A four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing

Abstract

The present invention relates to a four-way mixing chamber for radiation convection coupled aerodynamic thermal testing, comprising an airflow chamber and a radiation chamber, wherein the airflow chamber comprises a small end flange, a four-way inner shell, a four-way outer shell, an upstream flange, a large end flange and a first air inlet ring. The four-way outer shell is wrapped around the outside of the four-way inner shell. The small end flange is mounted on the small end side of the four-way inner shell, the upstream flange is mounted on both sides of the four-way inner shell, the large end flange is mounted on the large end side of the four-way inner shell, and the first air inlet ring is mounted on the inside of the large end flange. The radiation chamber comprises a connecting flange, a radiation chamber inner shell, a radiation chamber outer shell, a radiation flange and a second air inlet ring. The radiation chamber outer shell is wrapped around the outside of the radiation chamber inner shell, the connecting flange is mounted on the large end of the radiation chamber inner shell, the radiation flange is mounted on the small end, and the second air inlet ring is mounted on the inside of the radiation flange. When in use, the airflow chamber and the radiation chamber are connected together, and high-pressure cooling water and high-pressure cold air are respectively introduced into them. The present invention is mainly used for the integration of convective heat sources and radiant heat sources and the modulation of the convective heat source flow field in radiation convection coupled aerodynamic thermal ground simulation tests.

Description

Technical Field

[0001] The invention relates to a mixing chamber for a radiation-convection coupled aerodynamic-thermal test, and belongs to the field of aerospace aircraft aerodynamic-thermal ground simulation test devices. Technical Background

[0002] In ground-based simulations of aerodynamic thermal protection, radiation-convection coupled aerodynamic thermal testing has been gradually implemented as a key test method for the refined design of thermal protection structures for high-speed reentry vehicles. In these tests, high-temperature airflow generated by devices such as arc heaters and gas streams serves as a convective heat source, while high-energy flux radiation generated by devices such as quartz lamps, carbon arc lamps, and xenon arc lamps serves as a radiative heat source. These are applied simultaneously to the surface of the test model to simulate the coupled effects of convective heating from the atmosphere and radiative heating from high-intensity shock waves on the vehicle's thermal protection materials during high-speed reentry.

[0003] In the aforementioned convective and radiant heat source generation devices, the electric arc heaters or gas flow devices used as convective heat sources are typically large and complex, while radiant heat sources are typically simpler in structure. Therefore, the currently used radiant convection coupled aerodynamic thermal test devices are all improved upon convective heat source devices. However, conventional convective heating devices and the test model are both arranged on the same axis. Consequently, the radiation heat source generated by the improved radiant convection coupled test device must be reflected or obliquely illuminated to act on the test model, resulting in low radiant heat efficiency and low uniformity of radiation received by the test model surface. To improve the aforementioned radiant heat environment drawbacks of radiant convection coupled test devices, a completely new test device is needed. To this end, a device is needed within the test device that can integrate the convective and radiant heat sources, placing the radiant heat source and the high-temperature airflow on the same axis.

[0004] Patent content

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide an integrated device of convective heat source and radiant heat source that can generate a direct radiant heat environment while ensuring that the convective heat environment does not deteriorate.

[0006] The technical solution of the present invention is: a four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing, comprising an airflow chamber and a radiation chamber;

[0007] The airflow cavity includes a four-way inner shell, a first air intake ring, and a first connecting structure. The four-way inner shell is a cross-shaped cylindrical structure composed of a longitudinal cavity and a transverse cavity. The longitudinal cavity is a conical cylinder, and the transverse cavity is a cylindrical shape with small ends and a large middle. A channel for water cooling and air cooling is provided between the four-way inner shell and the first connecting structure outside the four-way inner shell. The cooling gas in the air intake channel eventually enters the four-way inner shell through the first air intake ring located at the large end of the longitudinal cavity.

