JP2009103604A - Device for measuring thrust of water jet propelled ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and easily measure a thrust. <P>SOLUTION: A lower part of a stern part installed with a water jet pump 4 is manufactured separately from a main hull model 2 as a stern portion model 3, in a hull model 1 of a water jet propelled ship. The stern portion model 3 is held to the main hull model 2 displaceably along a longitudinal horizontal direction via guide rails 9 and a guide block 10. A load cell 5 is attached to the main hull model 2, and a rear end of the load cell 5 is connected to an inner upper end position of a rear end wall of the stern portion model 3 via a longitudinal-directional connecting member 11. The thrust generated by a reaction of a water jet jetted rearwards by driving the water jet pump 4 is transmitted from the stern portion model 3 to the main hull model 2 via the connecting member 11 and the load cell 5, to advance the hull model 1, and the thrust acting actually as a driving force is directly measured therein by the load cell 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thrust measuring apparatus for a water jet propulsion ship used for measuring thrust as one of the propulsion performance tests of a ship equipped with a water jet propulsion apparatus.

  When conducting a ship propulsion performance test, it is necessary to measure the thrust generated by the propulsion device.

  In the case of a ship equipped with a propeller propulsion device, a method of directly measuring the thrust generated by the propeller directly with a load cell connected to the propeller shaft is employed.

  On the other hand, in the case of a ship equipped with a water jet propulsion device (hereinafter referred to as a water jet propulsion vessel), the thrust of the water jet propulsion device is boosted by a water jet pump and then reacts with the reaction force of the water jet (reaction) ) Is generated directly with respect to the hull to which the pump casing is fixed, and cannot be measured with a load cell connected to the drive shaft of the impeller (impeller) of the water jet pump.

  Therefore, as a method for measuring the thrust generated by a water jet propulsion device in a conventional water jet propulsion ship, a water jet injection nozzle is divided into two stages having a large diameter portion and a small diameter portion. Either a nozzle or a water pressure at a large diameter and a water pressure at a thin diameter are measured using pressure holes, respectively, and the measured values of the water pressure measured at the thick diameter and the thin diameter, The flow rate and flow velocity of water discharged from the water jet propulsion device are calculated using the Bernoulli's equation from the nozzle cross-sectional area of the thick and thin diameters, and the equation of motion is calculated from the calculated flow rate and flow velocity of the water. A method of calculating a thrust as a force by using the method has been mainly used (see, for example, Patent Document 1).

  Conventionally, as a test device for measuring the thrust of a single water jet propulsion device, as shown in FIG. 3, an engine b having a predetermined horsepower for testing is added to a box-shaped test carriage a that can be moved by wheels. A predetermined capacity water jet pump c connected to the engine b via an intermediate shaft d, and the test carriage a is placed in a water tank e such as a pool, and the test carriage a There has been proposed a water jet test apparatus in which a thrust meter f attached to the rear part can be pressed against the wall surface of the water tank e through a thrust receiver g.

  According to the water jet test apparatus having such a configuration, when the water jet pump c is driven by the operation of the engine b, the water in the water tank e is sucked into the water jet pump c from the suction port h, and is discharged from the injection nozzle i at a high speed. The thrust generated by the water jet can be measured by the thrust meter f. Here, j is an intake duct of the water jet pump c (see, for example, Patent Document 2).

JP 2005-225419 A JP-A-9-142383

  However, conventionally proposed methods for measuring the thrust generated by a water jet propulsion device in a water jet propulsion ship are different parts of the diameter of a two-stage nozzle or the pressure of water in a nozzle of a different diameter. Based on the differential pressure and the nozzle cross-sectional area, the flow rate and flow velocity of the water jet are calculated using theoretical equations, and the thrust is calculated from the flow rate and flow velocity using the equation of motion. There are many factors that introduce errors in the process of obtaining thrust, such as errors due to density changes due to, manufacturing errors of nozzle diameter when manufacturing the designed nozzle, errors for each sensor caused by using multiple sensors, etc. Therefore, the measurement accuracy of the thrust generated by the water jet propulsion device in the water jet propulsion ship is not so high. Is Jo.

