A cross-media ramjet based on paste propellant

Abstract

The application discloses a cross-medium ramjet engine based on paste propellant and relates to the technical field of ramjet engines, and specifically comprises the following parts: an engine shell, an air ramjet combustion unit installed at the end of the engine shell, a switching chamber arranged in the engine shell, a water ramjet propellant storage tank arranged in the engine shell, a nitrous oxide storage tank installed in the engine shell and communicated with the water ramjet propellant storage tank, a piston driving motor installed in the engine shell, a first piston installed on the output shaft of the piston driving motor, a second piston installed on the shaft end of the output shaft of the piston driving motor, a water inlet pipeline arranged in the side wall of the engine shell and a gas pipeline arranged outside the water ramjet propellant storage tank. The application solves the technical problem that the cross-medium ramjet engine using paste fuel cannot meet the diameter requirement of the nozzle throat under different working conditions by using conventional means.

Description

Technical Field

[0001] This invention relates to the field of ramjet engine technology, and more particularly to a transmedium ramjet engine based on paste propellant. Background Technology

[0002] Compared to other cross-medium propulsion modes such as waterjet and propeller, cross-medium ramjet engines have advantages such as simple structure, high thrust, and high degree of integration. Cross-medium anti-ship missiles using cross-medium ramjet engines can achieve supersonic cruise in the atmosphere and terminal underwater hypersonic strikes, possessing extremely high maneuverability and stealth, significantly improving the penetration capability of anti-ship missiles, and achieving efficient strikes against ship targets.

[0003] Existing cross-medium ramjet engines typically use either liquid or solid fuel. Both types of fuel have the following drawbacks: For liquid fuel, refueling is mostly done on an ad-hoc basis, which increases launch preparation time and reduces the missile's rapid response capability; at the same time, the missile is susceptible to shaking and leakage during transportation and flight, leading to flight instability; for solid fuel, although solid ramjet engines have a simple structure, the active gas flow regulation of solid propellants is quite complex, making it difficult to achieve variable thrust control and multiple ignition.

[0004] Currently, many scholars have conducted in-depth research on the physicochemical properties and combustion organization methods of kerosene paste propellants containing metal or boron particles used in air ramjet engines, as well as related technologies for cross-medium metal powder or boron powder ramjet engines. However, research on cross-medium ramjet engines using paste propellants is rarely reported. The technical challenges of paste-fueled cross-medium ramjet engines lie in the integrated design of the propellant supply system and the engine combustion organization system, and the fact that the ideal diameter of the engine nozzle throat and outlet varies beyond the adjustment capabilities of existing technologies depending on the operating mode. Summary of the Invention

[0005] The purpose of this invention is to provide a cross-medium ramjet engine based on paste propellant, which solves the technical problem that conventional technologies cannot meet the nozzle throat diameter requirements under different operating conditions in cross-medium ramjet engines using paste fuel.

[0006] This application discloses a cross-medium ramjet engine based on paste propellant, comprising: Engine housing; An air-ram combustion unit is installed at the end of the engine housing; A switching chamber is disposed inside the engine housing, and the switching chamber is connected to the air ram combustion unit; A water-blimp propellant tank is disposed inside the engine housing, and the water-blimp propellant tank is located on the side of the switching chamber away from the air-blimp combustion unit; A nitrous oxide tank is installed inside the engine housing, and the nitrous oxide tank is located on the side of the water ram propellant tank away from the switching chamber. The nitrous oxide tank is in communication with the water ram propellant tank. A piston drive motor is installed inside the engine housing, and the output shaft of the piston drive motor extends from the water-jet propellant tank to the switching chamber. The first piston is mounted on the output shaft of the piston drive motor, and the first piston is located inside the water-jet propellant tank. The second piston is mounted on the output shaft end of the piston drive motor, and the second piston is located inside the switching chamber; A piston plug is installed at the end of the second piston; The water inlet pipe is located inside the side wall of the engine housing, and the water inlet pipe is connected to the switching chamber; A gas pipeline is located outside the water-flushing propellant tank, and the gas pipeline is connected to the nitrous oxide tank and the switching chamber.

[0007] This application incorporates multiple chambers, one of which is a switching chamber, facilitating subsequent mode switching.

[0008] Based on the above technical solution, the embodiments of this application can be further improved as follows: Furthermore, the air ram combustion unit includes: An air-ram combustion chamber is installed at the end of the engine housing; The first air intake is located on the outside of the engine housing, and the end of the first air intake is connected to the air ram combustion chamber. A first atomizing nozzle is disposed at the end of the air ram combustion chamber, with one end of the first atomizing nozzle connected to the switching chamber and the other end connected to the air ram combustion chamber; The second air intake is located at the end of the air ram combustion chamber, and the second air intake is connected to the first atomizing nozzle and the first air intake, respectively. The tail nozzle is connected to the side of the air ram combustion chamber away from the engine housing. The advantage of this step is that multiple channels work together to generate thrust.

