A special nozzle with slight eccentric thrust

Abstract

The invention discloses a special-shaped nozzle with micro-thrust eccentricity, comprising a nozzle shell, a front protective layer, a nozzle throat liner, a rear protective layer and a nozzle tail cover; the front section of the inner cavity of the nozzle shell is sequentially bonded with the front protective layer and the nozzle throat liner, the rear section of the inner cavity of the nozzle shell is bonded with the rear protective layer, and the nozzle tail cover is threadedly connected to the rear end of the nozzle shell to limit the rear end of the rear protective layer; the front inner wall of the front protective layer is provided with a conical working surface that converges backwards, and the rear inner wall is provided with a concave arc working surface that expands backwards; the front section of the inner shape of the nozzle throat liner is a convex arc working surface that converges backwards, and the rear section is a convex arc working surface that expands backwards; the inner shape of the rear protective layer is a concave arc working surface that expands backwards; the front and rear ends of the nozzle throat liner are respectively connected with the concave arc working surface and the concave arc working surface of the front protective layer, and the inner cavity of the rear protective layer and the concave arc working surface at the rear end of the inner cavity of the front protective layer are spliced ​​into working surfaces with the same curvature. The special-shaped nozzle of the invention improves the reliability of the nozzle.

Description

Technical Field

[0001] The invention relates to a special-shaped nozzle with micro-thrust eccentricity, belonging to the technical field of special-shaped nozzle design and micro-thrust eccentric nozzle design. Background Art

[0002] The function of the solid rocket engine nozzle is to accelerate the flow of gas to generate thrust. The main task of nozzle aerodynamic surface design is to reasonably select the geometric structure of the convergent section, throat and divergent section to make the nozzle achieve higher efficiency.

[0003] The nozzle is the energy conversion device of the solid rocket engine. It converts the internal energy of the high-temperature combustion gas into the kinetic energy of the combustion gas, thereby generating thrust. At the same time, it is also a control device for the flow of combustion gas, which can establish a certain working pressure in the combustion chamber. Since the high-temperature combustion gas in the nozzle gradually accelerates its flow, its working conditions are very harsh.

[0004] Many scholars have conducted extensive research on solid rocket engine nozzles. The function of the nozzle expansion section is to accelerate the gas to supersonic speed and discharge it from the nozzle outlet to generate thrust. The inner surface of the expansion section is generally designed to be conical, with simple process and low cost. However, due to the high performance requirements of solid rocket engines or the short nozzle length requirements, special nozzles can only be used to design a larger expansion ratio within a given length range.

[0005] The shape of the special nozzle expansion section is more complex than that of the conical nozzle expansion section, but the inner profile of the special nozzle expansion section is designed according to the principle of aerodynamic characteristic lines, so its aerodynamic performance is better than that of the conical nozzle. The outlet airflow of the special nozzle is approximately parallel to the axis, the airflow expansion loss is small, and the propellant energy is fully exerted. Therefore, it is particularly important to optimize and improve the inner profile of the engine nozzle expansion section.

[0006] Due to the asymmetric flow of the combustion surface in the nozzle expansion section, there must be a certain angle between the thrust generated by the nozzle and the nozzle axis, that is, the thrust eccentricity angle. According to the design theory of the micro-thrust deflection nozzle, by changing the internal profile and length of the nozzle expansion section, the thrust direction generated by the nozzle is made close to the nozzle axis direction, the thrust eccentricity angle is reduced, and the reliability of the nozzle is improved.

[0007] When designing the nozzle, the following basic requirements should be met:

[0008] (1) High efficiency. Therefore, the nozzle should have an appropriate expansion ratio and a good profile to minimize friction loss, heat dissipation loss, airflow expansion loss, and two-phase flow loss.

[0009] (2) The nozzle throat size and profile should be kept intact during operation. The nozzle should have good thermal protection.

[0010] (3) Sufficient strength and rigidity. The nozzle shell must be thick enough and have a heat-insulating layer for protection.

[0011] (4) The structure should be light. The nozzle should have an appropriate expansion ratio and be made of suitable materials and structures.

[0012] (5) The thrust eccentricity is small.

[0013] (6) The structure has good processability and economy.