  In addition, in order to accurately grasp the relationship between the nozzle differential pressure and the flow rate, it is necessary to separately perform a calibration test using only the nozzle. For this calibration test, a separate test device dedicated to calibration is required. In fact, there is a problem that time and labor are increased.

  However, since the evaluation of the propulsion performance of the ship is performed in an area with a difference of several percent, the thrust generated by the water jet propulsion device in the water jet propulsion ship including the above error is measured. Even if it does, it will not be possible to perform the same propulsion performance evaluation as a ship equipped with a propeller propulsion machine.

  Therefore, in order to be able to correctly evaluate the propulsion performance of the water jet propulsion ship, the thrust generated by the water jet propulsion apparatus in the water jet propulsion ship can be measured more accurately and easily. It is hoped to do.

  The water jet test apparatus described in Patent Document 2 can measure the thrust of the water jet propulsion unit alone, but is applied to the measurement of the thrust generated by the water jet propulsion apparatus in the water jet propulsion ship. It is not possible.

  That is, when the water jet propulsion ship advances, in addition to the water sucked into the water jet pump through the intake duct from the inlet of the ship bottom by driving the water jet pump, the water jet propulsion ship moves along the bottom of the water jet propulsion ship as the water jet propulsion ship advances. Accordingly, a part of the relatively flowing water can flow into the intake duct from the suction port at the bottom of the ship, so that the inflow speed generated in the intake duct is the inflow generated only by the suction action of the water jet pump. Will be faster. In addition, since the flow velocity of water relatively flowing along the bottom of the water jet propulsion ship becomes slower as the water jet propulsion ship moves forward, the speed distribution is generated in the inflow in the intake duct.

  Therefore, in the water jet pump of the water jet propulsion unit equipped on the water jet propulsion ship, the flow speed and velocity distribution of the inflow reaching the impeller through the intake duct are different from the case of the water jet pump alone. Change.

  Further, when the water flowing relatively along the ship bottom as the water jet propulsion vessel moves forward flows into the intake duct of the water jet pump, the water flowing direction changes, A vortex may be generated in the impeller, and the impeller efficiency also changes when the vortex reaches the impeller.

  Therefore, even if the thrust of the water jet propulsion device alone can be measured, the thrust generated by the water jet propulsion device installed in the water jet propulsion ship cannot be measured accurately.

  In addition, when the water jet pump is driven in the water jet propulsion ship, water is filled in the pump casing, the intake duct, and the injection nozzle of the water jet pump, so that it acts on the stern portion of the water jet propulsion ship. The load increases, and the draft and trim of the stern part of the water jet propulsion ship change, and the hull resistance changes.

  Therefore, in order to accurately measure the thrust generated by the water jet propulsion apparatus of the water jet propulsion ship, it is necessary to measure the thrust while the water jet propulsion apparatus is mounted on the water jet propulsion ship.

  Therefore, the present invention is intended to provide a water jet propulsion ship thrust measurement device for enabling accurate and easy measurement of the thrust generated by the water jet propulsion device in the water jet propulsion vessel.

  In order to solve the above-mentioned problem, the present invention, corresponding to claim 1, the hull model of the water jet propulsion ship is a separate structure of the stern partial model including the water jet pump installation location and the main hull model. The stern partial model equipped with the water jet pump is held by the main hull model so as to be displaceable in the front-rear and horizontal directions, and the forward force of the stern partial model is maintained between the stern partial model and the main hull model. A load cell that measures the size, and the thrust that is input to the stern part model as the reaction force of the water jet generated by driving the water jet pump can be measured at the same time as it is transmitted to the main hull model through the load cell And

  In the above configuration, the load cell is installed on either the main hull model or the stern partial model, and the load cell is connected to either the main hull model or the stern partial model via a connecting member. The configuration is as follows.

