Injector cooling method

Abstract

According to the injector cooling method, cooling holes are formed in the inner wall of the head of a combustion chamber or an injector, and the cooling holes spray cooling liquid towards the position where a backflow area is located in a centrifugal spraying mode, so that the cooling liquid is broken into liquid drops; therefore, a liquid drop dispersing area which plays a role in isolation and continuously exists is formed on the outer side of the injector, backflow fuel gas is prevented from making contact with the injector, and then cooling of the injector is achieved. The invention provides a novel injector cooling mode, the wall surface of the injector is protected from being baked by high-temperature fuel gas by adopting a centrifugal injection cooling mode, and the service life of the injector is prolonged.

Description

Technical Field

[0001] The invention relates to a method for cooling an injector in a centrifugal manner, and belongs to the field of cooling design of injectors in the fields of machinery, aviation, aerospace, etc. Background Art

[0002] After the propellant of the liquid rocket engine enters the injector, it is atomized, evaporated, mixed and burned to produce high-temperature combustion gas. The high-temperature combustion gas burns the injector wall. Since the temperature of the high-temperature combustion gas is usually above 2000K, and the melting temperature of the injector material is usually no more than 2000K, the high-temperature combustion gas burning the injector wall for a long time will result in the burnout of the injector. In order to protect the injector wall from being burned by the combustion gas, the injector wall needs to be separated from the high-temperature combustion gas.

[0003] Traditional isolation methods include: coating the wall of the injector with a high-temperature resistant coating, which is a complex process and expensive; using high-temperature resistant materials, which are difficult to process and expensive; designing flow channels on the back of the material to cool the wall by liquid flow, which is a complex structure and has large mass and volume; reducing the temperature by material ablation, which is a short-lived method; or spraying liquid to form a protective film on the wall for protection, which is inefficient and prone to wall combustion, causing burns. Summary of the invention

[0004] The present invention aims to provide an injector cooling method which has a simple structure, high efficiency and low cost, is effectively different from the traditional injector cooling method, and provides a new idea for injector cooling.

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

[0006] The injector cooling method comprises the following steps:

[0007] Step 1, determining the gas flow field structure inside the combustion chamber corresponding to the injector;

[0008] Step 2, determining the location of the reflow area in the gas flow field structure, wherein the reflow area is the area where the gas flows toward the injector;

[0009] Step three, a cooling hole is opened on the inner wall of the combustion chamber head or on the injector, and the cooling hole sprays coolant toward the reflow area in a centrifugal manner, so that the coolant is broken into droplets, thereby forming an isolating and continuous droplet dispersion zone on the outside of the injector, preventing the reflowing gas from contacting the injector, thereby cooling the injector.

[0010] As a solution, in step 3, the cooling hole includes:

[0011] Injector cooling holes, wherein the axis of the injector cooling holes is perpendicular to the outer wall surface at the injector outlet;

[0012] A coolant inlet hole is provided on the injector cooling hole and penetrates the inner and outer wall surfaces of the injector cooling hole. The diameter of the coolant inlet hole is smaller than that of the injector cooling hole. A generatrix of the coolant inlet hole is tangent to the inner wall surface of the injector cooling hole. The hole axis of the coolant inlet hole is parallel to the outer wall surface at the injector outlet.

[0013] As a solution, the length of the axis of the coolant inlet hole from the outer wall of the injector cooling hole is equal to the aperture of the coolant inlet hole.

[0014] As a solution, the injector cooling hole and the coolant inlet hole are both cylindrical holes.

[0015] As an approach, the cooling liquid is a coolant or a propellant.

[0016] As an alternative, the propellant is diverted from a propellant flow channel in the injector.

[0017] As a solution, the injector is a straight-flow injector, and the cooling holes are distributed on the injector panel where the fuel injection holes are located and correspond to the reflow area.

[0018] As a solution, the injector is a pintle injector, a portion of the cooling holes are distributed on the inner wall of the combustion chamber head and correspond to the reflow area, and the other portion is located on the terminal end face of the pintle head.

