RU2386845C2 - Method to operate oxygen-kerosine liquid-propellant rocket engines and fuel composition therefor - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed method is based on using fuel additive that makes a coolant intended for chamber cooling and is introduced into gas generator that incorporates line feeding fuel from pressure lines of oxygen and kerosene feed burnt at stoichiometric ratio. Note that said fuel additive is used for ballasting of "neutral gas" and reducing of its temperature to values allowed by turbine structural materials. Note also that produced gas is fed into combustion chamber, together with oxidiser and fuel. Mind that said fuel additive represents liquefied ammonia (NH₃) in amount of 10% to 35% of total weight flow of fuel, while gas with aforesaid additive is burnt in engine chamber. Fuel composition for oxygen-kerosine liquid-propellant rocket engines contains liquefied oxygen and liquid kerosine as well as fuel additive improving perfomances of engines represented by liquefied ammonia (NH₃) in amount of 10% to 30% of total weight flow of fuel.

EFFECT: improved performances of proposed engines.

4 cl, 2 dwg

Description

Technical field

The proposed solution relates to liquid-propellant rocket engines, specifically to oxygen-kerosene-class rocket engines.

State of the art

In the modern rocket and space industry, oxygen-kerosene liquid rocket engines are widely used, made according to the scheme with afterburning of turbogas in the combustion chamber and characterized by high energy efficiency combined with the availability and environmental friendliness of the fuel components.

The method of operation of such engines is that the turbine of the turbopump unit, feeding on working gas from the gas generator, drives pumps that supply fuel components to the gas generator and the combustion chamber, and the working gas from the gas generator after operation on the turbine of the turbopump unit enters the combustion chamber, where its afterburning occurs. Thus, fuel energy is used to the fullest extent possible (see, for example, the book: Kozlov A.A. et al. Power supply and control system for liquid-propellant rocket propulsion systems. M. Mashinostroenie, 1988, pp. 115-125).

We take this decision as an analog.

However, such a scheme also has disadvantages, since when a high-temperature oxidizing gas is used to drive a turbine, the potential danger of ignition of the flow path of the oxidizing path remains. In addition, in some cases there are difficulties associated with the limited cooling ability of kerosene.

In the prototype method (RF patent No. 2273754, IPC F02K 9/48), liquefied helium is used to cool the chamber of the oxygen-kerosene engine, which is also an additive to the fuel composition. In this case, helium from the pump outlet enters the regenerative cooling channels of the engine chamber and then enters the gas generator. The gas generator provides stoichiometric (α = 1) combustion of oxygen and kerosene, and the necessary subsequent decrease in the temperature of the obtained gas to the values allowed by the used structural materials of the turbine is realized due to its ballasting by introducing helium into the gas generator. Thus obtained working gas is supplied to the turbine drive, and then to the combustion chamber.

The use of helium in oxygen-kerosene fuel vapor can significantly increase the energy characteristics of engines. So, for example, with the introduction of helium additives in an amount of 10% of the fuel mass flow rate, it is possible to increase the specific impulse of the engine by ~ 20 sec, and taking into account the rejection of the screen cooling of the chamber, to ~ 30 sec.

However, the use of helium in the fuel composition of oxygen-kerosene engines is limited by its high cost, as well as by the difficulties associated with its storage in the rocket tank and subsequent injection to high pressures.

Disclosure of invention

The proposed technical solution fulfills the task of ensuring reliable operation of an oxygen-kerosene liquid rocket engine with a new fuel composition, which is inexpensive and superior in terms of thermophysical properties to kerosene.

The stated technical problem is solved in that in a method for operating an oxygen-kerosene liquid propellant rocket engine based on the use of a fuel additive used as a coolant for flow cooling of a chamber and then introduced into a gas generator having a fuel supply from pressure lines of oxygen and kerosene burned during stoichiometric ratio, the fuel additive is used to ballast the "neutral gas" and reduce its temperature to the values allowed by the designs used GOVERNMENTAL turbine materials, and the produced gas after triggering the turbine is fed into the combustion chamber, into which also enters an oxidizer and fuel, and as a fuel additive used liquefied ammonia (NH _3), the proportion of which is from 10% to 35% of the mass flow total fuel, while the gas with ammonia additive after operation on the turbine is burned in the engine chamber.

A distinctive feature of the proposed technical solution is a new fuel composition.

The fuel composition for oxygen-kerosene liquid propellant rocket engines contains a fuel vapor comprising liquefied oxygen and liquid kerosene, as well as a fuel additive that improves the operational and energy characteristics of the engines, and liquefied ammonia (NH ₃ ) is used as a fuel additive, the percentage of which is from 10% to 30% of the total mass fuel consumption.

With the introduction of an ammonia additive in the amount of (10-20)%, the specific impulse of the oxygen-kerosene engine increases to ~ 5 sec (relative to the initial version), while the consumption of kerosene decreases by 2-4 times due to its corresponding replacement with ammonia, and with an increase in the additive up to 35%, the increase in specific impulse practically disappears, while at the same time it is natural that the consumption of kerosene is replaced by ammonia to a much greater extent.

