Strong powder mixing scramjet engine combustion chamber

Abstract

The invention discloses a strong mixing powder scramjet engine combustion chamber which comprises an equal straight isolation section, a partial covering concave cavity structure and an expansion section, the axis of the equal straight isolation section and the axis of the partial covering concave cavity structure are collinear, and the axis radius of the equal straight isolation section is smaller than that of the partial covering concave cavity structure; an annular baffle is arranged in the partial covering cavity structure and fixedly connected to the end, close to the equal-straight isolation section, of the partial covering cavity structure. The axis of the annular baffle is collinear with the axis of the partially covered concave cavity structure; the shaft radius of the annular baffle is larger than or equal to the shaft radius of the equal-straight isolation section and smaller than the shaft radius of part of the covering cavity structure. And at least one fuel through hole for injecting two-phase flow of powder fuel and combustible fluidized gas into the partial covering concave cavity structure is formed in the side wall of the partial covering concave cavity structure. According to the powder fuel combustion device, the retention time of powder fuel in the combustion chamber can be prolonged, the powder fuel is preheated, and the combustion efficiency of the powder fuel is improved.

Description

Technical Field

[0001] The invention relates to the technical field of scramjet engines, and in particular to a highly mixed powder scramjet engine combustion chamber. Background Art

[0002] A scramjet engine is a ramjet engine that burns fuel in a supersonic airflow, and has the characteristics of simple structure and high specific impulse performance. A powder scramjet engine is a scramjet engine that uses solid powder fuel. Compared with hydrocarbon fuels, the powder fuel represented by boron and aluminum has a high calorific value, no dissociation effect under high temperature conditions, and a high combustion temperature under low air-fuel ratio conditions.

[0003] When a powder fuel scramjet engine is working, pure cold powder fuel enters the combustion chamber in the form of gas-solid two-phase flow and undergoes evaporation, oxide film rupture, surface heterogeneous reaction, gas phase reaction and surface condensation, which requires a long ignition delay time and a high ignition temperature. However, the air flow speed in the supersonic combustion chamber is fast, and the residence time of the fuel in the combustion chamber is extremely short, mostly in the millisecond level. In addition, the powder particles have a large inertial force after entering the combustion chamber, which causes the flow characteristics of the particles to deteriorate, resulting in a decrease in the combustion efficiency of the powder fuel.

[0004] In order to solve the above problems, in the prior art, a pre-combustion chamber is usually set before the fuel injection port of the combustion chamber of the powder fuel scramjet engine, or a pre-combustion component is generated by burning a propellant rich in metal fuel, and then the pre-combustion component is injected into the combustion chamber through the fuel injection port to perform secondary combustion with the ram air under the action of the mixing and flame stabilizing structure to improve the powder combustion efficiency. However, adding a pre-combustion chamber will make the engine structure more complicated, and the flow rate is uncontrollable when injecting the pre-combustion component, which cannot give full play to the advantages of powder fuel over other fuels. Summary of the invention

[0005] Based on this, it is necessary to provide a highly mixed powder scramjet engine combustion chamber to address the above-mentioned technical problems, which can extend the residence time of the powder fuel in the combustion chamber, keep the powder fuel particle mixing degree at a relatively high level, and preheat the powder fuel to improve the combustion efficiency of the powder fuel.

[0006] The present invention provides a highly mixed powder scramjet combustion chamber, comprising a straight isolating section, a partially covered concave cavity structure and an expansion section, wherein the straight isolating section and the expansion section are respectively fixedly arranged at two ends of the partially covered concave cavity structure, and both the straight isolating section and the expansion section are connected to the partially covered concave cavity structure;

[0007] The straight isolation section and the partially covered concave cavity structure are both columnar, the axis of the straight isolation section is collinear with the axis of the partially covered concave cavity structure, and the axis radius of the straight isolation section is smaller than the axis radius of the partially covered concave cavity structure;

[0008] An annular baffle is arranged inside the partially covered concave cavity structure, and the annular baffle is fixedly connected to one end of the partially covered concave cavity structure close to the equal straight isolation section;

[0009] The axis of the annular baffle is colinear with the axis of the partially covered concave cavity structure;

[0010] The axial radius of the annular baffle is greater than or equal to the axial radius of the straight isolation section and less than the axial radius of the partially covered concave cavity structure;

[0011] The side wall of the partially covered cavity structure is provided with at least one fuel through hole for injecting powder fuel and combustible fluidizing gas two-phase flow into the partially covered cavity structure, and the projection of the fuel through hole relative to the annular baffle along the radial direction of the partially covered cavity structure is located on the annular baffle.

