WO2020025753A1 - Cavitation monitoring system and pod driver - Google Patents

Cavitation monitoring system and pod driver Download PDF

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Publication number
WO2020025753A1
WO2020025753A1 PCT/EP2019/070781 EP2019070781W WO2020025753A1 WO 2020025753 A1 WO2020025753 A1 WO 2020025753A1 EP 2019070781 W EP2019070781 W EP 2019070781W WO 2020025753 A1 WO2020025753 A1 WO 2020025753A1
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WO
WIPO (PCT)
Prior art keywords
cavitation
pressure
processing unit
rudder
liquid
Prior art date
Application number
PCT/EP2019/070781
Other languages
French (fr)
Inventor
Zhong Wei TIAN
Rui Chun DUAN
Yong Yang
Da Wei LIU
Rui Nan WANG
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2020025753A1 publication Critical patent/WO2020025753A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H1/00—Propulsive elements directly acting on water
    • B63H1/02—Propulsive elements directly acting on water of rotary type
    • B63H1/12—Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
    • B63H1/14—Propellers
    • B63H1/18—Propellers with means for diminishing cavitation, e.g. supercavitation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H1/00—Propulsive elements directly acting on water
    • B63H1/02—Propulsive elements directly acting on water of rotary type
    • B63H1/12—Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
    • B63H1/14—Propellers
    • B63H1/28—Other means for improving propeller efficiency
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
    • B63H25/06—Steering by rudders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
    • B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
    • B63H5/125—Arrangements on vessels of propulsion elements directly acting on water of propellers movably mounted with respect to hull, e.g. adjustable in direction, e.g. podded azimuthing thrusters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
    • B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
    • B63H2005/075—Arrangements on vessels of propulsion elements directly acting on water of propellers using non-azimuthing podded propulsor units, i.e. podded units without means for rotation about a vertical axis, e.g. rigidly connected to the hull
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
    • B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
    • B63H5/125—Arrangements on vessels of propulsion elements directly acting on water of propellers movably mounted with respect to hull, e.g. adjustable in direction, e.g. podded azimuthing thrusters
    • B63H2005/1254—Podded azimuthing thrusters, i.e. podded thruster units arranged inboard for rotation about vertical axis
    • B63H2005/1258—Podded azimuthing thrusters, i.e. podded thruster units arranged inboard for rotation about vertical axis with electric power transmission to propellers, i.e. with integrated electric propeller motors

Abstract

Cavitation monitoring system and a pod driver, comprising: a pressure sensing device, disposed on the surface of the rudder body of the pod driver sensing pressure on the surface of the rudder body; and a processing unit, configured to, obtain the pressure around the pressure sensing device and determine whether the obtained pressure is smaller than or equal to a preset threshold, wherein when the processing unit determines that the obtained pressure is smaller than or equal to the preset threshold, it determines that cavitation will occur in the liquid, the threshold being greater than or equal to the critical pressure under which cavitation occurs in a liquid around the pressure sensing device. Therefore, since cavitation can be determined in advance, the sailing status of the ship can be changed actively or automatically, thus avoiding cavitation.

Description

S p e c i f i c a t i o n
Cavitation monitoring system and pod driver
Technical Field
The present invention relates to a cavitation monitoring system and a pod driver.
Background Art
A pod driver can function as a driving unit of a ship. In such an application, the pod driver can be disposed outside of the hull of the ship and underwater, for example, in seawater A pod driver can comprise a motor and a motor-driven propeller to supply power to the ship. Such a driver is known as a pod driver .
A pod driver generally comprises a main body, in which a propeller and a motor for driving the propeller are mounted, and a rudder body connected between the main body and the hull of the ship. The frontal edge of the rudder body, located upstream of a water flow, generally has a large thickness, thereby ensuring that no cavitation occurs even when the rudder angle is large. However, such a design having a thick frontal edge may increase the resistance of the water flow, decreasing the overall efficiency of the pod driver.
Moreover, in actual operation, sudden acceleration, transverse flow, etc. may speed up cavitation. Therefore, a thicker frontal edge may need to be designed for the rudder body, thus preventing cavitation in such a case.
Summary of the Invention
An objective of the present invention is to provide a cavitation monitoring system and a pod driver for solving the above-mentioned technical solution and/or other technical solutions .
