CN-122015133-A - Smooth invasive fuel injector and design method

CN122015133ACN 122015133 ACN122015133 ACN 122015133ACN-122015133-A

Abstract

The invention discloses a smooth invasive fuel injector and a design method, and relates to the technical field of combustion chambers of scramjet engines.A fuel injector which is invasive to the center of a combustion chamber is arranged on the side wall of the combustion chamber, and comprises an arc section I, wherein the center of the arc section I is arranged outside the combustion chamber; the center of the circle is arranged in the combustion chamber and is positioned at the arc sections II and III at the two sides of the arc section I, wherein each arc section is tangent with the straight line section of the combustion chamber at the intersection point, the injection hole of the fuel injector is arranged at the top end of the arc section I, and smooth transition is formed between the corresponding arc section and the straight line section of the combustion chamber. Compared with the existing wall surface injection, the invention can increase the ratio of the fuel momentum to the air momentum by more than 1 time, and is beneficial to realizing the efficient mixing of the fuel under the high-speed flow condition.

Inventors

DENG WEIXIN
RAN WEI
ZHANG DONGQING
WU XUE
TANG BO
JIANG HUIWEN

Assignees

中国空气动力研究与发展中心空天技术研究所

Dates

Publication Date: 20260512
Application Date: 20260414

Claims (4)

1. A smooth intrusive fuel injector, wherein a fuel injector is provided on a sidewall of a combustion chamber that intrudes into a center of the combustion chamber, the fuel injector comprising: the circle center of the arc section I is arranged outside the combustion chamber; the circle center is arranged in the combustion chamber, and is positioned at the arc section II and the arc section III at the two sides of the arc section I; Wherein, between each arc section, each arc section is tangent with the straight line section of the combustion chamber at the intersection point, and the injection hole of the fuel injector is arranged at the top end of the arc section I; Smooth transition is formed between the corresponding arc section and the straight line section of the combustion chamber.
2. The smooth-invading fuel injector of claim 1, wherein the combustion chamber height is 50-80 mm, the number of injection holes is 30-100, and the diameter of each injection hole is 1mm.
3. The smooth-invading fuel injector of claim 1, wherein the fuel injector is located in an inlet section of the combustion chamber.
4. A method of designing a smooth-intrusive fuel injector for use in the smooth-intrusive fuel injector design of any one of claims 1 to 3, wherein a set of oblique shock waves are generated inside the combustion chamber based on the fuel injector intrusive to the combustion chamber flow field, the foregoing being defined as region I and region II based on the fore-aft relationship of the oblique shock waves; under the condition of the air flow parameters of the known area I, after the circle center position and the radius of each circular arc section are respectively optimized according to the mixing requirement of the fuel injection of the combustion chamber, the adjustment of the air flow parameters after oblique shock waves is completed, so that the appearance of the fuel injector which is favorable for the fuel mixing condition is obtained.

Description

Smooth invasive fuel injector and design method Technical Field The invention relates to the technical field of combustion chambers of scramjet engines. More particularly, the present invention relates to a smooth invasive fuel injector and method of design. Background The scramjet engine is one kind of high speed flying propulsion power unit, and the typical scramjet engine includes air inlet channel, isolating section, combustor, tail pipe, etc. The function of the combustion chamber is to achieve fuel injection mixing, reliable ignition and stable combustion. High efficiency fuel injection mixing is a necessary condition for reliable ignition and stable combustion. The pressure, temperature and velocity of the fuel and air mixture in the combustion chamber are required to meet certain conditions for efficient mixing, where the time required for the fuel to complete the physicochemical processes of atomization, breaking, evaporation and chemical reactions is called the ignition time. Under typical conditions, the ignition time of the fuel is about 5-10 milliseconds. To achieve reliable ignition, the residence time of the fuel in the combustion chamber must be greater than the ignition time. The length of the combustion chamber is generally about 1m, and the flow speed of the air flow in the combustion chamber exceeds 1000m/s under the high-speed flow condition, so that the residence time of the air flow in the combustion chamber is only about 1 millisecond, and the time requirement of full mixing required by ignition is difficult to meet. At present, researchers at home and abroad propose various designs of fuel injectors for solving the fuel mixing problem, and the designs are mainly divided into two types: (1) The wall surface injection, the injection hole is arranged on the wall surface of the combustion chamber, no part invaded into the flow field of the combustion chamber is arranged, fuel is injected from the small hole of the wall surface, and shearing and mixing with air are realized by virtue of the momentum of the fuel; (2) The invasive injection adopts parts such as a support plate, a support rod, a central body and the like to 'invade' the central area of the combustion chamber, and fuel is sprayed out from the invasive parts, so that the fuel can fully enter the combustion chamber to realize rapid mixing, and the defect is that the inner side structure and the outer side structure of the parts are subjected to extreme pneumatic and combustion heating, and are difficult to reliably service under high-temperature high-pressure high-speed working conditions for a long time, such as a stamping combustion chamber and a stamping combustion method based on flow channel central injection and shock wave induced combustion, which are disclosed in patent application number 202311208894.9. In addition, the intrusive components may also cause additional aerodynamic drag, degrading engine propulsion performance. In the prior art, although there is a wedge surface structure with an S-shaped curved surface (for example, a diagonal detonation power aircraft with an S-shaped curved surface wedge surface structure is disclosed in patent application No. 202311382732.7) arranged on the lower wall surface of the engine combustion chamber, the wedge surface structure is not used as an injector, and is mainly used for generating diagonal detonation waves, so that researches at home and abroad are integrated, and an injector capable of effectively enhancing fuel mixing capability and reducing heat load is not yet available at present. Disclosure of Invention It is an object of the present invention to address at least the above problems and/or disadvantages and to provide at least the advantages described below. To achieve these objects and other advantages and in accordance with the purpose of the invention, there is provided a smooth-invading fuel injector characterized in that a fuel injector invading toward a center of a combustion chamber is provided on a side wall of the combustion chamber, the fuel injector comprising: the circle center of the arc section I is arranged outside the combustion chamber; the circle center is arranged in the combustion chamber, and is positioned at the arc section II and the arc section III at the two sides of the arc section I; Wherein, between each arc section, each arc section is tangent with the straight line section of the combustion chamber at the intersection point, and the injection hole of the fuel injector is arranged at the top end of the arc section I; Smooth transition is formed between the corresponding arc section and the straight line section of the combustion chamber. Preferably, the height of the combustion chamber is 50-80 mm, the number of the injection holes is 30-100, and the diameter of each injection hole is 1mm. Preferably, the fuel injector is located at an inlet section of the combustion chamber. A design method of a smooth invasive fuel injector is appli