  Further, in each of the above configurations, a gap having a required dimension is formed between the front end portions of the bottom shell plate and the ship side skin plate of the stern partial model and the rear end portions of the bottom shell plate and the ship side skin plate of the main hull model. In addition, the outside of the gap is water-tightly attached with a sealing material to seal the gap.

  In each of the above-described configurations, a joint that transmits only the rotational driving force to the main shaft of the water jet pump installed in the stern partial model, and the shaft for power transmission connected to the driving device installed in the main hull model Connected via

According to the thrust measuring device for a water jet propulsion ship of the present invention, the following excellent effects are exhibited.
(1) The hull model of the water jet propulsion ship is a separate structure of the stern partial model including the location where the water jet pump is installed and the main hull model. Generated by driving the water jet pump with a load cell that measures the magnitude of the forward force of the stern partial model between the stern partial model and the main hull model. The thrust input to the stern partial model as the reaction force of the water jet to be transmitted is transmitted to the main hull model through the load cell and simultaneously measured, and the load cell is either the main hull model or the stern partial model. And connecting the load cell to the other one of the main hull model and the stern partial model. The water jet pump is driven to generate a water jet, and the thrust generated as a reaction force is once input to the stern partial model, and then the main hull via the load cell. By transmitting to the model, the hull model of the water jet propulsion ship can be caused to act as a propulsive force, and the hull model can be advanced against the resistance of water. At this time, since the thrust acting as the propulsive force of the hull model of the water jet propulsion ship can be measured by the load cell, a water jet propulsion device is generated in the hull model of the water jet propulsion ship. Since the thrust can be measured with high accuracy, and the thrust can be directly measured by the load cell, the thrust can be easily measured without requiring a complicated calculation.
(2) A clearance having a required dimension is formed between the front end portions of the bottom and outer side plates of the stern partial model and the rear end portions of the bottom and outer side plates of the main hull model, and When the forward force is applied to the stern partial model, the stern partial model and the main hull are configured so that the outside of the gap is water-tightly attached with a sealing material to seal the gap. Even if the gap with the model is somewhat reduced in the front-rear direction, it can be absorbed by the bending of the sealing material. In addition, direct transmission of force to the rear end of the ship side skin can be prevented. Therefore, it is possible to more accurately measure the thrust generated by the water jet propulsion device with the hull model of the water jet propulsion ship.
(3) A power transmission shaft connected to the drive unit installed on the main hull model is connected to the main shaft of the water jet pump installed on the stern partial model via a joint that transmits only the rotational driving force. When the water jet pump is driven by a drive device installed on the main hull model, the reaction force of the water jet generated by the water jet pump is caused by the main shaft of the water jet pump to The thrust generated by the water jet propulsion device can be measured more accurately in the hull model of the water jet propulsion ship. .

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1 and 2 show an embodiment of a water jet propulsion ship thrust measurement apparatus according to the present invention. A water hull model 1 having a desired hull shape desired for a water jet propulsion ship is installed in a water jet pump 4. 2 consisting of a main hull model 2 having a shape in which a lower part of a stern part serving as a part is cut out, and a stern partial model 3 having a shape only in a lower part of the stern part serving as a location for installing the water jet pump 4 in the hull model 1 Produced as a divided structure, the stern partial model 3 is equipped with a water jet pump 4.

  Further, the stern partial model 3 is held by the main hull model 2 so as to be displaceable in the front-rear and horizontal directions via a slide mechanism, which will be described later. A configuration is adopted in which a load cell 5 capable of measuring a force acting in the front-rear and horizontal directions is interposed and connected to a required portion. Thus, the thrust that acts on the stern partial model 3 provided with the water jet pump 4 by the reaction force of water (water jet) ejected from the water jet pump 4 is mainly transmitted through the load cell 5. The thrust is generated by the reaction force of the water jet so that the load cell 5 can measure the thrust.

