Propeller power absorption structure for a dynamometer
By using an inner and outer double-layered blade structure with opposite torque and a toothed connecting ring design, the problems of insufficient torque and cavitation risk of propellers in small sizes are solved, enabling the generation of large torque under zero thrust, improving measurement stability and space utilization efficiency, and reducing equipment size and weight.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2024-12-31
- Publication Date
- 2026-06-30
AI Technical Summary
Existing propellers cannot generate sufficient torque in a small size, have low space utilization efficiency, require large experimental equipment in terms of size and weight, and pose risks of cavitation and vortex, resulting in poor measurement stability and accuracy.
The blades adopt a double-layered structure with opposite torques. The inner and outer blades are arranged in opposite directions and connected by a toothed connecting ring. When the inner and outer blades rotate in the same direction, they generate opposite axial thrusts that cancel each other out. The sawtooth connecting ring design suppresses flow field vortices, and the outer ring suppresses tip vortex cavitation.
It generates large torque under almost zero thrust, reduces cavitation risk, improves measurement stability and accuracy, reduces the size and weight of experimental equipment, and adapts to torque-speed relationships for different experimental needs.
Smart Images
Figure CN122306362A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a technology in the field of fluid dynamics, specifically a propeller-driven energy absorption structure for a dynamometer. Background Technology
[0002] Existing propellers cannot generate sufficient torque in a small size, have low space utilization efficiency, and require large and heavy experimental equipment. The experiments also present significant risks of cavitation and tip vortices, resulting in low measurement stability and accuracy. Summary of the Invention
[0003] This invention addresses the shortcomings of existing technologies that fail to generate significant torque at near-zero thrust to meet dynamometer requirements, while also highlighting the high risk of cavitation due to the lack of flow field improvement. It proposes a propeller-driven dynamometer structure for the dynamometer disk. Through a double-layered blade structure with opposite torques, this structure provides significant torque even with near-zero axial thrust, while simultaneously suppressing vortex structures generated at the edge of the connecting ring due to abrupt changes in flow field direction. This reduces the cavitation risk and flow-induced noise of the dynamometer device.
[0004] This invention is achieved through the following technical solution:
[0005] This invention relates to a propeller power absorption structure for a dynamometer, comprising: a plurality of inner blades disposed on a hub and a connecting ring disposed outside the inner blades, wherein: a plurality of outer blades are disposed outside the connecting ring, and the inner blades and outer blades are arranged in opposite directions of rotation such that when the power absorption device rotates, the outer blades and inner blades generate opposite axial thrusts when rotating in the same direction, thereby canceling each other out. Technical effect
[0006] This invention employs blades with opposite inner and outer helical directions, connected by a toothed connecting ring. This allows the device to generate and absorb power with almost zero thrust, while also creating a small low-pressure zone and minimizing cavitation risk. Compared to existing technologies, the inner and outer blades of this invention's dynamometer can provide significant torque with almost zero thrust, enabling in-situ testing of the efficiency and noise characteristics of underwater motors under load in a stationary state. By adjusting the blade pitch parameters, the device can achieve different torque-speed relationships within a certain size range, adapting to various experimental requirements. Even at a smaller size, the device generates sufficient torque, significantly improving space utilization efficiency and reducing the size and weight requirements of the experimental equipment. The toothed connecting ring design effectively eliminates large flow field vortices, significantly reducing the cavitation risk of the power-absorbing device, thereby improving measurement stability and accuracy. The use of the outer ring reduces the risk of tip vortex generation and also minimizes the possibility of cavitation. Attached Figure Description
[0007] Figure 1 This is a schematic diagram of the structure of the present invention;
[0008] In the diagram: 1 Inner blade, 2 Hub, 3 Outer blade, 4 Connecting ring, 5 Outer ring;
[0009] Figure 2 This is an exploded view of the structure of the present invention;
[0010] Figure 3 Schematic diagram of inner and outer blades;
[0011] Figures 4-6 This is a schematic diagram illustrating the effect of an example. Detailed Implementation
[0012] like Figure 1 and Figure 3 As shown, this embodiment relates to a propeller power absorption structure for a dynamometer, including: a plurality of inner blades 1 disposed on a hub 2 and a connecting ring 4 disposed outside the inner blades 1, wherein: a plurality of outer blades 3 are disposed on the outer side of the connecting ring 4, and the inner blades 1 and the outer blades 3 are arranged in opposite directions of rotation so that when the power absorption device rotates, the outer blades 3 and the inner blades 1 generate opposite axial thrusts when rotating in the same direction, thereby canceling each other out.
[0013] The connecting ring 4 has a serrated structure on its edge facing away from the incoming flow direction to reduce flow field vortices, reduce the risk of cavitation around the propeller, delay the torque drop caused by large-area cavitation, and increase the operating speed range of the suction power device.
[0014] The outer blade 3 is preferably provided with an outer ring 5 to suppress the tip vortex and tip vortex cavitation generated by the outer blade 3, thereby increasing the cavitation initiation speed of the power absorption device.
[0015] Through specific practical experiments, numerical simulation of the dynamometer was performed using computational fluid dynamics (CFD). Referring to the ITTC recommended values, based on the maximum diameter D of the dynamometer propeller blades being 0.24 m, and considering the characteristics of the power-absorbing propeller, the distance from the inlet / outlet to the propeller was appropriately increased, especially for zero-infeed speed, to achieve a balance between forward and reverse thrust. The distance from the inlet to the propeller head was increased from the ITTC recommended 2D to 8D. The simulation results are shown in Table 1.
[0016] Table 1. Hydrodynamic Analysis Results of the Dystopometer blade diameter rotational speed Blade torque Internal blade thrust outer blade thrust Total thrust 0.24m 15r / s 17.5Nm 125N -150N -25N
[0017] As shown in Table 1, the total thrust obtained from the difference in thrust between the inner and outer blades is 16.7% of the thrust of the outer blade. It can be seen that the thrust of the inner blade and the thrust of the outer blade are relatively close, essentially achieving thrust balance. Figures 4-5The image shows the velocity distribution of the dynamometer disc and its corresponding surface pressure distribution during the simulation. It can be seen that the toothed structure of the connecting ring improves the vortex near the blades, resulting in a smaller low-pressure area. Figure 6 As shown, the blade pressure distribution in the dynamometer is relatively uniform, with the maximum pressure reduction being 40 kPa, mainly concentrated in the guide edge area.
[0018] Compared with existing technologies, this device can generate a large torque with almost zero thrust by setting the inner and outer blades to opposite rotation directions. This allows it to test the efficiency and noise characteristics of underwater motors under load in situ when stationary. The toothed design of the connecting ring can improve the vortex near the blades, generate a smaller low-pressure area, and reduce the risk of cavitation.
[0019] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.
Claims
1. A propeller-driven power absorption structure for a dynamometer, characterized in that, include: Several inner blades are disposed on the hub and a connecting ring is disposed outside the inner blades. The outer side of the connecting ring is provided with several outer blades. The inner blades and outer blades are arranged in opposite directions of rotation so that when the suction device rotates, the outer blades and inner blades generate opposite axial thrusts when rotating in the same direction, thus canceling each other out.
2. The propeller-absorbing structure for a dynamometer according to claim 1, characterized in that, The connecting ring has a serrated edge facing away from the incoming flow direction to reduce flow field vortices.
3. The propeller-absorbing structure for a dynamometer according to claim 1, characterized in that, The outer blade is provided with an outer ring to suppress the tip vortex and tip vortex cavitation generated by the outer blade, thereby increasing the cavitation initiation speed of the power absorption device.