Design of afterburner and gas generator
The use of polymer composite materials for ramjet engine housings, featuring carbon fiber and polyimide binder with heat-resistant coatings, addresses structural and manufacturing challenges, enhancing reliability and efficiency by managing heat and mechanical loads, thus improving thrust and tactical characteristics.
Patent Information
- Authority / Receiving Office
- RU · RU
- Patent Type
- Patents
- Current Assignee / Owner
- ROSSIJSKAJA FEDERATSIJA OT IMENI KOTOROJ VYSTUPAET MINISTSTVO PROMYSHLENNOSTI I TORGOVLI ROSSIJSKOJ FEDERATSII
- Filing Date
- 2024-11-02
- Publication Date
- 2026-07-01
AI Technical Summary
Existing ramjet engines face challenges in maintaining structural integrity and efficiency due to high operating temperatures, weight, and complex manufacturing processes, particularly in dual-mode operations where deformation and heat protection are critical.
The use of polymer composite materials (PCM) for the housings, comprising a carbon fiber and polyimide binder structure with internal and external heat-resistant coatings, addresses these issues by providing deformability, heat resistance, and reduced weight, enhancing the reliability and efficiency of the engine.
This design improves the structural integrity and efficiency of ramjet engines by reducing weight, increasing thrust, and simplifying manufacturing, while maintaining high-temperature operation and reliability through the use of PCM housings with deformable coatings that manage heat flux and mechanical loads.
Smart Images
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Abstract
Description
[0001] The invention relates to the design of a dual-pulse ramjet engine using solid fuel and describes the design of the housings of the afterburning chamber and the gas generator based on a polymer composite material.
[0002] Ramjet engines (RAMJETs), which operate by burning solid fuel gasification products in an airflow, are of great interest as propulsion systems for various aircraft. This propulsion system is a structure (see Fig. 1) consisting of the following major components: two housings—an afterburner 1 (AC) and a gas generator 2 (GG), a nozzle block 3, and an air intake device (AID) 4.
[0003] The uninterrupted operation of any power plant operating on hot gases or combustion products, maintaining the strength characteristics of the casing during operation, are the main tasks in the development of propulsion systems and consist, among other things, of ensuring reliable cooling of the engine structure or protecting the latter from the effects of heat flow.
[0004] At the same time, reducing the weight of the power plant, simplifying the design and manufacturing technologies, taking into account that the operating temperatures of ramjet engines are around 2000°C, poses the challenge for developers to use high-temperature composite materials in their development.
[0005] Hypersonic engines are known to use a liquid oxidizer (RU 2445491, published 20.12.2010), which is often used as a coolant (RU 2289716, published 20.12.2006).
[0006] A solid-fuel ramjet rocket engine (SPRE) is known (see Anti-aircraft missile systems of the Air Defense Forces. - Equipment and Armament, 1999, No. 5-6), which has a cylindrical gas generator with a propellant charge burning at the end. Fuel jets, over-enriched with combustible substances, flow from the gas generator through nozzles into the air chamber, where they mix and burn out in the cocurrent air flow coming from the air intake. A distinctive feature of the engine's operating process is the concentrated (localized) supply of air from the air intake at the beginning of the air chamber and fuel from the gas generator.
[0007] The disadvantage of this type of RPDT is the need to create reliable cooling of the combustion chamber walls.
[0008] A combustion chamber housing for an aircraft is known (RU Patent No. 2430306, published on September 27, 2011), made as a multi-layer product containing a metal shell that bears a mechanical load and layers of heat protection attached to the inner surface of the power shell, protecting the latter from contact with gases formed during fuel combustion.
[0009] The disadvantage of this technical solution is that the metal casing in such designs is less deformable than in common types of combustion chambers. During operation, the combustion chamber experiences loads that cause significant deformation of the combustion chamber relative to the load-bearing shell, which in turn leads to a reduction in performance characteristics, as the incompatible deformation of the load-bearing shell and combustion chamber leads to delamination and subsequent failure.
