A staged pre-cooled single wall nozzle extension

Abstract

The application relates to a staged pre-cooling single-wall nozzle extension section, which comprises a single-wall nozzle extension section upper section and a single-wall nozzle extension section lower section, turbine exhaust gas is proportionally divided into two streams, no more than 30% of the turbine exhaust gas forms a first supersonic speed gas film, a lower-temperature protective layer is formed in a region close to the inner wall surface of the single-wall upper section base body, so as to separate the higher-temperature main flow gas and the single-wall upper section base body, a second supersonic speed gas film is arranged at a position where the first gas film cooling efficiency is reduced to 80% or the maximum wall surface temperature of the single-wall nozzle extension section upper section approaches the material allowable temperature, and the remaining inner wall of the single-wall section is heat-protected. The application significantly reduces the maximum temperature of the structural wall surface under specific flow distribution.

Description

Technical Field

[0001] This invention relates to a staged pre-cooled single-wall nozzle extension section, belonging to the field of liquid rocket engine technology. Background Technology

[0002] Gas generator-cycle liquid rocket engines typically introduce turbine exhaust gas into the nozzle extension section in the form of a supersonic film cooling system, which, combined with radiative cooling, cools the lower section of the nozzle, forming a single-wall nozzle extension section. However, for upper-stage engines with a larger nozzle exit area ratio, due to the longer axial length of the nozzle extension section, and limited by the allowable temperature of the material, a single-stage supersonic cooling film cooling system cannot complete the cooling of a sufficiently long single-wall section of the nozzle extension.

[0003] Considering that a single-stage supersonic cooling film can cool the wall temperature of a single-wall section to near the total temperature of the film inlet in a certain area, the temperature of this section is far below the allowable temperature of the material. However, the wall temperature of the single-wall section begins to rise rapidly thereafter. That is, the cooling capacity is wasted near the supersonic film inlet section due to the large cooling flow and the excessive cooling effect. This can be addressed by allocating a certain cooling flow to fully utilize the heat resistance of the material and the cooling capacity of the turbine exhaust gas (coolant).

[0004] As the heat flux density gradually decreases on the downstream wall of the throat of a liquid rocket engine, the need for thermal protection is correspondingly reduced. To reduce structural weight, large-area-ratio upper-stage engine nozzles often adopt a segmented structure. The nozzle extension section often uses a single-layer thin-walled structure with a combination of radiation and supersonic film cooling. Commonly used materials include nickel-based alloys that can withstand temperatures around 1000℃, niobium-tungsten alloys that can withstand temperatures around 1500℃, and composite materials that can withstand temperatures above 1800℃. Niobium-tungsten alloys and composite materials are expensive, and the molding technology for composite materials with diameters greater than 1.5m is not mature in China. Therefore, nickel-based alloys such as GH3230 are often used for single-wall nozzles in China. For gas generator cycle liquid rocket engines, the supersonic film cooling usually comes from turbine exhaust gas. Existing structures at home and abroad introduce turbine exhaust gas at approximately 500℃ into the single-wall nozzle through a single large collector. The turbine exhaust gas forms a supersonic wall-attached flow through an annular or discrete orifice contraction-expansion type injection structure, providing thermal protection for the downstream single-wall nozzle wall. However, as the gas film mixes with the mainstream, the cooling capacity of a single-stage gas film rapidly decreases, and the cooling effect deteriorates accordingly. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a staged pre-cooled single-wall nozzle extension section, which significantly reduces the maximum temperature of the structural wall under specific flow distribution.

[0006] The solution of the present invention is:

[0007] A staged pre-cooled single-wall nozzle extension section includes an upper section and a lower section.

[0008] The outer wall of the single-wall nozzle is provided with an upper section of the single-wall nozzle extension. The upper section of the single-wall nozzle extension includes a primary air film inlet, a primary air film collector, a primary air film flow equalization plate, a primary air film contraction-expansion annular slit, and the single-wall upper section substrate.

