A thrust test device for open water test of a ducted propeller

Abstract

The application discloses a kind of conduit propeller open water test thrust testing device, including main body, propeller thrust testing mechanism, flow guide pipe thrust testing mechanism;The telescopic support of conduit thrust testing mechanism includes square plate and airfoil slender rod, multiple threaded holes are horizontally arranged in the middle part of both sides of square plate, bolt is arranged in threaded hole, square plate middle part is from below to top hole, airfoil slender rod enters square plate from below to top;Flow guide pipe is arranged in propeller blade outer periphery, flow guide pipe is connected with square plate by airfoil slender rod, the upper end of square plate is connected with cylindrical dynamometer, cylindrical dynamometer is connected with L-shaped beam by bolt, the vertical end of L-shaped beam is connected with one end of horizontal beam, the other end of horizontal beam is fixed on the top of open water tank, the horizontal end of L-shaped beam is connected with one page of hinge, the other page of hinge is connected with square plate.The application is accurate in testing precision, lower in cost, simple in structure, and can adapt to the testing needs of multiple flow guide pipes.

Description

Technical Field

[0001] This invention relates to a propeller thrust testing device, and more particularly to an open-water testing device for a ducted propeller. Background Technology

[0002] Open-water propeller testing involves placing a propeller model alone in a uniform water flow. The test can be conducted in a model test tank, circulating water tank, or cavitation tank. It is a relatively simple method for verifying and analyzing propeller performance. Propeller model testing plays a crucial role in studying its hydrodynamic performance, providing abundant data for propeller design and a reliable foundation for theoretical development. Furthermore, the advance rate coefficient should have a sufficiently large range of variation during the test. Two common methods are used to obtain different advance rate coefficient values: First method: Keep the model's rotational speed constant while conducting the test at different trailer speeds. Second method: Keep the model's trailer speed constant while conducting the test at different rotational speeds.

[0003] Ducted propellers are widely used propulsion devices in ships and underwater robots. They increase the overall thrust of the propeller by adding a duct around it to meet overall navigation requirements. However, the duct is subjected to significant pulsating pressure under the influence of the propeller's flow field, affecting its service life. Ducted propellers also generate different thrusts at different advance velocities. The thrust generated by the ducted propeller in open-water testing lacks a systematic method for measuring this thrust to meet design requirements. Therefore, determining the thrust of ducted propellers during the design and development phases using appropriate experimental equipment and open-water testing has become a significant challenge.

[0004] Chinese invention patent application 202210357629 discloses a device and method for measuring propeller thrust, comprising a stern plate fixing frame, a propeller mounting frame, a support frame, a force gauge connecting frame, a propeller, a first force gauge, and a second force gauge. The stern plate fixing frame is detachably connected to the stern plate of the ship, the propeller mounting frame is detachably connected to the propeller, the propeller mounting frame is rotatably connected to the support frame, the force gauge connecting frame is fixedly connected to the support frame, and rotatably connected to the stern plate fixing frame. One end of the first force gauge is connected to the force gauge connecting frame, and the other end is connected to the stern plate fixing frame. One end of the second force gauge is connected to the force gauge connecting frame, and the other end is connected to the propeller mounting frame. The propeller thrust-pull force measurement method uses the aforementioned propeller thrust-pull force measuring device. This technology, based on the lever principle, calculates the propeller thrust or pull force by performing torque balance calculations based on the first and second force gauges. However, this invention has two problems in measuring ducted propellers. First, it requires two fulcrums and three sets of lever arms for force measurement, which generates more measurement errors. This is because using multiple sets of lever arms amplifies the existing error between the thrust center and the force gauge center. Second, when measuring ducted propellers, the fixed propeller mounting bracket and stern plate mounting bracket are both large appendages, and the significant influence of hydrodynamics on the thrust of the ducted propeller is not considered. In particular, when measuring the open-water performance of ducted propellers, the force on the mounting bracket cannot be ignored, which will produce a large error. Summary of the Invention

[0005] The present invention mainly addresses the technical problems existing in the measurement of propeller thrust of ducts, and provides a precise, accurate, low-cost, simple structure, and adaptable propeller thrust testing device for open water tests.

