A method for enhancing premixed combustion of aviation piston gasoline engines

Abstract

The present invention belongs to the technical field of gasoline piston engines. It relates to a method for enhancing premixed combustion in an aviation piston gasoline engine, wherein the aviation piston gasoline engine comprises a fuel system, a combustion-supporting system, and a power system. The fuel system is used to provide gasoline, and the combustion-supporting system is used to provide combustion-supporting air required for fuel combustion. The gasoline and combustion-supporting air are premixed to form a premixed gas, and the obtained mixed gas enters the power system and is compressed and combusted to release heat. A monatomic noble gas supply system is added to the combustion-supporting system, and monatomic noble gas is added to the premixed gas through the monatomic noble gas supply system to increase the average adiabatic compression index and thermal conductivity of the premixed gas, thereby increasing the heat release intensity of the premixed gas during the compression process and the thermal conductivity of the airflow during the combustion process, accelerating the flame propagation rate during the ignition process, and reducing the fluctuation of the airflow combustion load.

Description

Technical Field

[0001] The invention belongs to the field of gasoline piston engines and relates to a method for enhancing premixed combustion of an aviation piston gasoline engine. Background Art

[0002] Gasoline, a traditional fossil fuel, is widely used in aircraft, particularly defense and military applications, due to its high energy density and rapid combustion. This demand is expected to persist for some time. Improving the low combustion efficiency and poor environmental adaptability of aviation piston gasoline engines is a pressing need for the development of high-performance unmanned systems.

[0003] Premixed combustion involves injecting a predetermined amount of fuel into the intake duct before the combustion chamber, where it is premixed with air. The fuel then enters the combustion chamber, where it is compressed and ignited. Under certain conditions, the chemical reaction rate between fuel and oxygen is determined by the initial temperature of the mixture. A lower initial temperature not only increases the time required for complete combustion but also weakens the premixing of fuel and air, increasing incomplete combustion losses. Furthermore, this premixed combustion mode requires that the combustion air required by gasoline engines cannot be preheated with high-temperature flue gas. Raising the air temperature lowers the explosive limit of the mixture, further limiting power gains. For military aircraft, the flight environment can vary significantly due to daytime, seasonal changes, and spatial movement. In particular, under extremely low temperatures, the combustion efficiency and response time of the combustion chamber can significantly deviate from normal operating conditions. Carbon deposits are more likely to form on the igniter surface at low temperatures, resulting in higher system fuel consumption and poor fuel economy. Therefore, expanding the engine's combustion range and reducing energy consumption are key to ensuring efficient and reliable operation in extreme and complex climates. Summary of the Invention

[0004] In light of this, the present invention aims to address the rapid ignition, combustion stability, and incomplete combustion of fuel in piston gasoline engines under low-temperature conditions by providing a method for enhancing premixed combustion in aviation piston gasoline engines. By adjusting the thermodynamic parameters of the combustion-supporting mixed gas, the initial temperature of the fuel mixture at ignition is increased without changing the gas's thermodynamic state parameters. This enhances the degree of fuel premixing, accelerates flame propagation, and reduces incomplete combustion of the premixed gas, thereby ensuring engine efficiency and system response.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for enhancing premixed combustion in an aviation piston gasoline engine comprises a fuel system, a combustion-supporting system, and a power system. The fuel system is used to provide gasoline fuel, and the combustion-supporting system is used to provide combustion-supporting air. The gasoline fuel and the combustion-supporting air are premixed to form a premixed gas, which enters the power system for compression and heat release combustion. A monatomic noble gas supply system is added to the combustion-supporting system. Monatomic noble gas is added to the premixed gas through the monatomic noble gas supply system to increase the average adiabatic compression index and thermal conductivity of the premixed gas, thereby increasing the heat release rate and thermal conductivity of the premixed gas during the compression process, accelerating the flame propagation rate during the ignition process, and reducing fluctuations in the airflow combustion load.

[0007] Furthermore, the premixing process adopts two-stage premixing. The first stage premixing is: premixing the combustion air with the monatomic rare gas to form mixed combustion air; the second stage premixing is: the mixed combustion air is fully premixed with the gasoline fuel to obtain a premixed gas with a preset chemical equivalence ratio.

[0008] Furthermore, by adding monatomic rare gas, the adiabatic compression temperature rise of the premixed gas is controlled to be no more than 20°C. When the engine compression ratio is 6 to 10, the average adiabatic compression index of the mixed gas is controlled between 1.410 and 1.428.

[0009] Furthermore, the monatomic noble gas is helium with a purity of no less than 99%. Helium has good chemical stability in an air environment at 2000°C to 2500°C. The present invention is not highly sensitive to the purity of helium, and rather than using 99.999% pure helium, relatively lower purity helium can be used within the permitted range, resulting in lower costs.

[0010] Furthermore, by increasing the mixing ratio of helium, the combustion ignition response time and the degree of complete combustion are shortened.

[0011] Furthermore, the mass ratio of combustion air to gasoline fuel is between 14.7:1 and 15:1, and the mixing ratio of combustion air to helium is adjusted according to the combustion response time of the combustion process or the working environment temperature. Under the same compression ratio conditions, the mass proportion of helium increases with the decrease of the ambient temperature, and the mass ratio of helium to air does not exceed 1 / 97.09.

