chemical composition and aggregative state are arranged in different propellant carrying sections. One or several propellant carrying sections are installed in narrowing (subsonic) part of engine exit nozzle.

EFFECT: improved mixing of propellant components providing complete combustion of propellant, improved stability of burning process in combustion chamber of ramjet engine.

3 cl, 5 dwg

Description

The invention relates to aircraft engine manufacturing, and in particular to ramjet engines, and can be used in propulsion systems of aircraft (high-speed aircraft). These include combined ramjet engines (ATRMs) and ramjet rocket engines (RPDs).

The problem of creating an effective propulsion system for operation in a wide range of altitudes and flight speeds is associated with the development of ramjet and RPD. Increased requirements for modern ramjet and their elements are determined by a wide range of heights (N = 0 ... 40 km) and application speeds (M = 2 ÷ 8) of the aircraft. On the agenda were issues related to the development of multi-mode ramjet rams with flow-controlled gas generators operating on high-energy fuels. Such ramjet engines contain in the primary combustion products in the gas generator a large amount of finely divided solid high-energy phase (> 30% by weight). There is a need to solve new problems for their efficient combustion in the combustion chamber. So, at a flight speed corresponding to the number M = 7, the temperature of the subsonic air stream entering the air chamber reaches T _B ≈ 2100 K. Studies show that a high temperature of the air stream improves the combustion of high-energy particles of the solid phase located in the entangled (with the air flow) gas-generating jets, but reduces the combustion efficiency of the gas phase.

As you know, the efficiency of the processes of mixing and combustion in the diffusion mode depends on the reduced length of the combustion chamber X _pr :

where L _cc is the length of the combustion chamber;

D _x - the diameter of the combustion chamber;

To _With - the number of nozzles of the gas generator;

α is the coefficient of excess air;

T _B - air temperature at the inlet to the chamber.

The deterioration of the diffusion process of combustion of the gas phase at a high temperature of the satellite air stream is associated with an increase in the lengths of diffusion jets and flares (Sosounov V.A. Some problems Concerning Optimal Ducted Rocket Engine with secondary Burning // Procedings of the 2rd ISABE Conf. 1974). On the contrary, at low flight speeds (Mach number M≈2) and, accordingly, low air flow temperatures, the combustion of the gas phase improves, but the combustion of solid particles sharply worsens.

Known solid-propellant rocket-propelled engine (RPDT) (Anti-aircraft missile systems air defense SV. Technique and armament, No. 5-6, 1999), which has a cylindrical gas generator with a charge burning at the end. Re-enriched with combustible substances fuel jets through nozzles flow from the gas generator into the air chamber, where they are mixed and burned out in a satellite air stream coming from the air intake. A feature of the working process in the engine was concentrated (localized) at the beginning of the air chamber air supply from the air intake and fuel from the gas generator. Due to the large chamber length and low value of the fuel stoichiometry coefficient L ₀ depending on the air excess coefficient α, a high completeness of burning η = 0.87 ÷ 0.95 of low calorific value fuel Hu <5000 kcal / kg in a satellite air flow was obtained. The low values of the braking temperature of the air flow T _B ≤500 K entering the air chamber also contributed to a good mixing of the propellant fuel jets with the air flow and their afterburning.

The disadvantages of this RPM are a narrow range of application speeds corresponding to the Mach number M≈2, low calorific value of RPD fuel and low specific engine parameters.

The possibilities of improving the processes of mixing and combustion of gas-generating jets in a satellite air stream, as is done in the combustion chamber of this engine (anti-aircraft missile systems air defense SV. Technique and armament, No. 5-6, 1999), are limited for two reasons. Firstly, the mixing of all fuel jets (total fuel consumption) flowing from the gas generator into the chamber, with the air flow flowing into it from the air intake device (VZU), begins in one place, in front of the chamber. As a result, the thickness of the flame, the length of the mixing layer and the required length of the chamber, which is limited by the total length of the propulsion system and the need to place a gas generator with fuel, increase. Secondly, there are restrictions on the maximum number of gas generator nozzles and their total area. The specificity of the controlled gas generator is that the number of nozzles and the size of their area, provided that they exceed or exceed a critical pressure drop, must be consistent with the surface area of the fuel charge that burns out according to the law:

U _T = U ₀ · P ^ν ,

where U _T is the burning rate of the fuel;

U ₀ is the speed coefficient;

P is the pressure in the gas generator;

ν is an exponent in the law of combustion.