[0012] In one embodiment, at least one fuel through hole is provided on the side wall of the partially covered concave cavity structure, and the projection of the fuel through hole relative to the annular baffle in the radial direction of the partially covered concave cavity structure is located at the middle position of the annular baffle in the axial direction;

[0013] A fuel nozzle is connected to the outside of any fuel through hole;

[0014] The axis of the fuel nozzle is perpendicular to the axis of the partially covered cavity structure;

[0015] The included angle between the tangent plane of the intersection of the axis of the fuel nozzle and the outer wall surface of the partially covered concave cavity structure and the axis of the fuel nozzle is 0° to 90°.

[0016] In one embodiment, the included angle between the tangent plane of the intersection of the axis of the fuel nozzle and a part of the outer wall of the cavity structure and the axis of the fuel nozzle is 60°.

[0017] In one embodiment, the length of the annular baffle along the axial direction is 25 mm to 45 mm.

[0018] In one of the embodiments, the length of the annular baffle along the axial direction is 35 mm.

[0019] In one embodiment, the depth of the partially covered cavity structure is 12 mm to 24 mm.

[0020] In one embodiment, the depth of the partially covered cavity structure is 24 mm.

[0021] The beneficial effects of the present invention are:

[0022] (1) The present invention separates the flow from the partially covered cavity structure from the flow from the fuel nozzle by arranging a baffle inside the partially covered cavity structure to form a baffle covered area in the cavity. Driven by the combustible fluidizing gas, the powdered fuel particles rotate in the baffle covered area. When the powdered fuel particles enter the partially covered cavity structure, due to the effect of inertia, a part of the particles collide with the baffle, thereby increasing their movement trajectory in the baffle covered area. The backflow rotation and collision can increase the residence time of the powdered fuel in the partially covered cavity structure, increase the powdered fuel concentration, and thus improve the powdered fuel combustion efficiency.

[0023] (2) In the partially covered cavity structure of the present invention, the baffle separates the cavity area from the supersonic mainstream, and the formed covered area increases the area of ​​the low-speed region in the combustion chamber. Since the static temperature corresponding to the low-speed region in the supersonic airflow is high, favorable conditions can be created for the ignition of the particles; and the combustible fluidizing gas can burn in the partially covered cavity area, which can continue to increase the temperature of the area, and can preheat the powdered fuel, further improving the combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of a highly mixed powder scramjet combustion chamber provided by an embodiment of the present invention;

[0025] Figure 2 for Figure 1 A schematic diagram of a cross-sectional structure along the axis of a partially covered concave cavity structure;

[0026] Figure 3 for Figure 1 Schematic diagram of the cross-section structure along the AA plane;

[0027] Figure 4 A schematic diagram of the structure of the baffle covering area provided by an embodiment of the present invention;

[0028] Figure 5 A comparison chart of particle retention time along the combustion chamber direction of a combustion chamber without baffles and a highly mixed powder scramjet combustion chamber provided in an embodiment of the present invention;

[0029] Figure 6 A comparison diagram of the particle residence time in the combustion chamber of a highly mixed powder scramjet engine combustion chamber at different powder fuel injection angles or powder nozzle installation angles provided in an embodiment of the present invention;

[0030] Figure 7 A powder particle combustion efficiency diagram corresponding to a highly mixed powder scramjet engine combustion chamber with different annular baffle lengths provided by an embodiment of the present invention;

[0031] Figure 8A powder particle combustion efficiency diagram corresponding to a highly mixed powder scramjet engine combustion chamber with different cavity structure depths provided by an embodiment of the present invention;

[0032] Fig. 9 A schematic diagram of airflow streamlines along the axial cross section of a highly mixed powder scramjet combustion chamber provided in an embodiment of the present invention;

[0033] Fig.10 A vector diagram of air flow velocity along a radial cross section of a fuel injection hole provided in an embodiment of the present invention.

