Volute for pneumatic turbine and pneumatic turbine

Abstract

The invention relates to the technical field of pneumatic turbines, in particular to a volute for a pneumatic turbine and the pneumatic turbine, and solves the problem that the flow loss is large due to the fact that an existing volute is difficult to realize stable conversion of airflow from circumferential uniform air inlet to axial circular ring air outlet. The volute comprises a volute body, the volute body is provided with an inlet flow channel in the circumferential direction and an axial outlet flow channel with the annular section, a seat ring cavity used for containing an axial opening of a first-stage seat ring is formed in the volute body, and the outlet flow channel is right opposite to and directly communicated with the seat ring cavity, so that airflow can enter the first-stage seat ring without turning. In the pneumatic turbine comprising the volute, the center flow surfaces of the multiple stages of seat rings and the rotating wheel and the center flow surface of the outlet flow channel are located on the same cylindrical surface, and the diameters of all stages of flow channels are matched with one another. According to the invention, the airflow steering loss is reduced, the airflow is ensured to be uniformly and symmetrically output in the axial direction, and the overall efficiency of the pneumatic turbine is improved.

Description

Technical Field

[0001] This invention relates to the field of pneumatic turbine technology, specifically to a volute housing for a pneumatic turbine and a pneumatic turbine. Background Technology

[0002] Underground coal seams contain abundant methane gas and water, which are released during coal mining. To ensure safety, sufficient compressed air from the surface layer outside the mine is piped to the working roadways in the coal seam, where the methane gas is expelled using a displacement effect. Seepage water from the coal seam is forcibly pumped out of the working roadways. Because coal seams are mostly located hundreds to thousands of meters underground and often form long, narrow coal belts, the working face is a long, semi-enclosed space with high temperatures, generally above 30 degrees Celsius, resulting in a harsh working environment. Due to the methane gas escaping from the coal seam, the electric water pumps used for drainage in the working roadways must be explosion-proof. Furthermore, the heat generated by the motor further increases the temperature within the working roadways. Currently, the commonly used diaphragm pumps in coal mining working roadways, which utilize compressed air, are too inefficient and generally cannot supply enough air for drainage requirements.

[0003] Therefore, the development of a high-efficiency, full-flow pneumatic turbine-driven water pump for drainage can meet the drainage requirements of most coal mining operations. The cooled exhaust gas, after performing work, is directly introduced into the coal mining roadway, which not only plays a role in strongly discharging methane gas but also reduces the ambient temperature inside the coal mining roadway. The high-efficiency, full-flow pneumatic turbine-driven drainage pump can be switched on when drainage is needed and switched off when drainage is not needed, thus meeting the safety requirements in the coal mining process.

[0004] As a core component for air intake and initial airflow guidance in pneumatic turbines, the volute casing's structural design directly affects the initial airflow distribution and energy conversion efficiency. In the field of pneumatic turbines, the volute casing must ensure the smooth introduction and proper distribution of high-pressure, high-speed airflow, providing uniform and stable flow conditions for subsequent multi-stage expansion. Existing volute casing technology is mainly concentrated in fluid machinery such as pumps, fans, and compressors, with design goals primarily focused on improving single-stage efficiency, reducing noise, or improving manufacturability. However, its application in multi-stage high-efficiency pneumatic turbines exhibits the following significant shortcomings: As disclosed in CN116221181A, the volute assembly adopts a detachable volute tongue design to improve the smoothness of the flow channel. However, it still belongs to the traditional centrifugal or mixed-flow volute structure. The airflow is generally radial or tangential inlet and axial outlet, and the outlet is mostly circular or rectangular. This type of volute cannot achieve a flow channel layout of "uniform inlet in the circumferential direction and circular outlet in the axial direction". It is difficult to achieve seamless and coaxial docking with the subsequent multi-stage annular nozzle flow channel and impeller flow channel. This causes unnecessary turning losses and flow separation of the airflow before entering the power stage, reducing the overall efficiency of the machine. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a volute casing and a pneumatic turbine for pneumatic turbines. Addressing the deficiencies of existing volute casing technologies, and considering the actual operating conditions and flow characteristics of high-efficiency full-flow-channel pneumatic turbines, a novel volute casing and a pneumatic turbine incorporating this volute casing are proposed. This volute casing optimizes the geometry of the inlet and outlet flow channels, achieves seamless connection with the seat ring cavity, and ensures axially symmetrical and uniform airflow output, thereby providing ideal initial flow conditions for multi-stage high-efficiency energy conversion and meeting the multiple requirements of pneumatic turbines in harsh environments such as coal mines for high efficiency, stability, explosion-proof performance, and cooling.

