RU2488712C2 - Method of operating space engine running on gas fuel - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: pre-gasified fuel components, helium gas from displacement system and aluminium powder are fed into prechamber for mixing. Further, made mix is fed via peripheral tangential swirler into combustion chamber on the side of nozzle cover. On gyrating along combustion chamber wall toward head section said mix protects combustion chamber walls against heat of active bed of flow part from engine axial section. Presence of helium decreases molecular weight of combustion products to add to engine specific pulse. To increase mix combustion temperature aluminium powder is added thereto.

EFFECT: higher thrust, better protection of chamber housing against combustion product heat.

4 dwg

Description

The invention relates to the field of rocket technology and can be used in the development of rocket engines running on gaseous components of the fuel mixture.

Currently, the most common types of rocket engines are liquid rocket engines (LRE) and solid fuel rocket engines (solid propellant rocket engines) [1]. The organization of combustion processes in a rocket engine using gaseous fuels can be used to create special propulsion systems. In particular, when creating small thrust rocket engines to remove the spent stages of launch vehicles from occupied orbits, it is promising to use gasified liquid components of the guaranteed rocket engine liquid fuel reserve as gaseous fuel [2].

A known method of organizing a working process in the combustion chamber of a rocket engine [3], in which self-igniting components of the fuel are used. At the same time, they are fed into the combustion chamber through tangential entries into the corresponding coaxial twisting chambers of the two-component centrifugal nozzle. The twisting of the components contributes to a more complete mixing of the components of the fuel mixture and provides thermal protection of the combustion chamber. The patent [4] proposes the use of a prechamber (prechamber) for swirling and mixing the fuel mixture by supplying gaseous components using a screw. To improve the energy characteristics of rocket engines in [5] it was proposed to use gaseous helium as an inert additive that reduces the molecular weight of the combustion products.

The closest in technical essence to the claimed method is the organization of the process of burning fuel in the combustion chamber using vortex motion to organize the processes of mixture formation and combustion of fuel components [6]. In this case, the main part of the components is supplied from the nozzle block side through nozzles located evenly tangentially to the circle at an angle of 60 ° to the surface of the roof of the combustion chamber.

The technical result of the present invention is the organization of the process of burning gaseous fuels, ensuring the achievement of the maximum value of the energy-traction characteristics of the propulsion system and the protection of the combustion chamber housing from thermal effects from the combustion zone while minimizing the dimensions of the structure.

The technical result is achieved in that in the combustion chamber of a space propulsion system using gaseous fuel, the fuel components are twisted by means of their tangential entry into the combustion chamber from the nozzle side of the engine cover. The gaseous fuel and oxidizing agent are pre-mixed in a prechamber with helium gas and aluminum powder with an average particle size of not more than 10 μm, and the mass fractions of the components of the fuel mixture (fuel, oxidizing agent, aluminum powder and helium) are in the ratio, respectively

z _f / z _ox / z _Al / z _He = 0.10 / 0.45 / 0.09 / 0.36

for fuel kerosene + oxygen,

z _f / z _ox / z _Al / z _He = 0.11 / 0.55 / 0.11 / 0.23

for fuel hydrogen + oxygen,

where z _f is the mass fraction of fuel;

z _ox is the mass fraction of the oxidizing agent;

z _Al is the mass fraction of aluminum powder;

z _He is the mass fraction of helium.

Helium is introduced into the prechamber from the liquid fuel engine fuel tank displacement system, and gaseous fuel and oxidizing agent are obtained by gasification of the guaranteed supply of liquid components in the liquid fuel engine tanks, and other hydrocarbon compounds, for example, methane, butane, are used along with the listed traditional components (kerosene, hydrogen) propane.

The achievement of the positive effect of the invention is provided by the following factors.

1. The use of preliminary mixing of the fuel components in the prechamber (prechamber) with inert gaseous helium and aluminum powder provides a more uniform fuel mixture.