[0008] The radiation cavity includes a radiation cavity inner shell, a second air inlet ring, and a second connecting structure. The radiation cavity inner shell is a semi-ellipsoidal structure, having a semi-ellipsoidal inner cavity, the small end of which is connected to the radiation source through the second air inlet ring. A channel for water cooling and air cooling is provided between the radiation cavity inner shell and the second connecting structure. The cooling gas in the air inlet channel enters the radiation cavity inner shell through the second air inlet ring and the air cooling channel.

[0009] During the test, the airflow cavity and the radiation cavity are fixedly connected, and the longitudinal cavity of the airflow cavity coincides with the axis of the semi-ellipsoidal inner cavity; convection heat sources are installed at both ends of the transverse cavity, and the irradiation direction of the radiation heat source and the outflow direction of the convection heat source flow field are on the same axis.

[0010] Preferably, the first connecting structure comprises a small end flange, a four-way housing, an upstream flange, and a large end flange;

[0011] The outer wall of the four-way inner shell has a rib structure; the four-way outer shell is wrapped around the outer side of the four-way inner shell, and the cavity formed between its inner wall and the ribs of the outer wall of the four-way inner shell is the first water cooling channel; the small end flange is installed on the small end side of the longitudinal cavity of the four-way inner shell, and the outer wall surface of the flange is provided with a first water outlet channel, and the inner wall surface is provided with a first annular water collecting trough; the upstream flange is installed on both sides of the transverse cavity of the four-way inner shell, with a total of two pieces, and the outer wall surface of the flange is provided with a first water inlet channel, and the inner wall surface is provided with a first annular water collecting trough; the large end flange is installed on the large end side of the longitudinal cavity of the four-way inner shell, and the outer wall surface of the flange is provided with a first water outlet channel and a first air inlet channel, and the inner wall surface is provided with a first annular water collecting trough and a first air collecting trough; the first air inlet ring is installed on the inner side of the first air collecting trough of the large end flange, and several first air inlet holes are evenly distributed on it.

[0012] Preferably, the first air intake ring is an equal-diameter circular ring, and the inlet direction of the first air intake hole on the outer circular surface of the first air intake ring is the same as the radial direction, and the outlet direction on the inner circular surface of the first air intake ring is at a 45° angle to the axis of the first air intake ring. There is a rounded transition between the two, and the radius of the transition rounded corner on the central axis of the first air intake hole is not less than the thickness of the first air intake ring.

[0013] Preferably, the sum of the cross-sectional areas of the first air inlet holes is equal to the sum of the cross-sectional areas of the first air inlet channels.

[0014] Preferably, the taper of the longitudinal through cavity is consistent with the converging light path of the radiation source.

[0015] Preferably, the inner surfaces of the longitudinal through cavity and the transverse through cavity are tangent to each other at their junction.

[0016] Preferably, the second connecting structural member includes a connecting flange, a radiation cavity shell, and a radiation flange;

[0017] Among them, the outer wall surface of the radiation cavity inner shell has ribs, and an air cooling channel is opened along the symmetry axis at the tip of the ellipsoid; the radiation cavity outer shell is wrapped around the outer side of the radiation cavity inner shell, and the channel between its inner wall surface and the ribs of the outer wall of the radiation cavity inner shell forms a second water cooling channel; the connecting flange is installed at the large end of the radiation cavity inner shell, and a second water outlet channel is opened on its circumferential outer wall surface, and a second annular water collecting groove is opened on the inner wall surface; the radiation flange is installed at the small end of the radiation cavity inner shell, and a second water inlet channel and a second air inlet channel are opened on the circumferential outer wall surface of the flange, and a second annular water collecting groove and a second air collecting groove are opened on the inner wall surface, and a radiation source mounting hole is opened on the end face close to the second air collecting groove along the symmetry axis; the second air inlet ring is installed on the inner side of the second air collecting groove of the radiation flange, and several second air inlet holes are evenly distributed on it.

[0018] Preferably, the second air inlet ring forms a 45° cone with the axis of the radiation cavity, and the second air inlet holes distributed thereon are perpendicular to the surface of the second air inlet ring.