[0019] Compared with the prior art, the present invention abandons the traditional cooling method and designs cooling holes on the inner wall of the combustion chamber head or on the injector corresponding to the gas reflux area. The cooling holes spray coolant toward the outer wall surface of the injector in a centrifugal jet manner, so that the coolant forms a continuous droplet dispersion area or liquid film at a distance away from the outer wall surface of the injector, which plays an isolating role, prevents the reflux gas from contacting the outer wall of the injector, thereby realizing cooling of the injector.

[0020] Compared with the method of applying a high temperature resistant coating, the implementation method of the present invention is simple and low in price.

[0021] Compared with the method of manufacturing the injector using high temperature resistant materials, the material cost and processing cost of the present invention are lower.

[0022] Compared with the method of using cooling channels on the injector, the method of the present invention does not require processing of the injector, will not complicate the structure of the injector, and will not increase the mass and volume of the injector due to processing of the cooling channels.

[0023] Compared with the method of material ablation, the present invention can isolate the reflowing high-temperature combustion gas for a long time without causing injector cooling failure due to exhaustion of ablation material.

[0024] Compared with the method of directly spraying coolant toward the outer wall of the injector to form a protective film, the coolant sprayed by the present invention does not stay or adhere to the outer wall of the injector, but uses the speed of the coolant tangentially ejected from the cooling hole to form a droplet dispersion zone at a distance from the outer wall of the injector, thereby preventing the return gas from contacting the injector wall. After the coolant leaves the cooling hole outlet, it interacts with the return high-temperature gas, so that the speed of the high-temperature gas toward the outer wall of the injector is reduced to zero, thereby avoiding wall combustion or burning caused by the direct action of the coolant and the high-temperature gas on the outer wall of the injector. Then the coolant brings the high-temperature gas into the combustion zone for combustion.

[0025] In summary, the cooling structure of the present invention is simple, the processing difficulty is low, and the production cost is low. The coolant forms a layer of rotating liquid film in the cooling hole of the injector, flows out of the cooling hole of the injector, and then breaks up after entering the combustion chamber to form a small droplet gathering area. The coolant can also directly use the propellant, thereby reducing the cooling cost and reducing the number of structural parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the cooling hole in the present invention;

[0027] Figure 2 It is a schematic diagram of the cooling holes arranged on the DC injector panel in the present invention;

[0028] Figure 3 It is a schematic diagram of the flow field distribution in the combustion chamber corresponding to the pintle injector;

[0029] Figure 4 yes Figure 1 The formation principle diagram of the cooling hole;

[0030] In the figure: 1—injector cooling hole; 2—coolant inlet hole. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0032] like Figure 1 and Figure 4As shown, a cooling hole designed in this embodiment includes an injector cooling hole 1 and a coolant inlet hole 2. The injector cooling hole 1 and the coolant inlet hole 2 are both cylindrical holes and their axes are perpendicular. A generatrix of the coolant inlet hole 2 is tangent to the inner wall surface of the injector cooling hole 1. Figure 4 The solid line in the middle shows the state where the cylindrical hole with a smaller outer diameter is perpendicularly tangent to the cylindrical hole with a larger outer diameter, wherein the outer diameter of the cylindrical hole with a smaller outer diameter is equal to the wall thickness of the cylindrical hole with a larger outer diameter, and finally a special-shaped outlet area is formed on the inner wall of the cylindrical hole with a larger outer diameter. The coolant enters the inner wall of the cylindrical hole with a larger outer diameter tangentially at the special-shaped outlet, and rotates along the inner wall under the action of the tangential velocity and the acceleration of the deadweight to the outlet of the injector cooling hole 1 for spraying.

[0033] like Figure 2 As shown, the cooling holes are arranged on the panel of the DC injector. There are multiple fuel injection holes (fuel, i.e., propellant) and cooling holes on the panel of the injector. The cooling holes are arranged between these fuel injection holes in the form of blind holes and correspond to the position of the gas reflux area. The number of cooling holes is significantly less than that of the fuel injection holes. The aperture of the injector cooling hole 1 among the cooling holes is significantly smaller than that of the fuel injection hole. The coolant inlet hole 2 in the cooling hole is connected to the fuel (propellant) flow channel. The injector cooling hole 1 is perpendicular to the injector outlet wall, and the coolant inlet hole 2 is parallel to the injector outlet wall.