[0010] One solution to this problem may be to use internal combustion chamber (or afterburner) walls (inserts) with transpiration cooling, made of a porous, permeable material. In this case, the coolant is supplied to the combustion chamber through pores in the wall material (RU 2171388, RU 2565131). This creates a protective curtain, and the heat flux density acting on the combustion chamber wall is reduced.
[0011] The disadvantage of this design is that introducing some coolant through the pores into the combustion chamber leads to a loss of engine efficiency. This design also significantly complicates the engine system, requiring separate channels for delivering coolant to the engine components and complex combustion chamber walls made from a deformed and diffusion-sintered stack of heat-resistant metal meshes.
[0012] Another important technical problem that needs to be solved is ensuring the strength characteristics of the housings of the KD and GG used in two pulse jet engines.
[0013] These engines operate in two modes. In the first mode, the booster solid rocket motor operates. In the second (cruise) mode, the gas generator operates, producing superheated, fuel-saturated gas, which, upon entering the booster, combusts completely in the oncoming airflow from the booster. Ramjets are often manufactured using an integrated circuit, where the booster charge is housed within the booster motor and does not have its own housing.
[0014] During the operation of such integrated systems, the pressure vessel is subjected to heat flow and internal pressure twice, in addition to the factors acting on the aircraft during flight (axial forces, bending moments, G-forces, etc.). Thus, in the first flight mode, when the booster solid rocket motor is operating, the pressure in the pressure vessel can reach up to 15 MPa. In the second flight mode, the pressure in the pressure vessel drops to 2.0 MPa. In the gas generator, the operating pressure in the second mode can reach up to 15 MPa.
[0015] The methods of operation of dual-mode solid propellant rocket motors are known, given in the descriptions of Russian Federation patents No. 2379539 (published 01 / 20 / 2010), 2435979 (published 12 / 10 / 2011), each of which includes operation in the first mode at elevated pressure and operation in the second mode at reduced pressure in the combustion chamber.
[0016] A disadvantage of the known methods of operating a dual-mode solid propellant rocket engine is the low ballistic efficiency of the aircraft (rocket) in the design of which such an engine is used, due to the excessive thickness of the combustion chamber wall when the engine is operating in the second mode, which increases its passive weight.
[0017] Also known is the invention according to the Russian Federation patent No. 2670287 (published on October 22, 2018), which considers the design of a dual-mode solid propellant rocket engine with a discardable outer coaxial shell, which provides the necessary strength characteristics of the combustion chamber in the starting mode.
[0018] The disadvantage of this design is the complication of the design, in particular the addition of aerodynamic flaps that extend above the surface of the shell during the calculated period of time upon command from the control system, which in turn leads to a decrease in the overall reliability of the design.
[0019] A known design for a cruise missile propulsion system (RU Patent No. 2554690, published June 27, 2015) comprises a shell that bears the mechanical load of internal pressure and a layer of heat-protective ceramic composite material that comes into contact with the gases formed during fuel combustion. The shell is made of a high-temperature ceramic composite material reinforced with carbon fibers, with a coefficient of linear expansion of no more than 5.2⋅10 -6 1 / °C, elastic modulus of at least 13⋅10 3 MPa, with a tensile strength of at least 90 MPa.
[0020] The disadvantages of this design include a decrease in the technological efficiency of manufacturing the engine casing, since the process of producing a shell from ceramic matrix composite materials (CMC) is technically complex and expensive.
[0021] The purpose of the proposed technical solution is
[0022] - Increasing the mass perfection of the ramjet design due to the replacement of the material of the power shells from metal to PCM, and the reduction of production and time costs in comparison with the production of housings from CCM;
[0023] - ensuring the joint operation of the layers of the TZP and the power body of the KD and GG;
[0024] - increase in the thrust and tactical and technical characteristics of the ramjet due to the improvement of the physical and mechanical characteristics of the KD and GG housings;
[0025] The stated goal is achieved by:
[0026] The proposed design of the KD and GG is made in the form of a layered product containing a power body (shell) based on high-strength carbon fiber and a heat-resistant polyimide binder, an erosion-resistant internal heat-protective coating (HPC) consisting of a thread frame based on heat-resistant fibers impregnated with an elastic polymer binder and a layer of external erosion-resistant HPC based on an elastic polymer binder, finely dispersed mineral filler and functional additives.