According to an exemplary embodiment, a pod driver is provided, comprising: a main body; a propeller, rotatably mounted at an end portion of the main body; a rudder body, configured to connect the main body to the hull of a ship mounted with and driven by the pod driver, and a pressure sensing device, disposed on the surface of the rudder body and configured to sense pressure of a liquid on the surface of the rudder body. Therefore, a pod driver according to the exemplary embodiment can obtain pressure on a surface of the rudder, for example, a place prone to cavitation; thus, whether cavitation will occur can be determined on the basis of the obtained pressure, and the operating status of the propeller can be changed actively or automatically to avoid cavitation .
The rudder body comprises a frontal edge, wherein the pressure sensing device is disposed on the surface of the frontal edge of the rudder body. The pressure sensing device comprises a plurality of pressure sensors, wherein the plurality of pressure sensors are respectively disposed on the surface of either side of the rudder body. A plurality of pressure sensors among the plurality of pressure sensors that are disposed on the surface of one of the two sides of the rudder body comprise one or more main pressure sensors and one or more secondary pressure sensors, wherein a secondary pressure sensor is configured to start when a main pressure sensor stops.
The pod driver further comprises: a processing unit, configured to, based on output from the pressure sensing device, obtain pressure of a liquid around the pressure sensing device . The processing unit is configured to determine whether the obtained pressure is smaller than or equal to a preset threshold and, when determining that the obtained pressure is smaller than or equal to the preset threshold, determine that cavitation will occur in the liquid, wherein the threshold is greater than or equal to the critical pressure under which cavitation occurs in a liquid around the pressure sensing device.
The pod driver further comprises: an alarm unit, connected to the processing unit, wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send an alarm command to the alarm unit so that the alarm unit gives the alarm. The processing unit is connected to a driving control system that is used to control the driving of a ship mounted with the pod driver, wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for adjusting the driving of the ship to the driving control system, thereby adjusting the driving of the ship. For example, the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for propeller speed regulation to a propeller speed regulation module comprised by the driving control system, thereby decreasing the rotation speed of the propeller. In addition, the processing unit is configured to, if the driving control system is in rudder deflection mode, when it determines that cavitation will occur in the liquid, send a rudder angle control command to a rudder angle control module comprised by the driving control system, thereby decreasing the rudder angle or decreasing the rotation speed of the rudder .
A pod driver according to the exemplary embodiment can actively suppress cavitation, thereby protecting the pod driver against damage by cavities. In addition, the requirements on the appearance design of the pod driver can be relaxed; for example, a relatively thin frontal edge can be designed for the rudder body. Thus, resistance to sailing can be further reduced to achieve a higher efficiency. In addition, noises of the pod driver generated during the sailing of the ship can be reduced to prolong its service life.
According to another exemplary embodiment, a cavitation monitoring system is provided, comprising: a pressure sensing device, disposed on the surface of the rudder body of the pod driver and configured to sense pressure of a liquid on the surface of the rudder body; a processing unit, configured to, based on output from the pressure sensing device, obtain the pressure of a liquid around the pressure sensing device and determine whether the obtained pressure is smaller than or equal to a preset threshold, wherein when the processing unit determines that the obtained pressure is smaller than or equal to the preset threshold, it determines that cavitation will occur in the liquid, the threshold being greater than or equal to the critical pressure under which cavitation occurs in a liquid around the pressure sensing device. Therefore, since cavitation can be determined in advance, the sailing status of the ship can be changed actively or automatically, thus avoiding cavitation.
The rudder body comprises a frontal edge, wherein the pressure sensing device is disposed on the surface of the frontal edge of the rudder body. The pressure sensing device comprises a plurality of pressure sensors, wherein the plurality of pressure sensors are respectively disposed on the surface of either side of the rudder body. A plurality of pressure sensors among the plurality of pressure sensors that are disposed on the surface of one of the two sides of the rudder body comprise one or more main pressure sensors and one or more secondary pressure sensors, wherein a secondary pressure sensor is configured to start when a main pressure sensor stops.
The cavitation monitoring system further comprises: an alarm unit, connected to the processing unit, wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send an alarm command to the alarm unit so that the alarm unit gives the alarm.
