CN113739207B

CN113739207B - Rotary detonation combustion chamber adopting pneumatic inner column

Info

Publication number: CN113739207B
Application number: CN202111106452.4A
Authority: CN
Inventors: 范玮; 焦中天; 王可; 赵明皓
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2021-09-22
Filing date: 2021-09-22
Publication date: 2022-04-29
Anticipated expiration: 2041-09-22
Also published as: CN113739207A

Abstract

The invention provides a rotary detonation combustor adopting a pneumatic inner column. The injection head comprises a splitter and an injector shell, an annular oxidant airflow channel is formed by the outer wall of the splitter and the injector shell in an enclosing mode, the fuel injection holes are located at the downstream of a throat of the oxidant airflow channel, and fuel and oxidant are mixed and then are subjected to rotary detonation combustion outside the body of the combustion chamber; inert gas or oxidant enter the body of the combustion chamber along the airflow channel enclosed by the inner wall of the flow divider to generate an axial flowing pneumatic inner column, and the axial flowing pneumatic inner column occupies the central area of the body of the combustion chamber, so that the rotation detonation product is prevented from flowing towards the center, and the loss generated by the inward lateral expansion of the rotation detonation wave is reduced. The combustion chamber avoids the phenomenon that partial rotation detonation products are temporarily retained in the central area, reduces the proportion of fresh mixed gas participating in slow combustion, is favorable for improving the thermal cycle efficiency of the combustion chamber, and simultaneously does not need to cool the pneumatic inner column. The invention can be applied to the technical field of rotary detonation propulsion.

Description

Rotary detonation combustion chamber adopting pneumatic inner column

Technical Field

The invention relates to the technical field of rotary detonation propulsion, in particular to a rotary detonation combustion chamber adopting a pneumatic inner column.

Background

The rotary detonation engine is a novel engine based on rotary detonation combustion, and compared with a traditional jet engine based on slow combustion, the rotary detonation engine is higher in thermal cycle efficiency and simpler in structure. Therefore, in recent years, rotary knocking engines have attracted much attention in the field of propulsion.

Rotary detonation combustors typically employ an annular structure having an inner column with an annular passage formed by an outer ring of the combustor and the inner column. The oxidant and the fuel are supplied from the head of the combustion chamber along the axial direction, the rotary detonation wave is rotationally propagated along the circumferential direction of the combustion chamber, the combustible mixture is continuously consumed, the burnt gas is generated, and the burnt gas is discharged along the axial direction to generate the thrust. In the annular channel, the detonation wave is limited by the wall surfaces on both sides, which is beneficial to reducing the lateral expansion loss of the detonation wave, but the inner column can cause additional heat and flow resistance loss, and simultaneously is completely exposed in high-temperature combustion products, so that the relatively outstanding cooling problem is faced.

In order to solve the problems, a hollow cylindrical rotary detonation combustor without an inner column is designed, and rotary detonation combustion is successfully realized. The rotary detonation combustor is the same as an annular combustor, oxidant and fuel are still supplied into the combustor through injector units arranged on the outer side, rotary detonation combustion products are generated on the outer side of the combustor, and due to the fact that inner columns are not limited, part of the combustion products enter the central area of the combustor and are temporarily retained at the position of the original inner columns, contact area of fresh mixed gas and high-temperature gas is greatly increased, the proportion of the fresh mixed gas participating in slow combustion is increased, and improvement of heat cycle efficiency is not facilitated.

Therefore, aiming at the problems existing in the design of the combustion chamber, the design of the rotary detonation combustion chamber which is low in cooling difficulty, small in detonation wave lateral expansion loss and high in fresh gas mixture ratio participating in detonation combustion is particularly important. The invention provides a rotary detonation combustor adopting a pneumatic inner column, which can solve the problems and improve the space utilization rate of the rotary detonation combustor.

Disclosure of Invention

The invention provides a rotary detonation combustor adopting a pneumatic inner column, which adopts the pneumatic inner column to replace a physical solid inner column, solves the cooling problem of the inner column, avoids a part of rotary detonation products from being temporarily retained in a central area, reduces the proportion of fresh mixed gas participating in slow combustion, and is beneficial to improving the thermal cycle efficiency of the combustor.

In order to achieve the purpose, the invention adopts the following technical scheme:

the rotary detonation combustor with the pneumatic inner column comprises an injection head and a combustor body, wherein the injection head and the combustor body are both rotary bodies, the central axes of the injection head and the combustor body are coincident, and the outer diameters of the injection head and the combustor body are D.