[0027] 1. By using layers of deformable external and internal heat-resistant coating, which reduce the impact of heat flow, it becomes possible to use a polymer composite material as the structural material for the housings of the CD and GG. The CD and GG are made of PCM based on a heat-resistant polyimide matrix (ρ пкм =1.5 g / cm 3 ) have a significantly lower mass compared to metal housings (ρ пкмfrom 2.5 to 7.8 g / cm 3 ), which leads to a significant weight gain.
[0028] The density of CCM is slightly higher than that of PCM, and the weight savings are less obvious. CCM also significantly exceeds all known PCMs in terms of permissible operating temperatures (up to 1800°C and higher for CCM), but the physical and mechanical properties of a polyimide-based PCM housing are superior to those of a similar CCM housing. Furthermore, PCM housings are more technologically advanced in production compared to CCM housings, which require significantly more time and production costs, such as high-temperature treatments, carbonization processes, saturation of carbon frames with a ceramic matrix, manufacturing of specialized tooling, and much more.
[0029] 2. The use of a polyimide-based composite material for the KD and GG housings ensures combined deformation of the load-bearing shell and the layers of the internal and external TZP during operation of the product, thereby increasing the reliability of the ramjet.
[0030] 3. Also, as a result of the use of erosion-resistant, elastic internal and external TZP, it was possible to reduce the impact of heat flow on the power casing, which in turn allowed for increased completeness of fuel combustion in the KD by raising the temperature in the flow core to 2500°C. Furthermore, this allows for an increase in the operating time of the propulsion system (PS).
[0031] 4. With the presence of a thermal protection factor in the engine design, capable of preventing the heating of the supporting body above the permissible operating temperatures of PCM on a polyimide matrix (temperatures up to 400°C), it becomes possible to manufacture it for use in the design of a ramjet. Thus, as a result of using a power casing made of heat-resistant PCM based on carbon fiber and a polyimide binder, it was possible to significantly improve the physical and mechanical properties of the KD and GG (the tensile strength of carbon fiber on a polyimide binder is 700 MPa, while that of carbon-ceramic composite material (CCCM) is 160 MPa. The tensile modulus of elasticity of PCM on polyimide is 62 GPa, while that of CCCM is slightly lower, ~ 55 GPa).In this way, it was possible to increase the energy efficiency of the ramjet, since a direct consequence of increasing the physical and mechanical properties of the ramjet and gas turbine is an increase in the pressure in the chambers, which directly leads to an increase in the efficiency of the engine, that is, an increase in the tactical and technical characteristics of the ramjet as a whole.
[0032] During the operation of the product (Fig. 2), the power shell based on carbon fiber and polyimide binder 5 absorbs mechanical loads, and the layers of the outer 6 and inner 7 heat-resistant coating absorb the heat flow, respectively, from the influence of the external environment and burning fuel.
[0033] The operating principle of the internal TZP is that, under the influence of heat flow, it heats up to the destruction temperature, at which point active gas and coke formation begins. The released gas forms a wall curtain (a blowing effect), thereby reducing the heat flow to the walls of the compressor or gas generator, and the formation of coke residue in the TZP absorbs thermal energy (thus establishing a steady-state thermal regime at the operating temperature of the compressor and gas generator power housing).
[0034] The outer TZP consists of a polymer base and a finely dispersed mineral filler. It operates by sublimation and the gradual removal of TZP pieces from the product's surface. During operation, a gas curtain is released (as in the inner TZP) and the outer layers gradually degrade and are subsequently removed.
[0035] The thickness of each TZP is selected so that the temperature load on the PCM power shell is reduced to a level that does not require additional external air cooling.
Claims
The housing of the afterburning chamber and gas generator of a jet engine, including a power housing, a layer of internal heat protection and a layer of external heat protection, characterized in that the power housing is made of a polymer composite material based on carbon fiber and a polyimide binder, the layer of internal heat protection is made of a composite material based on a thread frame of heat-resistant fibers impregnated with an elastic polymer binder, the layer of external heat protection is made of a composite material based on an elastic polymer binder and a finely dispersed mineral filler.