Rotor blade disc, rocket engine and engine control method
By designing movable moving blades in the rotor blade of the rocket engine, adjusting the overflow area of the fluid channel, the problem of reduced efficiency when the turbine operating conditions deviate from the high-efficiency point is solved, and the overall efficiency of the turbine is improved.
Patent Information
- Application Number
- CN202411978209.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-03-28
AI Technical Summary
In rocket engines, when the operating conditions of the turbine deviate from the high-efficiency point, the efficiency decreases rapidly, especially in impact turbines with high pressure ratios, the efficiency decreases sharply when it is far from the high-efficiency point.
A rotor blade is designed, including a rotor bracket and a moving blade. The moving blade is movably arranged on the rotor bracket, which can move in response to changes in rotation speed and adjust the overflow area of the fluid passage to avoid airflow blockage or separation.
The overflow area of the fluid channel is adjusted through the movement of the moving blades, which avoids the reduction of turbine efficiency and improves the efficiency of the turbine when the working conditions deviate from the high-efficiency point.
Smart Images
Figure CN119712352A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of rocket engines, and in particular to a rotor blade disk, a rocket engine and an engine control method. Background Art
[0002] In rocket engines of related technologies, turbines can generally only maintain high efficiency near the designed high efficiency point (rated operating conditions). However, in scenarios such as reusable rockets, rocket engines are required to have the ability to change thrust deeply and self-start, so that the operating conditions of the turbine (flow rate and Mach number) can vary within a larger range.
[0003] When the operating conditions of the turbine deviate from the high efficiency point, the passage of the turbine blades may be blocked or the airflow may separate, causing the efficiency of the turbine to drop rapidly. Especially in the impulse turbine with high pressure ratio, the efficiency of the turbine drops sharply when it is far away from the high efficiency point. Summary of the invention
[0004] In view of this, the present invention provides a rotor blade disk, a rocket engine and an engine control method to solve the problem of rapid reduction in efficiency when the operating condition of the turbine deviates from the high efficiency point.
[0005] In a first aspect, the present invention provides a rotor blade disk, comprising a rotor support and moving blades, wherein the rotor support comprises an inner ring support and an outer ring support, a fluid channel is formed between the inner ring support and the outer ring support, the moving blades are movably arranged on the rotor support, the moving blades are partially exposed in the fluid channel, the moving blades can move in response to changes in the rotational speed of the rotor blade disk, and the moving blades are used to increase the flow area of the fluid channel as the rotational speed increases.
[0006] Beneficial effect: When the mass flow rate of the fuel gas increases or decreases, the rotation speed of the rotor blades increases or decreases accordingly, and the moving blades move under the action of centrifugal force, thereby changing the posture of the moving blades in the fluid channel, and ultimately increasing or decreasing the flow area of the fluid channel, thereby avoiding gas flow blockage or separation at the rotor blades, which leads to a decrease in turbine efficiency. Therefore, the rotor blades help solve the problem of rapid decrease in efficiency when the operating conditions of the turbine deviate from the high efficiency point.
[0007] In an optional embodiment, the moving blades are used to make the cube of the rate of change of the flow area proportional to the rate of change of the rotational speed.
[0008] Beneficial effect: By adopting a cubic proportional relationship, the change in the flow area can better compensate for the change in the rotational speed, which helps to further reduce the degree of reduction in efficiency when the operating condition of the turbine deviates from the high efficiency point.
[0009] In an optional implementation, the moving blades are capable of moving on the rotor support along a radial direction of the rotor support, and along the radial direction, the blade thickness of the moving blades gradually increases from the inside to the outside.
[0010] Beneficial effect: As the moving blade moves radially, the part of the moving blade exposed in the fluid channel also changes accordingly. Since the blade thickness of the moving blade gradually increases from the inside to the outside, when the moving blade moves radially outward, the flow area of the fluid channel increases, and when the moving blade moves radially inward, the flow area of the fluid channel decreases.