[0019] Preferably, the sum of the cross-sectional areas of the second air inlet holes is equal to the sum of the cross-sectional areas of the second air inlet channels.

[0020] Preferably, the sum of the number and cross-sectional area of ​​the second air intake channels is respectively greater than the sum of the number and cross-sectional area of ​​the first air intake channels.

[0021] Preferably, the semi-ellipsoidal inner cavity has the same outer wall shape as the ellipsoidal reflector used by the radiation source.

[0022] Preferably, the four-way inner shell and the radiation cavity inner shell are made of zirconium bronze, and the remaining components are made of stainless steel. All components of the airflow cavity and the radiation cavity are assembled by vacuum furnace brazing.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention can install a radiation heat source. When it is used in a radiation-convection coupling test device, the irradiation direction of the radiation heat source and the outflow direction of the convection heat source flow field are on the same axis, which can effectively improve the radiation heat efficiency and the radiation uniformity of the receiving surface;

[0025] (2) The present invention can simultaneously install two convection heat sources, thereby improving the integration level and performing total temperature modulation, voltage stabilization, and rectification on the high-temperature airflow generated by the convection heat sources;

[0026] (3) The radiation cavity of the present invention can effectively cool the outer shell and the core of the radiation heat source, which can effectively increase the service life of the radiation heat source;

[0027] (4) The water-cooling structure of the present invention and the brazing process used can increase the service life of the device itself and can withstand high-temperature and high-pressure convection flow field environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an isometric side sectional view of a four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to an embodiment of the present invention;

[0029] Figure 2 A cross-sectional view of the airflow cavity according to an embodiment of the present invention;

[0030] Figure 3 is a cross-sectional view of a radiation cavity according to an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of the use of an embodiment of the present invention. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0033] The present invention provides a four-way mixing chamber for radiation convection coupled aerodynamic thermal testing, comprising an airflow chamber 1 and a radiation chamber 2. Figure 1 The airflow cavity 1 includes a small end flange 11, a four-way inner shell 12, a four-way outer shell 13, an upstream flange 14, a large end flange 15 and a first air inlet ring 16, as shown. Figure 2As shown. Among them, the four-way inner shell 12 is a cross-shaped cylindrical structure composed of a longitudinal through cavity 104 and a transverse through cavity 106. The longitudinal through cavity 104 is a conical cylinder, and the transverse through cavity 106 is a cylindrical shape with small ends and a large middle. The outer wall of the four-way inner shell 12 has a rib structure. The four-way outer shell 13 is wrapped around the outside of the four-way inner shell 12, and the cavity formed between its inner wall and the ribs on the outer wall of the four-way inner shell 12 is the first water cooling channel 103. The small end flange 11 is installed on the small end side of the longitudinal through cavity 104 of the four-way inner shell 12. The outer wall surface of the flange is provided with a first water outlet channel 101, and the inner wall surface is provided with a first annular water collecting trough 102. The upstream flange 14 is installed on both sides of the transverse through cavity 106 of the four-way inner shell 12, with a total of two pieces. The outer wall surface of the flange is provided with a first water inlet channel 105, and the inner wall surface is provided with a first annular water collecting trough 102. The large end flange 15 is mounted on the large end of the longitudinal through cavity 104 of the four-way inner shell 12. The flange's circumferential outer wall defines a first water outlet channel 101 and a first air inlet channel 107, while its inner wall defines an annular first water collecting groove 102 and a first air collecting groove 108. A first air inlet ring 16 is mounted on the inner side of the first air collecting groove 108 of the large end flange 15 and is uniformly distributed with a plurality of first air inlet holes 109.