[0014] At present, there are relatively few studies on the design of special micro-thrust eccentric nozzles. Special nozzles mainly include double-arc and parabolic nozzles. Since their structures are more complicated than ordinary conical nozzles, there is a lack of mature design solutions. In recent years, there have been more studies on micro-thrust eccentric nozzles, most of which are design studies of conical micro-thrust eccentric nozzles, and there are fewer designs and studies on special micro-thrust eccentric nozzles. Summary of the invention

[0015] The purpose of the present invention is to provide a special nozzle with micro-thrust eccentricity, which can be used to reduce the thrust eccentricity moment of the rocket engine, increase the thrust of the rocket engine nozzle, reduce the deviation of the rocket from the expected trajectory during flight, and effectively improve the problem of low density of uncontrolled rockets.

[0016] The objective of the present invention is achieved through the following technical solutions:

[0017] The invention discloses a special-shaped nozzle with micro-thrust eccentricity, comprising a nozzle shell, a front protective layer, a nozzle throat liner, a rear protective layer and a nozzle tail cover;

[0018] The front section of the nozzle housing has a stepped cylindrical through hole with a large diameter at the front end and a small diameter at the rear end, and the rear section of the nozzle housing is a cone that expands backward and is connected to the front section of the nozzle housing; the front inner wall and the rear outer wall of the nozzle housing are both processed with connecting threads;

[0019] The front protective layer is a cylindrical part whose outer diameter matches the small diameter through hole of the front section of the nozzle shell, the outer wall of the front port portion of the front protective layer is provided with an annular positioning platform extending radially outward, the inner wall of the front port portion of the front protective layer is processed with a conical working surface converging backward, the inner side of the rear port portion of the front protective layer is provided with a throat liner positioning platform, the front end surface of the throat liner positioning platform is an annular positioning surface, and the inner wall of the throat liner positioning platform is a concave arc-shaped working surface expanding backward;

[0020] The outer wall of the front protective layer is bonded to the small-diameter through hole at the rear end of the inner cavity of the front section of the nozzle shell, and the annular positioning platform at the front end of the front protective layer is bonded to the stepped surface of the inner cavity of the front section of the nozzle shell;

[0021] The front inner section of the nozzle throat liner is a convex arc-shaped working surface that converges backwards, and the rear inner section of the nozzle throat liner is a convex arc-shaped working surface that expands backwards, and the axial arcs of the front and rear sections of the convex arc-shaped working surfaces of the nozzle throat liner are tangent at the intersection;

[0022] The nozzle throat liner is bonded to the inner cavity of the front protective layer, so that the front and rear ends of the inner shape of the nozzle throat liner are respectively connected with the conical working surface at the front end of the inner cavity of the front protective layer and the concave arc working surface at the rear end of the inner cavity, and the axial arc of the convex arc working surface of the rear section of the nozzle throat liner and the concave arc working surface at the rear end of the inner cavity of the front protective layer are tangent at the intersection;

[0023] The outer shape of the rear protective layer matches the inner shape of the cone of the rear section of the nozzle shell, and the inner shape of the rear protective layer is a concave arc-shaped working surface that expands backwards;

[0024] The rear protective layer is bonded to the inner wall of the cone of the rear section of the nozzle shell, and the inner cavity of the rear protective layer and the concave arc-shaped working surface at the rear end of the inner cavity of the front protective layer are spliced ​​into working surfaces with the same arc; the nozzle tail cover is threadedly connected to the rear end of the outer wall of the rear section of the nozzle shell, and the rear port of the nozzle tail cover is provided with an annular positioning platform extending radially inward, and the nozzle tail cover limits the rear end of the rear protective layer through the annular positioning platform; the front end of the nozzle shell is threadedly connected to the rear end of the combustion chamber;

[0025] Wherein, the throat diameter Rt of the nozzle throat liner satisfies the following formula:

[0026] RL=100Rt 2 ;

[0027] Where R is the diameter of the engine charge and L is the length of the engine charge;

[0028] The arc radius of the arc-shaped working surface of the front section of the nozzle throat liner is 1 to 2 times the throat diameter of the nozzle throat liner;

[0029] The arc radius of the convex arc-shaped working surface of the rear section of the nozzle throat liner, the arc radius of the inner wall of the throat liner positioning platform at the rear end of the front protective layer, and the arc radius of the concave arc-shaped working surface of the rear protective layer are all 5 to 10 times the arc radius of the arc-shaped working surface of the front section of the nozzle throat liner;

[0030] The axial length of the nozzle expansion section is 4 to 5 times the throat diameter of the nozzle throat liner.