[0006] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions:

[0007] A thrust testing device for open-water test of a ducted propeller includes a main body, a propeller thrust testing mechanism, and a duct thrust testing mechanism; the main body includes a connecting bracket and an open-water tank; the open-water tank is a cavity structure with a cavity; the connecting bracket is fixed to the top of the cavity structure;

[0008] The propeller thrust testing mechanism includes a drive shaft, propeller blades, a motor, and a propeller power instrument; the motor, propeller power instrument, and drive shaft are connected in sequence, the motor and propeller power instrument are located at the bottom of the open water tank cavity and on the front-to-back central axis of the open water tank, and the other end of the drive shaft extends out of the open water tank cavity and connects to the propeller blades;

[0009] The aforementioned guide tube thrust testing mechanism includes a guide tube, a telescopic support, a hinge, a cylindrical force gauge, a horizontal beam, and an L-shaped beam. The telescopic support includes a square plate and an airfoil-shaped slender rod. Multiple threaded holes are spaced horizontally from both sides of the square plate towards the center, with bolts installed in these holes. An opening runs from bottom to top in the center of the square plate, and the airfoil-shaped slender rod enters the square plate from bottom to top. The guide tube is positioned on the outer periphery of the propeller blade and is connected to the square plate via the airfoil-shaped slender rod. The upper end of the square plate is connected to the cylindrical force gauge, which is bolted to the L-shaped beam. The vertical end of the L-shaped beam is connected to one end of the horizontal beam, and the other end of the horizontal beam is fixed to the top of the open water tank. One hinge is connected to the horizontal end of the L-shaped beam, and the other hinge is connected to the square plate. The centerlines of the horizontal beam and the drive shaft are on the same vertical plane.

[0010] To further achieve the purpose of the present invention, preferably, the main body also includes a wave-damping plate, which is disposed on the outer periphery of the open water tank and rigidly connected to the open water tank.

[0011] Preferably, the wave-damping plate is positioned at 1 / 3 to 2 / 3 of the height of the open water tank, from top to bottom.

[0012] Preferably, the open water tank is a rectangular cavity structure with rounded ends; there are two connecting brackets, which are symmetrically arranged about the central axis of the open water tank in the left and right directions.

[0013] Preferably, the drive shaft is located at the lower end of the wave deflector; the drive shaft is connected to the propeller blade key via a flat key.

[0014] Preferably, the propeller thrust testing mechanism further includes a universal joint, through which the motor is connected to the drive shaft.

[0015] Preferably, the square plate is fixed to the cylindrical force gauge by bolts.

[0016] Preferably, the other hinge leaf is bolted to the lower horizontal center of the square plate.

[0017] Preferably, the cylindrical force gauge is selected from SBT674~SBT671 from SBT Corporation, WD-50~WD-1000 from Weldon Corporation, or DYZ-100~DYZ-101 from Ocean Sensing.

[0018] Preferably, the propeller power unit is selected from CUSSONS Technology Company's R25-1~R73-1 propeller power unit, Kempf & Remmers Company's R25~R73 propeller power unit, or Hanlin Kechuang Company's PropellerBox1500 propeller power unit.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) Precision and Accuracy. This invention utilizes a frame structure formed by hinges, horizontal beams, telescopic supports, and a cylindrical force gauge with the duct, effectively enhancing the strength and stability of the duct thrust measurement structure. This prevents the duct from vibrating during measurement, ensuring that the duct thrust is accurately transmitted to the cylindrical force gauge via the hinges. Furthermore, the propeller blade thrust is transmitted to the propeller power instrument via a longer drive shaft, avoiding the influence of the wake from the open water tank. The propeller power instrument directly measures the propeller blade thrust at the corresponding advance speed, while the cylindrical force gauge, using the lever principle with an equal-length lever arm, measures the thrust as the reaction force of the guide tube thrust. Therefore, the total thrust of the duct propeller at the corresponding advance speed is obtained by inverting the force measured by the cylindrical force gauge and adding it to the thrust measured by the propeller power instrument.