[0011] In an optional embodiment, the inner ring bracket is provided with a first slot, which is open outward in the radial direction, and the outer ring bracket is provided with a second slot, which is open inward in the radial direction, one end of the moving blade is inserted in the first slot, and the other end of the moving blade is inserted in the second slot.
[0012] Beneficial effect: The first slot and the second slot are used to install the moving blade, so that the moving blade has radial freedom of movement and is limited at the same time, thereby preventing the moving blade from falling off the rotor bracket.
[0013] In an optional embodiment, the first slot and the second slot are open in the axial direction of the rotor support, and the rotor blade disk further includes a cover plate, which is arranged on the rotor support and closes the first slot and the second slot in the axial direction.
[0014] Beneficial effect: By opening the first slot and the second slot in the axial direction, it is possible to facilitate the axial installation of the moving blades into the first slot and the second slot, and then use the cover plate to close the first slot and the second slot to cover the moving blades, so that the moving blades are stably limited and prevented from falling off the rotor bracket.
[0015] In an optional embodiment, the rotor blade disk further includes an elastic member, and the elastic member is used to apply a radially inward force to the moving blade.
[0016] Beneficial effect: The elastic member pushes the moving blades inward. When the rotor blade disk rotates, the centrifugal force enables the moving blades to overcome the elastic force of the elastic member and move radially outward. The faster the rotation speed, the greater the degree of outward movement of the moving blades, thereby achieving an increase in the flow area of the fluid channel as the rotation speed increases.
[0017] In an optional embodiment, the elastic member includes a disc spring, the disc spring is disposed in the second slot, and the disc spring abuts against the moving blade in the radial direction.
[0018] Beneficial effects: On the one hand, hiding the elastic part in the second slot can prevent the exposed elastic part from affecting the aerodynamic shape of the rotor blade disk, which is helpful for the shape design of the rotor blade disk. On the other hand, the disc spring is relatively thin, which can avoid occupying too much space.
[0019] In an optional embodiment, the blade placement angle of the moving blade changes along the radial direction.
[0020] Beneficial effect: By designing a blade placement angle that varies radially for the moving blade, different blade placement angle designs can be adopted according to different flow areas, which helps the turbine maintain a high efficiency.
[0021] In a second aspect, the present invention further provides a rocket engine, comprising a rotating shaft and a rotor blade disk provided by the present invention, wherein the rotor blades are arranged on the rotating shaft.
[0022] In a third aspect, the present invention further provides a rotor blade control method, which uses the rotor blade of the present invention. The rotor blade control method includes: the moving blade moves in response to the rotational speed of the rotor blade to change the state of the moving blade exposed in the fluid channel, thereby increasing the flow area of the fluid channel of the rotor blade as the rotational speed increases.
[0023] Beneficial effects: The rocket engine provided by the present invention includes the rotor blade disk provided by the present invention, and the rotor blade disk control method provided by the present invention uses the rotor blade disk of the present invention, and therefore has the corresponding beneficial effects brought by the rotor blade disk, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0025] Figure 1 A front cross-sectional view of a rotor blade disk according to an embodiment of the present invention; Figure 2 for Figure 1 A front cutaway view of a rotor blade disk is shown with most of the moving blades hidden; Figure 3 for Figure 2 A partial enlarged view of the D area in the middle; Figure 4 for Figure 1 A side cross-sectional view of a rotor blade disk is shown; Figure 5 for Figure 1 A perspective view of a moving blade of a rotor blade disk is shown; Figure 6 for Figure 1 The shown rotor blades are a front view of the rotor blades and cross-sectional views at three positions A, B, and C.
[0026] Description of reference numerals: 1. Rotor bracket; 101. Inner ring bracket; 102. Outer ring bracket; 103. Connecting blade; 104. First slot; 105. Second slot; 2. Moving blade; 201. Blade; 202. Inner slider; 203. Outer slider; 3. Elastic member; 4. Cover plate. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.