2. The filing of a swirling flow from the nozzle side allows one to reduce the dimensions of the combustion chamber and organize effective thermal protection of the walls of the combustion chamber.

3. Using a mixture of aluminum powder during combustion increases the temperature in the combustion chamber T, which ensures stable combustion of the fuel with an inert diluent (helium) z _He > wt.%.

4. The use of aluminum powder in the combustion process with a dispersion of not less than 10 microns makes it possible to achieve high completeness of combustion of aluminum.

5. The addition of an inert gaseous helium to the fuel mixture reduces the molecular mass of the working fluid and increases the specific thrust impulse, [1]:

$$I_{\mathrm{at}d}~\sqrt{\frac{T}{M}},\text{(one)}$$

where I _beats - specific impulse of thrust;

T is the temperature in the combustion chamber;

M is the molecular weight of the working fluid.

6. The use for the operation of the engine of gasified components of liquid fuel from the guaranteed reserves of liquid propellant rocket engines and gaseous helium from the system of displacing fuel tanks allows for more complete utilization of them, which increases the energy-mass characteristics of the engine.

The invention is illustrated in the diagram (Figure 1), which presents a method of organizing a work process in a space propulsion system using gaseous fuel. The numbers indicate: 1. - the housing of the combustion chamber; 2. - nozzle; 3. - fuel tank; 4. - oxidizer tank; 5. - prechamber; 6. - peripheral tangential swirl. The implementation of the method is as follows. The pre-gasified fuel components (fuel and oxidizer) together with gaseous helium from the displacement system are fed to the mixing chamber. At the same time, aluminum powder with a fineness of at least 10 μm enters the same prechamber. From the prechamber, the mixture through the peripheral tangential swirler enters the combustion chamber from the nozzle cover towards the head of the chamber. Moving in a spiral along the wall of the combustion chamber towards the head part, the mixture prepared for combustion is heated. Ignition of an already heated mixture occurs when the flow turns in the region of the head cover of the combustion chamber. The burning part of the flow occupies the central part of the chamber cavity in the region of the axis of the propulsion system. At the same time, while heating, the peripheral part of the mixture flow protects the walls of the combustion chamber from thermal effects from the burning part of the flow from the axial region of the engine.

Implementation Example 1

For a propulsion system with kerosene as fuel and oxygen as an oxidizing agent, the fuel mixture includes kerosene, oxygen, aluminum powder and helium. The optimal ratio of the mass fractions of each component (z _f , z _ox , z _Al and z _He , respectively) was determined by analyzing the results of parametric calculations of the specific impulse for the degree of nozzle expansion p _k / p _a = 1 / 0.05 (p _k - pressure in the combustion chamber, p _a - external pressure). The choice of the degree of expansion is determined by the operating conditions of the engine in space at the height of the separation of the stages of the carrier rocket with the LRE. In the calculations performed using the Astra-2 program [7], it was assumed that in this mixture the combustible components (kerosene and aluminum) with an oxidizing agent (oxygen) are in a stoichiometric ratio. Moreover, the content of aluminum powder is 20 wt.% Of the mass of the gaseous components of the fuel (kerosene and oxygen required for its combustion). To determine the optimal helium content in this mixture, its mass fraction z _{He was} varied. The results of the calculation of I _beats from z _He are shown in Figure 2. Analysis of the results presented in figure 2, shows that for the composition without aluminum (curve 1), the maximum value of I _beats = 2.77 km / s is achieved at z _He = 0.37. For the composition with aluminum (curve 2), the maximum value of I _beats = 3.19 km / s is achieved at z _He = 0.45. Thus, the introduction of aluminum powder into this mixture increases the specific impulse by 15%. It can be seen from these graphs that, first, the addition of a fraction of helium in the fuel mixture leads to an increase in the specific impulse, and then an increase in the fraction of helium leads to a decrease in the specific impulse. Thus, the ratio of the mass fractions of the components optimal for this example is z _f / z _ox / z _Al / z _He = 0.10 / 0.45 / 0.09 / 0.36.