[0009] The upper section of the single-walled substrate is connected to the outer wall of the single-walled nozzle in a gap. At the gap, a primary air film inlet, a primary air film collector, a primary air film flow equalization plate, and a primary air film contraction-expansion annular slit are sequentially arranged.

[0010] The lower section of the single-wall nozzle extension is located at the end of the outer wall of the upper section of the single-wall nozzle extension. The lower section of the single-wall nozzle extension includes a secondary film inlet, a secondary film collector, a secondary film flow equalization plate, a secondary film contraction-expansion annular slot, and the substrate of the lower section of the single-wall nozzle.

[0011] The lower section of the single-walled nozzle substrate is connected to the outer wall of the upper section of the single-walled nozzle extension section in a gap. At the gap, a secondary air film inlet, a secondary air film collector, a secondary air film flow equalization plate, and a secondary air film contraction-expansion annular slot are sequentially arranged.

[0012] The turbine exhaust gas is divided into two streams according to a certain ratio. No more than 30% of the turbine exhaust gas forms a first-stage supersonic gas film, which forms a lower-temperature protective layer in the area near the inner wall of the upper section of the single-wall substrate to separate the higher-temperature mainstream combustion gas from the upper section of the single-wall substrate. A second-stage supersonic gas film is set at the location where the cooling efficiency of the first-stage gas film drops to 80% or the highest wall temperature of the upper section of the single-wall nozzle extension is close to the allowable temperature of the material to provide thermal protection for the remaining inner wall of the single-wall substrate.

[0013] Furthermore, the first-stage air film contraction-expansion annular gap is smaller than the second-stage air film contraction-expansion annular gap.

[0014] Furthermore, both the primary and secondary air film contraction-expansion annular seams are tapered throats, with the size of the annular seams determined based on the cooling flow rate.

[0015] Furthermore, several holes are evenly distributed on the primary air film flow equalization plate, and the number and size of the holes are designed based on the local flow velocity.

[0016] Furthermore, the first-stage air film collector is semi-circularly attached to the outer wall of the single-wall nozzle, forming a flow equalization cavity at the inlet of the first-stage air film.

[0017] Furthermore, several holes are evenly distributed on the primary air film equalization plate to ensure that the turbine exhaust gas entering the primary air film collector through the primary air film inlet enters the primary air film contraction-expansion annular gap in a circumferential direction.

[0018] Furthermore, the contraction-expansion annular gap causes the turbine exhaust gas to expand and accelerate, forming a first-stage supersonic gas film. The lower-temperature supersonic gas film flows closely against the inner wall of the upper section of the single-wall matrix, separating the upper section of the single-wall matrix from the higher-temperature mainstream combustion gas, thus achieving cooling.

[0019] Furthermore, the secondary air film collector is semi-circularly attached to the outer wall of the upper section of the single-wall nozzle extension, forming a flow equalization cavity at the inlet of the secondary air film.

[0020] Furthermore, the secondary film gas equalization plate has several holes evenly distributed to ensure that the turbine exhaust gas entering the secondary film gas collector through the secondary film gas inlet enters the secondary film gas contraction-expansion annular gap in a circumferential direction.

[0021] Furthermore, the secondary film gas contraction-expansion annular gap causes the turbine exhaust gas to expand and accelerate, forming a secondary supersonic gas film. The lower temperature secondary supersonic gas film flows closely against the inner wall of the lower section of the single-wall matrix, separating the lower section of the single-wall matrix from the higher temperature mainstream combustion gas, thus achieving cooling.

[0022] The advantages of this invention compared to the prior art are:

[0023] (1) Compared with the single-stage supersonic air film cooling scheme, the present invention can effectively extend the total effective air film length and can be applied to the extension section of the upper stage engine nozzle with a larger area ratio. While keeping the total flow rate of turbine exhaust gas, inlet parameters, nozzle length of single wall section and radiation emissivity of single wall section material unchanged, the highest wall surface temperature of single wall section can be reduced by more than 140K, with a reduction of up to 10%.