[0028] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "" as used herein may also be meant to include the plural forms. The terms "comprise", "include", and "have" are inclusive and therefore specify the presence of stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.
[0029] Although the terms first, second, etc. may be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. In addition, in the description of this application, unless otherwise clearly specified and limited, the terms "set" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.
[0030] For ease of description, spatial relative terms can be used in the text to describe the relationship of an element or feature as shown in the figure relative to another element or feature, and these relative terms are, for example, "end", "length", "inside", "outside", etc. This spatial relative term is intended to include different orientations of the mechanism in use or operation except the orientation depicted in the figure. For example, if the mechanism in the figure flips, the element described as "below other elements or features" or "below other elements or features" will be subsequently oriented to "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include the orientation on and below. The mechanism can be oriented in addition (rotated 90 degrees or in other directions) and the spatial relative descriptors used in the text are interpreted accordingly.
[0031] In liquid rocket engines, the turbine achieves higher efficiency near the high-efficiency point of the operating conditions (rated operating conditions with high flow and high Mach number). Due to the development needs of reusable rockets, related technologies require that rocket engines develop in the direction of deep variable thrust and self-generation and self-starting. Therefore, the turbine is required to maintain a high efficiency when it is far away from the high-efficiency point (low operating conditions with low flow and low Mach number).
[0032] However, the turbine blades in the related art are often designed in a fixed manner, and their flow area and blade placement angle are fixed. When the mass flow of the gas changes, the pressure at the turbine inlet changes accordingly because the area of the turbine nozzle throat is a fixed value, but the pressure at the blade outlet remains unchanged, which eventually causes the Mach number at the blade inlet (turbine nozzle outlet) to change, causing the blade designed based on the rated operating conditions to experience airflow blockage or separation, resulting in a sharp drop in turbine efficiency.
[0033] Combine the following Figures 1 to 6 , describing an embodiment of the present invention.
[0034] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4 According to an embodiment of the present invention, in a first aspect, a rotor blade disk is provided, the rotor blade disk includes a rotor support 1 and a moving blade 2, the rotor support 1 includes an inner ring support 101 and an outer ring support 102, a fluid channel is formed between the inner ring support 101 and the outer ring support 102, the moving blade 2 is movably arranged on the rotor support 1, and the moving blade 2 is used to increase the flow area of the fluid channel as the rotation speed increases.
[0035] Specifically, the moving blade 2 is partially exposed in the fluid channel, and the moving blade 2 can move in response to the rotation speed change of the rotor blade disk, so that the flow area of the fluid channel increases with the increase of the rotation speed.
[0036] Rocket engines often achieve changes in engine thrust by adjusting the parameters of the gas supplied to the turbopump. Theoretically, the higher the gas temperature, the more efficient the gas utilization rate. However, due to the temperature resistance of the material, the gas temperature generally remains unchanged (the gas mixing ratio remains unchanged). Therefore, the conventional adjustment method is to adjust the mass flow rate of the gas (bypass fuel and oxidant) while keeping the mixing ratio unchanged, which results in the flow rate of the fluid channel increasing with the increase of the Mach number.
[0037] The rotor blade disk of the present invention is used for the turbine of a rocket engine, especially for an impulse turbine with a high pressure drop ratio. When in use, as the mass flow rate of the gas at the turbine inlet increases, the velocity at the turbine nozzle outlet increases, the total pressure height at the turbine inlet increases, and the mass of the gas doing work increases, so that the energy of the gas input to the turbine increases, and the rotation speed of the rotor blade disk increases.
[0038] At this time, the moving blades 2 move accordingly with the increase in rotational speed, thereby causing the moving blades 2 exposed in the fluid channel to change, so that the flow area of the fluid channel increases with the increase in rotational speed, which helps to avoid gas flow blockage or separation at the rotor blade disk, resulting in a decrease in turbine efficiency. Therefore, the rotor blade disk helps to solve the problem of rapid decrease in efficiency when the operating conditions of the turbine deviate from the high efficiency point.