[0012] Furthermore, the monatomic rare gas supply system operates in a low-temperature intake environment of -30°C to 0°C and during a load increase process. Working in a low-temperature intake environment of -30°C to 0°C is used to improve the success rate of premixed combustion ignition in a low-temperature environment and shorten the ignition time. Working in a low-temperature intake environment of -30°C to 0°C is used to accelerate the response speed of the engine.

[0013] Furthermore, when the empty piston gasoline engine is in high-speed operation and a single cycle time is less than 1.25 ms, the mass ratio of helium to air is not less than 1 / 400.

[0014] Furthermore, the monatomic noble gas supply system utilizes a constant-pressure system, with reusable high-pressure gas cylinders containing a safety factor of no less than 1.5. These cylinders possess high strength and thermal conductivity, enabling rapid gas filling and discharge, and boasting high gas filling efficiency, ensuring rapid readiness after the aircraft returns to standby mode.

[0015] The beneficial effects of the present invention are:

[0016] The present invention adjusts the thermal compression coefficient of the combustion-supporting air required by the gasoline engine and the thermal conductivity of the premixed combustion gas by adopting rare gases with large adiabatic index and thermal conductivity and stable chemical properties. Specifically, on the one hand, a certain amount of gas with a large adiabatic compression index is mixed into the air. Under the same compression ratio conditions, the mixed airflow with a larger adiabatic compression index can obtain more heat during the compression process; in addition, the addition of monatomic gases with high thermal conductivity and stable chemical properties can accelerate the propagation speed of the premixed flame and the unevenness of the heat load during the combustion process, and the combustion characteristics of the gasoline premixed combustion can be further enhanced.

[0017] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0019] Figure 1 Schematic diagram of the principle of the premixed combustion process in the present invention. DETAILED DESCRIPTION

[0020] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0021] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0022] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0023] See also Figure 1 , which is a method for enhancing premixed combustion of an aviation piston gasoline engine. The aviation piston gasoline engine includes a fuel system, a combustion-supporting system and a power system. The fuel system is used to provide gasoline fuel, and the combustion-supporting system is used to provide combustion-supporting air. The gasoline fuel and the combustion-supporting air are premixed to form a premixed gas, and the premixed gas enters the power system for compression and heat release combustion. A monatomic rare gas supply system is added to the combustion-supporting system. Monatomic rare gas is added to the premixed gas through the monatomic rare gas supply system to increase the average adiabatic compression index and thermal conductivity of the premixed gas, thereby increasing the heat release rate and thermal conductivity of the premixed gas in the compression process, accelerating the flame propagation rate in the ignition process, and reducing the fluctuation of the airflow combustion load.

[0024] Among them, the premixing process adopts two-stage premixing. The first-stage premixing is: premixing the combustion air with the monatomic rare gas to form mixed combustion air; the second-stage premixing is: the mixed combustion air is then fully premixed with the gasoline fuel to obtain a premixed gas with a preset chemical equivalence ratio.

[0025] Among them, the premixing process adopts two-stage premixing. The first-stage premixing is: premixing the combustion air and the monatomic noble gas to form mixed combustion air; the second-stage premixing is: the mixed combustion air is fully premixed with the gasoline fuel to obtain a mixed gas with a preset chemical equivalence ratio; in the premixing process, the mixing ratio of the combustion air, monatomic noble gas and gasoline fuel is adjusted to change the heat release of the mixed fuel in the compression combustion process to ensure the heat required in the initial stage of combustion.

[0026] In this embodiment, the monatomic noble gas is helium with a purity of not less than 99% and an adiabatic compression index of 1.66. The combustion air is air. Because the present invention is not highly sensitive to the purity of helium, the relatively inexpensive 99% pure helium is directly used instead of 99.999% pure helium to reduce costs.

[0027] The monatomic noble gas supply system operates in a low-temperature intake air environment of -30°C to 0°C and during load ramp-up. Operating in this low-temperature intake air environment improves the success rate of premixed combustion ignition and shortens ignition time in low-temperature environments, while operating during load ramp-up accelerates engine response. When the empty-piston gasoline engine is operating at high speed, with a single cycle time of less than 1.25ms, the helium-to-air mass ratio must be no less than 1 / 400.

[0028] The range of air, helium, and gasoline fuel mixture ratios is primarily determined by the mixture's combustion response time and ambient temperature. At the same compression ratio, the helium mass percentage increases as ambient temperature decreases. For example, at a compression ratio of 6 and an initial ambient temperature of 300K, adding only 0.405g of helium to 1kg of gasoline raises the mixture's initial combustion temperature by 10°C.

[0029] The efficient and rapid combustion of the mixed gas is mainly determined by the thermodynamic characteristics of the combustion-supporting system, and the rapid ignition process is mainly determined by the overall temperature level of the compressed mixed gas. As an option, under the conditions of a compression ratio of 6 and a temperature rise of 10°C, the mass ratio of air to fuel is 14.7:1, and the mass ratio of air to helium is 193.87:1.