In case subcritical pressure drop in the nozzles of the gas generator the number K _with limited possibility of merging flames and deterioration mixing. In addition, at high pressure in the gas generator, in the case of using output nozzles of small diameter, the likelihood of slagging increases. Therefore, there is a maximum of K _C and a minimum of the diameter of the critical section of the outlet nozzle d _c.cr , beyond which the combined operation of the gas generator (with solid fuel) and the combustion chamber is difficult. Due to limitations on K _{C, the} benefits of using rectangular and other nozzle shapes are not great.

The current level of parameter values of controlled gas generators and their fuels determines the interval K _c = 3 ÷ 16 and a minimum of d _c.kr > 4 ÷ 6 mm. Calculations show that in RPDT having a reduced chamber length X _pr > 20 (K _C = 8 ÷ 10) and 50% of the solid phase in the fuel jets, the completeness of fuel combustion in the chamber does not exceed 0.6 ÷ 0.7 at an air temperature equal to T _B ≈800 K (Annushkin Yu.M., Sverdlov E.D. Patterns of change in the length of the diffusion flame of gas-generating fuels in a satellite air stream. Explosion Combustion Physics, No. 3, 1984, pp. 256-268. V. Zakharov, Klyachko LA, Repnikov AA, Strokin VN Diffusion and heterogeneous combustion processes in jet engines (in relation to RPTT). TsIAM.Moscow, 1969 p. 327). With such a large underburning of fuel, the RPM thrust, for example, under flight conditions at H = 10 km and M = 4.85, can be two times (or more) less than the RPM thrust, in which the combustion process proceeds with fullness η = 0.87. It should be noted that an increase in the energy of solid fuels (TT) ramjet inevitably leads to an increase in the amount of high-energy solid phase in the primary combustion products in the gas generator. Therefore, the above-described disadvantages of the working process inherent in this engine design are fundamental in nature and limit its use in modern conditions.

Known IPVRD combined cycle (US patent USP No. 4441312, 06.22.79), containing an air intake, a gas generator with fuel RPD, a combustion chamber with a charge of a boost acceleration engine (RD) and a charge of solid fuel ramjet and an output nozzle, and in direct-flow mode The engine carries out a joint process of afterburning gas-generating fuel jets and distributed along the charge of solid fuel heat and mass supply in the boundary layer on its surface.

The disadvantage of this technical solution adopted for the prototype is that the effective mixing and afterburning of combustible components accumulated in the boundary layer requires a large chamber length, which can be a serious drawback with overall design restrictions.

The objective of the invention is to ensure the efficiency of the engine workflow at supersonic and supersonic air flow rates in the chamber.

The technical result consists in improving the mixing of fuel jets with the air flow, increasing the completeness of fuel combustion, the ability to control fuel consumption and the enthalpy of combustion products.

The solution to the technical problem is achieved by the fact that all or part of the fuel supply of the direct-flow stage is located in N-insulated fuel-carrying sections (TS) located in the combustion chamber, incl. gas generating, with nozzles directed at an angle to the gas flow.

The technical result is achieved by the fact that in a ramjet engine (ramjet) containing an air intake, a gas generator with fuel, a combustion chamber with a fuel unit (fuel) and an engine outlet nozzle, fuel-carrying sections with nozzles for flowing out connected to the control unit are installed in the combustion chamber fuel jets from the internal cavities of the sections into the internal space of the combustion chamber, and in each fuel-carrying section of the nozzle are distributed around the perimeter of the combustion chamber, and their axes are directed at an angle of 90 ≥β> 0 ° to the axis of the combustion chamber.

The technical result is also achieved by the fact that in different fuel-carrying sections are placed fuel charges, different in chemical composition and state of aggregation.

In addition, the technical result is achieved in that one or more fuel-carrying sections can be installed in the tapering (subsonic) part of the output nozzle of the engine.