[0009] Furthermore, an intake baffle is movably installed at the end of the second air intake. The beneficial effect of this step is to realize the opening and closing of the second air intake and to better complete the control.

[0010] Furthermore, a ejectable component is installed on the inner wall of the tail nozzle. The beneficial effect of this step is to adjust the inner diameter of the tail nozzle, thereby better adapting to the pressure of the combustion chamber.

[0011] Furthermore, an auxiliary channel is provided on the side of the air ram combustion chamber. One end of the auxiliary channel is connected to the first air intake, and the other end is connected to the air ram combustion chamber. An airflow baffle is movably installed at the first end of the auxiliary channel. The beneficial effect of this step is that the airflow is regulated by the airflow baffle, thereby achieving better fuel combustion.

[0012] Furthermore, a locking tongue is installed on the inner wall of the switching chamber, and an opening is provided on the side of the switching chamber facing the air ram combustion unit; the beneficial effect of this step is to achieve the switching of the second piston function through the locking tongue.

[0013] Furthermore, the gap between the locking tongue and the inner wall of the switching chamber end is L; The thickness of the second piston is D, and L≥D. The beneficial effect of this step is that it works in conjunction with the movable locking tongue, so that the second piston can be limited by the locking tongue after it passes over the locking tongue.

[0014] Furthermore, after the second piston passes the locking tongue, the locking tongue abuts against the back side of the second piston, the switching chamber changes from an air-rammed propellant tank to a water-rammed combustion chamber, the piston plug opens, and the second piston changes to a water-rammed mode nozzle.

[0015] Furthermore, it also includes a second atomizing nozzle and a third atomizing nozzle, wherein the second atomizing nozzle is connected and disposed on the side of the water-jet propellant tank facing the switching chamber; The third atomizing nozzle is disposed on the side wall of the switching chamber, and the third atomizing nozzle is connected to the switching chamber and the water inlet pipe respectively. The beneficial effect of this step is that the seawater is atomized by multiple atomizing nozzles, which is conducive to rapid vaporization into water vapor, and thus facilitates the full mixing of water vapor and propellant, which is beneficial to combustion and improves fuel utilization efficiency.

[0016] Furthermore, both the water-flushing propellant tank and the switching chamber store paste propellant. The advantage of this step is that paste propellant replaces both liquid and solid fuels, combining the advantages of both liquid and solid propellants. Moreover, the propellant flow rate is controllable, and the propellant storage is safe and convenient.

[0017] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. This application is designed with a switching chamber and a second piston to realize the integrated design of the propellant supply piston and the tail nozzle in the water ramjet mode, which can meet the requirements of the ramjet engine for the throat diameter of the tail nozzle in both water ramjet and air ramjet modes.

[0018] 2. The switching chamber in this application can be used as both an air-ramjet propellant tank and a water-ramjet combustion chamber, which reduces the structural mass and volume of the engine to a certain extent.

[0019] 3. This application uses a paste propellant, which combines the advantages of both liquid and solid fuels, while also offering adjustable flow rate and safe and convenient storage. Compared to traditional oxygen-deficient solid fuels, paste propellants have a higher energy density, providing ample power.

[0020] 4. This application designs the overall structure, reducing the structural mass and volume of the engine. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a transmedium ramjet engine based on paste propellant according to a specific embodiment of the present invention; 1-Engine housing; 2-Air ramjet combustion unit; 3-Switching chamber; 4-Water ramjet propellant tank; 5-Nitrous oxide tank; 6-Piston drive motor; 7-First piston; 8-Second piston; 9-Water inlet pipe; 10-Gas pipe; 11-Lock; 12-Second atomizing nozzle; 13-Third atomizing nozzle; 14-Opening; 15-Piston plug; 201-Air ram combustion chamber; 202-First air intake; 203-First atomizing nozzle; 204-Second air intake; 205-Tail nozzle; 206-Throwable component; 207-Auxiliary channel; 208-Baffle drive motor; 209-Intake duct plug; 210-Intake baffle; 211-Airflow baffle. Detailed Implementation

[0023] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0024] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by those skilled in the art to which this invention pertains.