The injector head includes a shunt and an injector housing. The inner wall of the flow divider is enclosed into a pneumatic inner column airflow channel, the diameter of the airflow channel is 2/5-4/5D, and the airflow direction is ensured to be axial; an annular oxidant airflow channel is formed by the outer wall of the flow divider and the injector shell in an enclosing mode, hill-shaped smooth protrusions are arranged on the outer wall of the flow divider and the injector shell and are opposite to each other to form a throat part of the oxidant airflow channel, and the width of a throat circular seam is 1/200D; the fuel storage box is arranged inside the flow divider, the inlet of the fuel spray hole is connected with the fuel storage box, the outlet of the fuel spray hole is positioned at the downstream of the throat of the oxidant airflow channel and is uniformly distributed along the circumferential direction of the outer wall surface of the flow divider, the diameter of the spray hole is 1/500-1/400D, when gaseous fuel is adopted, the arc length of the spray hole interval is smaller than 1/100D, when liquid fuel is adopted, the arc length of the spray hole interval is smaller than 1/200D, and the acute angle between the spray hole jet flow and the central axis of the combustion chamber is 30-80 degrees.

The combustion chamber body is formed by surrounding the combustion chamber, and the interior of the combustion chamber body can be divided into a rotary detonation annular channel and a pneumatic inner column. The pneumatic inner column is formed by gas flow flowing into the combustion chamber through the pneumatic inner column gas flow channel, and can be inert gases such as argon and nitrogen, and can also be oxidizing agents. If the latter is adopted, it is necessary to ensure that even if a small amount of fuel enters the pneumatic inner column, the equivalence ratio in the pneumatic inner column is still below the combustible lean oil boundary, so that the pneumatic inner column does not combust. The rotary detonation annular channel is a virtual annular region between the outer ring of the combustion chamber and the inner aerodynamic column, in which rotary detonation combustion is organized by means of a combustible mixture fed by the injection head.

By adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects:

according to the rotary detonation combustion chamber adopting the pneumatic inner column, the pneumatic inner column is generated in the center of the rotary detonation combustion chamber by adopting high-speed airflow, so that the rotary detonation products on the outer side are prevented from entering the central area of the combustion chamber, the loss caused by inward lateral expansion of rotary detonation waves is reduced, the proportion of fresh mixed gas participating in slow combustion is reduced, and meanwhile, the pneumatic inner column is not required to be cooled.

The invention provides a rotary detonation combustion chamber adopting a pneumatic inner column, wherein a fuel spray hole is arranged at the downstream of the throat part of an oxidant airflow channel, and high-speed incoming flow air can accelerate the atomization and crushing processes of fuel; meanwhile, the spray holes which are uniformly and densely arranged in the circumferential direction can improve the circumferential uniformity degree of fuel distribution, improve the mixing efficiency of the fuel/oxidant and contribute to the full combustion of the fuel/oxidant.

Drawings

FIG. 1 is a schematic diagram of a rotary detonation combustor employing a pneumatic inner column according to the present invention;

FIG. 2 is a schematic view (embodiment) of the overall engine mechanism when the present invention is applied to a ramjet engine;

FIG. 3 is a sectional view taken in the direction A-A shown in FIG. 2;

FIG. 4 is an enlarged view of a portion of the injector structure of FIG. 2;

wherein, 1 is a splitter which comprises a splitter outer wall bulge 1-1, a fuel storage tank 1-2, a fuel spray hole 1-3 and a ribbed plate structure 1-4; 2, an injector shell comprises an injector shell bulge 2-1; 3 is a combustion chamber outer ring; 4 is a guide cone; 5 is a Laval nozzle; 6 is a culvert supporting plate; and 7 is a culvert supporting plate.

Detailed Description

The invention will be further explained with reference to the drawings and the specific implementation process:

referring to fig. 1, a rotary detonation combustor employing a pneumatic inner column is generally comprised of a flow divider 1, an injector housing 2, and a combustor outer ring 3. When the combustor works, oxidant enters from an oxidant airflow channel formed by the outer wall surface of the flow divider and the ejector shell in a surrounding mode, flows through the throat of the oxidant airflow channel formed by the protrusions 1-1 on the outer wall of the flow divider and the protrusions 2-1 on the ejector shell and enters a combustion chamber; the fuel in the fuel storage tank 1-2 in the splitter 1 is injected into the high-speed oxidant gas flow through the fuel injection holes 1-3 and is mixed with the oxidant, and a fresh gas mixture layer with a certain thickness is formed at the head part of the combustion chamber. The detonation wave is transmitted along the circumferential direction of the combustion chamber in a rotating way, so that fresh mixed gas is continuously consumed, and high-temperature and high-pressure fuel gas is generated. The high-speed pneumatic inner column occupies the central area of the combustion chamber after entering the combustion chamber, and peripheral high-temperature and high-pressure detonation products can be prevented from entering the central area.