The processing unit is connected to a driving control system that is used to control the driving of a ship mounted with the pod driver, wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for adjusting the driving of the ship to the driving control system, thereby adjusting the driving of the ship. For example, the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for propeller speed regulation to a propeller speed regulation module comprised by the driving control system, thereby decreasing the rotation speed of the propeller. In addition, the processing unit is configured to, if the driving control system is in rudder deflection mode, when it determines that cavitation will occur in the liquid, send a rudder angle control command to a rudder angle control module comprised by the driving control system, thereby decreasing the rudder angle or decreasing the rotation speed of the rudder .
A cavitation monitoring system according to the exemplary embodiment can actively suppress cavitation, thereby protecting the pod driver against damage by cavities. In addition, the requirements on the appearance design of the pod driver can be relaxed; for example, a relatively thin frontal edge can be designed for the rudder body. Thus, resistance to sailing can be further reduced to achieve a higher efficiency. In addition, noises of the pod driver generated during the sailing of the ship can be reduced to prolong its service life.
Brief Description of the Drawings
The following drawings are only intended to illustrate and explain the present invention, instead of limiting the scope of the present invention. In the drawings,
Figure 1 is a schematic plan view of a pod driver according to an exemplary embodiment; and
Figure 2 is a schematic diagram for a cavitation monitoring system according to an exemplary embodiment .
Description of reference numerals
100: Main body 300: Propeller 500: Rudder body 510: Frontal edge
710: Pressure sensing device 730: Analog-to-digital converter 750: Processing unit 770: Alarm unit
10: Driving control system 11: Propeller speed regulation module 13: Rudder angle control module
Specific Embodiments
A specific embodiment of the present invention will be described below with reference to the drawings to provide a better understanding of the technical characteristics, objectives, and effects of the present invention.
Figure 1 is a schematic plan view of a pod driver according to an exemplary embodiment. As shown in Figure 1, a pod driver according to the exemplary embodiment comprises a main body 100, a propeller 300, and a rudder body 500. The pod driver can be mounted on the hull (not shown) of the ship, and can be submerged (for example, go under seawater) , thereby pushing the ship forward.
The main body 100 may have a streamlined shape and be capable of accommodating a motor for driving the propeller 300.
The propeller 300 may be installed at one end portion or both end portions of the main body. The propeller 300 may be driven by the motor to rotate, thereby propelling the ship mounted with the pod driver. The propeller 300 shown in Figure 1 is mounted at the end portion of the main body 100 that is upstream of the water flow.
The rudder body 500 may connect the main body 100 to the hull of the ship. The rudder body 500 may function as the rudder of the ship. The rudder body 500 may comprise a frontal edge 510. Here, the frontal edge 510 may be the end portion of the rudder body 500 that is upstream of the water flow passing by the rudder body 500. In Figure 1, the direction of the water flow is indicated by an arrow, wherein the direction of the water flow may be opposite to the sailing direction of the ship. Therefore, the frontal edge 510 of the rudder body 500 shown in Figure 1 may be the end portion near the left side in Figure 1.
As shown in Figure l,the pod driver may further comprise a pressure sensing device 710. The pressure sensing device 710 may be disposed on the surface of the rudder body 500. The rudder body 500 may sense pressure of a fluid on the surface of the rudder body. When a ship mounted with a pod driver sails in seawater or any other liquid medium, the pressure of the water on the surface of the rudder body 500 of the pod driver may change; when the pressure drops to a specific threshold or below, cavitation may occur. A threshold of such pressure may be related to the density and temperature of the liquid medium, and may be calculated on the basis of the characteristics of the liquid medium in which the ship currently sails. Cavities may affect the sailing of the ship and may also damage the character of the surface of the rudder body 500 where cavitation occurs. For example, the surface of the rudder body 500 may be coarsened, or a large number of crateriform indents having various diameters may be formed on it. According to the exemplary example, the pressure sensing device 710 may be disposed in a position of the surface of the rudder body 500 that is most prone to cavitation. As shown in Figure 1, the pressure sensing device 710 may be disposed on the surface of the frontal edge 510 of the rudder body 500 that is prone to cavitation.
The pressure sensing device 710 may comprise a plurality of pressure sensors. The pressure sensors may be distributed on the surface of either side of the rudder body. For example, the pressure sensing device 710 may comprise four pressure sensors, of which two may be disposed on the side face of the frontal edge of the rudder body 500 that is shown in Figure 1, and the other two may be correspondingly disposed on the other side face of the frontal edge of the rudder body 500 that is not shown in Figure 1.