At various modes of engine operation, the following advantages are defined:

- effective mixing of fuel jets with the oncoming air flow and high completeness of combustion of fuel in the combustion chamber;

- change in the enthalpy of combustion products by including sections with fuels of different chemical composition;

- effective engine operation at supersonic and supersonic air flow rates in the chamber.

Figure 1 shows the engine in longitudinal section.

Figure 2 shows the cross section of the engine aa.

Figure 3 presents the N-section fuel module (including a gas generator) with a vehicle of circular and rectangular cross section.

Figure 4 shows a longitudinal section of one section with a charge of solid fuel burning around the circumference with a speed U _T flowing out of a fuel stream with a flow rate G _T.

Figure 5 shows a flow diagram in a carrying gas stream with a flow rate G _B.

A propulsion system with a multi-section fuel module (MTM) of solid (or any other aggregate state) fuel is proposed, which is made in the form of an annular cylinder. The inner surface of the cylinder is an integral part of the shell of the combustion chamber, into which air enters from the air intake device (VZU), and the fuel jets are blown from the openings in the fuel sections (TS), equipped with nozzles and placed on the shell of the combustion chamber or engine exhaust nozzle. The nozzles of the vehicle are distributed along the length and circumference of the combustion chamber and are directed at an angle to the gas flow so that heat and mass distribution and combustion with a high degree of completeness (η> 0.8) of fuel combustion are realized. Fuel is placed in the inner cavity of each section, located around the perimeter inside the combustion chamber and representing a channel of round (oval) or rectangular cross section. A round tube is known to withstand the greatest pressure. With a wall thickness of δ = 1 mm, a steel tube with an inner diameter of d = 10 mm withstands a pressure of P≈300 kg / cm ² .

A feature of the proposed scheme of a propulsion system (DU) with a multi-section fuel module is that the fuel consumption that each vehicle produces is 10-30 g / s. The pressure level does not exceed P = 30 kg / cm ² . Therefore, in order to obtain the maximum filling with MTM fuel and reduce its length, it is preferable to use fuel-carrying sections of rectangular cross section.

The advantages of MTM include a large number of vehicle nozzles for fuel injection. So, for example, for a vehicle with an inner diameter of d = 120 mm and an area (by fuel) of rectangular cross section S _T = 10 cm ² (width b = 2.8 cm, height h = 3.57 cm, see FIG. 3), fuel mass M _t = 23 kg, with a density ρ _t = 1.3 g / cm ³ , is located in 36 sections (tori). Accordingly, the number of nozzles TC N _mc = 36. In the case of using fuel sections with combustion at two ends, the number of nozzles of the vehicle doubles, the reduced length of the combustion chamber (X _pr > 80) and the completeness of combustion increase.

The expected increase in the completeness of combustion is associated not only with an increase in the number of nozzles of the vehicle. A characteristic feature and advantage of the transverse injection of fuel jets into the air stream is their rapid mixing with air. With transverse blowing, the torch becomes short. It is known (G.N. Abramovich, M.T. Bortnikov and others. Edited by B.P. Lebedev. Combustion chambers of aircraft gas turbine engines / MAP USSR / Institute named after P.I. Baranov. Moscow. 1957) that the length of the torch can be within 1-2 calibers of the diameter of the outlet. In addition, as can be seen from Figs. 3 and 5, under the influence of a blowing air stream, the fuel jet unfolds and acquires a horseshoe shape, inside which there is a vortex structure that contributes to stabilization and combustion processes. The shape of the jet and its penetration depth (Y / X ratio, FIG. 3) depend on the ratio of the high-pressure heads of the air flow and the fuel jet, as well as the diameter of the nozzle TC and the angle between the drift stream and the jet flowing from the nozzle.

An important advantage of MTM is the lack of a fuel consumption regulator. The stepwise increase in fuel consumption, as well as its decrease (zeroing) are provided by the number and order of switching sections.