[0006] The objective of this invention can be achieved through the following technical solution: a volute for a pneumatic turbine, comprising a volute body, wherein the volute body has a circumferential inlet channel and an axial outlet channel, the outlet channel having an annular cross-section, and a seat ring cavity for accommodating a first-stage seat ring within the volute body, the seat ring cavity being an axially open annular cavity; the outlet channel is axially aligned with and directly connected to the seat ring cavity, allowing gas flowing out of the outlet channel to enter the first-stage seat ring in the seat ring cavity without detour. The volute is the first intake channel directly connected to the external compressed air. To ensure a more stable and uniform entry of compressed air into the outlet channel and ultimately into the first-stage seat ring, the rationality of its channel design directly affects the energy conversion efficiency between subsequent stage seat rings and the turbine. By optimizing the shape of the volute channel and the outlet structure, efficient and stable conversion of the internal energy of the compressed air into kinetic energy is achieved, providing uniform and stable airflow conditions for subsequent multi-stage work.

[0007] Furthermore, the central flow surface of the outlet flow channel and the central flow surface of the first-stage seat ring are located on the same cylindrical surface.

[0008] Furthermore, the primary seat ring has a primary nozzle flow channel, and the diameters of the inner and outer circumferential surfaces of the outlet flow channel are the same as the diameters of the inner and outer circumferential surfaces of the primary nozzle flow channel.

[0009] Furthermore, an air intake chamber is provided between the inlet and outlet flow channels. The longitudinal section of the air intake chamber is a fully elliptical cross-section, and its longitudinal cross-sectional area gradually decreases along the airflow direction. The inlet flow channel is located on the circumferential sidewall of the air intake chamber, and the outlet flow channel is located on the axial end face of the air intake chamber. The ratio of the major to minor axis of the fully elliptical cross-section of the air intake chamber changes linearly from the inlet to the outlet.

[0010] Furthermore, the longitudinal section at the junction of the inlet channel and the air intake chamber is circular.

[0011] Furthermore, the outer circumferential surface of the seat ring cavity is recessed outward with a positioning groove, and a limiting protrusion protrudes outward from the outer circumferential surface of the first-stage seat ring, the limiting protrusion abutting axially with the positioning groove.

[0012] Furthermore, a bearing seat is formed in the middle of the volute body, and a bearing cap is fixedly connected to the outer end of the bearing seat.

[0013] A pneumatic turbine includes a volute casing for a pneumatic turbine as described in any one of claims 1 to 7. The volute casing body is sequentially fixedly connected with a secondary seat ring, a tertiary seat ring, and a quaternary seat ring along the axial direction. The secondary, tertiary, and quaternary seat rings each have a secondary nozzle flow channel, a tertiary nozzle flow channel, and a quaternary nozzle flow channel, respectively. The central flow surfaces of the secondary, tertiary, and quaternary nozzle flow channels and the central flow surface of the outlet flow channel are located on the same cylindrical surface.

[0014] Furthermore, a first-stage impeller, a second-stage impeller, a third-stage impeller, and a fourth-stage impeller are respectively provided between the first-stage, second-stage, third-stage, and fourth-stage impellers. The first-stage, second-stage, third-stage, and fourth-stage impellers each have a first-stage impeller flow channel, a second-stage impeller flow channel, a third-stage impeller flow channel, and a fourth-stage impeller flow channel. The central flow surfaces of the first-stage, second-stage, third-stage, and fourth-stage impeller flow channels are located on the same cylindrical surface as the central flow surface of the outlet flow channel.

[0015] Furthermore, the inlet diameter of the first-stage nozzle flow channel is the same as the outlet diameter of the outlet flow channel, and the outlet diameter of the first-stage nozzle flow channel is the same as the inlet diameter of the first-stage blade flow channel; the inlet diameter of the second-stage nozzle flow channel is the same as the outlet diameter of the first-stage blade flow channel, and the outlet diameter of the second-stage nozzle flow channel is the same as the inlet diameter of the second-stage blade flow channel; the inlet diameter of the third-stage nozzle flow channel is the same as the outlet diameter of the second-stage blade flow channel, and the outlet diameter of the third-stage nozzle flow channel is the same as the inlet diameter of the third-stage blade flow channel; the inlet diameter of the fourth-stage nozzle flow channel is the same as the outlet diameter of the third-stage blade flow channel, and the outlet diameter of the fourth-stage nozzle flow channel is the same as the inlet diameter of the fourth-stage blade flow channel.

[0016] Compared with existing technologies, the technical advantages of this invention are as follows: First, the volute has a circumferential inlet channel and an axial outlet channel, achieving a structural transformation that guides external compressed air from the circumferential inlet to the axial outlet. Through its internal variable cross-sectional area and fully elliptical cross-section volute channel, the airflow maintains a uniform average circumferential velocity component during flow, achieving smooth airflow turning and axial outflow. Second, the volute outlet channel has an annular cross-section and is geometrically perfectly aligned with the inlet end of the first-stage nozzle channel of the first-stage seat ring, ensuring that the airflow can uniformly enter the first-stage nozzle channel. This design avoids turbulence and loss of airflow during the turning process, improving energy transfer efficiency. Attached Figure Description

[0017] Figure 1 This is a three-dimensional cross-sectional view of the volute shell of the present invention.