[0031] Beneficial Effects

[0032] The special nozzle of the present invention has a simple structure, is easy to install, and works reliably. When installed on different rocket engines or spacecraft, there is no need to make too many changes to the structural layout of the nozzle. It can be installed directly after upgrading and transforming according to the existing rocket engine size. It has low cost, short development cycle, and is easier to carry out experiments and put into mass production. The expansion section of the special nozzle of the present invention adopts a double arc nozzle profile design, which can increase the expansion ratio of the nozzle under the premise of equal nozzle length, increase the space of the nozzle expansion section, and make the gas fully expand in the nozzle expansion section to achieve the effect of increasing the thrust of the nozzle. The special nozzle of the present invention designs the length of the nozzle expansion section according to the thrust eccentricity zero point, so as to achieve the purpose of the thrust eccentricity moment of the nozzle tending to zero and improve the reliability of the nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the special nozzle of the present invention;

[0034] In the figure, 1-nozzle throat liner, 2-nozzle tail cover, 3-nozzle shell, 4-expansion section, 5-protective layer. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] Example

[0037] like Figure 1 As shown, a micro-thrust eccentric special nozzle of the present invention comprises a nozzle shell 3, a front protective layer 5, a nozzle throat liner 1, a rear protective layer 4 and a nozzle tail cover 2;

[0038] The front section of the nozzle housing 3 is a stepped cylindrical through hole with a large diameter at the front end and a small diameter at the rear end, and the rear section of the nozzle housing 3 is a cone that expands backward and is connected to the front section of the nozzle housing 3; the front inner wall and the rear outer wall of the nozzle housing 3 are both processed with connecting threads;

[0039] The front protective layer 5 is a cylindrical part whose outer diameter matches the small-diameter through hole of the front section of the nozzle shell 3. The outer wall of the front port portion of the front protective layer 5 is provided with an annular positioning platform extending radially outward, and the inner wall of the front port portion of the front protective layer 5 is processed with a conical working surface converging backward, and the inclination angle of the conical working surface is 45°. A throat liner positioning platform is provided on the inner side of the rear port portion of the front protective layer 5, and the front end surface of the throat liner positioning platform is an annular positioning surface, and the inner wall of the throat liner positioning platform is a concave arc working surface expanding backward, and the arc radius of the concave arc working surface is 155mm;

[0040] The outer wall of the front protective layer 5 is glued to the small diameter through hole at the rear end of the front inner cavity of the nozzle shell 3, and the annular positioning platform at the front end of the front protective layer 5 is glued to the stepped surface of the front inner cavity of the nozzle shell 3;

[0041] The inner front section of the nozzle throat liner 1 is a convex arc-shaped working surface that converges backwards, and the arc radius of the convex arc-shaped working surface is 50 mm. The inner rear section of the nozzle throat liner 1 is a convex arc-shaped working surface that expands backwards, and the arc radius of the convex arc-shaped working surface is 155 mm. The axial arcs of the front and rear sections of the convex arc-shaped working surfaces of the nozzle throat liner 1 are tangent at the intersection, and the throat diameter of the nozzle throat liner 1 is 12.5 mm.

[0042] The nozzle throat liner 1 is bonded to the inner cavity of the front protective layer 5, so that the front and rear ends of the inner shape of the nozzle throat liner 1 are respectively connected with the conical working surface at the front end of the inner cavity of the front protective layer 5 and the concave arc working surface at the rear end of the inner cavity, and the axial arc of the convex arc working surface of the rear section of the nozzle throat liner 1 and the concave arc working surface at the rear end of the inner cavity of the front protective layer 5 are tangent at the intersection;

[0043] The outer shape of the rear protective layer 4 matches the inner shape of the rear cone of the nozzle housing 3. The inner shape of the rear protective layer 4 is a concave arc-shaped working surface that expands backwards. The arc radius of the concave arc-shaped working surface is 155 mm. The inner wall radius of the outlet end of the rear protective layer 4 is 30 mm.

[0044] The rear protective layer 4 is adhered to the inner wall of the cone of the rear section of the nozzle shell 3, and the inner cavity of the rear protective layer 4 and the concave arc-shaped working surface at the rear end of the inner cavity of the front protective layer 5 are spliced ​​into working surfaces with the same arc. The axial length of the nozzle expansion section (from the throat diameter of the nozzle throat liner 1 to the outlet end of the rear protective layer 4) is 55 mm; the nozzle tail cover 2 is threadedly connected to the rear end of the outer wall of the rear section of the nozzle shell 3, and the rear port portion of the nozzle tail cover 2 is provided with a radially inwardly extending annular positioning platform, and the nozzle tail cover 2 limits the rear end of the rear protective layer 4 through the annular positioning platform; the front end of the nozzle shell 3 is threadedly connected to the rear end of the combustion chamber.