[0024] (2) The graded precooling scheme of the present invention significantly reduces the highest wall temperature of a single wall section by distributing a certain cooling flow rate, which can avoid the use of complex processes such as high emissivity coatings and thermal barrier coatings. Attached Figure Description

[0025] Figure 1 Schematic diagram of the extension section of a staged precooled single-wall nozzle;

[0026] Figure 2 This is a structural diagram of the extension section of a single-walled nozzle.

[0027] Figure 3 This is a structural diagram of the upper section of the single-wall nozzle extension.

[0028] Figure 4 This is a structural diagram of the lower section of the single-wall nozzle extension.

[0029] Figure 5 A comparison chart of the wall surface temperature of a single wall section in existing single-stage and the graded supersonic air film cooling system of this invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the embodiments.

[0031] A staged pre-cooled single-wall nozzle extension section, such as Figure 1-4 As shown, it includes the upper section 2 of the single-wall nozzle extension and the lower section 4 of the single-wall nozzle extension.

[0032] The upper section 2 of the single-wall nozzle extension is provided at the end of the outer wall of the single-wall nozzle. The upper section 2 of the single-wall nozzle extension includes a primary air film inlet 21, a primary air film collector 22, a primary air film flow equalization plate 23, a primary air film contraction-expansion annular slit 24, and a single-wall upper section substrate 25.

[0033] The upper section of the single-walled substrate 25 is connected to the outer wall of the single-walled nozzle with gaps. At the gaps, a primary air film inlet 21, a primary air film collector 22, a primary air film flow equalization plate 23, and a primary air film contraction-expansion annular slit 24 are sequentially arranged.

[0034] A lower section 4 of the single-wall nozzle extension is provided at the end of the outer wall of the upper section 2 of the single-wall nozzle extension. The lower section 4 of the single-wall nozzle extension includes a secondary air film inlet 41, a secondary air film collector 42, a secondary air film flow equalization plate 43, a secondary air film contraction-expansion annular slit 44, and a single-wall lower section substrate 45.

[0035] The lower section of the single-walled nozzle substrate 45 is connected to the outer wall of the upper section 2 of the single-walled nozzle extension section in a gap. At the gap, a secondary air film inlet 41, a secondary air film collector 42, a secondary air film flow equalization plate 43, and a secondary air film contraction-expansion annular seam 44 are sequentially arranged.

[0036] The turbine exhaust gas is divided into two streams according to a certain ratio. No more than 30% of the turbine exhaust gas forms a first-stage supersonic gas film 3, which forms a lower-temperature protective layer in the area near the inner wall of the upper section of the single-wall substrate 25 to separate the higher-temperature mainstream combustion gas from the upper section of the single-wall substrate 25. A second-stage supersonic gas film 5 is set at the location where the cooling efficiency of the first-stage gas film drops to 80% or the highest wall surface temperature of the upper section 2 of the single-wall nozzle extension is close to the allowable temperature of the material to provide thermal protection for the remaining inner wall of the single-wall substrate.

[0037] Both the primary film shrinkage-expansion annular joint at point 24 and the secondary film shrinkage-expansion annular joint at point 44 are conical throats, with the size of the joints determined based on the cooling flow rate. The primary film shrinkage-expansion annular joint at point 24 is smaller than that at point 44.

[0038] The primary air film equalization plate 23 has several holes evenly distributed on it. The number and size of the holes are designed based on the local flow velocity. The primary air film equalization plate 23 has several holes evenly distributed on it so that the turbine exhaust gas entering the primary air film collector 22 through the primary air film inlet 21 can enter the primary air film contraction-expansion annular gap 24 evenly in the circumferential direction.

[0039] The first-stage air film collector 22 is semi-circularly attached to the outer wall of the single-wall nozzle, forming a flow equalization cavity at the first-stage air film inlet 21. The second-stage air film collector 42 is semi-circularly attached to the outer wall of the upper section 2 of the single-wall nozzle extension, forming a flow equalization cavity at the second-stage air film inlet 41.