[0034] Explanation of reference numerals: 100, straight isolation section; 200, partially covered cavity structure; 300, annular baffle; 400, expansion section; 500, fuel nozzle. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] It should be noted that in the description of the present invention, “upper”, “lower”, “top”, “bottom”, orientation or position relationship is based on the attached Figure 1 Regarding the orientation or positional relationship shown, it should be understood that these orientation terms 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 orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] In one embodiment, Figures 1 to 3 As shown, the highly blended powder scramjet engine combustion chamber of the present embodiment is characterized in that it includes an equal straight isolation section 100, a partially covered concave cavity structure 200 and an expansion section 400, wherein the equal straight isolation section 100 and the expansion section 400 are respectively fixedly arranged at the two ends of the partially covered concave cavity structure 200, and both the equal straight isolation section 100 and the expansion section 400 are connected to the partially covered concave cavity structure 200.

[0038] Specifically, the straight isolation section 100 is used to direct the supersonic incoming flow into the partially covered concave cavity structure 200, the partially covered concave cavity structure 200 is used to ignite the powdered fuel and mix and burn it with the supersonic incoming flow, and the expansion section 400 is used to accelerate the high-temperature combustion gas after combustion to a higher speed, thereby increasing the thrust of the engine and converting thermal energy into kinetic energy.

[0039] In this embodiment, the straight isolation segment 100 and the partially covered concave cavity structure 200 are both columnar, the axis of the straight isolation segment 100 is collinear with the axis of the partially covered concave cavity structure 200 , and the axial radius of the straight isolation segment 100 is smaller than the axial radius of the partially covered concave cavity structure 200 .

[0040] Among them, an annular baffle 300 is arranged inside the partially covered concave cavity structure 200, and the annular baffle 300 is fixedly connected to one end of the partially covered concave cavity structure 200 close to the equal straight isolation section 100. The axis of the annular baffle 300 is colinear with the axis of the partially covered concave cavity structure 200. The axial radius of the annular baffle 300 is greater than or equal to the axial radius of the equal straight isolation section 100, and less than the axial radius of the partially covered concave cavity structure 200.

[0041] like Figure 4 As shown, the annular baffle 300 can be arranged to partially cover the interior of the concave cavity structure 200, and a baffle covering area is formed between the baffle and the side wall of the partially covered concave cavity structure 200. Figure 4 In FIG. 1 , D represents the depth of the partially covered cavity structure 200, L represents the length of the partially covered cavity structure 200, and Lc represents the baffle length. Preferably, the axial radius of the annular baffle 300 is equal to the axial radius of the straight isolation section 100, in which case the baffle covers the largest area.

[0042] The side wall of the partially covered cavity structure 200 is provided with at least one fuel through hole for injecting a two-phase flow of powdered fuel and combustible fluidizing gas into the partially covered cavity structure 200, and the fuel through hole is located on the annular baffle 300 along the radial direction of the partially covered cavity structure 200 relative to the projection of the annular baffle 300.

[0043] Specifically, this embodiment uses combustible gas as the fluidizing gas, which can make the powdered fuel particles reach the ignition temperature faster.

[0044] Under the action of the fluidizing gas, the powdered fuel is injected into the combustion chamber at a certain speed under the entrainment of the combustible fluidizing gas, and will reflux and rotate in the baffle coverage area without directly contacting the supersonic incoming flow. In addition, when the powdered fuel particles enter the partially covered cavity structure 200, due to the effect of inertia, a part of the fuel particles will collide with the baffle, thereby increasing their movement trajectory in the baffle coverage area. The reflux rotation and collision can increase the residence time of the powdered fuel in the partially covered cavity structure 200, thereby improving the combustion efficiency of the powdered fuel.

[0045] In addition, the internal velocity of the partially covered cavity structure is relatively low. In the supersonic airflow, the static temperature corresponding to the low velocity area is high. Therefore, the combustible fluidizing gas can burn stably in this area. The combustion in this area can cause the temperature of this area to continue to increase, which can preheat the powder particles in the baffle coverage area and further improve the combustion efficiency.