[0045] The internal flow field of the nozzle of the embodiment is simulated and calculated, that is, the thrust vector in different cross sections of the nozzle expansion section is integrated, and the main thrust Fx along the axial direction of each cross section perpendicular to the axis of the nozzle expansion section and the lateral force Fy perpendicular to the nozzle axis can be obtained. According to the calculation formula of the thrust eccentricity angle α: tanα=Fy / Fx, it can be calculated that the thrust eccentricity angle of the special nozzle obtained in the embodiment is 0.65°. Under the conditions of the same expansion ratio and expansion section length, the thrust eccentricity angle of the conventional structure nozzle is 2.35°. It can be seen that the special nozzle obtained in the embodiment greatly reduces the thrust eccentricity effect of the nozzle and improves the stability of the nozzle thrust.

Claims

1. A special type nozzle with micro-thrust eccentricity, characterized by: It includes nozzle shell, front protective layer, nozzle throat liner, rear protective layer and nozzle tail cover; The front section of the nozzle housing has a stepped cylindrical through hole with a large diameter at the front end and a small diameter at the rear end, and the rear section of the nozzle housing is a cone that expands backward and is connected to the front section of the nozzle housing; the front inner wall and the rear outer wall of the nozzle housing are both processed with connecting threads; The front protective layer is a cylindrical part whose outer diameter matches the small diameter through hole of the front section of the nozzle shell, the outer wall of the front port portion of the front protective layer is provided with an annular positioning platform extending radially outward, the inner wall of the front port portion of the front protective layer is processed with a conical working surface converging backward, the inner side of the rear port portion of the front protective layer is provided with a throat liner positioning platform, the front end surface of the throat liner positioning platform is an annular positioning surface, and the inner wall of the throat liner positioning platform is a concave arc-shaped working surface expanding backward; The outer wall of the front protective layer is bonded to the small-diameter through hole at the rear end of the inner cavity of the front section of the nozzle shell, and the annular positioning platform at the front end of the front protective layer is bonded to the stepped surface of the inner cavity of the front section of the nozzle shell; The front inner section of the nozzle throat liner is a convex arc-shaped working surface that converges backwards, and the rear inner section of the nozzle throat liner is a convex arc-shaped working surface that expands backwards, and the axial arcs of the front and rear sections of the convex arc-shaped working surfaces of the nozzle throat liner are tangent at the intersection; The nozzle throat liner is bonded to the inner cavity of the front protective layer, so that the front and rear ends of the inner shape of the nozzle throat liner are respectively connected with the conical working surface at the front end of the inner cavity of the front protective layer and the concave arc working surface at the rear end of the inner cavity, and the axial arc of the convex arc working surface of the rear section of the nozzle throat liner and the concave arc working surface at the rear end of the inner cavity of the front protective layer are tangent at the intersection; The outer shape of the rear protective layer matches the inner shape of the cone of the rear section of the nozzle shell, and the inner shape of the rear protective layer is a concave arc-shaped working surface that expands backwards; The rear protective layer is adhered to the inner wall of the cone of the rear section of the nozzle shell, and the inner cavity of the rear protective layer and the concave arc-shaped working surface at the rear end of the inner cavity of the front protective layer are spliced ​​into working surfaces with the same arc; the nozzle tail cover is threadedly connected to the rear end of the outer wall of the rear section of the nozzle shell, and the rear port portion of the nozzle tail cover is provided with an annular positioning platform extending radially inward, and the nozzle tail cover limits the rear end of the rear protective layer by the annular positioning platform; the front end of the nozzle shell is threadedly connected to the rear end of the combustion chamber.

2. A micro-thrust eccentric special nozzle as claimed in claim 1, characterized in that: The throat diameter Rt of the nozzle throat liner satisfies the following formula: RL=100Rt 2 ; Where R is the diameter of the engine charge and L is the length of the engine charge; The arc radius of the arc-shaped working surface of the front section of the nozzle throat liner is 1 to 2 times the throat diameter of the nozzle throat liner; The arc radius of the convex arc-shaped working surface of the rear section of the nozzle throat liner, the arc radius of the inner wall of the throat liner positioning platform at the rear end of the front protective layer, and the arc radius of the concave arc-shaped working surface of the rear protective layer are all 5 to 10 times the arc radius of the arc-shaped working surface of the front section of the nozzle throat liner; The axial length of the nozzle expansion section is 4 to 5 times the throat diameter of the nozzle throat liner.

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