[0021] (2) Lower cost. Existing ducted propellers require numerous sensors and are integrated into a single structure, resulting in high maintenance costs. The propeller power meter and cylindrical force gauge used in this invention are conventional instruments required for open-water propeller experiments. Therefore, only a hinge, telescopic bracket, and corresponding rigid beam are needed to measure the thrust of the ducted propeller, thus avoiding the cost of purchasing other high-value sensors. Furthermore, this invention features a modular design, with both the guide tube and the propeller blade force measuring device being detachable. This modular design allows for the replacement of damaged parts at any time, reducing the force measurement cost of the ducted propeller. In summary, this invention has the advantage of lower cost.

[0022] (3) Simple structure. This invention consists of a main body, a duct force measuring mechanism, and a propeller force measuring mechanism. The duct force measuring mechanism is a frame structure consisting of a horizontal beam, a telescopic support, a duct, a hinge, and a cylindrical force gauge. The propeller thrust testing mechanism consists of a drive shaft, a motor, and a propeller power meter. The main body consists of an open water tank, a connecting support, and a wave-damping plate. Apart from necessary welding, the corresponding assemblies only require bolt connections. In summary, the structure of this invention is relatively simple.

[0023] (4) Adaptability to various guide tubes. Since the ducted propeller used in actual tests changes according to design requirements each time, the alignment position of the guide tube corresponding to the propeller blades also changes. This invention utilizes a telescopic bracket to adjust the vertical position of the guide tube according to actual needs, thereby adapting to the propeller being measured and achieving integration of the ducted propeller force measuring device. In summary, this invention can adapt to various guide tubes. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a thrust testing device for an open-water test of a ducted propeller according to the present invention;

[0025] Figure 2This is the present invention. Figure 1 Top view of the thrust testing device for open-water ducted propeller tests;

[0026] Figure 3 This is the present invention. Figure 1 Right view of the thrust testing device for open-water ducted propeller test;

[0027] Figure 4 This is the present invention. Figure 1 Front view of the thrust testing device for open-water ducted propeller test;

[0028] Figure 5 yes Figure 4 Enlarged view of part A in the image;

[0029] Figure 6 yes Figure 3 BB section view in the middle;

[0030] Figure 7 yes Figure 4 Partial section view of C in the middle;

[0031] Figure 8 This is a schematic diagram of the connection between the square plate and the slender airfoil rod in the guide tube thrust testing mechanism.

[0032] The diagram shows: main body 1, connecting bracket 1-1, open water tank 1-2, wave deflector 1-3; propeller thrust testing mechanism 2, drive shaft 2-1, propeller blade 2-2, motor 2-3, universal joint 2-4, propeller power instrument 2-5; guide tube thrust testing mechanism 3, guide tube 3-1, telescopic bracket 3-2, hinge 3-3, cylindrical force gauge 3-4, horizontal beam 3-5, L-shaped beam 3-6, square plate 3-7, airfoil slender rod 3-8, bolt 3-9. Detailed Implementation

[0033] To better illustrate the present invention, the following description is provided in conjunction with the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0034] like Figure 1-4As shown, a thrust testing device for open-water ducted propellers includes a main body 1, a propeller thrust testing mechanism 2, and a guide tube thrust testing mechanism 3. The main body 1 includes a connecting bracket 1-1, an open water tank 1-2, and a wave-damping plate 1-3. The open water tank 1-2 is a cavity structure with a hollow interior; preferably, it is a rectangular cavity structure with rounded ends, used to house the main components of the propeller thrust testing mechanism 2. The connecting bracket is fixed to the top of the cavity structure and is used to connect a water tank trailer, which provides power to the open-water ducted propeller thrust testing device. The connecting bracket 1-1 is symmetrically arranged above the central axis of the open water tank 1-2 in the left-right direction and is rigidly connected to the outer wall of the open water tank 1-2. The wave-damping plate is arranged at a position 1 / 3-2 / 3 below the top of the open water tank 1-2 and is rigidly connected to the open water tank. The wave-damping plate 1-3 extends along the outer periphery of the open water tank 1-2. Wave deflectors 1-3 are used to prevent waves generated by the main body 1 when it moves forward from entering the propeller thrust test mechanism 2.