[0039] In some embodiments, the moving blade 2 is configured to make the cube of the rate of change of the flow area proportional to the rate of change of the rotational speed, so that the flow area of the fluid channel better matches the rotational speed of the rotor blade disk, better compensates for the change in rotational speed, and helps to further reduce the degree of reduction in efficiency when the operating condition of the turbine deviates from the high efficiency point.
[0040] Specifically, the flow area is defined as S, the speed of the rotor blade is defined as V, and the flow area and speed satisfy the following relationship: ; in, is the change of flow area per unit time, is the change of speed per unit time, and k is the coefficient between the two.
[0041] It should be pointed out that the inner ring bracket 101 and the outer ring bracket 102 need to be connected together via a connecting piece so that the rotor bracket 1 remains stable.
[0042] Optionally, the rotor support 1 may further include a connecting blade 103, a plurality of connecting blades 103 are arranged at intervals along the circumferential direction, and the connecting blades 103 are connected between the inner ring support 101 and the outer ring support 102. The aerodynamic shape of the connecting blade 103 is the same as or similar to the moving blade 2, so as to reduce the disturbance of the flow field, and the connecting blade 103 separates a plurality of fluid channels between the inner ring support 101 and the outer ring support 102, and the moving blade 2 is arranged in each fluid channel.
[0043] Specifically in Figure 1 and Figure 2 In the illustrated embodiment, the rotor support 1 has an even number of connecting blades 103 (specifically, four connecting blades 103 ), which not only stabilizes the connection but also effectively reduces the disturbance to the flow field.
[0044] It is understandable that the moving blade 2 can be changed in different ways, for example, the installation posture and position of the moving blade 2 on the rotor support 1 can be changed, as long as the flow area of the fluid channel increases with the increase of the rotation speed.
[0045] Optionally, in some embodiments, the flow area of the fluid channel is changed by changing the installation position of the moving blades 2 on the rotor support 1 .
[0046] For example, in conjunction with reference Figure 5 and Figure 6 In some embodiments, the moving blade 2 can move on the rotor support 1 along the radial direction of the rotor support 1, and the blade thickness T of the moving blade 2 gradually increases from the inside to the outside along the radial direction (such as Figure 6 (as shown in the three cross-sectional views A, B, and C in FIG.
[0047] It is understandable that the blade thickness refers to the diameter of the maximum inscribed circle of the blade profile at the current cross-sectional area. The blade thickness determines the minimum cross-sectional area of the fluid channel on the airflow route, which is referred to as the flow area in the present invention.
[0048] Since the moving blade 2 is partially exposed in the fluid channel, the area of the moving blade 2 exposed in the fluid channel changes with the radial movement of the moving blade 2. Since the blade thickness of the moving blade 2 gradually increases from the inside to the outside, when the moving blade 2 moves radially outward, the axial projection area of the moving blade 2 exposed in the fluid channel decreases, and the flow area of the fluid channel increases accordingly. Conversely, when the moving blade 2 moves radially inward, the flow area of the fluid channel decreases, thereby achieving control of the flow area.
[0049] Alternatively, in some embodiments not shown, one end of the moving blade 2 is hinged to the inner ring bracket 101, and the hinge axis is parallel to the axial direction. The moving blade 2 can change the interval exposed to the fluid channel by swinging, thereby achieving control of the flow area.
[0050] Back to Figure 5 and Figure 6In the illustrated embodiment, it should be noted that, in order to partially expose the moving blade 2 in the fluid channel, at least one end of the moving blade 2 needs to extend into the rotor support 1, and a portion of the moving blade 2 is blocked by the inner ring support 101 and / or the outer ring support 102. To this end, in some embodiments, the inner ring support 101 is provided with a first slot 104, the first slot 104 is radially open outward, the outer ring support 102 is provided with a second slot 105, the second slot 105 is radially open inward, one end of the moving blade 2 is inserted in the first slot 104, and the other end of the moving blade 2 is inserted in the second slot 105.
