Structure for improving separation and backflow of fluid at trailing edge of stand column

Abstract

The invention relates to the technical field of contra-rotating steering oars, and discloses a structure for improving separation and backflow of fluid at the tail edge of a stand column, the structure comprises the stand column and a pod, the top of the pod is fixedly mounted at the bottom of the stand column, a front oar is fixedly mounted at one end of the pod, and a rear oar is fixedly mounted at the other end of the pod; the flow guiding device is fixedly installed at the bottom of one end of the stand column and located at the tail edge of the stand column, the flow guiding device is composed of a plurality of flow guiding pieces, the flow guiding pieces are additionally arranged on the two sides of the tail edge of the stand column of the contra-rotating steering oar, the front oar rotates to generate pre-rotational flow to pass through the flow guiding pieces, and the flow guiding pieces can better comb water flow flowing through a flow field; a vacuum area generated by the tail edge of the stand column is reduced, flow separation and backflow in the tail edge area of the stand column in an existing scheme can be effectively improved, the flow environment at the ground radius of the rear propeller of the contra-rotating steering oar can be improved, the thrust conversion efficiency at the low radius of the rear propeller blade can be further excavated, and the propelling efficiency can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of counter-rotating full-revolving rudder propellers, and in particular to a structure for improving fluid separation and reflux at the trailing edge of a column. Background Art

[0002] The counter-rotating full-turn propeller has gradually become a commonly used propeller. The counter-rotating full-turn propeller includes front and rear propellers that rotate in opposite directions, as well as the lower shell column and pod in the middle. Compared with conventional full-turn propellers, it has the advantages of high efficiency and low vibration. Therefore, it has a wide range of application prospects in various ships and vessels. Its advantages are mainly reflected in the following two aspects: First, the rear propeller in the counter-rotating propeller can recover the energy in the rotating vortex of the front propeller to improve the propulsion efficiency; second, the counter-rotating propeller can comb the water flow field at the tail of the ship to improve the vibration and hydrodynamic noise of the tail of the ship. Although the efficiency of the counter-rotating full-turn propeller is already high, improving the efficiency of the counter-rotating propeller as much as possible has also become one of the core ways for propeller manufacturers to improve the competitiveness of their products.

[0003] The existing technical solutions mainly focus on optimizing the flow field before and after the propeller of the straight-axis propeller or hybrid propeller, including the optimization design of the propeller itself, to achieve the purpose of improving the efficiency of the entire propeller. After years of development, the following technical means can be used to improve the efficiency of the propeller before and after the propeller: 1. Install a pre-swirl guide wheel and a wake compensation duct in front of the propeller to improve the quality of the propeller inlet flow, increase the uniformity of the wake field on the propeller disk, generate a pre-swirl flow in the opposite direction of the propeller rotation, and improve the propulsion efficiency of the propeller; 2. Installing a rudder ball or vortex-eliminating fin behind the propeller can adjust the pressure field at the stern, recover the circumferential rotation energy of the stern flow, attenuate or split various vortices, reduce vortex resistance and provide additional thrust, thereby improving propulsion efficiency and saving energy.

[0004] Among the above technical means, the pre-swirl guide wheel and the wake compensation duct device are mostly used for the front propeller of a single propeller or a hybrid propeller. The flow field in front of the propeller is relatively simple, and there is no pre-swirl flow. The rudder ball or vortex-eliminating fin is located behind the propeller, which only improves the flow field behind the propeller. For the counter-rotating full-rotation rudder propeller, there is a propeller flow field between the front and rear propellers. The propeller flow field is affected by the front and rear propellers, and is also affected by the solid boundaries of the columns and the pod.

[0005] In view of the above problems, it is urgent to design a structure to improve the fluid separation and reflux at the trailing edge of the column and improve the propulsion efficiency of the propeller. Summary of the invention

[0006] In order to solve the existing technical problem of taking into account the solid boundary influence of the front propeller, the rear propeller and the column and the pod at the same time, thereby limiting the further improvement of the propeller efficiency, the present invention provides a structure for improving fluid separation and reflux at the trailing edge of the column.

[0007] The present invention is implemented by the following technical scheme: a structure for improving fluid separation and reflux at the trailing edge of a column, comprising a column and a pod, wherein the top of the pod is fixedly mounted on the bottom of the column, a front propeller is fixedly mounted on one end of the pod, a rear propeller is fixedly mounted on the other end of the pod, a flow guide device is fixedly mounted on the bottom of one end of the column, the flow guide device is located at the trailing edge of the column, the flow guide device is close to the rear propeller at one end of the pod, and the flow guide device is composed of a plurality of guide plates.

[0008] Preferably, the plurality of guide vanes are respectively installed on both sides of the trailing edge of the column, and the axial position gradually transitions from the middle of the column to the trailing edge.

[0009] Preferably, the guide vanes on both sides of the trailing edge of the column are symmetrical to each other, and the guide vanes are wing streamlined and have a smooth surface.

[0010] Preferably, three guide vanes are installed on one side of the trailing edge of the column, and the guide vanes are evenly distributed in front of the rear propeller 0.35R-0.90R.

[0011] Preferably, the guide vane adjusts its angle according to the flow field generated by the front propeller pre-swirl guide.

[0012] Preferably, the angle between the column and the guide plate is less than 90 degrees.