Specific examples are given below:

referring to fig. 2, when the rotary knocking combustor using a pneumatic inner cylinder according to the present invention is applied to a ramjet engine, the injector housing 2 is optimized as an inlet wall surface in the present embodiment, the splitter 1 divides the inlet into a culvert constituted by the injector housing 2 and the splitter outer wall surface and 6 culvert support plates 7 connecting the two, and the inlet culvert constituted by the splitter inner wall and the guide cone 4 and 6 culvert support plates 6 connecting the two. 3 inner diameter D of combustion chamber outer ring₁And then connected with a laval nozzle 5.

Referring to fig. 3, inside the bypass support plate 7 is a fuel supply passage for uniformly supplying liquid fuel to the fuel storage tank 1-2 in the circumferential direction, and the fuel storage tank is designed into a groove-milled rib plate structure 1-4 to form a fuel regeneration cooling channel.

Referring to FIG. 3, the fuel nozzle holes 1-3 of the present embodiment have a diameter of 1/500D₁Circumferentially spaced arc lengths 1/250D₁And the acute angles with the central axis are all 80 degrees.

When the device works, liquid fuel enters a fuel regeneration cooling channel through a fuel supply passage in a bypass support plate 7, fully exchanges heat with high-temperature incoming flow of a bypass and an inner bypass of an air inlet channel, and is sprayed into a combustion chamber through fuel spray holes 1-3; the outer culvert airflow enters the body part of the combustion chamber through the throat part of the oxidant annular seam to promote the fuel to be atomized and crushed and is mixed with the fuel to form combustible mixed gas required by the rotary detonation combustion; because the rotary detonation wave is mainly transmitted along the circumferential direction near the inner wall surface of the combustion chamber, the central pressure of the combustion chamber is relatively small, the contained airflow can enter the combustion chamber in a high-speed air column mode, a pneumatic inner column is formed in the center of the combustion chamber, and the outward detonation product is limited from expanding inwards. The inner and outer culvert airflows are mixed continuously at the rear section of the combustion chamber and are discharged in an accelerating way through the tail nozzle to generate thrust.

While the present invention has been described in detail and with reference to the drawings and the detailed description thereof, it is not intended to limit the invention to the embodiment, but it is possible for those skilled in the art to make various changes and modifications without departing from the spirit of the invention.

Claims

1. A rotary detonation combustor adopting a pneumatic inner column comprises a jetting head part and a combustor body part, wherein the jetting head part comprises a splitter and a jetting device shell, the inner wall of the splitter surrounds a pneumatic inner column airflow channel, the outer wall of the splitter and the jetting device shell surround an annular oxidant airflow channel, the outer wall of the splitter and the jetting device shell are both provided with a hill-shaped smooth bulge, the hill-shaped smooth bulge and the hill-shaped smooth bulge are oppositely arranged to form a throat part of the oxidant airflow channel, a fuel storage tank is arranged in the splitter, a fuel jet hole inlet is connected with the fuel storage tank, and an outlet is positioned at the downstream of the throat part of the oxidant airflow channel; the combustion chamber body part is formed by surrounding the combustion chamber, and the interior of the combustion chamber body part can be divided into a rotary detonation annular channel and a pneumatic inner column; the rotary detonation annular channel is a virtual annular area between the outer ring of the combustion chamber and the pneumatic inner column, and the rotary detonation combustion is organized by using a combustible mixture fed by the injection head in the area; the pneumatic inner column is formed by gas flow flowing into the combustion chamber through the pneumatic inner column gas flow channel, and can be inert gases such as argon, nitrogen and the like or oxidizing agents; if the latter is adopted, it is necessary to ensure that even if a small amount of fuel enters the pneumatic inner column, the equivalence ratio in the pneumatic inner column is still below the combustible lean oil boundary, so that combustion does not occur in the pneumatic inner column.

2. The rotary detonation combustor of claim 1, wherein the injector head and the combustor body are solid of revolution with their central axes coincident and outer diameter D.

3. The rotary detonation combustor of claim 1, wherein the aerodynamic inner column airflow channel has a diameter of 2/5-4/5D, and the airflow direction is axial.

4. The rotary detonation combustor of claim 1, wherein the throat of the oxidant gas flow channel has a throat girth width of 1/200D.

5. The rotary detonation combustor of claim 1, wherein the fuel injection holes are evenly circumferentially distributed along the outer wall of the splitter, the diameter of the injection holes is 1/500-1/400D, the arc length between injection holes is less than 1/100D when gaseous fuel is used, the arc length between injection holes is less than 1/200D when liquid fuel is used, and the acute angle between the injection hole jet and the central axis of the combustor is 30-80 degrees.