[0035] The propeller thrust testing mechanism 2 includes a drive shaft 2-1, propeller blades 2-2, a motor 2-3, a universal joint 2-4, and a propeller power meter 2-5. The drive shaft 2-1 is located to the lower right of the wave deflector 1-3. One end is keyed to the propeller blades 2-2 via a flat key, and the other end passes through the open water tank 1-2, inserts into the propeller power meter 2-5, and is connected to the motor 2-3 via the universal joint 2-4. The motor 2-3 and propeller power meter 2-5 are horizontally placed at the front-rear central axis position of the open water tank 1-2 and are fixed to the bottom of the open water tank 1-2 by bolts. The power generated by the motor 2-3 is transmitted to the drive shaft 2-1 through the universal joint 2-4, causing the propeller blades 2-2 fixed to the drive shaft 2-1 to rotate at a specified speed and generate corresponding thrust in the water. The thrust of the propeller blades 2-2 can be measured by the propeller power meter 2-5.

[0036] like Figures 1-7As shown, the guide tube thrust testing mechanism 3 includes a guide tube 3-1, a telescopic bracket 3-2, a hinge 3-3, a cylindrical force gauge 3-4, a horizontal beam 3-5, an L-shaped beam 3-6, a square plate 3-7, an airfoil slender rod 3-8, and a bolt 3-9. The telescopic support 3-2 consists of a square plate 3-7, an airfoil-shaped slender rod 3-8, and bolts 3-9. Several threaded holes are spaced apart on both sides of the square plate 3-7 towards the center, and bolts 3-9 are installed in these threaded holes. A hole is opened in the center of the square plate 3-7 from bottom to top, with a diameter large enough to accommodate the airfoil-shaped slender rod 3-8. The airfoil-shaped slender rod 3-8 is inserted from the bottom of the square plate 3-7. The bolts 3-9 in the threaded holes on both sides are used to loosen or tighten the airfoil-shaped slender rod 3-8, allowing it to extend and retract vertically relative to the square plate. The airfoil-shaped cross-section of the airfoil-shaped slender rod 3-8 significantly reduces the fluid resistance it experiences in water and suppresses vibration, making the thrust it generates relative to the guide tube negligible. The guide pipe 3-1 is fastened to the lower end of the slender, wing-shaped rod 3-8 of the telescopic support 3-2 by bolts 3-9; the upper part of the square plate 3-7 is fixed to one end of the cylindrical force gauge 3-4 by bolts; the other end of the cylindrical force gauge 3-4 is connected to the L-shaped beam 3-6 by bolts 3-9; one end of the horizontal beam 3-5 is rigidly connected to the vertical end of the L-shaped beam 3-6 by welding, and the other end of the horizontal beam 3-5 is welded to the top of the open water tank 1-2; one hinge 3-3 is connected to the horizontal end of the L-shaped beam 3-6, and the other hinge 3-3 is connected to the square plate 3-7. The center lines of the horizontal beam 3-5 and the transmission shaft 2-1 are on the same vertical plane.

[0037] For propeller power meters 2-5, the following types of propeller power meters are selected: CUSSONS Technology Company R25-1~R73-1, Kempf & Remmers Company R25 ~ R73, or Hanlin Kechuang Company PropellerBox1500. These types of propeller power meters use modern rotating and non-rotating sensor technology and can measure the thrust of a ship at different speeds during self-propulsion.

[0038] The cylindrical force gauges 3-4 selected are SBT674~SBT671 from SBT Corporation, WD-50~WD-1000 from Vedo Corporation, and DYZ-100~DYZ-101 from Ocean Sensing. These cylindrical force gauges have a cylindrical shape and high accuracy, and can measure the thrust generated by the guide tube at different speeds during self-propulsion.