[0013] Compared with the prior art, the present invention has the following beneficial effects: When the present invention is in use, guide vanes are added on both sides of the trailing edge of the counter-rotating fully-rotating rudder propeller column. When the front propeller rotates to generate pre-swirl passing through the guide vanes, the guide vanes can better comb the water flowing through the flow field, reduce the vacuum area generated by the trailing edge of the column, and effectively improve the flow separation and backflow in the trailing edge area of ​​the column in the existing solution, improve the flow environment at the low radius of the rear propeller of the counter-rotating fully-rotating rudder propeller, so that the water flow is more fully absorbed by the rear propeller, which is beneficial to further explore the thrust conversion efficiency at the low radius of the rear propeller blade, and can effectively improve the propulsion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side view of the installation of the counter-rotating full-rotation rudder propeller guide vane of the present invention; Figure 2 This is a rear view of the installation of the counter-rotating full-rotation propeller guide vane of the present invention; Figure 3 It is a top view of the guide plate of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0016] Example 1: Please refer to Figure 1 - Figure 3 , a structure for improving fluid separation and reflux at the trailing edge of a column in this embodiment comprises a column and a pod, the top of the pod is fixedly mounted on the bottom of the column, a front propeller is fixedly mounted on one end of the pod, a rear propeller is fixedly mounted on the other end of the pod, a flow guide device is fixedly mounted on the bottom of one end of the column, the flow guide device is located at the trailing edge of the column, the flow guide device is close to the rear propeller at one end of the pod, the flow guide device is composed of a plurality of guide vanes, the plurality of guide vanes are respectively mounted on both sides of the trailing edge of the column, the axial position gradually transitions from the middle of the column to the trailing edge, the guide vanes on both sides of the trailing edge of the column are symmetrical to each other, the guide vanes adopt a wing streamline shape, and the surface is smooth, three guide vanes are mounted on one side of the trailing edge of the column, and the guide vanes are evenly distributed in front of the rear propeller 0.35R-0.90R; Among them, when the front propeller rotates to generate pre-swirl flow passing through the guide vane, the guide vane can better comb the water flowing through the flow field, reduce the vacuum area generated by the trailing edge of the column, improve the flow separation and backflow near the trailing edge of the column, so that the water flow is more fully absorbed by the rear propeller, and improve the open water efficiency of the entire propeller; Due to the significant reduction in the area of ​​the vacuum region, the water flow is pressurized and accelerated after passing through the guide vane. The accelerated water flow converges into the rear propeller at 0.30R-0.90R, especially at the low radius, thereby increasing the flow velocity of the water flow at the low radius. This overcomes the defect of the traditional solution that the low flow velocity at this location is low, and the low-speed fluid is prone to flow separation under the influence of boundary layer interference and adverse pressure gradient. This can increase the design load at the low radius of the blade and inhibit the occurrence of flow separation, thereby achieving the purpose of improving the blade efficiency. In addition, since the vacuum area is greatly reduced, it helps to reduce the vibration and hydrodynamic noise of the rear propeller; In some examples, the guide vane adjusts its angle according to the flow field generated by the pre-swirl guide of the front propeller, the angle between the column and the guide vane is less than 90 degrees, and the left and right guide vanes should adjust their angles according to the flow field generated by the pre-swirl guide of the front propeller. The guide device can take into account the pre-swirl guide brought by the rotation of the front propeller and rectify it through the column and pod of the lower shell, improve the fluid separation and reflux generated by the trailing edge of the column, improve the propulsion efficiency of the propeller behind the column, improve the cavitation performance on the blade surface, improve the efficiency of the entire counter-rotating full-rotation propeller, and reduce the vibration caused by cavitation at the tail of the column. Working principle: By adding guide vanes on both sides of the trailing edge of the counter-rotating full-revolving rudder propeller column, when the propeller rotates to generate pre-swirl passing through the guide vanes, the guide vanes can better comb the water flowing through the flow field and reduce the vacuum area generated by the trailing edge of the column. It can effectively improve the flow separation and reflux in the trailing edge area of ​​the column in the existing scheme, and improve the flow environment at the radius of the rear propeller of the counter-rotating full-revolving rudder propeller, so that the water flow is more fully absorbed by the rear propeller, which is conducive to further exploring the thrust conversion efficiency at the low radius of the rear propeller blade, and can effectively improve the propulsion efficiency of the rear propeller.

[0017] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A structure for improving fluid separation and reflux at the trailing edge of a column, comprising a column and a pod, characterized in that: The top of the pod is fixedly mounted on the bottom of the column, a front propeller is fixedly mounted on one end of the pod, a rear propeller is fixedly mounted on the other end of the pod, a flow guide device is fixedly mounted on the bottom of one end of the column, the flow guide device is located at the trailing edge of the column, the flow guide device is close to the rear propeller at one end of the pod, and the flow guide device is composed of a plurality of guide vanes.

2. The structure for improving fluid separation and reflux at the trailing edge of a column according to claim 1, characterized in that: The plurality of guide vanes are respectively installed on both sides of the rear edge of the column, and the axial position gradually transitions from the middle of the column to the rear edge.

3. The structure for improving fluid separation and reflux at the trailing edge of a column according to claim 1, characterized in that: The guide vanes on both sides of the trailing edge of the column are symmetrical to each other, and the guide vanes are wing streamlined and have smooth surfaces.

4. The structure for improving fluid separation and reflux at the trailing edge of a column according to claim 1, characterized in that: Three guide vanes are installed on one side of the trailing edge of the column, and the guide vanes are evenly distributed in front of the rear propeller 0.35R-0.90R.

5. The structure for improving fluid separation and reflux at the trailing edge of a column according to claim 1, characterized in that: The guide vane adjusts its angle according to the flow field generated by the front propeller pre-swirl guide.

6. The structure for improving fluid separation and reflux at the trailing edge of a column according to claim 1, characterized in that: The angle between the column and the guide plate is less than 90 degrees.

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