[0018] Figure 2 This is a cross-sectional view of the volute casing of the present invention.

[0019] Figure 3 This is a schematic diagram showing the shape and size of the elliptical and circular cross-sections of the volute casing of the present invention.

[0020] Figure 4 This is a schematic diagram of the volute casing of the present invention.

[0021] Figure 5 This is a half-sectional perspective view of the pneumatic turbine of the present invention.

[0022] Figure 6 This is a schematic diagram of the first-stage guide vane of the pneumatic turbine of the present invention.

[0023] Figure 7 This is a schematic diagram of the second-stage, third-stage, and fourth-stage guide vanes of the pneumatic turbine of this invention.

[0024] Figure 8 This is a schematic diagram of the first-stage, second-stage, third-stage, and fourth-stage blades of the pneumatic turbine of this invention.

[0025] Figure 9 This is a cross-sectional view of the pneumatic turbine of the present invention.

[0026] Drawing number markings: 1. Volute body; 101. Inlet flow channel; 102. Outlet flow channel; 103. Seat ring cavity; 104. Full elliptical cross section; 105. Circular cross section; 106. Positioning groove; 107. Bearing housing; 108. Inlet chamber; 2. Bearing cap; 3. First-stage seat ring; 301. First-stage guide vane; 302. First-stage nozzle flow channel; 303. Limiting convex ring; 4. Second-stage seat ring; 401. Second-stage guide vane; 402. Second-stage nozzle flow channel; 5. Third-stage seat ring; 501. Third-stage guide vane; 502. Third-stage nozzle flow channel; 6. Fourth-stage seat ring 601, Fourth-stage guide vane; 602, Fourth-stage nozzle flow channel; 7, First-stage impeller; 701, First-stage blade; 702, First-stage blade flow channel; 8, Second-stage impeller; 801, Second-stage blade; 802, Second-stage blade flow channel; 9, Third-stage impeller; 901, Third-stage blade; 902, Third-stage blade flow channel; 10, Fourth-stage impeller; 1001, Fourth-stage blade; 1002, Fourth-stage blade flow channel; 11, Main shaft; 12, Enclosure; 13, Seal; 14, Sealing groove; 15, Sealing protrusion; 16, Bearing support; 1601, Exhaust channel. Detailed Implementation

[0027] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0028] according to Figures 1 to 5The diagram shows a volute for a pneumatic turbine, comprising a volute body 1. The volute body 1 has a circumferential inlet channel 101 and an axial outlet channel 102. The outlet channel 102 has an annular cross-section. The volute body 1 contains a seat ring cavity 103 for accommodating a first-stage seat ring 3. The seat ring cavity 103 is an axially open annular cavity. The outlet channel 102 is axially aligned with and directly connected to the seat ring cavity 103, allowing gas flowing from the outlet channel 102 to enter the first-stage seat ring 3 in the seat ring cavity 103 without any detours. The volute is the first intake channel for compressed air directly connected to the outside. To ensure a more stable and uniform flow of compressed air into the outlet channel 102 and ultimately into the first-stage seat ring 3, the rationality of its channel design directly affects the energy conversion efficiency between subsequent seat rings and the turbine. By optimizing the shape of the volute channel and the outlet structure, efficient and stable conversion of the compressed air's internal energy into kinetic energy is achieved, providing uniform and stable airflow conditions for subsequent multi-stage work.

[0029] The central flow surface of the outlet flow channel 102 and the central flow surface of the first-stage seat ring 3 are located on the same cylindrical surface. The first-stage seat ring 3 contains a first-stage nozzle flow channel 302, and the diameters of the inner and outer circumferential surfaces of the outlet flow channel 102 are the same as the diameters of the inner and outer circumferential surfaces of the first-stage nozzle flow channel 302. An intake chamber 108 is located between the inlet flow channel 101 and the outlet flow channel 102. The longitudinal section of the intake chamber 108 is a fully elliptical section 104, and its longitudinal cross-sectional area gradually decreases along the airflow direction. The inlet flow channel 101 is located on the circumferential sidewall of the intake chamber 108, and the outlet flow channel 102 is located on the axial end face of the intake chamber 108. The ratio of the major axis to the minor axis of the fully elliptical section 104 of the intake chamber 108 changes linearly from the inlet to the outlet. The longitudinal section at the junction of the inlet flow channel 101 and the intake chamber 108 is a circular section 105. The outer circumferential surface of the seat ring cavity 103 has a positioning groove 106 recessed outwards, and a limiting protrusion ring 303 protrudes outwards from the outer circumferential surface of the first-stage seat ring 3, which axially abuts against the positioning groove 106. A bearing seat 107 is formed in the middle of the volute body 1, and a bearing cap 2 is fixedly connected to the outer end of the bearing seat 107. The central flow surface is the curved surface formed by the midpoint of the radial thickness of the flow channel. Specifically, the central flow surface of the volute outlet flow channel 102 is a cylindrical surface coaxial with the main shaft 11.