[0025] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] To better understand the above technical solutions, the following will provide a detailed description of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0027] Example: like Figure 1 As shown in the figure, this application discloses a cross-medium ramjet engine based on paste propellant. From the front end to the rear end, it is divided into several parts such as a nitrous oxide tank, a water ramjet propellant tank, a switching chamber, an air ramjet combustion chamber, and a tail nozzle. The water ramjet propellant tank stores paste propellant. Compared with traditional oxygen-deficient solid fuel, paste propellant has a higher energy density and can achieve high-speed penetration, high-speed attack, and high-speed hit characteristics. The specific structure of this application includes: Engine housing 1, the engine housing 1 having an internal cavity for installing the remaining combustion chambers and storage tanks; The air ramjet combustion unit 2 is located at the end of the engine housing 1, which facilitates its use during the high-altitude cruise phase and can be completely jettisoned later. A switching chamber 3 is located inside the engine housing 1 and is connected to the air-ramjet combustion unit 2. The switching chamber 3 can be filled with air-ramjet paste propellant. After the combustion material in the switching chamber 3 is exhausted, it switches to a water-ramjet combustion chamber. Another function of the switching chamber 3 is that its connection to the air-ramjet combustion unit 2, acting as an air-ramjet propellant tank, allows paste propellant containing high-energy solid particles to be supplied into the air-ramjet combustion unit 2, where it mixes and combusts with ramjet air to provide power for the air-ramjet flight phase. A water-blimp propellant tank 4 is disposed inside the engine housing 1, and the water-blimp propellant tank 4 is located on the side of the switching chamber 3 away from the air-blimp combustion unit 2. The water-blimp propellant tank 4 stores water-blimp paste propellant, which is convenient to be subsequently pressed into the switching chamber 3 for combustion. A nitrous oxide storage tank 5 is installed inside the engine housing 1, and the nitrous oxide storage tank 5 is located on the side of the water-impact propellant tank 4 away from the switching chamber 3. The nitrous oxide storage tank 5 is connected to the water-impact propellant tank 4, specifically through a pipeline. The nitrous oxide stored in the nitrous oxide storage tank 5 is used to provide power to pressurize the paste propellant in the water-impact propellant tank into the switching chamber. For easy adjustment, a regulating valve can be installed on the pipeline to regulate the flow rate of nitrous oxide, thereby regulating the supply speed of the paste propellant. A piston drive motor 6 is installed inside the engine housing 1, and the output shaft of the piston drive motor 6 extends from the water-jet propellant tank 4 to the switching chamber 3. The piston drive motor 6 is used to drive the subsequent first piston and second piston, thereby realizing the supply of materials. The first piston 7 is installed on the output shaft of the piston drive motor 6 and is located inside the water-blister propellant tank 4. The first piston 7 is used to push the propellant inside the water-blister propellant tank 4. The second piston 8 is installed on the output shaft end of the piston drive motor 6 and is located inside the switching chamber 3. The second piston 8 is an integrated piston. During installation, the piston plug 15 is first installed on the output shaft end of the piston drive motor 6, and then the second piston 8 is connected by an explosion bolt. At this time, the piston plug 15 is located at the end of the second piston 8. After the explosion bolt is actuated, under the action of the high-pressure gas transported by the nitrous oxide storage tank 5, the piston plug is thrown out. At this time, the second piston 8 arrives at the end of the switching chamber and is used as a nozzle structure. The water inlet pipe 9 is located inside the side wall of the engine housing 1 and is connected to the switching chamber 3. The water inlet pipe 9 has an inlet to facilitate the entry of seawater into the water inlet pipe 9. After the seawater enters the water inlet pipe 9, it is atomized through a corresponding atomizing nozzle. Gas pipeline 10 is located outside the water-flushing propellant tank 4. Gas pipeline 10 is connected to the nitrous oxide tank 5 and the switching chamber 3 respectively. Gas pipeline 10 facilitates nitrous oxide to push the corresponding propellant into the next combustion chamber.

[0028] In one embodiment, during a subsequent process, the air ram-combustion unit 2 is ejected as a whole, and its specific structure includes: The air ram combustion chamber 201 is installed at the end of the engine housing 1, and the specific connection method can be the connection method of explosive bolts; The first air intake duct 202 is located on the outside of the engine housing 1, and the end of the first air intake duct 202 is connected to the air ram combustion chamber 201. The first air intake duct 202 is also connected to the engine housing 1 by explosive bolts. When the first air intake duct 202 is working, it captures the incoming air and enters the air ram combustion chamber 201 to serve as an oxidant for the propellant to burn. The first atomizing nozzle 203 is disposed at the end of the air ram combustion chamber 201. One end of the first atomizing nozzle 203 is connected to the switching chamber 3, and the other end is connected to the air ram combustion chamber 201. The atomizing nozzle 203 facilitates the atomization of the paste propellant, thereby improving the fuel utilization rate. The second air intake 204 is disposed at the end of the air ram combustion chamber 201. One end of the second air intake 204 is connected to the first atomizing nozzle 203, and the other end is connected to the first air intake 202. It is connected and cooperates with the aforementioned first atomizing nozzle 203 to provide airflow and complete the supply of propellant material. The tail nozzle 205 is connected to the side of the air ram combustion chamber 201 away from the engine housing 1 to meet the engine's operating requirements in air ram mode.