[0040] The contraction-expansion annular gap 24 causes the turbine exhaust gas to expand and accelerate, forming a first-stage supersonic film gas 3. The lower-temperature supersonic film gas 3 flows closely against the inner wall of the upper section of the single-wall substrate 25, connecting the upper section of the single-wall substrate 25 with the higher-temperature supersonic film gas 3.

[0041] The secondary film flow equalization plate 43 has several holes evenly distributed on it so that the turbine exhaust gas entering the secondary film collector 42 through the secondary film inlet 41 can enter the secondary film contraction-expansion annular gap 44 evenly in the circumferential direction.

[0042] The secondary film contraction-expansion annular gap 44 causes the turbine exhaust gas to expand and accelerate, forming a secondary supersonic film gas 5. The lower temperature secondary supersonic film gas 5 flows closely against the inner wall of the lower section of the single-wall substrate 45, separating the lower section of the single-wall substrate 45 from the higher temperature mainstream combustion gas 0, thus achieving cooling.

[0043] Existing single-stage supersonic film cooling introduces all turbine exhaust gas into the nozzle extension section through a single contraction-expansion annular slot, forming a supersonic wall-following flow. Along the nozzle axis, as the supersonic film gas mixes with the mainstream combustion gas, the supersonic film cooling capacity rapidly weakens after a certain distance, and the wall temperature of the single-wall section rises rapidly. In a relatively long region near the film gas outlet, the single-wall section wall temperature is essentially equivalent to the turbine exhaust gas temperature at the film gas inlet, far below the allowable temperature of the single-wall nozzle material, before rapidly increasing again.

[0044] The core idea of ​​this patent is to increase the wall temperature of the single-wall nozzle near the film cooling outlet section by allocating cooling flow (turbine exhaust gas), ensuring that its maximum temperature is slightly below the allowable temperature of the material. This saves more cooling flow for secondary film cooling, providing thermal protection for a longer area of ​​the lower section of the single-wall nozzle. This results in the maximum wall temperatures downstream of the primary and secondary film cooling systems being essentially the same, both below the allowable temperature of the material, thus fully utilizing the material's heat resistance and the turbine exhaust gas cooling capacity.

[0045] This invention uses a small amount (about 30%) of turbine exhaust gas to form a primary supersonic gas film, forming a lower temperature protective layer in the region near the inner wall of the single-wall section substrate to separate the higher temperature mainstream combustion gas from the single-wall section substrate. A secondary supersonic gas film is introduced when the cooling efficiency of the primary gas film drops to about 80% or the temperature of the single-wall section wall is close to the allowable temperature of the material to provide thermal protection for the remaining inner wall of the single-wall section substrate.

[0046] Compared to single-stage supersonic film cooling solutions, this invention effectively extends the total effective film length and can be applied to the nozzle extension section of upper-stage engines with larger area ratios. While maintaining the total turbine exhaust gas flow rate, inlet parameters, single-wall nozzle length, and single-wall material emissivity unchanged, it can reduce the highest wall surface temperature of the single-wall section by more than 140K, a reduction of up to 10%. Figure 5 As shown.

[0047] The graded precooling scheme of this invention significantly reduces the highest wall surface temperature of a single wall section by distributing a certain cooling flow rate, thus avoiding the use of complex processes such as high emissivity coatings and thermal barrier coatings.