Brief Description of the Drawings

The proposed technical solution is illustrated in figures 1 and 2:

figure 1 presents a diagram of a liquid rocket engine;

figure 2 shows the dependence of the ideal specific impulse of the engine (I _beats ) on the ratio of the flow rates of the fuel components (K _m ) in the chamber (the ratio of the mass flow rate of oxygen to the mass flow rate of kerosene) for ammonia additives of various magnitude (in% of the total flow rate of fuel components) .

An example implementation of the invention

The liquid rocket engine (Fig. 1) comprises a chamber 1 with a nozzle head 2 and a nozzle 3, a turbopump unit 4, which includes a coaxially mounted oxidizer pump 5 with a booster stage 6, a kerosene pump 7 with a booster stage 8, an ammonia pump 9 and a gas turbine 10 With its feed manifold 11, the turbine is connected to the gas generator 12, and the outlet pipe 13 to the nozzle head 2 of the chamber 1.

The gas generator 12 is supplied with liquid oxidizer and fuel from high-pressure lines 14 and 15, which are connected to the booster stages 6 and 8 of the oxidizer and fuel pumps, respectively. The chamber 1 is supplied with liquid oxidizer and fuel from high-pressure lines 16 and 17, which are connected to the first stages of the oxidizer pump 5 and fuel pump 7, respectively. The liquefied ammonia pump 9 is connected by a high-pressure pipe 18 to the regenerative flow cooling path of the chamber and nozzle 19 and 20, which is connected to the gas generator 12 by the outlet.

Liquid rocket engine operation

Liquefied oxygen enters the pump 5, from which through the pipe 16 it is supplied to the nozzle head 2 of the chamber 1, and from the booster stage 6 through the pipe 14 to the gas generator 12. Liquid kerosene enters the pump 7, from which through the pipe 17 enters the nozzle head 2 and to the pumping stage 8 and then through the pipeline 15 to the gas generator 12. The liquefied ammonia enters the pump 9, from which it is supplied through the pipe 18 to the regenerative cooling path 19 and 20 of the combustion chamber 1 and nozzle 3, and then to the gas generator 12.

As a result of stoichiometric combustion of the liquid fuel components (oxygen and kerosene), a “neutral” high-temperature gas is formed in the gas generator, which is then cooled to the values allowed by the turbine material by introducing the ammonia chamber that passed through the regenerative cooling path. The resulting turbogas enters the blades of the turbine 10, which drives the pumps 5, 6, 7, 8, 9 through a common shaft with it. From the outlet of the turbine, gas through a pipe 13 enters the nozzle head 2 of the combustion chamber 1. In it, the exhaust gas from the turbine 10 is burned with a liquid oxidizer and fuel, and the high-temperature combustion products expand further in the jet nozzle 3, creating a thrust of a liquid rocket engine.

For the proposed method, calculations were made of the dependence of the achievable specific impulse of the engine on the ratio of fuel components (K _t ) for ammonia additives of various magnitude (in% of the total consumption of fuel components) (see figure 2). Here, for a series of ammonia additives in the amount of (10-20)% - curves A - increase in specific impulse due to the improvement of the thermodynamic characteristics of the fuel in total with an increase in specific impulse due to the possibility of reducing the flow rate for curtain cooling of the chamber using an ammonia cooling scheme, ~ 5 is estimated sec And with a further increase in ammonia additives to (25 - 30)% - curves B - there is a significant substitution of the mass flow of kerosene to ammonia.

Thus, the use of fuel additives (from (10-30)%) in the form of liquefied ammonia to the fuel composition (oxygen-kerosene) can improve the energy characteristics of oxygen-kerosene liquid rocket engines.

Industrial applicability

The proposed LRE and fuel composition will find application in engines of both small thrust engines and powerful engines of launch vehicles.

Claims (4)

1. The method of operation of oxygen-kerosene liquid rocket engines with a fuel additive, in which the fuel additive is used as a refrigerant for flow cooling of the chamber, and then introduced into a gas generator having a fuel supply from pressure lines of liquefied oxygen and liquid kerosene and generating gas at stoichiometric ( α = 1) the combustion of these components, while the fuel additive is used to ballast "neutral gas" in order to reduce its temperature, and the resulting turbogas after operation The turbine is fed into the engine chamber, which also receives liquefied oxygen and liquid kerosene from the pressure stages of the pumps, characterized in that liquid ammonia is used as a fuel additive, while the proportion of ammonia in the fuel composition is 10-35% of the mass fuel consumption In addition, ammonia, which is part of turbogas, is burned in the combustion chamber. 2. A fuel composition for oxygen-kerosene liquid rocket engines containing liquefied oxygen, liquid kerosene and a fuel additive that improves the energy and operational characteristics of engines, characterized in that liquefied ammonia (NH ₃ ) is used as a fuel additive, while the proportion of ammonia in fuel composition is 10-35% of the mass fuel consumption. 3. The fuel composition according to claim 2, characterized in that the fuel additive in the form of liquefied ammonia, the proportion of which is 10-20% of the mass fuel consumption, increases the specific impulse of the engines to ~ 5 s. 4. The fuel composition according to claim 2, characterized in that the fuel additive in the form of liquefied ammonia, whose share is 20-35% of the mass fuel consumption, implements a substantial substitution of kerosene with cheaper ammonia.

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