[0039] During installation, the force measuring device for the ducted propeller is first assembled according to the testing requirements of the open-water test. First, the propeller thrust testing mechanism 2 is assembled. The motor 2-3 and the propeller power unit 2-5 are fixed to the bottom of the open-water tank 1-2 in the main body 1 using bolts. The propeller power unit 2-5 and the motor 2-3 are connected via a universal joint 2-4, allowing the corresponding kinetic energy to be transmitted to the drive shaft 2-1 through the universal joint 2-4. The side of the propeller power unit 2-5 facing the propeller blade is inserted into the drive shaft 2-1. The drive shaft 2-1 passes through the open-water tank 1-2, and a waterproof gasket is provided at the through-hole. The drive shaft 2-1 is keyed to the propeller blade 2-2 via a flat key. The cable is connected to the motor 2-3, and the propeller thrust testing mechanism 2 is tested in the air at different motor speeds to see if it can measure force normally. For example, whether the universal joint 2-4 and the drive shaft 2-1 can normally transmit power to the propeller blade 2-2, and whether the propeller power unit 2-5 can work normally.

[0040] The upper square plate of the telescopic bracket 3-2 is bolted to one end of the hinge 3-3; the other end of the hinge 3-3 is connected to the L-shaped beam 3-6; the upper end of the telescopic bracket 3-2 is a square plate 3-7, which is fixed to one end of the cylindrical force gauge 3-4 by bolts; the vertical side of the L-shaped beam 3-6 is fastened to the cylindrical force gauge 3-4 by bolts; the hinge 3-3 allows the integrated structure formed by the guide tube 3-1 and the telescopic bracket 3-2 to rotate relative to the L-shaped beam 3-6; utilizing the lever principle, the hinge 3-3 becomes the fulcrum, and the thrust generated by the guide tube 3-1 is transmitted to the cylindrical force gauge 3-4. Connect the cable and signal line to the cylindrical force gauge 3-4 and observe whether the corresponding force on the guide tube is normal.

[0041] After the duct and propeller force measuring mechanism are assembled, the main body 1 is lifted to the position of the water tank trailer by a crane, and the connecting bracket 1-1 is fastened to the water tank trailer with bolts; the submersion depth of the open water tank 1-2 should not be less than the diameter of the duct propeller, so that the corresponding duct propeller is submerged to the experimental water depth, thereby eliminating the influence of wave generation on the water surface.

[0042] During testing, motor 2-3 is started, and the rotational speed of propeller blade 2-2 is set. The thrust of propeller blade 2-2 and guide tube 3-1 is measured by propeller force measuring mechanism 2 and guide tube force measuring mechanism 3, respectively. The results are added together to obtain the total thrust of the ducted propeller at zero advance speed under different rotational speeds. The tank trailer carries the main body 1 forward at different speeds, and the rated rotational speed of the ducted propeller is set using motor 2-3. This yields the total thrust of the ducted propeller at different advance speeds. The advance speed is the speed at which the tank trailer moves forward, set by relevant instruments on the tank trailer.

[0043] Compared to Chinese invention patent application 202210357629, this invention can adjust the vertical position of the guide tube 3-1 via the telescopic bracket 3-2, achieving alignment between the guide tube 3-1 and the propeller blade 2-2. This reduces the thrust center deviation caused by manufacturing errors and improves the accuracy of measuring the propeller thrust of the guide tube. In contrast, Chinese invention patent application 202210357629, without being able to change this manufacturing error, requires the use of three sets of lever arms to calculate the corresponding thrust or pull. Each set of lever arms has a measurement error in length, and the conversion process also introduces corresponding errors.

[0044] The bottom guide tube 3-1 of this invention is detachable, which can meet the needs of measuring the fit between various guide tubes and a certain propeller blade when actually developing and designing a ducted propeller. For example, when considering the effect of the Ka 4-70 propeller blade and the guide tube, different guide tubes 3-1 can be replaced and installed on the airfoil slender rod 3-8 to measure the thrust of different guide tubes 3-1.

[0045] One side of hinge 3-3 connects to the horizontal end of L-shaped beam 3-6, and the other side of hinge 3-3 connects to square plate 3-7. Hinge 3-3 serves as a fulcrum to transfer the thrust of the guide tube to the cylindrical force gauge, and also connects the L-shaped beam and telescopic bracket 3-2, making it a stable frame structure. The combination of telescopic bracket 3-2, hinge 3-3, and L-shaped beam 3-6 effectively enhances the strength and stability of the guide tube thrust measurement mechanism 3, preventing the cylindrical force gauge from shaking and causing a decrease in force measurement accuracy when the guide tube is under force.