[0030] The volute has a circumferential inlet channel 101 and an axial outlet channel 102, enabling the structural conversion of external compressed air from the circumferential inlet to the axial outlet. Through its internal variable cross-sectional area and fully elliptical cross-section 104, the volute channel maintains a uniform average circumferential velocity component during airflow, achieving smooth airflow turning and axial outflow. The volute outlet channel 102 has an annular cross-section and is geometrically perfectly aligned with the inlet end of the first-stage nozzle channel 302 of the first-stage seat ring 3, ensuring uniform airflow into the first-stage nozzle channel 302. This design avoids turbulence and loss during airflow turning, improving energy transfer efficiency.

[0031] The outlet flow channel 102 of the volute body 1 is designed with an annular cross section, and its central flow surface is kept on the same cylindrical surface as the central flow surfaces of all subsequent seat rings, impellers and exhaust channels. Its core function is to achieve efficient, stable and uniform transmission of compressed air from the volute to the multi-stage power section: This structure allows the airflow to turn from the circumferential inlet to the axial outlet without turning or abrupt change in cross section, avoiding turbulence and separation losses; at the same time, it ensures that the airflow is uniformly distributed in the circumferential direction and naturally connects to the subsequent multi-stage flow channels along the axial direction, providing streamlined and aligned flow channel conditions for four-stage continuous energy conversion, thereby maximizing energy extraction efficiency.

[0032] according to Figures 5 to 9 As shown: A pneumatic turbine, with a volute body 1, and a secondary seat ring 4, a tertiary seat ring 5 and a quaternary seat ring 6 fixedly connected along the axial direction. The secondary seat ring 4, the tertiary seat ring 5 and the quaternary seat ring 6 respectively have a secondary nozzle flow channel 402, a tertiary nozzle flow channel 502 and a quaternary nozzle flow channel 602. The central flow surfaces of the secondary nozzle flow channel 402, the tertiary nozzle flow channel 502 and the quaternary nozzle flow channel 602 are located on the same cylindrical surface as the central flow surface of the outlet flow channel 102.

[0033] A first-stage rotor 7, a second-stage rotor 8, a third-stage rotor 9, and a fourth-stage rotor 10 are respectively arranged between the first-stage bearing ring 3, the second-stage bearing ring 4, the third-stage bearing ring 5, and the fourth-stage bearing ring 6. Each of the first-stage rotor 7, the second-stage rotor 8, the third-stage rotor 9, and the fourth-stage rotor 10 has a first-stage blade flow channel 702, a second-stage blade flow channel 802, a third-stage blade flow channel 902, and a fourth-stage blade flow channel 1002. The central flow surfaces of the first-stage blade flow channels 702, 802, 902, and 1002 are located on the same cylindrical surface as the central flow surface of the outlet flow channel 102. A main shaft 11 is fixedly connected between the first-stage rotor 7, the second-stage rotor 8, the third-stage rotor 9, and the fourth-stage rotor 10.

[0034] The inlet diameter of the first-stage nozzle flow channel 302 is the same as the outlet diameter of the outlet flow channel 102, and the outlet diameter of the first-stage nozzle flow channel 302 is the same as the inlet diameter of the first-stage blade flow channel 702; the inlet diameter of the second-stage nozzle flow channel 402 is the same as the outlet diameter of the first-stage blade flow channel 702, and the outlet diameter of the second-stage nozzle flow channel 402 is the same as the inlet diameter of the second-stage blade flow channel 802; the inlet diameter of the third-stage nozzle flow channel 502 is the same as the outlet diameter of the second-stage blade flow channel 802, and the outlet diameter of the third-stage nozzle flow channel 502 is the same as the inlet diameter of the third-stage blade flow channel 902; the inlet diameter of the fourth-stage nozzle flow channel 602 is the same as the outlet diameter of the third-stage blade flow channel 902, and the outlet diameter of the fourth-stage nozzle flow channel 602 is the same as the inlet diameter of the fourth-stage blade flow channel 1002.

