A drag reduction structure and its application in a rotating test bed

Abstract

The application discloses a drag reduction structure and application thereof to a rotating experiment table, relates to the technical field of drag reduction structures, and comprises a rotating shaft and a rotating center block which is in key connection with the rotating shaft, the two end faces of the rotating center block are fixedly connected with one end of two rotating arms respectively, the other end of each rotating arm is fixedly connected with an experiment cabin with a longitudinal cross section in the shape of a water drop, and an air inlet pipe and an air outlet pipe are arranged on each rotating arm; each rotating arm is wrapped with a skin with a longitudinal cross section in the shape of a water drop, the air inlet pipe and the air outlet pipe are wrapped inside the skin and are in communication with the experiment cabin. The application designs a rotating structure of a rotating arm + an experiment cabin for the rotating experiment table, a water drop-shaped skin is covered on the outside of a cylindrical rotating arm, pipelines and other equipment for air supply and air exhaust are installed in the space between the rotating arm and the skin, and the cross section of the experiment cabin is also designed in the shape of a water drop. The application reduces the air resistance of the rotating experiment table, reduces noise and vibration, and improves the stability and safety of an experiment system.

Description

Technical Field

[0001] This invention relates to the field of drag reduction structure technology, and in particular to a drag reduction structure and its application in a rotating experimental stage. Background Technology

[0002] In recent years, blade cooling technology has been widely applied, playing a crucial role in improving the thermal efficiency of gas turbines and ensuring their efficient and stable operation. Blade cooling technology includes two types: internal cooling and external cooling. Internal cooling mainly involves the forced convection heat transfer through the flow of low-temperature cooling air within the serpentine channels inside the hollow blade. For gas turbine blades, the Coriolis force and rotational buoyancy caused by high-speed rotation have a significant impact on the flow and heat transfer characteristics of the internal cooling channels, with the heat transfer coefficient changing by up to 50% compared to the static state. Therefore, elucidating the flow and heat transfer characteristics within the blade cooling channels under rotating conditions, especially the mechanisms of Coriolis force and rotational buoyancy, is crucial for the design of heavy-duty gas turbines.

[0003] Under laboratory conditions, it is difficult to directly simulate the real high-temperature and high-pressure environment of a gas turbine. Therefore, modeling experiments are necessary. The characteristic modeling criteria for describing the flow inside the moving blades include the Reynolds number (Re), the rotational number (Ro), and the buoyancy coefficient (Bo), defined as follows:

[0004]

[0005]

[0006]

[0007] Where: U - fluid velocity, D H - Channel hydraulic diameter, υ - fluid dynamic viscosity coefficient, Ω - rotational speed, ρ - fluid density, R - radius of rotation.

[0008] Rotary test benches are currently important modeling experimental devices used to investigate the rotational cooling characteristics of blades. By mounting the experimental section on a rotating test bench, the Coriolis force and rotational buoyancy generated by the rotation of a gas turbine can be simulated, enabling the measurement of internal cooling flow and heat transfer characteristics under rotational conditions. As can be seen from the definitions of rotational speed and buoyancy coefficient, to achieve a similar high rotational speed and high buoyancy coefficient as a high-speed gas turbine, it is necessary to increase the rotational speed and rotation radius of the test bench. However, high rotational speed and large rotation radius bring greater wind resistance, noise, and vibration problems, posing a significant challenge to the design of the rotating test bench. Therefore, a drag-reducing structure is urgently needed to address the wind resistance, noise, and vibration problems faced by high-speed rotating test benches.

[0009] Existing rotating experimental platforms typically include structures using rotating disks and structures using rotating arms plus experimental chambers.

[0010] In a rotating disk structure, the experimental section and measuring equipment are directly mounted on the disk and exposed to the elements. When the experimental platform rotates, the irregular shape of the experimental section and measuring equipment introduces significant wind resistance. This results in increased noise and vibration, affecting experimental stability and signal transmission, and also poses significant safety hazards. Furthermore, for experimental platforms with large rotation radii, using a rotating disk structure would lead to an excessively heavy overall experimental system, significantly increasing construction costs.

[0011] In the rotating arm + experimental chamber structure, the experimental section and measuring equipment are installed inside the experimental chamber, which reduces wind resistance to a certain extent. The rotating arm is usually designed as a hollow cylindrical structure with welded flanges at both ends for connecting the rotating shaft and the pressurization chamber, respectively. For ease of maintenance, the air supply and exhaust pipes, power signal transmission wires, and other equipment are installed outside the rotating arm. This design is easy to manufacture and reduces the cost of the experimental system. However, the cylindrical shape of the rotating arm results in greater wind resistance during rotation, and the exposed pipes, wires, and other equipment outside the rotating arm also contribute to greater wind resistance. Under high rotational speeds, this leads to significant noise and vibration. Summary of the Invention

[0012] This invention provides a drag-reducing structure and its application in a rotating test bench, which solves the problems of high wind resistance, noise and vibration that occur in the existing rotating arm + test chamber structure under high rotation speed conditions.