The plurality of pressure sensors in the pressure sensing device 710 may comprise one or more main pressure sensors and one or more secondary pressure sensors. For example, each of the pressure sensors disposed on either side face of the rudder body may comprise a main pressure sensor and a secondary pressure sensor. A main pressure sensor may be started in general use to sense pressure, and a secondary pressure sensor may, when the main pressure sensor stops, start to sense pressure in place of the main pressure sensor. In other words, a secondary pressure sensor may function as a standby pressure sensor. Alternatively, a secondary pressure sensor may be started as needed; for example, if the pressure of the place where a secondary pressure sensor is mounted needs to be known, the secondary pressure sensor may be started.
As shown in Figure l,the pod driver may further comprise a processing unit 750. When the pressure sensing device 710 senses the pressure of a liquid, the pressure sensing device 710 may receive a sensing signal related to the pressure and send the received signal to the processing unit 750. Since a pressure sensor of the pressure sensing device 710 may receive an analog signal, the pod driver may further comprise an analog-to-digital converter 730, as shown in Figure 1. The analog-to-digital converter 730 may be disposed between the pressure sensing device 710 and the processing unit 750 to convert an analog signal from the pressure sensing device 710 into a digital signal and then provide the converted digital signal to the processing unit 750.
In an embodiment, the processing unit 750 may be disposed separately from the pressure sensing device 710. In such a case, signal lines of the sensors in the pressure sensing device 710 may be led out through a slip ring together with other cables of the pod driver and connected to the processing unit 750; therefore, few passages are occupied.
The processing unit 750 may, based on output (that is, a sensing signal) from the pressure sensing device 710, obtain the pressure of the liquid around the pressure sensing device 710. Further, the processing unit 750 may determine whether the obtained pressure is smaller than or equal to a preset threshold and, when it determines that the obtained pressure is smaller than or equal to the preset threshold, determine that cavitation will occur in the liquid. Here, the threshold may be greater than or equal to the critical pressure under which cavitation occurs in the current liquid around the pressure sensing device, and may be determined on the basis of the characteristics, including density and temperature, of the liquid.
When the processing unit 750 determines that the obtained pressure is smaller than or equal to the threshold and thus that cavitation will occur in the liquid, the processing unit 750 may send various commands. For example, the pod driver may comprise an alarm unit 770, as shown in Figure 1. The processing unit 750 may be connected to the alarm unit 770. Upon determining that cavitation will occur, the processing unit 750 may send an alarm to the alarm unit 770 so that the alarm unit 770 gives the alarm. The alarm unit 770 may comprise an alarm signal lamp disposed in the steering room of the ship, for emitting light to warn the steersman that cavitation will occur, so that the steersman changes the current sailing status of the ship to avoid cavitation.
Further, the processing unit 750 may be connected to a driving control system 10 that is used to control the driving of a ship mounted with the pod driver, as shown in Figure 1. The processing unit 750 may be configured to, when it determines that cavitation will occur in the liquid, send a command for adjusting the driving of the ship to the driving control system 10, thereby adjusting the driving of the ship. For example, the processing unit 750 may, when it determines that cavitation will occur in the liquid, send a command for propeller speed regulation to a propeller speed regulation module 11 comprised by the driving control system, so that the propeller speed regulation module 11 decreases the rotation speed of the propeller. In another exemplary embodiment, if the driving control system 10 is in rudder deflection mode, the processing unit 750 may, when it determines that cavitation will occur in the liquid, send a rudder angle control command to a rudder angle control module 13 comprised by the driving control system 10, so that the rudder angle or the rotation speed of the rudder is decreased as controlled by the rudder angle control module 13.
A cavitation monitoring system according to an exemplary embodiment will be described below with reference to Figure 2. The components of a cavitation monitoring system may be identical to or similar to those of a pod driver described above with reference to Figure 1. Therefore, for brevity and clarity in the following detailed description, identical or similar components will be indicated by identical or similar reference numerals, and detailed descriptions of identical or similar components will be omitted.
Figure 2 is a schematic diagram for a cavitation monitoring system according to an exemplary embodiment . As shown in Figure 2, the cavitation monitoring system may comprise the pressure sensing device 710 and the processing unit 750.