[0035] The energy contained in compressed air is converted into a velocity airflow with a certain direction and velocity through the first-stage nozzle flow channel 302 of the volute and first-stage seat ring 3. This airflow then enters the first-stage blade flow channel 702 of the first-stage impeller 7, driving the first-stage impeller 7 to rotate around the main shaft 11 of the high-efficiency full-flow-channel pneumatic turbine and perform work. The airflow that has performed work flowing out of the first-stage blade flow channel 702 of the first-stage impeller 7 is converted into a velocity airflow with a certain direction and velocity through the second-stage nozzle of the second-stage seat ring 4. This airflow then enters the second-stage blade flow channel 802 of the second-stage impeller 8 in the power-running section, driving the second-stage impeller 8 to rotate around the main shaft 11 of the high-efficiency full-flow-channel pneumatic turbine and perform work. The airflow that has performed work flowing out of the second-stage blade flow channel 802 of the second-stage impeller 8 is converted into a velocity airflow with a certain direction and velocity through the third-stage nozzle of the third-stage seat ring 5. The first-stage nozzle converts the airflow into a velocity-driven airflow of a certain speed and direction, which then enters the third-stage impeller flow channel 902 of the third-stage rotor 9 in the power-operating section, driving the third-stage rotor 9 to rotate around the main shaft 11 of the high-efficiency full-flow-channel pneumatic turbine to perform work. The airflow that has performed work flowing out of the third-stage impeller flow channel 902 of the third-stage rotor 9 is converted into a velocity-driven airflow of a certain speed and direction through the fourth-stage nozzle of the fourth-stage seat ring 6, which then enters the fourth-stage impeller flow channel 1002 of the fourth-stage rotor 10 in the power-operating section, driving the fourth-stage rotor 10 to rotate around the main shaft 11 of the high-efficiency full-flow-channel pneumatic turbine to perform work. The exhaust air that has performed work flowing out of the fourth-stage impeller flow channel 1002 of the fourth-stage rotor 10 is discharged from the high-efficiency full-flow-channel pneumatic turbine through the exhaust channel 1601 of the bearing support 16. The rotational mechanical work performed by the four rotors is output through the main shaft 11 of the high-efficiency full-flow-channel pneumatic turbine, which is connected to all the rotors. One end of the spindle 11 extends out of the volute to connect to equipment used for driving drainage, ventilation, or drilling.

[0036] The primary nozzle flow channel 302 is a conical annular tapered flow channel with a large inlet thickness and a small outlet thickness. The flow channel tapering ratio is 0.007 to 0.009, preferably 0.008 to 0.009, and more preferably 0.0082, 0.0083, 0.0084, or 0.0085. The first-stage guide vane 301 is a three-dimensional twisted airfoil structure. The outer side of the airfoil has a relative thickness of 10.02%, a relative camber of 1.76%, an inlet installation angle of 21.95 degrees, and an outlet installation angle of 13.12 degrees. The leading edge of the outer side is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 6.16 mm. The trailing edge of the outer side is a circle with a diameter of 2 mm. The inner side has a relative thickness of 10.09%, a relative camber of 2.09%, an inlet installation angle of 19.77 degrees, and an outlet installation angle of 11.62 degrees. The leading edge of the inner side is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5.36 mm. The trailing edge of the inner side is a circle with a diameter of 2 mm.

[0037] Secondary nozzle channels 402, tertiary nozzle channels 502, and quaternary nozzle channels 602 are respectively provided on the secondary seat ring 4, tertiary seat ring 5, and quaternary seat ring 6. The configuration of each nozzle channel is a conical annular structure with a gradually expanding cross-sectional area along the airflow direction. Furthermore, the central flow surfaces of the secondary nozzle channels 402, tertiary nozzle channels 502, and quaternary nozzle channels 602 are all coplanar with the central flow surface of the outlet channel 102. Within each nozzle channel, multiple airfoil-shaped guide vanes with three-dimensional twisted structures are evenly distributed along their circumference, namely secondary guide vanes 401, tertiary guide vanes 501, and quaternary guide vanes 601. The secondary seat ring 4, tertiary seat ring 5, and quaternary seat ring 6 are hollow, disc-shaped structures with the same or similar shape and external dimensions. When the secondary nozzle channel 402, tertiary nozzle channel 502, and quaternary nozzle channel 602 are gradually expanding nozzle channels, the channel expansion ratio is 0.005 to 0.008, preferably 0.006 to 0.0070, and more preferably 0.0061, 0.0062, 0.0063, 0.0064, and 0.0065.

[0038] The second-stage guide vane 401, the third-stage guide vane 501, and the fourth-stage guide vane 601 are three-dimensional twisted airfoil structures. The relative thickness of the outer side of each airfoil is 13% to 15%, the relative camber of the outer side is 16% to 19%, the inlet installation angle of the outer side is 90 degrees, and the outlet installation angle of the outer side is 12 to 14 degrees. The relative thickness of the inner side is 11% to 13%, the relative camber of the inner side is 19% to 21%, the inlet installation angle of the inner side is 90 degrees, and the outlet installation angle of the inner side is 10 to 13 degrees. The leading edge of the airfoil is elliptical, and the trailing edge is circular.

[0039] The preferred secondary guide vane 401 has a relative thickness of 14.86% on the outer side, a relative camber of 18.54% on the outer side, an inlet installation angle of 90 degrees on the outer side, an outlet installation angle of 13.15 degrees on the outer side, an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5.5 mm on the outer side, and a circular shape with a diameter of 2 mm on the outer side. The relative thickness of the inner side is 12.47%, the relative camber of the inner side is 20.02%, an inlet installation angle of 90 degrees on the inner side, an outlet installation angle of 11.59 degrees on the inner side, an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm on the inner side, and a circular shape with a diameter of 2 mm on the inner side.