[0013] The present invention provides a drag reduction structure, comprising a rotating shaft rotatably mounted on a rotating experimental platform and a rotating center block connected thereto by a key, characterized in that the two end faces of the rotating center block are respectively fixedly connected to one end of two rotating arms, and the other end of each rotating arm is fixedly connected to an experimental chamber with a teardrop-shaped longitudinal section, and each rotating arm is provided with an air inlet pipe and an exhaust pipe;

[0014] Each of the rotating arms is covered with a teardrop-shaped skin, and the air intake pipe and exhaust pipe are wrapped inside the skin. One end of the air intake pipe and exhaust pipe is connected to the experimental chamber, and the other end is connected to the rotating shaft.

[0015] Preferably, each of the rotating arms is uniformly welded with multiple annular plates, and the outer side of each annular plate is fixedly connected to a teardrop-shaped skin support by multiple spokes.

[0016] Preferably, the intake pipe and exhaust pipe pass through the hollow area between the annular plate and the skin support.

[0017] Preferably, the skin includes a front skin and a rear skin, both of which are fixed to multiple skin supports by bolts.

[0018] Preferably, the rotating arm is also provided with wires for transmitting power and signals, and the wires are all located inside the skin.

[0019] Preferably, the rotating arm is a hollow aluminum tube.

[0020] Preferably, aluminum flanges are welded to both ends of the rotating arm, and are fixedly connected to the rotating center block and the experimental chamber respectively through the aluminum flanges.

[0021] Preferably, the aluminum flange is welded with multiple reinforcing ribs.

[0022] Preferably, the experimental chamber includes a front cover, a cylindrical body, and an end cover. The longitudinal sections of the front cover, the cylindrical body, and the end cover are all teardrop-shaped, and the material is aluminum alloy. They are connected by flanges.

[0023] A rotating experimental platform includes a rotating experimental platform body and the aforementioned drag-reducing structure. The rotation axis of the drag-reducing structure is mounted on the rotating experimental platform body, and the projected radius of curvature of the outer end face of the end cap in the horizontal direction is the same as the maximum rotation radius of the rotating experimental platform body.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention employs a rotating arm + experimental chamber structure. A teardrop-shaped skin is covered on the outside of the cylindrical rotating arm, and the air supply and exhaust pipes and other equipment are installed in the space between the rotating arm and the skin. The experimental chamber's cross-section is also designed in a teardrop shape. This design reduces wind resistance on the rotating experimental platform, decreases noise and vibration, and helps improve the stability and safety of the experimental system. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a drag reduction structure according to the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of the skin and skin support of the present invention;

[0029] Figure 3 This is a side view of the experimental chamber of the present invention.

[0030] Figure 4 This is a three-dimensional structural diagram of the experimental chamber of the present invention.

[0031] In the diagram: 1-rotating shaft, 2-rotating center block, 3-rotating arm, 4-skin support, 5-skin, 5-1-front skin, 5-2-rear skin, 7-intake pipe, 8-exhaust pipe, 9-experimental chamber, 9-1-front cover, 9-2-cylinder, 9-3-end cover. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Reference Figure 1-4 This invention provides a drag-reducing structure, including a rotating shaft 1, a rotating center block 2, rotating arms 3, a skin support 4, a skin 5, an experimental chamber 9, an air inlet pipe 7, and an exhaust pipe 8. The rotating center block 2 is rotatably mounted on the rotating shaft 1. Both ends of the rotating center block 2 are fixedly connected to one end of each of the two rotating arms 3. The other end of each rotating arm 3 is fixedly connected to an experimental chamber 9 with a teardrop-shaped longitudinal section. Each rotating arm 3 is equipped with an air inlet pipe 7 and an exhaust pipe 8.

[0034] In this embodiment, considering weight reduction and strength requirements, the rotating arm 3 is made of hollow aluminum tubing, with aluminum flanges welded to both ends. One end is connected to the rotating center block 2, and the other end is connected to the experimental chamber 9. To ensure structural strength, multiple reinforcing ribs are welded to the flanges of the rotating arm.

[0035] To facilitate the installation of the skin 5, multiple skin supports 4 are evenly arranged on each rotating arm 3. Specifically, considering the weight reduction requirements of the rotating equipment and the structural strength requirements of the skin supports 4, multiple annular plates are evenly arranged on each rotating arm 3, and these annular plates are welded to the outer side of the rotating arm 3. Each annular plate is fixedly connected to a teardrop-shaped skin support 4 via multiple spokes. The skin supports 4, annular plates, and spokes are all made of aluminum. The skin 5 is wrapped around the multiple skin supports 4. The intake pipe 7 and exhaust pipe 8 are both located inside the skin 5.

[0036] To further reduce wind resistance, the air intake pipe 7 and exhaust pipe 8, which are led out from the side hole of the rotating arm 3, pass through the hollow area between the annular plate and the skin support 4, and then connect to the experimental chamber 9.

[0037] By covering the intake pipe 7, exhaust pipe 8, and power and signal transmission wires with skin 5, the resulting wind resistance is reduced.