[0051] The first slot 104 and the second slot 105 are used to install the moving blade 2 , so that the moving blade 2 has radial freedom of movement and is limited at the same time, thereby preventing the moving blade 2 from falling off the rotor bracket 1 .
[0052] In some embodiments, the moving blade 2 may include a blade 201, an inner slider 202, and an outer slider 203. The thickness of the blade 201 gradually increases from the inside to the outside along the radial direction. The inner slider 202 is arranged at one end of the blade 201 for matching with the first slot 104. The outer slider 203 is arranged at the other end of the blade 201 for matching with the second slot 105. By providing the inner slider 202 and the outer slider 203 specifically for matching, the assembly of the moving blade 2 and the rotor bracket 1 can be made more secure and stable.
[0053] Optionally, in order to better constrain the freedom of the moving blade 2, at least one of the inner slider 202 and the outer slider 203 is in a prism shape, for example Figure 5 and Figure 6 In the illustrated embodiment, the inner slider 202 and the outer slider 203 are in the shape of a rectangular parallelepiped (i.e., a quadrangular prism). The contact limit between the side surface of the prism and the first slot 104 / the second slot 105 can effectively constrain the rotational freedom of the moving blade 2, and only retain the movement freedom of the moving blade 2 along the radial direction.
[0054] Return to reference Figure 4 In some embodiments, the first slot 104 and the second slot 105 are open in the axial direction of the rotor support 1, and the rotor blade disk also includes a cover plate 4, which is arranged on the rotor support 1, and the cover plate 4 closes the first slot 104 and the second slot 105 in the axial direction.
[0055] By opening the first slot 104 and the second slot 105 in the axial direction, the moving blade 2 can be easily inserted into the first slot 104 and the second slot 105 from the axial direction, and then the first slot 104 and the second slot 105 are closed by the cover plate 4 to cover the moving blade 2, so that the moving blade 2 is stably limited to prevent the moving blade 2 from falling off the rotor bracket 1.
[0056] The cover plate 4 can be arranged on the rotor support 1 by welding or other conventional connection methods, which is not limited in the present application.
[0057] Continue to refer to Figure 2 , Figure 3 and Figure 4 In some embodiments, the rotor blade disk further includes an elastic member 3 , and the elastic member 3 is used to apply a radially inward force to the moving blade 2 .
[0058] The elastic member 3 pushes the moving blade 2 inward. When the rotor blade disk rotates, the centrifugal force enables the moving blade 2 to overcome the elastic force of the elastic member 3 and move radially outward. The faster the rotation speed, the greater the degree of outward movement of the moving blade 2, thereby achieving an increase in the flow area of the fluid channel as the rotation speed increases. By using the elastic member 3 to provide a force for the moving blade 2, on the one hand, the moving blade 2 can respond sensitively to changes in the rotation speed, and on the other hand, it can avoid setting a complex electric or hydraulic drive device for the moving blade 2, simplifying the structural design of the rotor blade disk.
[0059] Specifically in Figure 2 and Figure 4 In the illustrated embodiment, the elastic member 3 includes a disc spring, which is disposed in the second slot 105 and abuts against the moving blade 2 in the radial direction.
[0060] On the one hand, hiding the elastic member 3 in the second slot 105 can prevent the exposed elastic member 3 from affecting the aerodynamic shape of the rotor disk, which is helpful for the shape design of the rotor disk. On the other hand, the disc spring is relatively thin, which can avoid occupying too much space.
[0061] It should be noted that, in some embodiments, in addition to the blade thickness, the blade placement angle β of the moving blade 2 may also vary along the radial direction, so that the moving blade 2 can produce different dynamic effects according to the change of the interval exposed to the fluid channel.
[0062] Specifically, the blade placement angle can be designed according to the flow area of the rotor blade disk under different working conditions. For example, the blade placement angle can be gradually reduced from the inside to the outside. For example, in some embodiments, the blade placement angle can be gradually reduced from 25 degrees to 15 degrees.