[0030] At the same time, the proportion of helium needs to be adjusted according to the feedback of the control system on the inlet temperature level of the combustion system.

[0031] The monatomic noble gas supply system is a constant-pressure gas supply system, primarily consisting of a pressure reducing valve, gas cylinders, and piping. The cylinders must possess high strength and thermal conductivity, enabling rapid gas filling and discharge, with high gas filling efficiency to ensure rapid return to standby mode after the aircraft returns. The weight of the monatomic noble gas supply system should not increase the power system's energy consumption. The cylinders should have a defined lifespan, maintaining high performance while maintaining a long service life. The allowable safety factor should be no less than 1.5. The monatomic noble gas supply system should be a key piece of equipment requiring regular maintenance.

[0032] Because the gas used in the engine comes from the atmosphere of the flight environment, the monatomic rare gas supply system is only used as a backup in high temperature weather and is not put into use under cruise conditions.

[0033] When the present invention is applied, it is completed by the cooperation of three parts: the combustion-supporting system, the fuel system and the power system. The air required for the combustion process is pressurized by the compression system, and then high-pressure helium is mixed into the combustion-supporting air to form mixed combustion-supporting air. The obtained mixed combustion-supporting air is fully premixed with gasoline fuel again downstream to obtain a mixed gas with a suitable chemical equivalence ratio. Finally, the mixed gas enters the cylinder through the gasoline engine flow channel and is compressed and releases heat under the action of the piston, thereby improving the combustion and working capacity of the engine; at the same time, helium can obtain a lower exhaust temperature, which can ensure the safety of the tail system. This method fundamentally improves the combustion response characteristics of the power system and makes up for the low efficiency of the initial stage of gasoline premixed combustion, especially in low-temperature environments. By premixing a certain amount of helium in the combustion-supporting air, the adiabatic compression process can obtain more heat than the heat released by the compression process of a single air. Therefore, timely input and adjustment of the mixing amount of helium according to different needs can greatly improve the system performance.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for enhancing premixed combustion in an aviation piston gasoline engine, the aviation piston gasoline engine comprising a fuel system, a combustion-supporting system, and a power system, wherein the fuel system is configured to provide gasoline fuel, the combustion-supporting system is configured to provide combustion-supporting air, the gasoline fuel and combustion-supporting air being premixed to form premixed gas, which enters the power system for compression and exothermic combustion, and is characterized by: A monatomic noble gas supply system is added to the combustion-supporting system. Monatomic noble gas is added to the premixed gas through the monatomic noble gas supply system to increase the average adiabatic compression index and thermal conductivity of the premixed gas, thereby increasing the heat release rate and thermal conductivity of the premixed gas during the compression process, accelerating the flame propagation rate during the ignition process, and reducing fluctuations in the airflow combustion load. By adding monatomic rare gas, the adiabatic compression temperature rise of the premixed gas is kept below 20°C. When the engine pressure ratio is 6-10, the average adiabatic compression index of the premixed gas is controlled between 1.410 and 1.

428. The monatomic rare gas supply system operates in a low-temperature intake environment of -30°C to 0°C and during a load increase process. Working in a low-temperature intake environment of -30°C to 0°C is used to improve the success rate of premixed combustion ignition in a low-temperature environment and shorten the ignition time. Working in a load increase process is used to accelerate the response speed of the engine.

2. The method for enhancing premixed combustion of an aviation piston gasoline engine according to claim 1, characterized in that: The premixing process adopts two-stage premixing. The first stage premixing is: premixing the combustion air with the monatomic rare gas to form mixed combustion air; the second stage premixing is: the mixed combustion air is fully premixed with the gasoline fuel to obtain a premixed gas with a preset chemical equivalence ratio.

3. The method for enhancing premixed combustion of an aviation piston gasoline engine according to claim 2, characterized in that: The monatomic noble gas is helium with a purity of not less than 99%.

4. The method for enhancing premixed combustion of an aviation piston gasoline engine according to claim 3, characterized in that: The mass ratio of combustion air to gasoline fuel is between 14.7:1 and 15:

1. The mixture ratio of combustion air to helium is adjusted according to the combustion response time of the combustion process or the working environment temperature. Under the same compression ratio conditions, the mass proportion of helium increases as the ambient temperature decreases.

5. The method for enhancing premixed combustion of an aviation piston gasoline engine according to claim 3, characterized in that: By increasing the mixing ratio of helium, the combustion ignition response time and the degree of complete combustion are shortened.

6. The method for enhancing premixed combustion of an aviation piston gasoline engine according to claim 5, characterized in that: When the aviation piston gasoline engine is in high-speed operation and the single cycle time is less than 1.25ms, the mass ratio of helium to air is not less than 1 / 400.

7. The method for enhancing premixed combustion of an aviation piston gasoline engine according to claim 1, characterized in that: The monatomic noble gas supply system adopts a constant pressure gas supply system, and the gas storage device therein adopts a reusable high-pressure gas cylinder, and the allowable safety use factor of the high-pressure gas cylinder is not less than 1.5.

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