[0040] The preferred three-stage guide vane 501 has an outer relative thickness of 12.94%, an outer relative camber of 18.00%, an outer inlet installation angle of 90 degrees, an outer outlet installation angle of 13.15 degrees, an outer leading edge that is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm, and an outer trailing edge that is a circle with a diameter of 2 mm; the inner relative thickness is 12.47%, the inner relative camber is 20.24%, the inner inlet installation angle is 90 degrees, the inner outlet installation angle is 11.56 degrees, the inner leading edge that is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm, and an inner trailing edge that is a circle with a diameter of 2 mm.

[0041] The preferred fourth-stage guide vane 601 has an outer relative thickness of 12.95%, an outer relative camber of 18.01%, an outer inlet installation angle of 90 degrees, an outer outlet installation angle of 13.18 degrees, an outer leading edge that is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5.5 mm, and an outer trailing edge that is a circle with a diameter of 2 mm; the inner relative thickness is 12.46%, the inner relative camber is 20.23%, the inner inlet installation angle is 90 degrees, the inner outlet installation angle is 11.55 degrees, the inner leading edge that is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm, and an inner trailing edge that is a circle with a diameter of 2 mm.

[0042] The first-stage runner 7, second-stage runner 8, third-stage runner 9, and fourth-stage runner 10 are respectively equipped with a first-stage blade flow channel 702, a second-stage blade flow channel 802, a third-stage blade flow channel 902, and a fourth-stage blade flow channel 1002. Each blade flow channel has a conical annular structure with a gradually expanding cross-sectional area along the airflow direction, and the central flow surface of each blade flow channel is coplanar with the central flow surface of the outlet flow channel 102. Within each blade flow channel, three-dimensionally twisted airfoil blades are evenly distributed along its circumference, corresponding to the first-stage blade 701, second-stage blade 801, third-stage blade 901, and fourth-stage blade 1001.

[0043] The diffusion ratio of the conical annular blade channel with a gradually expanding cross-sectional area along the airflow direction is 0.005 to 0.008. Preferably, the diffusion ratio is 0.006 to 0.007. A diffusion ratio of 0.006 to 0.007, and more preferably 0.0061, 0.0062, or 0.0063, is beneficial for the smooth expansion and deceleration of the airflow within the channel, more effectively transferring the pressure and kinetic energy of the airflow to the airfoil blades and converting it into the rotational torque of the rotor.

[0044] The airfoil blades have a relative thickness of 10%–12% on the outer side, a relative camber of 11%–13%, an inlet angle of 55–65 degrees, and an outlet angle of 10–12 degrees. On the inner side, the relative thickness is 15%–17%, the relative camber is 27%–29%, the inlet angle is -60–-55 degrees, and the outlet angle is 12–14 degrees. The leading edge is elliptical, and the trailing edge is circular. Airflow enters from the leading edge and exits from the trailing edge. The different inlet angles and relative cambers on the inner and outer sides allow the airfoil to better adapt to variations in relative velocity and direction of airflow from the rotor hub to the outer ring, ensuring that airflow across the entire blade span impacts the blade at the optimal angle, resulting in higher work capacity and lower drag, thus significantly improving efficiency.

[0045] The preferred first-stage blade 701 has a relative thickness of 10.13% on the outer side, a relative camber of 12.72% on the outer side, an inlet installation angle of 61.39 degrees on the outer side, an outlet installation angle of 11.47 degrees on the outer side, an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm on the outer side, and a circular shape with a diameter of 2 mm on the outer side. The relative thickness of the inner side is 16.83%, the relative camber of the inner side is 28.39%, an inlet installation angle of -59.4 degrees on the inner side, an outlet installation angle of 13.54 degrees on the inner side, an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm on the inner side, and a circular shape with a diameter of 2 mm on the inner side.

[0046] The outer side of the second-stage blade 801 has a relative thickness of 11.00%, a relative camber of 12.95%, an inlet installation angle of 60.40 degrees, and an outlet installation angle of 11.44 degrees. The leading edge of the outer side is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm, while the trailing edge of the outer side is a circle with a diameter of 2 mm. The inner side has a relative thickness of 16.72%, a relative camber of 28.5%, an inlet installation angle of -58.36 degrees, and an outlet installation angle of 13.58 degrees. The leading edge of the inner side is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm, while the trailing edge of the inner side is a circle with a diameter of 2 mm.

[0047] The outer edge of the third-stage blade 901 has a relative thickness of 11.26%, a relative camber of 12.79%, an inlet angle of 59.33 degrees, and an outlet angle of 11.41 degrees. The leading edge of the outer edge is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm. The trailing edge of the outer edge is a circle with a diameter of 2 mm. The inner edge has a relative thickness of 16.65%, a relative camber of 28.74%, an inlet angle of -57.24 degrees, and an outlet angle of 13.62 degrees. The leading edge of the inner edge is an ellipse with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm. The trailing edge of the inner edge is a circle with a diameter of 2 mm.