[0046] This invention utilizes an airfoil-shaped slender rod 3-8 to significantly reduce the hydrodynamic force it experiences, making it negligible compared to the thrust of the guide tube 3-1 to be measured. This is equivalent to the cylindrical force gauge 3-4 directly measuring the thrust of the guide tube 3-1. This reduces the intermediate conversion process and improves the accuracy of measuring the thrust of the guide tube 3-1. In contrast, Chinese invention patent application 202210357629 uses a large propeller mounting bracket and stern plate mounting bracket, which do not consider the significant impact of their hydrodynamic forces on the thrust of the ducted propeller. Especially when measuring the open-water performance of the ducted propeller, the force on this bracket is not negligible, and the resulting eddies have a significant impact on the ducted propeller, leading to a large thrust error.

[0047] It should be noted that the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent alternatives and shall be included within the protection scope of the present invention.

Claims

1. A thrust testing device for an open-water ducted propeller, characterized in that, It includes a main body, a propeller thrust testing mechanism, and a guide tube thrust testing mechanism; the main body includes a connecting bracket and an open water tank; the open water tank is a cavity structure with a hollow cavity; the connecting bracket is fixed to the top of the cavity structure; The propeller thrust testing mechanism includes a drive shaft, propeller blades, a motor, and a propeller power instrument; the motor, propeller power instrument, and drive shaft are connected in sequence, the motor and propeller power instrument are located at the bottom of the open water tank cavity and on the front-to-back central axis of the open water tank, and the other end of the drive shaft extends out of the open water tank cavity and connects to the propeller blades; The aforementioned guide tube thrust testing mechanism includes a guide tube, a telescopic support, a hinge, a cylindrical force gauge, a horizontal beam, and an L-shaped beam. The telescopic support includes a square plate and an airfoil-shaped slender rod. Multiple threaded holes are spaced horizontally from both sides of the square plate towards the center, with bolts installed in these holes. An opening runs from bottom to top in the center of the square plate, and the airfoil-shaped slender rod enters the square plate from bottom to top. The guide tube is positioned on the outer periphery of the propeller blade and is connected to the square plate via the airfoil-shaped slender rod. The upper end of the square plate is connected to the cylindrical force gauge, which is bolted to the L-shaped beam. The vertical end of the L-shaped beam is connected to one end of the horizontal beam, and the other end of the horizontal beam is fixed to the top of the open water tank. One hinge is connected to the horizontal end of the L-shaped beam, and the other hinge is connected to the square plate. The centerlines of the horizontal beam and the drive shaft are on the same vertical plane.

2. The thrust testing device for open-water ducted propellers according to claim 1, characterized in that, The main body also includes a wave-damping plate, which is disposed on the outer periphery of the open water tank and rigidly connected to the open water tank.

3. The thrust testing device for open-water ducted propellers according to claim 2, characterized in that, Counting from top to bottom, the wave-damping plate is positioned at 1 / 3 to 2 / 3 of the height of the open water tank.

4. The thrust testing device for open-water ducted propellers according to claim 1, characterized in that, The open water tank is a rectangular cavity structure with rounded ends; there are two connecting brackets, which are symmetrically arranged about the central axis of the open water tank in the left and right directions.

5. The thrust testing device for open-water ducted propellers according to claim 1, characterized in that, The drive shaft is located at the lower end of the wave deflector; the drive shaft is connected to the propeller blade via a flat key.

6. The thrust testing device for open-water ducted propellers according to claim 1, characterized in that, The propeller thrust testing mechanism also includes a universal joint, through which the motor is connected to the drive shaft.

7. The thrust testing device for open-water ducted propellers according to claim 1, characterized in that, The square plate is fixed to the cylindrical force gauge by bolts.

8. The thrust testing device for open-water ducted propellers according to claim 1, characterized in that, The other hinge is connected to the lower horizontal center of the square plate by bolts.

Images