The choice of z _Al in the amount of 20 wt.% Is due to the analysis of published data [8] on the optimal content of aluminum powder for solid rocket fuels. The analysis shows that a further increase in the aluminum content leads to an increase in two-phase losses and, ultimately, to a decrease in I _beats .

The presence of the optimal value of z _He in the fuel mixture is associated with the presence of two alternative mechanisms of the influence of helium additives on the specific impulse of the engine. On the one hand, the low molecular weight of helium M _He leads to a decrease in the molecular weight of the mixture M and an increase in I _beats , according to relation (1), and, on the other hand, helium is an inert substance, does not participate in the combustion process, and reduces the overall temperature in the chamber like a ballast substance.

In this example implementation 1, the maximum increase in I _beats with the combined effect of additives of aluminum and helium powder in the fuel mixture relative to I _beats at z _He = 0 and z _Al = 0 was 52%.

Implementation Example 2.

For a propulsion system (FIG. 1), an inert diluent — helium — is added to the fuel mixture including an oxidizing agent — oxygen, fuel — hydrogen, and aluminum powder. As in implementation example 1 — the ratio of fuel to oxidizer is selected stoichiometric, the proportion of aluminum is 20 wt.% Of mass gaseous fuel component (hydrogen and oxygen needed for its combustion), and the optimum ratio of the weight fraction of each component (respectively, _f z, z _ox, and z _Al z _Not) was determined by analyzing the results of the parametric pa chetov value for the specific impulse of the expansion nozzle _to p / p _a = 1 / 0.05, conducted under the "Astra-2". The results of the calculation of I _beats from z _He are shown in Fig.3. An analysis of the results presented in Figure 4 shows that for the composition without aluminum (curve 1), the maximum value of I _beats = 3.95 km / s is achieved at z _He = 0.25. For the composition with aluminum (curve 2), the maximum value of I _beats = 4.27 km / s is achieved at z _He = 0.23. Thus, the introduction of aluminum powder into this mixture increases the specific impulse by 8%. It can be seen from these graphs that, first, the addition of a fraction of helium in the fuel mixture leads to an increase in the specific impulse, and then an increase in the fraction of helium leads to a decrease in the specific impulse. Thus, the ratio of the mass fractions of the components optimal for this example is z _f / z _ox / z _Al / z _He = 0.11 / 0.55 / 0.11 / 0.23.

In this example implementation 2, the maximum increase in I _beats with the combined effect of additives of aluminum and helium powder in the fuel mixture relative to I _beats at z _He = 0 and z _Al = 0 was 22%.

Implementation Example 3.

Other hydrocarbons may also be used as fuel in the fuel mixture. In particular, for a propulsion system (FIG. 1), an inert diluent, helium, is added to the fuel mixture, which includes an oxidizing agent - oxygen, fuel - methane and aluminum powder. As in implementation example 1, the ratio of fuel and oxidizing agent is chosen stoichiometrically, the proportion of aluminum is 20 wt.% Of the mass of the gaseous components of the fuel (methane and oxygen required for its combustion), and the optimal ratio of the mass fractions of each component (respectively, z _f , z _ox , z _Al and z _Hе ) were determined by analyzing the results of parametric calculations of the specific impulse for the degree of expansion of the nozzle p _k / p _a = 1 / 0.05, carried out according to the Astra-2 program. The calculation results of I _beats from z _He are shown in figure 3. An analysis of the results presented in Figure 4 shows that for the composition without aluminum (curve 1), the maximum value of I _beats = 3.71 km / s is achieved at z _He = 0.25. For the composition with aluminum (curve 2), the maximum value of I _beats = 3.93 km / s is achieved at z _He = 0.25. Thus, the introduction of aluminum powder into this mixture increases the specific impulse by 5%. It can be seen from these graphs that, first, the addition of a fraction of helium in the fuel mixture leads to an increase in the specific impulse, and then an increase in the fraction of helium leads to a decrease in the specific impulse. Thus, the ratio of the mass fractions of the components optimal for this example is z _f / z _ox / z _Al / z _He = 0.11 / 0.53 / 0.11 / 0.25.