[0048] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A staged pre-cooled single-wall nozzle extension, characterized by, It includes the upper section (2) of the single-wall nozzle extension and the lower section (4) of the single-wall nozzle extension. The upper section (2) of the single-wall nozzle extension is provided at the end of the outer wall of the single-wall nozzle. The upper section (2) of the single-wall nozzle extension includes a primary air film inlet (21), a primary air film collector (22), a primary air film flow equalization plate (23), a primary air film contraction-expansion annular seam (24), and a single-wall upper section substrate (25). The upper section of the single-wall substrate (25) is connected to the outer wall of the single-wall nozzle in a gap. At the gap, a primary air film inlet (21), a primary air film collector (22), a primary air film flow equalization plate (23), and a primary air film contraction-expansion annular seam (24) are arranged in sequence. The upper section (2) of the single-wall nozzle extension section is provided with a lower section (4) of the single-wall nozzle extension section at the end of the outer wall. The lower section (4) of the single-wall nozzle extension section includes a secondary air film inlet (41), a secondary air film collector (42), a secondary air film flow equalization plate (43), a secondary air film contraction-expansion annular seam (44), and a single-wall lower section substrate (45). The lower section of the single-walled substrate (45) is connected to the outer wall of the upper section (2) of the single-walled nozzle extension section in a gap. At the gap between the lower section of the single-walled substrate (45) and the upper section (2) of the single-walled nozzle extension section, a secondary air film inlet (41), a secondary air film collector (42), a secondary air film flow equalization plate (43) and a secondary air film contraction-expansion annular seam (44) are arranged in sequence. The turbine exhaust gas is divided into two streams according to the ratio. No more than 30% of the turbine exhaust gas forms a first-stage supersonic gas film (3), which forms a lower temperature protective layer in the area near the inner wall of the upper section of the single-wall substrate (25) to separate the higher temperature mainstream gas from the upper section of the single-wall substrate (25). A second-stage supersonic gas film (5) is set at the location where the cooling efficiency of the first-stage gas film decreases to 80% or the highest wall temperature of the upper section (2) of the single-wall nozzle extension is close to the allowable temperature of the material to provide thermal protection for the inner wall of the lower section of the single-wall substrate (45).

2. A staged pre-cooled single wall nozzle extension in accordance with claim 1, wherein, Both the primary air film contraction-expansion annular seam (24) and the secondary air film contraction-expansion annular seam (44) are conical throats, and the size of the annular seam is determined based on the cooling flow rate.

3. A staged pre-cooled single wall nozzle extension in accordance with claim 1, wherein, Several holes are evenly distributed on the primary air film equalization plate (23), and the number and size of the holes are designed based on the local flow velocity.

4. A staged pre-cooled single wall nozzle extension in accordance with claim 1, wherein, The primary air film collector (22) is semi-circularly attached to the outer wall of the single-wall nozzle, forming a flow equalization cavity at the primary air film inlet (21).

5. A staged pre-cooled single wall nozzle extension in accordance with claim 1, wherein, Several holes are evenly distributed on the primary air film equalization plate (23) so that the turbine exhaust gas entering the primary air film collector (22) through the primary air film inlet (21) can enter the primary air film contraction-expansion annular gap (24) evenly in the circumferential direction.

6. The staged pre-cooled single-wall nozzle extension section according to claim 1, characterized in that, The first-stage gas film contraction-expansion annular gap (24) causes the turbine exhaust gas to expand and accelerate, forming a first-stage supersonic gas film (3). The lower-temperature first-stage supersonic gas film (3) flows closely against the inner wall of the upper section of the single-wall substrate (25), separating the upper section of the single-wall substrate (25) from the higher-temperature mainstream gas (0) to achieve cooling.

7. The staged pre-cooled single-wall nozzle extension section according to claim 1, characterized in that, The secondary air film collector (42) is semi-circularly attached to the outer wall of the upper section (2) of the single-wall nozzle extension, forming a flow equalization cavity at the secondary air film inlet (41).

8. The staged pre-cooled single-wall nozzle extension section according to claim 1, characterized in that, The secondary air film equalization plate (43) has several holes evenly distributed so that the turbine exhaust gas entering the secondary air film collector (42) through the secondary air film inlet (41) can enter the secondary air film contraction-expansion annular gap (44) evenly in the circumferential direction.

9. The staged pre-cooled single-wall nozzle extension section according to claim 1, characterized in that, The secondary gas film contraction-expansion annular gap (44) causes the turbine exhaust gas to expand and accelerate, forming a secondary supersonic gas film (5). The lower temperature secondary supersonic gas film (5) flows closely against the inner wall of the lower section of the single wall substrate (45), separating the lower section of the single wall substrate (45) from the higher temperature mainstream gas (0) to achieve cooling.

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