A throttle-based assisted ignition device

Abstract

The application discloses a kind of throttling-based auxiliary ignition device, including circular cross-section combustion chamber, kerosene injection support plate and injection hole installation point, combustion chamber includes isolation section, groove section and expansion section, kerosene injection support plate is installed in isolation section export, injection hole installation point and the installation position of kerosene injection support plate are in the same section, injection hole installation point is spaced distribution with kerosene injection support plate, and a group of air injection holes are installed in injection hole installation point.The application can promote kerosene reliable ignition to start stable combustion under the condition of not using flammable gas, high-frequency spark plug and igniter, and can be reused, simplify auxiliary ignition device, reduce system complexity, improve reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of scramjet engine, in particular to an auxiliary ignition device based on throttling. BACKGROUND

[0002] For the combustion chamber of scramjet engine, when the total temperature of airflow is greater than or equal to 1200K, the injected kerosene can be self-ignited and stably combusted; when the total temperature of airflow is less than or equal to 1000K, the injected kerosene cannot be self-ignited and needs to be ignited by an auxiliary ignition device. The commonly used auxiliary ignition devices include: ①pioneer flame auxiliary ignition, using flammable gas such as hydrogen or methane to ignite first and then ignite kerosene by high-frequency spark plug, the disadvantage is that flammable and explosive gas and high-frequency spark plug are needed; ②plasma auxiliary ignition, using high-voltage to break through air to form an electric arc, heating inert gas (such as argon, helium) to form a hot high-temperature flow to ignite kerosene, the disadvantage is that high-voltage power supply is needed; ③electric ignition tube auxiliary ignition, solid fuel is ignited and combusted to form a high-heat particle flow to ignite kerosene, the disadvantage is that it can only be used once, and multiple backups need to be pre-installed to prevent accidental engine shutdown.

[0003] For supersonic airflow with total temperature of 1000-1200K, the total temperature is slightly higher than the lower limit of kerosene self-ignition temperature, so there is a possibility of not using flammable gas, high-frequency spark plug, ignition tube, etc. to produce flame or hot gas flow, and only using a relatively simple way to promote kerosene ignition and stable combustion. Accordingly, the present application proposes a simple auxiliary ignition method, which sprays air at the kerosene injection position to promote kerosene ignition and combustion without using additional ignition devices, and can be reused multiple times. SUMMARY

[0004] The present application aims to provide an auxiliary ignition device based on throttling, which can promote kerosene ignition and combustion without using additional ignition devices, and can be reused multiple times.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] An auxiliary ignition device based on throttling, comprising a circular cross-section combustion chamber, a kerosene injection support plate and a spray hole mounting point, the combustion chamber comprises an isolation section, a groove section and an expansion section, the kerosene injection support plate is installed at the outlet of the isolation section, the spray hole mounting point and the installation position of the kerosene injection support plate are in the same cross-section, the spray hole mounting point is distributed with the kerosene injection support plate, and the spray hole mounting point is installed with a group of air spray holes.

[0007] Further, the spray hole mounting point has four, and the kerosene injection support plate has four.

[0008] Further, the number of spray holes of a group of air spray holes is obtained by the following steps:

[0009] (1) According to the flow of supersonic airflow into the combustion chamber Determine the air injection amount

[0010] (2) According to the formula Get the relationship between injection pressure and the number of injection holes, where γ is the specific heat ratio of air, R is the gas constant, T is the air temperature, P is the air injection pressure; M is the air injection hole outlet Mach number, take 1 Mach, A is the total flow area of all injection holes;

[0011] (3) According to the total flow area of all injection holes and the number of injection hole mounting points, the number of injection holes at each injection hole mounting point is distributed, and the diameter of the injection hole is 0.8-1.2mm.

[0012] Further, in step (3), the total flow area of the injection holes is converted into the total number of injection holes, and the total number of injection holes is evenly distributed to each injection hole mounting point. If the total number of injection holes and the injection hole mounting points are not in a multiple relationship, one injection hole is added or reduced, and the air injection pressure is adjusted to meet the flow requirement.

[0013] Further, in step (3), the number of injection holes at each injection hole mounting point is determined according to the distribution characteristics of kerosene. The area where the kerosene injection amount is large can increase the number of injection holes at the injection hole mounting point.

[0014] Further, in step (3), when the radius of the combustion chamber exceeds 100mm, a 0.8mm diameter injection hole is used.

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

[0016] The present application proposes a kerosene auxiliary ignition method and device under low total temperature conditions. For supersonic airflow with a total temperature of 1000K-1200K, a certain pressure (flow) of air is injected at the kerosene injection position, a throttling effect is formed at the local section to slow down the supersonic airflow, and the injected air can also improve the mixing performance of kerosene to quickly reach the ignition condition. Therefore, under the condition of not using flammable gas, high-frequency spark plug and igniter, kerosene can be reliably ignited to start stable combustion, and can be repeatedly used, simplifying the auxiliary ignition device, reducing system complexity and improving reliability. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A combustion chamber structure diagram of an auxiliary ignition device based on throttling is provided for an embodiment of the present application;

[0018] Figure 2 An air injection hole and kerosene injection support plate arrangement diagram is provided for an embodiment of the present application.