In this example of implementation 3, the maximum increase in I _beats with the combined effect of additives of aluminum and helium powder in the fuel mixture relative to I _beats at z _He = 0 and z _Al = 0 was 26%.

The presented results of the analysis of implementation examples prove that the task to increase energy-mass perfection (in particular, the specific impulse of the rocket system) using gasified fuel components, gaseous helium from the displacement system and aluminum powder has been solved.

LITERATURE

1. Alemasov V.E. et al. Theory of rocket engines: A textbook for students of engineering special universities / V.E. Alemasov, A.F. Dregalin, A.P. Tishin; under the editorship of V.P. Glushko. - M.: Mechanical Engineering, 1980 .-- 533 p.

2. Belokonov I.V., Kruglov G.E., Trushlyakov V.I., Yudintsev V.V. Evaluation of the possibility of controlled descent from the orbit of the upper stage of the Soyuz launch vehicle through the use of fuel residues in the tanks. All-Russian scientific and technical conference "Actual problems of rocket and space technology and its role in the sustainable socio-economic development of society", dedicated to the 50th anniversary of the founding of the Central Design Bureau and the 90th anniversary of the birth of D. I. Kozlov. (4/2) Samara. 2009 (p. 68-72).

3. Kazankin F.A., Kutuev R.Kh., Larin E.G., Mezenin P.B. The method of organizing the working process in the chamber of a liquid propulsion thruster: RU 2192556 C2. Russian Federation // B.I. 11/10/2002.

4. Vesnovatov A.G., Barsukov O.A. Liquid thruster and method for starting a liquid thruster: RU 2183761 C2. Russian Federation // B.I. 05/20/2002.

5. Chvanov V.A., Arkhangelsky V.I., Klepikov I.A., Sternin L.E., Khazov V.N., Konovalov S.G., Katorin B.I. Liquid propellant rocket engine containing helium additive: RU 2273754 C2. Russian Federation // B.I. 03/20/2005.

6. Timoshenko I.K. Vortex rocket engine: RU 2300007 C1. Russian Federation // B.I. 05/27/2007.

7. The use of computers for thermodynamic calculations of metallurgical processes / G. B. Sinyarev, N. A. Watolin, B. G. Trusov, G. K. Moiseev. M .: Nauka, 1982.- 263 p.

8. A.V. Aliev et al. Internal ballistics of solid propellant rocket engines / A.V. Aliev, G.N. Amarantov, V.F. Akhmadeev, ed. A.M. Lipanova, Yu.M. Milekhina Series: Reference book of a developer-researcher. - M: Engineering, 2007, - 501 p.

Claims (2)

1. A method of organizing a working process in a space propulsion system using gaseous fuel, comprising swirling the fuel components by tangentially introducing them into the combustion chamber from the nozzle side of the engine cover, characterized in that the gaseous fuel and oxidizing agent are pre-mixed in a prechamber with helium gas and aluminum powder with the average particle size of not more than 10 microns, and the mass fractions of the components of the fuel mixture - fuel, oxidizer, aluminum powder, helium are in the ratio
z _f / z _ox / z _Al / z _He = 0.10 / 0.45 / 0.09 / 0.36
for fuel kerosene + oxygen,
z _f / z _ox / z _Al / z _He = 0.11 / 0.55 / 0.11 / 0.23
for fuel hydrogen + oxygen,
where z _f is the mass fraction of fuel;
z _ox is the mass fraction of the oxidizing agent;
z _Al is the mass fraction of aluminum powder;
z _He is the mass fraction of helium,
helium is introduced into the prechamber from the liquid fuel tank displacement system, and gaseous fuel and oxidizing agent are obtained by gasification of the guaranteed supply of liquid components in the liquid fuel engine fuel tanks. 2. The method according to claim 1, characterized in that other hydrocarbon fuels, for example methane, butane, propane, are used as fuel.

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