[0048] The fourth-stage blade 1001 has a relative thickness of 11.21% on the outer side, a relative camber of 12.55%, an inlet installation angle of 58.16 degrees, an outlet installation angle of 11.37 degrees, and an elliptical outer leading edge with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm. The outer trailing edge is a circle with a diameter of 2 mm. The relative thickness of the inner side is 16.71%, a relative camber of 28.87%, an inlet installation angle of -56.02 degrees, an outlet installation angle of 13.67 degrees, and an elliptical inner leading edge with a major-to-minor axis ratio of 3:1 and a minor axis length of 5 mm. The inner trailing edge is a circle with a diameter of 2 mm.

[0049] Relative thickness of the outer wing: The ratio of the thickness of the outer wing surface to the wing length (the straight-line distance between the inlet and outlet of the wing centerline).

[0050] Relative camber on the outer side of the wing: The ratio of the maximum distance from the centerline of the outer side of the wing to the wing length (the straight-line distance between the inlet and outlet of the wing centerline) to the wing length.

[0051] Outer wing inlet installation angle: The angle between the direction of fluid inflow on the outer wing and the opposite direction of the circumferential velocity component on the outer wing.

[0052] Outlet installation angle on the outer side of the wing: The angle between the direction of fluid outflow on the outer side of the wing and the opposite direction of the circumferential velocity component on the outer side of the wing.

[0053] The same applies to the inner side of the wing. The side closer to the main shaft 11 is the inner side, and the side farther from the main shaft 11 is the outer side. The outer side of the wing is the side away from the main shaft 11, and the inner side of the wing is the side closer to the main shaft 11.

[0054] Using compressed air, which is commonly used in coal mining operations, as a power source, this method drives equipment such as drainage pumps, forced ventilation fans, and anchor drilling rigs in coal mining roadways, replacing electric motors. This meets the needs of coal mining operations for gas and seepage water discharge, drilling, etc., and can also improve the comfort of the working environment and meet explosion-proof requirements, thus having good economic and social benefits.

[0055] Employing a compact structure with alternating series and coaxial arrangement of multi-stage seat rings and impellers, and through a fully coplanar design where the central flow surfaces of the volute outlet flow channel 102, all nozzle flow channels, impeller flow channels, and exhaust channels are located on the same reference cylindrical surface, a shock-free, low-turbulence axial flow path is constructed. This significantly reduces local losses and vortex generation during airflow turning and expansion / contraction processes, allowing airflow energy to be used to the maximum extent to drive the impeller and perform work, rather than being dissipated as useless heat energy. Compared to traditional pneumatic motors or turbomachinery with discontinuous flow channels, the flow channel efficiency of this invention is significantly improved, providing a core structural guarantee for achieving a high overall efficiency of over 80%.

[0056] This invention does not simply expand compressed air to perform work in a single step, but rather employs a sophisticated aerodynamic design—connecting the annular outlet channel 102 of the volute with multi-stage seat rings and multi-stage impellers—to achieve multi-stage control and energy extraction of the airflow. The tapered design of the first-stage nozzle channel 302 focuses on efficiently converting pressure energy into kinetic energy; the matching of the multi-stage expanding nozzle channels with the blade channels enables the gradual and smooth recovery of residual pressure and kinetic energy from the airflow. Each stage of guide vanes and blades utilizes aerodynamically optimized three-dimensional twisted airfoils, ensuring a high lift-to-drag ratio and aerodynamic efficiency across a wide operating range. This ensures a smooth and sufficient energy conversion process, which is crucial for simultaneously achieving high power output and deep cooling.

[0057] The core of the power conversion in this invention is a rotary mechanical structure, eliminating the reciprocating moving parts and vulnerable diaphragm found in diaphragm pumps. This fundamentally avoids leakage and efficiency degradation caused by fatigue and wear, resulting in a longer service life and more stable operation. Furthermore, the labyrinthine sealing system formed by the seal 13, sealing groove 14, and sealing protrusion 15 between the volute, seat ring, and enclosure 12 effectively controls internal leakage, ensuring sustained efficiency over long-term operation. This makes it particularly suitable for the harsh environment of high dust and humidity in underground coal mines.

[0058] This invention not only serves as an independent power conversion device, but its operation is also deeply aligned with the environmental management needs of coal mine roadways, achieving a multi-faceted systemic benefit. The low-temperature exhaust gas discharged after work is directly used to reduce roadway temperature and improve the working environment; its continuously flowing carrier characteristics also act as an active airflow to disperse and dilute methane gas, enhancing the ventilation and methane removal effect. This means that a single compressed air input is converted into three effective outputs within the same device: mechanical work, cooling energy, and safe ventilation airflow, achieving a tiered and comprehensive utilization of energy.

[0059] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection defined by the claims of the present invention.