[0029] Specifically, an air intake baffle 210 is movably installed at the first end of the second air intake duct 204 to facilitate subsequent atomized air intake and to adjust the flow rate.

[0030] In one embodiment, a ejectable component 206 is installed on the inner wall of the tail nozzle 205. Specifically, the ejectable component is connected by an explosive bolt and is subsequently detached from the tail nozzle 205, thereby increasing the inner diameter of the tail nozzle 205 to accommodate the pressure of the air ram combustion chamber 201.

[0031] In another embodiment, an auxiliary channel 207 is provided on the side of the air ram combustion chamber 201. One end of the auxiliary channel 207 is connected to the first air intake 202, and the other end is connected to the air ram combustion chamber 201. An airflow baffle 211 is movably installed at the first end of the auxiliary channel 207, which is specifically started by a drive motor 208.

[0032] The auxiliary channel 207 in this application can divide the airflow into front-entry or rear-entry sections, thereby achieving airflow diversion and ensuring the energy utilization rate of the propellant.

[0033] Specifically, an intake duct plug 209 is installed at the end of the first intake duct 202. The intake duct plug 209 is used to open and close the first intake duct 202. After entering the air ram mode in this application, the intake duct plug 209 is opened, and the captured incoming air is introduced into the air ram combustion chamber 201.

[0034] In another embodiment, a locking tongue 11 is installed on the inner wall of the switching chamber 3, and an opening 14 is provided on the side of the switching chamber 3 facing the air ram combustion unit 2; the locking tongue 11 is a movable part that can move up and down, for example, the locking tongue 11 will pop out after the second piston 8 passes through the locking tongue 11.

[0035] The gap between the locking tongue 11 and the inner wall of the end of the switching chamber 3 is L; The thickness of the second piston 8 is D, and L ≥ D. Specifically, L can be slightly greater than D; this facilitates the movement of the second piston 8.

[0036] To further explain the above structure, during the subsequent water entry transition phase, the piston plug is ejected under the action of high-pressure nitrous oxide gas, and the second piston 8 transforms into a water-rammed mode nozzle. At this time, the switching chamber 3 transforms from an air-rammed propellant tank into a water-rammed combustion chamber. The second piston 8 is mounted on the output shaft of the piston drive motor 6. At this time, the second piston 8 slides out of the output shaft, and the through hole in the middle is used as a nozzle.

[0037] In this application, the air intake cover 209, air intake baffle 210, and airflow baffle 211 are all movable mechanisms driven by corresponding motors.

[0038] In another embodiment, the present application further includes a second atomizing nozzle 12 and a third atomizing nozzle 13, wherein the second atomizing nozzle 12 is connected to the side of the water-jet propellant tank 4 facing the switching chamber 3; The third atomizing nozzle 13 is disposed on the side wall of the switching chamber 3 and is connected to the switching chamber 3. This application achieves atomization treatment through multiple atomizing nozzles, which is conducive to the rapid vaporization of seawater into water vapor, thereby facilitating the full mixing of water vapor and propellant, which is beneficial to combustion and improves fuel utilization efficiency.

[0039] Specifically, the water-flushing propellant tank 4 described in this application stores paste propellant inside.

[0040] The working process for this application is as follows: When this application is launched from the ground (air), the solid propellant in the air-ramjet combustion chamber 201 ignites first to generate thrust and propel the missile to the predetermined cruise altitude and cruise Mach number. After entering the high-altitude cruise phase, the intake duct plug 209 is opened, and ram air enters from the first intake duct 202. The piston drive motor 6 starts to work, and the nitrous oxide tank provides high-pressure nitrous oxide gas. This gas enters the switching chamber 3 from the gas pipeline 10. In conjunction with the piston drive motor 6, the paste propellant (containing high-energy solid particles) in the gas is supplied into the air ramjet combustion chamber 201, where it mixes and burns with the ramjet air, and the ejectable parts 206 are thrown away. This increases the throat diameter of the tail nozzle 205 to adapt to the combustion chamber pressure and gas flow rate during the ramjet propulsion phase. During the water transition phase, the air ramjet combustion unit 2 is jettisoned. At this time, the second piston 8 is fixed to the end of the switching chamber 3 by the locking tongue 11. The piston plug is opened and thrown out under the action of high-pressure nitrous oxide gas. The second piston 8 is transformed into a water ramjet mode nozzle. At this time, the switching chamber 3 is transformed from an air ramjet propellant tank into a water ramjet combustion chamber.