[0034] like Figure 3 The figure shows the flow field distribution diagram of the combustion chamber corresponding to the pintle injector, which includes the central reflow area and the head reflow area, where the gas forms a reflow. The three positions indicated by the arrows in the figure are respectively set Figure 1 The cooling holes shown in the figure are provided with cooling holes on the inner wall of the combustion chamber head corresponding to the head reflow zone, and cooling holes are provided at the end of the pintle of the pintle injector corresponding to the center reflow zone. Each cooling hole includes two cylindrical holes, namely the injector cooling hole 1 and the coolant inlet hole 2. The apertures of these two cylindrical holes are large and small, and they are vertically connected to each other. The distance between the central axis of the coolant inlet hole 2 with a smaller aperture and the inner wall surface of the injector cooling hole 1 with a larger aperture is equal to the radius of the coolant inlet hole 2. The coolant is diverted from the injector flow channel, flows into the coolant inlet hole 2, and then flows along the wall surface of the injector cooling hole 1. The coolant rotates in the injector cooling hole 1, forming a centrifugal-like spray. After entering the combustion chamber, it is broken into small mists, which isolate the injector wall surface from the high-temperature combustion gas, thereby protecting the injector wall surface and achieving a cooling effect.

[0035] regardless Figure 2 still Figure 3 The coolant in the combustion chamber will participate in the combustion after injection. Under the premise of reasonable design, it can not only meet the cooling needs of the injector, but also minimize the impact on combustion efficiency.

[0036] The above are the main concepts of the invention, and any injector cooling method designed according to the concept of the present invention falls within the protection scope of the present invention.

Claims

1. Injector cooling method, characterized in that: The following steps are involved: Step 1, determining the gas flow field structure inside the combustion chamber corresponding to the injector; Step 2, determining the location of the reflow area in the gas flow field structure, wherein the reflow area is the area where the gas flows toward the injector; Step three, a cooling hole is opened on the inner wall of the combustion chamber head or on the injector, and the cooling hole sprays coolant toward the reflow area in a centrifugal manner, so that the coolant is broken into droplets, thereby forming an isolating and continuous droplet dispersion zone on the outside of the injector, preventing the reflowing gas from contacting the injector, thereby cooling the injector.

2. The injector cooling method according to claim 1, characterized in that: In step three, the cooling hole comprises: An injector cooling hole (1), wherein the axis of the injector cooling hole (1) is perpendicular to the outer wall surface at the injector outlet; A coolant inlet hole (2), wherein the coolant inlet hole (2) is provided on the injector cooling hole (1) and penetrates the inner and outer wall surfaces of the injector cooling hole (1), the diameter of the coolant inlet hole (2) is smaller than that of the injector cooling hole (1), a generatrix of the coolant inlet hole (2) is tangent to the inner wall surface of the injector cooling hole (1), and the hole axis of the coolant inlet hole (2) is parallel to the outer wall surface at the injector outlet.

3. The injector cooling method according to claim 2, characterized in that: The length of the axis of the coolant inlet hole (2) from the outer wall surface of the injector cooling hole (1) is equal to the hole diameter of the coolant inlet hole (2).

4. The injector cooling method according to claim 2, characterized in that: The injector cooling hole (1) and the coolant inlet hole (2) are both cylindrical holes.

5. The injector cooling method according to claim 1, characterized in that: The cooling liquid is a coolant or a propellant.

6. The injector cooling method according to claim 5, characterized in that: The propellant is branched from a propellant flow channel in the injector.

7. The injector cooling method according to claim 1, characterized in that: The injector is a straight-flow injector, and the cooling holes are distributed on the injector panel where the fuel injection holes are located and correspond to the reflow area.

8. The injector cooling method according to claim 1, characterized in that: The injector is a pintle injector, a portion of cooling holes are distributed on the inner wall of the combustion chamber head and correspond to the reflow area, and the other portion is located on the terminal end surface of the pintle head.

Images