  More specifically, the main hull model 2 and the stern partial model 3 are configured such that the lower part of the stern part of the hull model 1 of the water jet propulsion ship is above the required dimension above the water line and above the injection nozzle 6 of the water jet pump 4. A horizontal plane at a height position above and a vertical plane perpendicular to the bow-stern direction at a position ahead of a required dimension from the inlet 8 which is an opening on the bottom side of the intake duct 7 of the water jet pump 4, Each is manufactured in a key-shaped shape when viewed from the side.

  The left and right bottom sides of the stern-side projecting portion 2a projecting rearward from the stern-side upper end of the main hull model 2 to the upper position of the stern-part model 3 For example, a guide rail 9 extending in the front-rear horizontal direction and a guide block 10 attached to the guide rail 9 so as to be slidable in the longitudinal direction are connected to the upper end portion of the ship side outer plate as a slide mechanism. Thereby, the stern partial model 3 can be displaced in the front-rear horizontal direction with respect to the main hull model 2.

  Further, as a connecting structure including the load cell 5 of the main hull model 2 and the stern partial model 3, for example, a force acting in the front-rear direction on the lower side of the stern-side protruding portion 2a in the main hull model 2 can be measured. The load cell 5 is attached to the inside of the stern partial model 3 so as to project the required dimension, and the rear end portion of the load cell 5 and the inner side of the rear end wall of the stern partial model 3 located on the rear side in the horizontal direction. The upper end position is connected to the main hull model 2 of the stern partial model 3 by fixing the position of the upper end part via a connecting member 11 extending in the front-rear direction. As a result, the forward force input to the stern partial model 3 can be transmitted to the main hull model 2 via the connecting member 11 and the load cell 5, and the main hull from the stern partial model 3. The magnitude of the forward force transmitted to the model 2 can be measured by the load cell 5.

  When the main hull model 2 and the stern partial model 3 are connected via the connecting member 11 and the load cell 5 as described above, the ship bottom skin and the front end of the ship side skin of the stern partial model 3 face each other. In the main hull model 2, a gap with a size of several millimeters to several tens of millimeters is formed in the front-rear direction between the stern side bottom skin plate and the rear end portion of the ship side skin plate. Both end edges in the front-rear width direction of the wide tape-shaped sealing material 12 such as aluminum tape arranged so as to cover the gap from the outside, and the front edge of the ship bottom skin and ship side skin of the stern partial model 3, Affixed to the stern-side ship bottom skin and the rear edge of the ship-side skin in the main hull model 2 facing each other. Thus, waterproofing is performed between the front end portions of the bottom shell plate and the ship side skin plate of the stern partial model 3 and the rear end portions of the ship bottom skin plate and the ship side skin plate of the main hull model 2 opposed thereto. It is. Further, when a forward force in the horizontal direction acts on the stern partial model 3, even if the gap between the stern partial model 3 and the main hull model 2 is somewhat reduced in the front-rear direction, the stern partial model 3 is absorbed by the bending of the sealing material 12. This prevents the transmission of direct force from the front end of the stern part model 3 to the stern side bottom plate and to the rear end of the ship side skin in the main hull model 2. I can do it. In FIG. 1, for convenience of illustration, the thickness of the sealing material 12 is shown thick. However, in actuality, during the navigation test using the hull model 1 of the water jet propulsion ship, the main hull model 2 and the stern part are shown. It is assumed that the thickness dimension is such that the influence on the water flow generated along the ship bottom skin and the ship side skin of the model 3 is almost negligible.

  The stern partial model 3 includes an intake duct 7 that communicates a suction port 8 that is opened to the bottom of the ship and an injection nozzle 6 that is opened to the stern end, and the inside of the intake duct 7 via a bearing 14 on the hull side. A water jet pump 4 is provided that includes a main shaft 13 that is rotatably supported and an impeller 15 that constitutes an axial flow pump attached to the tip of the main shaft 13.