[0034] The radiation cavity 2 includes a connecting flange 21, a radiation cavity inner shell 22, a radiation cavity outer shell 23, a radiation flange 24 and a second air inlet ring 25. Figure 3 As shown. The radiation cavity inner shell 22 is a semi-ellipsoidal inner shell 204, whose outer wall has ribs, and an air-cooling channel 209 is opened along the symmetry axis at the apex of the ellipsoid. The radiation cavity outer shell 23 is wrapped around the outer side of the radiation cavity inner shell 22, and the channel between its inner wall and the ribs on the outer wall of the radiation cavity inner shell 22 forms a second water-cooling channel 203. The connecting flange 21 is installed at the large end of the radiation cavity inner shell 22, and its circumferential outer wall is opened with a second water outlet channel 201, and its inner wall is opened with an annular second water collecting groove 202. The radiation flange 24 is installed at the small end of the radiation cavity inner shell 22, and its circumferential outer wall is opened with a second water inlet channel 210 and a second air inlet channel 205, and its inner wall is opened with an annular second water collecting groove 202 and a second air collecting groove 206. The flange has a radiation source mounting hole 208 along the symmetry axis on the end face near the second air collecting groove 206. The second air inlet ring 25 is installed on the inner side of the second air collecting groove 206 of the radiation flange 24 and has a plurality of second air inlet holes 207 evenly distributed thereon.

[0035] When using, such as Figure 4As shown, the airflow chamber 1 and the radiation chamber 2 are bolted together via the large end flange 15 and the connecting flange 21, and high-pressure cooling water and high-pressure cold air are respectively introduced into the airflow chamber 1 and the radiation chamber 2. For the airflow chamber 1, the high-pressure cooling water flows from the first water inlet channel 105 of the two upstream flanges 14, passes through the first water collecting trough 102, enters the first water cooling channel 103, and then merges at the intersection of the longitudinal through cavity 104 and the transverse through cavity 106. After that, it flows out from the first water outlet channels 101 on both sides, namely the small end flange 11 and the large end flange 15. The high-pressure cold air flows from the first air inlet channel 107 of the large end flange 15, enters the first air collecting trough 108, and then enters the four-way inner shell 12 through the several first air inlet holes 109 of the first air inlet ring 16. For the radiation cavity 2, high-pressure cooling water enters the second water cooling channel 203 from the second water inlet channel 210 of the radiation flange 24 through the second water collecting tank 202, and then flows out from the second water outlet channel 201 of the connecting flange 21. High-pressure cold air enters the second air collecting tank 206 from the second air inlet channel 205 of the radiation flange 24, passes through several second air inlet holes 207 of the second air inlet ring 25, flows through the air cooling channel 209, and then enters the radiation cavity inner shell 22.

[0036] Specifically, the first air intake ring 16 of the air flow cavity 1 is an equal-diameter circular ring, and the inlet direction of the first air intake hole 109 thereon on the outer circular surface of the first air intake ring 16 is the same as the radial direction, and the outlet direction on the inner circular surface of the first air intake ring 16 is at a 45° angle to the axis of the first air intake ring 16. There is a rounded transition between the two, and the radius of the transition rounded corner on the central axis of the first air intake hole 109 is not less than the thickness of the first air intake ring 16.

[0037] Specifically, the second air inlet ring 25 of the radiation cavity 2 forms a 45° cone with respect to the axis of the radiation cavity 2 , and the second air inlet holes 207 distributed thereon are perpendicular to the surface of the second air inlet ring 25 .

[0038] Specifically, the sum of the cross-sectional areas of the first air inlet holes 109 of the air flow cavity 1 is equal to the sum of the cross-sectional areas of the first air inlet channel 107 , and the sum of the cross-sectional areas of the second air inlet holes 207 of the radiation cavity 2 is equal to the sum of the cross-sectional areas of the second air inlet channel 205 .

[0039] Specifically, the sum of the number and cross-sectional area of ​​the second air intake channels 205 is greater than the sum of the number and cross-sectional area of ​​the first air intake channels 107 .

[0040] Specifically, the taper of the longitudinal through cavity 104 of the airflow cavity 1 is consistent with the converging light path of the radiation source.