Claims

1. A volute for a pneumatic turbine, comprising a volute body (1), characterized in that: The volute body (1) is provided with a circumferential inlet channel (101) and an axial outlet channel (102). The outlet channel (102) has an annular cross section. The volute body (1) is provided with a seat ring cavity (103) for accommodating the first-stage seat ring (3). The seat ring cavity (103) is an axially open annular cavity. The outlet channel (102) is directly connected to the seat ring cavity (103) in the axial direction, so that the gas flowing out from the outlet channel (102) can enter the first-stage seat ring (3) in the seat ring cavity (103) without turning.

2. The volute casing for a pneumatic turbine according to claim 1, characterized in that: The central flow surface of the outlet flow channel (102) and the central flow surface of the first-stage seat ring (3) are located on the same cylindrical surface.

3. A volute casing for a pneumatic turbine according to claim 2, characterized in that: The first-stage seat ring (3) has a first-stage nozzle flow channel (302), and the diameters of the inner and outer circumferential surfaces of the outlet flow channel (102) are the same as the diameters of the inner and outer circumferential surfaces of the first-stage nozzle flow channel (302).

4. A volute casing for a pneumatic turbine according to claim 3, characterized in that: An air intake chamber (108) is provided between the inlet flow channel (101) and the outlet flow channel (102). The longitudinal section of the air intake chamber (108) is a fully elliptical cross section (104), and its longitudinal cross-sectional area gradually decreases along the airflow direction. The inlet flow channel (101) is located on the circumferential sidewall of the air intake chamber (108), and the outlet flow channel (102) is located on the axial end face of the air intake chamber (108).

5. The ratio of the major axis to the minor axis of the fully elliptical cross section (104) of the air intake chamber (108) changes linearly from the inlet to the outlet.

6. A volute casing for a pneumatic turbine according to claim 4, characterized in that: The longitudinal section at the junction of the inlet flow channel (101) and the air intake chamber (108) is circular (105).

7. A volute casing for a pneumatic turbine according to any one of claims 1 to 5, characterized in that: The outer circumferential surface of the seat ring cavity (103) is recessed with a positioning groove (106), and the outer circumferential surface of the first-stage seat ring (3) has a limiting protrusion ring (303) protruding outward, and the limiting protrusion ring (303) abuts against the positioning groove (106) axially.

8. A volute casing for a pneumatic turbine according to any one of claims 1 to 5, characterized in that: The volute body (1) has a bearing seat (107) formed in the middle, and a bearing cap (2) is fixedly connected to the outer end of the bearing seat (107).

9. A pneumatic turbine, comprising a volute casing for a pneumatic turbine as described in any one of claims 1 to 7, characterized in that: The volute body (1) is fixedly connected in sequence along the axial direction with a secondary seat ring (4), a tertiary seat ring (5) and a quaternary seat ring (6). The secondary seat ring (4), the tertiary seat ring (5) and the quaternary seat ring (6) have a secondary nozzle flow channel (402), a tertiary nozzle flow channel (502) and a quaternary nozzle flow channel (602) respectively. The central flow surface of the secondary nozzle flow channel (402), the tertiary nozzle flow channel (502) and the quaternary nozzle flow channel (602) is located on the same cylindrical surface as the central flow surface of the outlet flow channel (102).

10. A pneumatic turbine according to claim 8, characterized in that: A first-stage impeller (7), a second-stage impeller (8), a third-stage impeller (9), and a fourth-stage impeller (10) are respectively provided between the first-stage impeller (3), the second-stage impeller (4), the third-stage impeller (5), and the fourth-stage impeller (6). The first-stage impeller (7), the second-stage impeller (8), the third-stage impeller (9), and the fourth-stage impeller (10) have a first-stage impeller flow channel (702), a second-stage impeller flow channel (802), a third-stage impeller flow channel (902), and a fourth-stage impeller flow channel (1002). The central flow surfaces of the first-stage impeller flow channel (702), the second-stage impeller flow channel (802), the third-stage impeller flow channel (902), and the fourth-stage impeller flow channel (1002) are located on the same cylindrical surface as the central flow surface of the outlet flow channel (102).

11. A pneumatic turbine according to claim 9, characterized in that: The inlet diameter of the first-stage nozzle flow channel (302) is the same as the outlet diameter of the outlet flow channel (102), and the outlet diameter of the first-stage nozzle flow channel (302) is the same as the inlet diameter of the first-stage blade flow channel (702); the inlet diameter of the second-stage nozzle flow channel (402) is the same as the outlet diameter of the first-stage blade flow channel (702), and the outlet diameter of the second-stage nozzle flow channel (402) is the same as the inlet diameter of the second-stage blade flow channel (802); the inlet diameter of the third-stage nozzle flow channel (502) is the same as the outlet diameter of the second-stage blade flow channel (802), and the outlet diameter of the third-stage nozzle flow channel (502) is the same as the inlet diameter of the third-stage blade flow channel (902); the inlet diameter of the fourth-stage nozzle flow channel (602) is the same as the outlet diameter of the third-stage blade flow channel (902), and the outlet diameter of the fourth-stage nozzle flow channel (602) is the same as the inlet diameter of the fourth-stage blade flow channel (1002).

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