  Further, the main shaft 13 of the water jet pump 4 is thrust on the tip of a power transmission shaft 17 connected to the output side of a drive motor 16 as a drive device installed at a required location of the main hull model 2. As the free joint, for example, it is configured to be connected via a thrust free joint 18 including a spline shaft and a spline bearing (not shown). As a result, the rotational driving force output by the operation of the drive motor 16 is transmitted to the main shaft 13 of the water jet pump 4 through the shaft 17 and the thrust-free joint 18, and integrated with the main shaft 13 in the intake duct 7. By rotating the impeller 15, the water sucked into the intake duct 7 from the suction port 8 provided on the bottom of the ship can be injected as a water jet backward from the injection nozzle 6 after being pressurized by the rotating impeller 15. It is. At this time, the thrust generated as the reaction force of the water jet acts as a forward force on the main shaft 13 of the water jet pump 4. The forward force acting on the main shaft 13 is caused by the main shaft 13 and the shaft 17. Is absorbed by a thrust-free joint 18 interposed therebetween, so that it is not transmitted to the drive motor 16 installed on the main hull model 2 side via the shaft 17.

  When the thrust measuring device for a water jet propulsion ship having the above-described configuration is used, the water jet pump 4 is driven by the operation of the drive motor 16, and the water sucked into the intake duct 7 from the suction port 8 provided on the bottom of the ship. After being pressurized by the water jet pump 4, it is injected as a water jet from the injection nozzle 6, and the hull model 1 of the water jet propulsion ship is advanced by its reaction force (reaction). At this time, the thrust generated as the reaction force of the water jet is once inputted to the stern partial model 3 provided with the water jet pump 4 and then transmitted to the main hull model 2 via the connecting member 11 and the load cell 5. As a result, the hull model 1 of the water jet propulsion ship acts as a propulsive force for advancing against the resistance of the water, so that the hull of the water jet propulsion ship is generated as a reaction force of the water jet. The thrust actually acting on the model 1 as a driving force is directly measured by the load cell 5.

  As described above, according to the thrust measuring device for a water jet propulsion ship of the present invention, the water jet propulsion device in which the water jet pump 4 is driven by the drive motor 16 and the water jet is jetted from the jet nozzle 6 is used. Since the thrust of the water jet propulsion device acting as the propulsive force of the water jet propulsion vessel can be directly measured by the load cell 5 when the hull model 1 of the jet propulsion vessel is actually advanced, the value of the thrust is calculated. Accurate measurement is possible.

  In addition, the thrust of the water jet propulsion device can be easily obtained as an actual measurement value in the load cell 5 without requiring a complicated calculation.

  In addition, this invention is not limited only to the said embodiment, The load cell 5 for measuring the force which acts on the said front-back direction is the stern part hold | maintained to the main hull model 2 so that the displacement to the front-back direction was possible. The stern part 3 is connected so as to be interposed between the required part of the model 3 and the required part of the main hull model 2, and the position of the stern part model 3 with respect to the main hull model 2 is fixed. The forward force input to the model 3 may be configured to be transmitted to the main hull model 2 after passing through the load cell 5. Therefore, the stern partial model 3 and the main hull model that are provided with the load cell 5 interposed therebetween. For example, as shown in FIG. 2 (a), the stern partial model 3 below the load cell 5 is attached to the lower end of the load cell 5 attached to the required portion of the stern-side protrusion 2a of the main hull model 2. Inside The connecting portion 19 provided at the location is configured to be connected via a connecting member 20 in the vertical direction, or as shown in FIG. 2 (B), it is attached to a required location on the inner bottom portion of the main hull model 2 via an attachment member 21. The connecting portion 22 provided at a required position on the inner bottom portion of the stern partial model 3 that is behind the load cell 5 may be connected via a rod-like connecting member 23 that extends in the front-rear direction. Good. In addition, the load cell 5 may be provided on the stern partial model 3 side, such as the water jet pump 4 provided on the stern partial model 3, the drive motor 16 provided on the main hull model 2, and the shaft 17 within a range not interfering with each other. Any configuration other than that illustrated may be employed. 2A and 2B, the description of the water jet pump is omitted for convenience of illustrating the above-described configuration.