[0038] To facilitate regular maintenance of the intake pipe 6, exhaust pipe 7, and wiring, the skin 5 includes a front skin 5-1 and a rear skin 5-2, both of which are fixed to multiple skin brackets 4 by bolts.

[0039] The experimental chamber 9 consists of a front cover 9-1, a cylindrical body 9-2, and end covers 9-3, all made of aluminum alloy to reduce weight. The front cover 9-1, cylindrical body 9-2, and end covers 9-3 are all connected by flanges. To reduce wind resistance, the cross-sectional shapes of the front cover 9-1, cylindrical body 9-2, and end covers 9-3 are all designed in a teardrop shape. Furthermore, the flange holes are countersunk, with the bolt heads fully recessed into the holes to reduce the resistance generated by friction between the outer end face of the experimental chamber and the protruding bolt heads and the air.

[0040] A rotating experimental platform includes a rotating experimental platform body and the aforementioned drag-reducing structure. The rotating shaft 1 of the drag-reducing structure is mounted on the rotating experimental platform body. The projection radius of curvature of the outer end face of the end cover 9-3 in the horizontal direction is the same as the maximum rotation radius of the rotating experimental platform body.

[0041] For a rotating arm + experimental chamber structure, the wind resistance primarily depends on the cross-sectional shape of the rotating arm and the experimental chamber. When fluid flows, without external constraints, it always moves according to the "principle of least resistance." A teardrop shape, formed by the free movement of a droplet in air, is considered to have the lowest known drag coefficient, approximately 0.05. Currently, the commonly used rotating arm and experimental chamber cross-sections are circular, with a drag coefficient of approximately 0.5. Replacing the circular cross-section with a teardrop shape can significantly reduce the wind resistance of the rotating experimental platform. For rotating arms with long axial dimensions, directly machining their cross-section into a teardrop shape is difficult and costly. Therefore, a teardrop-shaped skin structure is more suitable. Furthermore, encasing auxiliary equipment such as air intake pipes, exhaust pipes, and wiring within the skin can further reduce the experimental platform's wind resistance.

[0042] This invention relates to a rotating experimental platform with a rotating arm and an experimental chamber structure. A teardrop-shaped skin is applied to the outside of the cylindrical rotating arm, housing the air supply and exhaust pipes, power signal transmission wires, and other equipment within the space between the rotating arm and the skin. The experimental chamber is also designed with a teardrop-shaped cross-section. This design reduces wind resistance, noise, and vibration issues, improving the stability and safety of the experimental system, while also reducing construction costs.

[0043] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0044] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A drag-reducing structure, characterized in that, It includes a rotating shaft (1) and a rotating center block (2) connected to it by a key. The two ends of the rotating center block (2) are fixedly connected to one end of two rotating arms (3), and the other end of each rotating arm (3) is fixedly connected to an experimental chamber (9) with a teardrop-shaped longitudinal section. Each rotating arm (3) is provided with an air inlet pipe (7) and an exhaust pipe (8). Each of the rotating arms (3) is covered with a skin (5) with a teardrop-shaped longitudinal section. The air intake pipe (7) and the exhaust pipe (8) are covered inside the skin (5). One end of the air intake pipe (7) and the exhaust pipe (8) are connected to the experimental chamber (9), and the other end is connected to the rotating shaft (1). Multiple annular plates are uniformly welded on each of the rotating arms (3), and a teardrop-shaped skin support (4) is fixedly connected to the outer side of the annular plates by multiple spokes. The intake pipe (7) and exhaust pipe (8) pass through the hollow area between the annular plate and the skin support (4).

2. The drag-reducing structure as described in claim 1, characterized in that, The skin (5) includes a front skin (5-1) and a rear skin (5-2), both of which are fixed to multiple skin supports (4) by bolts.

3. The drag-reducing structure as described in claim 1, characterized in that, The rotating arm (3) is also provided with wires for transmitting power and signals, and the wires are all located inside the skin (5).

4. The drag reduction structure as described in claim 1, characterized in that, The rotating arm (3) is a hollow aluminum tube.

5. The drag-reducing structure as described in claim 1, characterized in that, Both ends of the rotating arm (3) are welded with aluminum flanges, which are fixedly connected to the rotating center block (2) and the experimental chamber respectively.

6. The drag reduction structure as described in claim 5, characterized in that, The aluminum flange is welded with multiple reinforcing ribs.

7. The drag-reducing structure as described in claim 1, characterized in that, The experimental chamber (9) includes a front cover (9-1), a cylindrical body (9-2), and an end cover (9-3). The longitudinal sections of the front cover (9-1), the cylindrical body (9-2), and the end cover (9-3) are all teardrop-shaped, and the material is aluminum alloy. They are connected by flanges.

8. A rotating experimental stage, characterized in that, The invention includes a rotating experimental platform body and a drag-reducing structure as described in claim 7. The rotating shaft (1) of the drag-reducing structure is mounted on the rotating experimental platform body, and the projected radius of curvature of the outer end face of the end cap (9-3) in the horizontal direction is the same as the maximum rotation radius of the rotating experimental platform body.

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