The total length L of such an MTM, depending on the thickness of the partitions between the vehicles, varies within 1045 mm <L <1200 mm and is 200-300 mm longer than the length of a monoblock gas generator (MG) together with a regulator. However, the length of the flow path of the ramjet (RPD) combustion chamber with the vehicle also increases and, in the event of a complete replacement of the monoblock gas generator, becomes equal to the length of the entire engine. At the same time, as estimates show, the amount of fuel of the booster stage (not shown in the drawing) remains unchanged.

The proposed HPLC, schematically shown in the drawing (Fig. 1), contains a monoblock gas generator (MG) 1 with nozzles MG 2, a multi-section fuel module with fuel 3, made in the form of an annular cylinder. The inner surface of the cylinder is the side of the combustion chamber 4, into which air enters from the VZU 5, and the fuel jets are blown from the nozzles of the vehicle 6 (Figs. 1, 3, 4) located on the internal surface of the vehicle, distributed along the length and circumference of the chamber and directed under angle to the air flow so that a heat and mass distribution distributed along the length with high completeness (η> 0.8) of fuel combustion is realized. The fuel charge is placed in the internal cavities of the section (FIGS. 1, 2, 3, 4), preferably of a rectangular cross section. Another part of the direct-flow fuel of the engine stage is located in the gas generator 1 and in the fuel unit 7. The order of switching on all fuel charges (TK) is determined by the control unit TK 9, which is connected to the onboard computer. At the end of the chamber, an output nozzle of the engine 8 is installed, in the narrowing (subsonic) part of which one or several vehicles can also be placed.

The inventive combined ramjet engine distributed along the length of the heat and mass supply, which is schematically shown in the drawing, operates as follows.

When the aircraft leaves the ramjet engine at the flight speed corresponding to the calculated operating mode of the air intake 5 in one or more (all) fuel-carrying sections 3, upon a command from the on-board computer, the TK 9 control unit initiates the fuel supply process. Also, on command, the process of supplying fuel from the monoblock gas generator 1 is initiated. Gasified combustion products burning up on the surface with a solid fuel charge rate Up in TS 3 (Figs. 3, 4) are fed to the nozzle of the TS 6 and then sent in the form of a jet rich in combustible components into the combustion chamber 4 (figure 1). Under the influence of the high-pressure head of the air flow entering the chamber 4 from the air intake device (VZU) 5, the high-temperature fuel jet is deformed (Fig. 5) and is intensively mixed with air, fuel jets flowing from the nozzles 2 of the monoblock gas generator 1, and burns in the combustion chamber 4. Further, the burning gas-air mixture enters the channel of the combustion chamber, where the fuel unit 7 is located, and contributes to its efficient combustion. The combustion products of the fuel injection valve expire from the output nozzle of the remote control 8, creating traction.

Estimates show that the effect of increasing the completeness of combustion of fuel with transverse injection of jets at a speed of W _c at an angle of 0 ° <β≤90 °, (Fig. 5), in most cases, compensates for the increase in total pressure loss in the combustion chamber compared to the satellite supply of fuel jets. The direction of the velocity vector W _c coincides with the axis of the nozzle TC О _С , and the X axis is parallel to the axis of the combustion chamber 4. To compensate for excessively large losses in total pressure, the mass of fuel can be redistributed towards the monoblock gas generator 1 with a satellite fuel supply.

Thus, the proposed technical solution can significantly improve the mixing of fuel with air, providing high completeness of combustion. In addition, the use of the proposed technical solution allows you to put in the fuel sections of different state of aggregation - solid, liquid, bulk, pasty.

Claims (3)

1. A ramjet engine (ramjet) containing an air intake, a gas generator with fuel, a combustion chamber with a fuel (fuel) unit and an output nozzle, characterized in that fuel-carrying sections with nozzles for expelling fuel jets connected to the control unit are installed from the internal cavities of the sections into the internal space of the combustion chamber, moreover, in each fuel-carrying section the nozzles are distributed along the perimeter of the combustion chamber, and their axes are directed at an angle of 90 °> β> 0 ° to the axis of the combustion chamber. 2. The engine according to claim 1, characterized in that fuel charges of different chemical composition and state of aggregation are placed in different fuel-carrying sections. 3. The engine according to claim 1, characterized in that one or more fuel-carrying sections are installed in the tapering (subsonic) part of the engine output nozzle.

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