  The thrust-free joint 18 used for connection between the main shaft 13 of the water jet pump 4 and the shaft 17 connected to the drive motor 16 transmits only the rotational drive force and does not transmit the axial force. Any type of thrust free joint other than the type consisting of a spline shaft and a spline bearing may be used.

  If the stern partial model 3 can be held in the main hull model 2 so as to be displaceable in the front-rear and horizontal directions, the stern can be formed by any configuration other than the front-rear and horizontal guide rails 9 and the guide blocks 10 slidably attached to the guide rails 9. The partial model 3 may be held by the main hull model 2.

  The dividing surface that divides the main hull model 2 and the stern partial model 3 in the front-rear direction may be slightly inclined in the front-rear direction from the vertical direction. Further, the main hull model 2 and the stern partial model 3 are orthogonal to the stern direction of the stern portion of the hull model 1 at a position ahead of the suction port 8 at the bottom of the intake duct 7 of the water jet pump 4 by a required dimension. It is good also as a shape divided | segmented only by the perpendicular | vertical surface or the division | segmentation surface slightly inclined in the front-back direction from the perpendicular direction. In this case, for example, one of the main hull model 2 or the stern partial model 3 is provided with a front / rear horizontal guide rail extending inward of the other side of the main hull model 2 or the stern partial model 3, What is necessary is just to employ | adopt the structure of attaching the guide block attached to the other of the main hull model 2 or the stern partial model 3 so that sliding is possible.

  As long as the gap between the bottom skin and the ship side skin of the main hull model 2 and the stern partial model 3 can be sealed in a water-tight manner and can absorb some shrinkage of the gap, a sealing material other than tape 12 may be used.

  As a hull model of a water jet propulsion ship, the number of water jet pumps 4 is one or a plurality of types, the type in which the drive unit is an engine instead of the drive motor, and the plurality of water jet pumps are driven by one drive unit. Needless to say, the present invention can be applied to any form such as the above-described forms, and various modifications can be made without departing from the scope of the present invention.

1 is a schematic cut side view showing an embodiment of a thrust measuring device for a water jet propulsion ship of the present invention. (A) and (b) are schematic views showing modified examples of the connecting structure in which the load cell between the stern partial model and the main hull model is interposed in the apparatus of FIG. It is a figure which shows the outline | summary of the water jet test apparatus conventionally conventionally proposed in order to measure the thrust of a water jet propulsion apparatus alone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water jet propulsion ship hull model 2 Main hull model 3 Stern partial model 4 Water jet pump 5 Load cell 11 Connecting member 12 Sealing material 13 Spindle 16 Drive motor (drive device)
17 Shaft 18 Thrust-free fitting (Fitting)

Claims (4)

  The hull model of the water jet propulsion ship is a separate structure of the stern partial model including the location where the water jet pump is installed and the main hull model, and the stern partial model equipped with the water jet pump is placed in front of and behind the main hull model. A water jet that is held so as to be displaceable in the horizontal direction and that measures a forward force of the stern partial model between the stern partial model and the main hull model, and is generated by driving the water jet pump. A thrust measuring device for a water jet propulsion ship, characterized in that the thrust input to the stern partial model as a reaction force can be measured at the same time as being transmitted to the main hull model through the load cell.   2. The load cell is installed on one of a main hull model and a stern partial model, and the load cell is connected to one of the main hull model and the stern partial model via a connecting member. Thrust measurement device for water jet propulsion vessels.   A gap of a required dimension is formed between the front end of the bottom shell plate and the ship side skin of the stern partial model and the rear end portion of the bottom shell plate and the ship side skin of the main hull model, and the gap The thrust measuring device for a water jet propulsion ship according to claim 1 or 2, wherein the outside is affixed with a sealing material in a watertight manner to seal the gap.   Claims where the shaft for power transmission connected to the drive unit installed on the main hull model is connected to the main shaft of the water jet pump mounted on the stern partial model via a joint that transmits only the rotational driving force. Item 4. The water jet propulsion ship thrust measurement device according to Item 1, 2 or 3.

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