[0046] In one embodiment, the projection of the fuel through hole relative to the annular baffle 300 in the radial direction of the partially covered concave cavity structure 200 is located at the middle position of the annular baffle 300 along the axial direction. The fuel through hole is located in the middle position of the baffle in the vertical direction, which can retain the combustion trajectory of the fuel particles when they collide with the baffle as much as possible.

[0047] The outer side of any fuel through hole is connected to a fuel nozzle 500. The other end of the fuel nozzle 500 is connected to the gas pressure driven piston supply device.

[0048] In this embodiment, the axis of the fuel nozzle 500 is perpendicular to the axis of the partially covered concave structure 200; the angle between the tangent plane of the intersection of the axis of the fuel nozzle 500 and the outer wall of the partially covered concave structure 200 and the axis of the fuel nozzle 500 is 0° to 90°.

[0049] In order to verify the effect of the highly mixed powder scramjet combustion chamber of this embodiment, the particle retention time along the combustion chamber direction of the combustion chamber without baffles and the highly mixed powder scramjet combustion chamber of this embodiment was compared under the same incoming flow conditions, wherein the two combustion chambers maintained the same data such as the powder injection position, size, and the injection amount of powder fuel particles and combustible fluidizing gas. Figure 5 It can be seen that the highly mixed powder scramjet engine combustion chamber of this embodiment can effectively enhance the residence time of powder combustion particles in the combustion chamber, wherein the horizontal axis x represents the distance from the entrance of the iso-straight isolation section 100 to the exit of the expansion section 400.

[0050] In one embodiment, the included angle between the tangent plane of the intersection of the axis of the fuel nozzle 500 and a part of the outer wall of the cavity structure 200 and the axis of the fuel nozzle 500 is 60°.

[0051] In this embodiment, the angle between the axis of the fuel nozzle 500 and the tangent plane of the intersection of the part covering the outer wall of the cavity structure 200 and the axis of the fuel nozzle 500 is defined as the injection angle. Figure 6 As shown, Figure 6 This is a comparison chart of the particle retention time in the combustion chamber of the highly mixed powder scramjet engine combustion chamber of this embodiment at different powder fuel injection angles or powder nozzle installation angles. Figure 6 It can be seen that when the injection angle is 60°, that is, the powder fuel particles stay in the baffle coverage area for the longest time.

[0052] In one embodiment, along the axial direction, the length of the annular baffle 300 is 25 mm to 45 mm.

[0053] In one embodiment, the length of the annular baffle 300 along the axial direction is 35 mm.

[0054] like Figure 7 As shown, Figure 7 The powder particle combustion efficiency diagram corresponding to different lengths of the annular baffle 300 of the highly mixed powder scramjet engine combustion chamber of this embodiment. When the length of the annular baffle 300 is 35 mm, the powder particle combustion efficiency is the highest.

[0055] In one embodiment, the depth of the partially covered cavity structure 200 is 12 mm to 24 mm.

[0056] In one embodiment, the depth of the partially covered cavity structure 200 is 24 mm. Figure 8 As shown, Figure 8 1 is a graph of the powder particle combustion efficiency of the highly mixed powder scramjet engine combustion chamber of this embodiment corresponding to different depths of the partially covered cavity structure 200. When the depth of the partially covered cavity structure 200 is 24 mm, the powder particle combustion efficiency is the highest.

[0057] In a specific embodiment, the injection angle of the highly mixed powder scramjet engine combustion chamber of this embodiment is 60°, the length of the annular baffle 300 is 35 mm, the depth of the partially covered cavity structure 200 is 24 mm, and the projection of the fuel through-hole relative to the annular baffle 300 along the radial direction of the partially covered cavity structure 200 is located in the middle position of the annular baffle 300 along the axial direction. Using the fluent numerical simulation method, the total pressure at the inlet of the equal straight isolation section is set to 1.65 MPa, the total temperature is 1600K, the Mach number is 2.52, and the speed of the two-phase flow of powder fuel and combustible fluidizing gas injected through the fuel through-hole is 30 m / s. Finally, the schematic diagram of the airflow streamlines of the highly mixed powder scramjet engine combustion chamber along the axial section is obtained as shown in the figure below. Fig. 9 As shown, the velocity vector diagram of the airflow along the radial section of the fuel nozzle is as follows: Fig.10 As shown. Fig. 9 It can be seen that after adding the baffle, due to the influence of the backflow vortex in the uncovered area, a small backflow vortex is induced in the baffle covered area. The powder particles are affected by both in the partially covered cavity structure, and the backflow vortex can increase the residence time of the powder particles in the baffle covered area. Fig.10 It mainly describes the velocity distribution in the cross-sectional area of ​​the combustion chamber when the fuel nozzle 500 injects two-phase flow of powdered fuel and combustible fluidizing gas. It can be seen that when the injection angle is 60°, a clockwise velocity deviation occurs in the flow field area. Macroscopically, the particles are affected by the deflection force and move in the area covered by the low-speed reflux baffle, which increases the residence time and creates conditions for efficient combustion.