[0041] Specifically, the inner surfaces of the longitudinal through cavity 104 and the transverse through cavity 106 of the airflow cavity 1 are tangent to each other at their intersection.

[0042] Specifically, the semi-ellipsoidal inner cavity 204 of the radiation cavity inner shell 22 of the radiation cavity 2 has the same outer wall shape as the ellipsoidal reflector used by the radiation source.

[0043] Specifically, the four-way inner shell 12 and the radiation cavity inner shell 22 are made of zirconium bronze, and the remaining components are made of stainless steel. All components of the airflow cavity 1 and the radiation cavity 2 are assembled by vacuum furnace brazing.

[0044] This embodiment involves a four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing. Its component description and experimental verification demonstrate the unique features of the present invention. Its cross-shaped airflow cavity allows for the simultaneous installation of two convective heat sources. When used in a radiation-convection coupled test device, the radiation heat source's irradiation direction and the convective heat source's flow field are coaxial, effectively improving both the radiation heat efficiency and the radiation uniformity across the receiving surface while increasing integration.

[0045] The first air inlet channel and the second air inlet channel of this embodiment can simultaneously introduce high-pressure cold air into the airflow cavity, and by adjusting the flow ratio of the high-pressure cold air and the high-temperature airflow generated by the convection heat source, the convection flow field has the effects of total temperature regulation, voltage stabilization and rectification.

[0046] The radiation cavity used in this embodiment can effectively cool the outer shell and the core of the radiation heat source, which can effectively increase the service life of the radiation heat source;

[0047] The water-cooling structure and the brazing process used in this embodiment can increase the service life of the device itself and can withstand a high-temperature and high-pressure convection flow field environment.

[0048] The present invention can be applied to a radiation-convection coupled aerodynamic thermal test device, and the undisclosed technology is common knowledge to those skilled in the art. Although the present invention has been disclosed above with respect to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art may utilize the methods and techniques disclosed above to make possible variations and modifications to the technical solutions of the present invention without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent variations, and modifications 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 are within the scope of protection of the technical solutions of the present invention.

[0049] Parts of the present invention that are not described in detail belong to the common knowledge of those skilled in the art.

Claims

1. A four-way mixing chamber for radiation convection coupled aerodynamic thermal testing, characterized in that including an airflow cavity and a radiation cavity; The airflow cavity includes a four-way inner shell, a first air intake ring, and a first connecting structure. The four-way inner shell is a cross-shaped cylindrical structure composed of a longitudinal cavity and a transverse cavity. The longitudinal cavity is a conical cylinder, and the transverse cavity is a cylindrical shape with small ends and a large middle. A channel for water cooling and air cooling is provided between the four-way inner shell and the first connecting structure outside the four-way inner shell. The cooling gas in the air intake channel eventually enters the four-way inner shell through the first air intake ring located at the large end of the longitudinal cavity. The radiation cavity includes a radiation cavity inner shell, a second air inlet ring, and a second connecting structure. The radiation cavity inner shell is a semi-ellipsoidal structure, having a semi-ellipsoidal inner cavity, the small end of which is connected to the radiation source through the second air inlet ring. A channel for water cooling and air cooling is provided between the radiation cavity inner shell and the second connecting structure. The cooling gas in the air inlet channel enters the radiation cavity inner shell through the second air inlet ring and the air cooling channel. During the test, the airflow cavity and the radiation cavity are fixedly connected, and the longitudinal through cavity of the airflow cavity coincides with the axis of the semi-ellipsoidal cavity; Convection heat sources are installed at both ends of the transverse cavity, and the irradiation direction of the radiation heat source and the outflow direction of the convection heat source flow field are on the same axis.