[0041] After entering underwater cruising mode, the engine fuel is switched to water-rammed paste propellant. At this time, the superheated steam formed by heating and atomizing seawater in the combustion chamber (i.e., switching chamber 3) is used as the oxidant. The high-pressure nitrous oxide gas in the nitrous oxide tank 5 decomposes to generate high-temperature and high-pressure oxygen-containing gas to assist the ignition and combustion of the water-rammed paste propellant. The engine operates in water-rammed mode. The missile uses the water-rammed engine and is supplemented by supercavitation drag reduction technology to achieve high-speed penetration, high-speed attack, and high-speed hit characteristics.

[0042] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0043] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A transmedium ramjet engine based on paste propellant, characterized in that, include: Engine housing; An air-ram combustion unit is installed at the end of the engine housing; A switching chamber is disposed inside the engine housing, and the switching chamber is connected to the air ram combustion unit; A water-blimp propellant tank is disposed inside the engine housing, and the water-blimp propellant tank is located on the side of the switching chamber away from the air-blimp combustion unit; A nitrous oxide tank is installed inside the engine housing, and the nitrous oxide tank is located on the side of the water ram propellant tank away from the switching chamber. The nitrous oxide tank is in communication with the water ram propellant tank. A piston drive motor is installed inside the engine housing, and the output shaft of the piston drive motor extends from the water-jet propellant tank to the switching chamber. The first piston is mounted on the output shaft of the piston drive motor, and the first piston is located inside the water-jet propellant tank. The second piston is mounted on the output shaft end of the piston drive motor, and the second piston is located inside the switching chamber; A piston plug is installed at the end of the second piston; The water inlet pipe is located inside the side wall of the engine housing, and the water inlet pipe is connected to the switching chamber; A gas pipeline is located outside the water-flushing propellant tank, and the gas pipeline is connected to the nitrous oxide tank and the switching chamber.

2. The transmedium ramjet engine according to claim 1, characterized in that, The inner wall of the switching chamber is equipped with a locking tongue; The switching chamber has an opening on the side facing the air ram combustion unit.

3. The transmedium ramjet engine according to claim 2, characterized in that, The gap between the locking tongue and the inner wall of the end of the switching chamber is L; The thickness of the second piston is D, and L ≥ D.

4. The transmedium ramjet engine according to claim 3, characterized in that, When the second piston passes the locking tongue, the locking tongue abuts against the back side of the second piston, the switching chamber changes from an air-rammed propellant tank to a water-rammed combustion chamber, the piston plug opens, and the second piston changes to a water-rammed mode nozzle.

5. The transmedium ramjet engine according to claim 1, characterized in that, The air ram combustion unit includes: An air-ram combustion chamber is installed at the end of the engine housing; The first air intake is located on the outside of the engine housing, and the end of the first air intake is connected to the air ram combustion chamber. A first atomizing nozzle is disposed at the end of the air ram combustion chamber, with one end of the first atomizing nozzle connected to the switching chamber and the other end connected to the air ram combustion chamber; The second air intake is located at the end of the air ram combustion chamber, and the second air intake is connected to the first atomizing nozzle and the first air intake, respectively. The tail nozzle is connected to the side of the air ram combustion chamber away from the engine housing.

6. The transmedium ramjet engine according to claim 5, characterized in that, An intake baffle is movably installed at the end of the second air intake.

7. The transmedium ramjet engine according to claim 5, characterized in that, An auxiliary channel is provided on the side of the air ramjet combustion chamber. One end of the auxiliary channel is connected to the first air intake, and the other end is connected to the air ramjet combustion chamber. An airflow baffle is movably installed at the first end of the auxiliary channel, and the airflow baffle is used to open and close the auxiliary channel.

8. The transmedium ramjet engine according to claim 1, characterized in that, It also includes a second atomizing nozzle and a third atomizing nozzle, wherein the second atomizing nozzle is connected to and disposed on the side of the water-jet propellant tank facing the switching chamber; The third atomizing nozzle is disposed on the side wall of the switching chamber, and the third atomizing nozzle is connected to both the switching chamber and the water inlet pipe.

9. The transmedium ramjet engine according to claim 1, characterized in that, Both the water-flushing propellant tank and the switching chamber contain paste propellant.

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