[0058] The highly mixed powder scramjet engine combustion chamber of the present embodiment generates a small backflow in the baffle covered area. The powder combustion particles are affected by factors such as the collision between the backflow area and the combustion chamber wall, thereby avoiding direct contact with the area not covered by the baffle, increasing the residence time in the partially covered cavity structure 200, and thus increasing the particle combustion efficiency.

[0059] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A highly mixed powder scramjet combustion chamber, characterized in that: The invention comprises an equal straight isolation section (100), a partially covered concave cavity structure (200) and an expansion section (400), wherein the equal straight isolation section (100) and the expansion section (400) are respectively fixedly arranged at two ends of the partially covered concave cavity structure (200), and the equal straight isolation section (100) and the expansion section (400) are both connected to the partially covered concave cavity structure (200); The straight isolation section (100) and the partially covered concave cavity structure (200) are both columnar, the axis of the straight isolation section (100) is collinear with the axis of the partially covered concave cavity structure (200), and the axial radius of the straight isolation section (100) is smaller than the axial radius of the partially covered concave cavity structure (200); An annular baffle (300) is provided inside the partially covered concave cavity structure (200), and the annular baffle (300) is fixedly connected to one end of the partially covered concave cavity structure (200) close to the equal straight isolation section (100); The axis of the annular baffle (300) is colinear with the axis of the partially covered concave cavity structure (200); The axial radius of the annular baffle (300) is greater than or equal to the axial radius of the straight isolation section (100), and smaller than the axial radius of the partially covered concave cavity structure (200); The side wall of the partially covered concave cavity structure (200) is provided with at least one fuel through hole for injecting a two-phase flow of powdered fuel and combustible fluidizing gas into the partially covered concave cavity structure (200); the projection of the fuel through hole relative to the annular baffle (300) along the radial direction of the partially covered concave cavity structure (200) is located on the annular baffle (300).

2. The highly blended powder scramjet combustion chamber according to claim 1, characterized in that: The projection of the fuel through hole relative to the annular baffle (300) in the radial direction of the partially covered concave cavity structure (200) is located at a middle position of the annular baffle (300) in the axial direction; A fuel nozzle (500) is connected to the outside of any fuel through hole; The axis of the fuel nozzle (500) is perpendicular to the axis of the partially covered concave cavity structure (200); The included angle between the tangent plane of the intersection of the axis of the fuel nozzle (500) and the outer wall of the partially covered concave cavity structure (200) and the axis of the fuel nozzle (500) is 0° to 90°.

3. The highly blended powder scramjet combustion chamber according to claim 2, characterized in that: The included angle between the tangent plane of the intersection of the axis of the fuel nozzle (500) and the outer wall of the partially covered concave cavity structure (200) and the axis of the fuel nozzle (500) is 60°.

4. The highly blended powder scramjet combustion chamber according to claim 1, characterized in that: Along the axial direction, the length of the annular baffle (300) is 25 mm to 45 mm.

5. The highly blended powder scramjet combustion chamber according to claim 4, characterized in that: Along the axial direction, the length of the annular baffle (300) is 35 mm.

6. The highly blended powder scramjet combustion chamber according to claim 1, characterized in that: The depth of the partially covered concave cavity structure (200) is 12 mm to 24 mm.

7. The highly blended powder scramjet combustion chamber according to claim 6, characterized in that: The depth of the partially covered cavity structure (200) is 24 mm.

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