2. The four-way mixing chamber for radiation convection coupled aerodynamic thermal testing according to claim 1, characterized in that: The first connecting structure includes a small end flange, a cross shell, an upstream flange, and a large end flange; The outer wall of the four-way inner shell has a rib structure; the four-way outer shell is wrapped around the outer side of the four-way inner shell, and the cavity formed between its inner wall and the ribs of the outer wall of the four-way inner shell is the first water cooling channel; the small end flange is installed on the small end side of the longitudinal cavity of the four-way inner shell, and the outer wall surface of the flange is provided with a first water outlet channel, and the inner wall surface is provided with a first annular water collecting trough; the upstream flange is installed on both sides of the transverse cavity of the four-way inner shell, with a total of two pieces, and the outer wall surface of the flange is provided with a first water inlet channel, and the inner wall surface is provided with a first annular water collecting trough; the large end flange is installed on the large end side of the longitudinal cavity of the four-way inner shell, and the outer wall surface of the flange is provided with a first water outlet channel and a first air inlet channel, and the inner wall surface is provided with a first annular water collecting trough and a first air collecting trough; the first air inlet ring is installed on the inner side of the first air collecting trough of the large end flange, and several first air inlet holes are evenly distributed on it.

3. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 2, characterized in that: The first air intake ring is an equal-diameter circular ring, and the inlet direction of the first air intake hole on the outer circular surface of the first air intake ring is the same as the radial direction, and the outlet direction on the inner circular surface of the first air intake ring is at a 45° angle to the axis of the first air intake ring. There is a rounded transition between the two, and the radius of the transition rounded corner on the central axis of the first air intake hole is not less than the thickness of the first air intake ring.

4. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 2, characterized in that: The sum of the cross-sectional areas of the first air inlet holes is equal to the sum of the cross-sectional areas of the first air inlet channels.

5. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 1, characterized in that: The taper of the longitudinal through cavity is consistent with the converging light path of the radiation source.

6. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 1, characterized in that: The inner surfaces of the longitudinal through cavity and the transverse through cavity are tangent to each other at their junction.

7. The four-way mixing chamber for radiation convection coupled aerodynamic thermal testing according to claim 1 or 2, characterized in that: The second connecting structure includes a connecting flange, a radiation cavity shell, and a radiation flange; Among them, the outer wall surface of the radiation cavity inner shell has ribs, and an air cooling channel is opened along the symmetry axis at the tip of the ellipsoid; the radiation cavity outer shell is wrapped around the outer side of the radiation cavity inner shell, and the channel between its inner wall surface and the ribs of the outer wall of the radiation cavity inner shell forms a second water cooling channel; the connecting flange is installed at the large end of the radiation cavity inner shell, and a second water outlet channel is opened on its circumferential outer wall surface, and a second annular water collecting groove is opened on the inner wall surface; the radiation flange is installed at the small end of the radiation cavity inner shell, and a second water inlet channel and a second air inlet channel are opened on the circumferential outer wall surface of the flange, and a second annular water collecting groove and a second air collecting groove are opened on the inner wall surface, and a radiation source mounting hole is opened on the end face close to the second air collecting groove along the symmetry axis; the second air inlet ring is installed on the inner side of the second air collecting groove of the radiation flange, and several second air inlet holes are evenly distributed on it.

8. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 7, characterized in that: The second air inlet ring forms a 45° cone with the axis of the radiation cavity, and the second air inlet holes distributed thereon are perpendicular to the surface of the second air inlet ring.

9. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 7, characterized in that: The sum of the cross-sectional areas of the second air inlet holes is equal to the sum of the cross-sectional areas of the second air inlet channels.

10. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 7, characterized in that: The sum of the number and cross-sectional area of ​​the second air intake channels is respectively greater than the sum of the number and cross-sectional area of ​​the first air intake channels.

11. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 1, characterized in that: The semi-ellipsoidal inner cavity has the same outer wall shape as the ellipsoidal reflector used by the radiation source.

12. The four-way mixing chamber for radiation-convection coupled aerodynamic thermal testing according to claim 1, characterized in that: The four-way inner shell and the radiation cavity inner shell are made of zirconium bronze, and the remaining parts are made of stainless steel. All parts of the airflow cavity and the radiation cavity are assembled by vacuum furnace brazing.

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