[0063] According to an embodiment of the present invention, in a second aspect, a rocket engine is also provided, the rocket engine comprising the rotor blade disk of the present invention. Therefore, the rocket engine also has the beneficial effects brought by the rotor blade disk, which will not be described in detail here.
[0064] According to an embodiment of the present invention, in a third aspect, a rotor blade disk control method is also provided, and the rotor blade disk control method uses the rotor blade disk of the present invention. Specifically, the rotor blade disk control method includes: the moving blade 2 moves in response to the rotation speed of the rotor blade disk to change the state of the moving blade 2 exposed in the fluid channel, thereby increasing the flow area of the fluid channel of the rotor blade disk as the rotation speed increases.
[0065] The flow area of the fluid channel increases with the increase of rotational speed, which helps to avoid blockage or separation of the gas flow at the rotor blades, resulting in a decrease in turbine efficiency. Therefore, the rotor blade control method helps to solve the problem of rapid decrease in efficiency when the operating conditions of the turbine deviate from the high efficiency point.
[0066] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.
Claims
1. A rotor blade disk, characterized in that: include: A rotor support (1), the rotor support (1) comprising an inner ring support (101) and an outer ring support (102), a fluid channel being formed between the inner ring support (101) and the outer ring support (102); A moving blade (2), wherein the moving blade (2) is movably arranged on the rotor support (1), the moving blade (2) is partially exposed in the fluid channel, the moving blade (2) can move in response to a change in the rotation speed of the rotor blade disk, and the moving blade (2) is used to increase the flow area of the fluid channel as the rotation speed increases.
2. The rotor blade according to claim 1, characterized in that: The moving blade (2) is configured so that the cube of the rate of change of the flow area is proportional to the rate of change of the rotational speed.
3. The rotor blade according to claim 1, characterized in that: The moving blade (2) is capable of moving on the rotor support (1) along a radial direction of the rotor support (1), and along the radial direction, the thickness of the blade (201) of the moving blade (2) gradually increases from the inside to the outside.
4. The rotor blade according to claim 3, characterized in that: The inner ring support (101) is provided with a first slot (104), the first slot (104) is open outward in the radial direction, the outer ring support (102) is provided with a second slot (105), the second slot (105) is open inward in the radial direction, one end of the moving blade (2) is inserted into the first slot (104), and the other end of the moving blade (2) is inserted into the second slot (105).
5. The rotor blade according to claim 4, characterized in that: The first slot (104) and the second slot (105) are open in the axial direction of the rotor support (1), and the rotor blade disk further comprises a cover plate (4), wherein the cover plate (4) is arranged on the rotor support (1), and the cover plate (4) closes the first slot (104) and the second slot (105) in the axial direction.
6. The rotor blade according to claim 4, characterized in that The rotor blade disk further comprises an elastic member (3), wherein the elastic member (3) is used to apply a force inwardly in the radial direction to the moving blade (2).
7. The rotor blade according to claim 6, characterized in that The elastic member (3) comprises a disc spring, the disc spring being arranged in the second slot (105), the disc spring abutting against the moving blade (2) in the radial direction.
8. The rotor blade according to claim 3, characterized in that: The placement angle of the blade (201) of the moving blade (2) varies along the radial direction.
9. A rocket engine, characterized in that: The rocket engine comprises a rotor blade disk as described in any one of claims 1 to 8 and a rotating shaft, and the rotor blade disk is arranged on the rotating shaft.
10. A rotor blade control method, characterized in that: The rotor blade disk control method uses the rotor blade disk according to any one of claims 1 to 8, and the rotor blade disk control method comprises: The moving blade (2) moves in response to the rotation speed of the rotor blade disk to change the state of the moving blade (2) exposed in the fluid channel, thereby increasing the flow area of the fluid channel of the rotor blade disk as the rotation speed increases.