[0019] In the figure, the reference signs are: 1, isolation section; 2, recess section; 3, expansion section; 4, air injection hole; 5, kerosene injection support plate. DETAILED DESCRIPTION

[0020] The application will be further described in detail below in combination with the drawings and embodiments:

[0021] As shown in Figure 1 and Figure 2 , a throttling-based auxiliary ignition device includes a circular cross-section combustion chamber, a kerosene injection support plate 5 and an injection hole mounting point, the combustion chamber includes an isolation section 1, a recess section 2 and an expansion section 3, the kerosene injection support plate 5 is installed at the outlet of the isolation section 1, the recess section 2 provides a low-speed, high-temperature zone, and the combination of the support plate + recess is a commonly used combustion organization method in the current supersonic combustion chamber research, and the configuration thereof will not be described herein. The installation position of the injection hole mounting point and the kerosene injection support plate 5 is in the same cross-section, and the injection hole mounting point and the kerosene injection support plate 5 are spaced apart, the injection hole mounting point of the embodiment has four, the kerosene injection support plate 5 has four, and the injection hole mounting point is installed with a group of air injection holes 4.

[0022] The number of injection holes of the group of air injection holes 4 is obtained by the following steps:

[0023] (1) According to the flow of the supersonic airflow entering the combustion chamber determine the air injection amount

[0024] (2) According to the formula obtain the relationship between the injection pressure and the number of injection holes, in which γ is the specific heat ratio of air, R is the gas constant, T is the air temperature, P is the air injection pressure; M is the Mach number of the air injection hole outlet, which is taken as 1 Mach, and A is the total flow area of all injection holes;

[0025] (3) According to the total flow area of all injection holes and the number of injection hole mounting points, the number of injection holes of each injection hole mounting point is distributed, and the injection hole diameter is 0.8-1.2mm.

[0026] The total flow area of the injection holes is converted into the total number of injection holes, and the total number of injection holes is evenly distributed to each injection hole mounting point, if the total number of injection holes and the injection hole mounting points are not in a multiple relationship, then one injection hole is increased or decreased, and then the air injection pressure is adjusted to meet the flow requirement; or the number of injection holes of each injection hole mounting point can be determined according to the kerosene distribution characteristics, and the number of injection holes of the injection hole mounting point in the region with more kerosene injection amount can be increased.

[0027] The air injection pressure and the injection hole diameter directly affect the penetration depth of the air jet, and further affect the influence range of the air jet. When the radius of the combustion chamber exceeds 100 mm, a smaller diameter injection hole should be used, the injection pressure is increased to increase the penetration depth, and the embodiment is preferably 0.8 mm; in the case that the injection pressure and the required injection area are unchanged, the smaller the injection hole diameter is, the more injection holes are, a plurality of smaller diameter injection holes can be used at one injection position to form an aerodynamic slope and increase the penetration depth.

[0028] The specific working principle is as follows:

[0029] After the inlet of the combustion chamber is stabilized, air injection is started, the local flow field is blocked to form throttling, shock waves are generated in the flow field downstream of the air injection position, and further affect the thermodynamic parameters of the flow field to form a new flow field. The kerosene starts to be injected into the combustion chamber, the shock wave string in the new flow field is beneficial to the diffusion and mixing of the kerosene, and the concentration condition required for ignition is reached faster, combined with the conditions of reduced airflow velocity, increased temperature and pressure after the wave, to promote the kerosene to ignite quickly and keep the flame stable, and ignite more kerosene to participate in combustion.

[0030] In addition, the air injection hole 4 can inject oxygen-enriched air or even pure oxygen to promote the kerosene to burn at a higher efficiency; when the total temperature of the airflow is <1000K, low ignition point gas (such as methane, hydrogen, etc.) can be injected to self-ignite or be ignited by a downstream high-frequency spark plug to ignite the kerosene.

[0031] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A throttling-based assisted ignition device, characterized by: The application relates to a circular cross-section combustion chamber, a kerosene injection branch plate (5) and a jet hole installation point, wherein the combustion chamber comprises an isolation section (1), a groove section (2) and an expansion section (3), the kerosene injection branch plate (5) is installed at the outlet of the isolation section (1), the jet hole installation point is in the same section as the installation position of the kerosene injection branch plate (5), the jet hole installation points are distributed at intervals from the kerosene injection branch plate (5), and a group of air jet holes (4) are installed at the jet hole installation points.

2. A restriction-based assisted ignition device according to claim 1, characterized in that: The jet hole installation point has four jet hole installation points, and the kerosene injection branch plate (5) has four kerosene injection branch plates.

3. A throttle-based assisted ignition device according to claim 2, wherein: The number of jet holes in a group of the air jet holes (4) is obtained by the following steps: (1) according to the flow rate of the supersonic air flow entering the combustion chamber determining the air injection amount (2) According to the formula The relationship between the injection pressure and the number of injection holes is obtained, wherein γ is the specific heat ratio of air, R is the gas constant, T is the air temperature, P is the air injection pressure; M is the Mach number of the air injection hole outlet, which is taken as 1 Mach, and A is the total flow area of all injection holes. (3) According to the total flow area of all jet holes and the number of jet hole installation points, the number of jet holes in each jet hole installation point is distributed, and the diameter of the jet holes is 0.8-1.2 mm.

4. A throttle-based auxiliary ignition device according to claim 3, characterized in that: In the step (3), the total flow area of the jet holes is converted into the total number of jet holes, the total number of jet holes is evenly distributed in each jet hole installation point, if the total number of jet holes and the number of jet hole installation points are not in a multiple relationship, one jet hole is added or reduced, and then the air injection pressure is adjusted to meet the flow requirement.

5. A throttle-based auxiliary ignition device according to claim 3, characterized in that: In the step (3), the number of jet holes in each jet hole installation point is determined according to the distribution characteristics of kerosene, and the number of jet holes in the jet hole installation point in the region with more kerosene injection quantity can be increased.

6. A choke-based auxiliary ignition device according to claim 3, characterized in that: In the step (3), when the radius of the combustion chamber exceeds 100 mm, the diameter of the jet holes is 0.8 mm.

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