The pressure sensing device 710 may be disposed, for example, on the surface of the rudder body of the pod driver described above with reference to Figure 1, and may sense the pressure of a liquid on the surface of the rudder body. The processing unit 750 may, based on output of the pressure sensing device, obtain the pressure of a liquid around the pressure sensing device and determine whether the obtained pressure is smaller than or equal to a preset threshold. When the processing unit 750 determines that the obtained pressure is smaller than or equal to the preset threshold, it determines that cavitation will occur in the liquid. Here, the threshold may be greater than or equal to the critical pressure under which cavitation occurs in a liquid around the pressure sensing device.
The pressure sensing device 710 may be disposed on the surface of the frontal edge of the rudder body. For example, the pressure sensing device 710 may comprise a plurality of pressure sensors that may be respectively disposed on the surface of either side of the rudder body. Each of the pressure sensors disposed on either side face of the rudder body may comprise a main pressure sensor and a secondary pressure sensor. A secondary pressure sensor may start when a main pressure sensor stops or may start as needed.
Since a pressure sensor of the pressure sensing device 710 may receive an analog signal, the pod driver may further comprise an analog-to-digital converter 730. The analog-to-digital converter 730 may be disposed between the pressure sensing device 710 and the processing unit 750 to convert an analog signal from the pressure sensing device 710 into a digital signal and then provide the converted digital signal to the processing unit 750.
Further, the processing unit 750 may be connected to a driving control system that is used to control the driving of a ship mounted with the pod driver (see 10 in Figure 1) . The processing unit 750 may, when it determines that cavitation will occur in the liquid, send a command for adjusting the driving of the ship to the driving control system, thereby adjusting the driving of the ship. For example, the processing unit 750 may, when it determines that cavitation will occur in the liquid, send a command for propeller speed regulation to a propeller speed regulation module (11 in Figure 1) comprised by the driving control system, so that the propeller speed regulation module decreases the rotation speed of the propeller. In another exemplary embodiment, if the driving control system is in rudder deflection mode, the processing unit 750 may, when it determines that cavitation will occur in the liquid, send a rudder angle control command to a rudder angle control module (13 in Figure 1) comprised by the driving control system, so that the rudder angle or the rotation speed of the rudder is decreased as controlled by the rudder angle control module.
A cavitation monitoring system and a pod driver comprising the cavitation monitoring system according to the exemplary embodiment can actively suppress cavitation, thereby protecting the pod driver against damage by cavities. In addition, the requirements on the appearance design of the pod driver can be relaxed; for example, a relatively thin frontal edge can be designed for the rudder body. Thus, resistance to sailing can be further reduced to achieve a higher efficiency. In addition, noises of the pod driver generated during the sailing of the ship can be reduced to prolong its service life.
It should be understood that although the specification describes the embodiments separately, an embodiment does not contain only one independent technical solution, and that such a method of description is only for the sake of clarity; those of ordinary skill in the art should treat the specification as a whole, and the technical solutions provided in the embodiments can be appropriately combined into other embodiments that those of ordinary skill in the art understand .
The above-described specific embodiments are only illustrative of the present invention, instead of limiting the scope of the present invention. Any equivalent variations, modifications, or combinations made by any of those of ordinary skill in the art without departing from the spirit or principle of the prevent invention shall fall into the scope of the present invention.

Claims

Claims
1. A pod driver, characterized in that the pod driver comprises :
a main body (100) ;
a propeller (300) , rotatably mounted at an end portion of the main body;
a rudder body (500) , configured to connect the main body to the hull of a ship mounted with and driven by the pod driver, and
a pressure sensing device (710) , disposed on the surface of the rudder body and configured to sense pressure of a liquid on the surface of the rudder body.
2. The pod driver as claimed in claim 1, characterized in that the rudder body comprises a frontal edge (510) , wherein the pressure sensing device is disposed on the surface of the frontal edge of the rudder body.
3. The pod driver as claimed in claim 1, characterized in that the pressure sensing device comprises a plurality of pressure sensors, wherein the plurality of pressure sensors are respectively disposed on the surface of either side of the rudder body.
4. The pod driver as claimed in claim 3, characterized in that a plurality of pressure sensors among the plurality of pressure sensors that are disposed on the surface of one of the two sides of the rudder body comprise one or more main pressure sensors and one or more secondary pressure sensors, wherein a secondary pressure sensor is configured to start when a main pressure sensor stops.
5. The pod driver as claimed in claim 1, characterized in that the pod driver further comprises:
a processing unit (750) , configured to, based on output from the pressure sensing device, obtain pressure of a liquid around the pressure sensing device.
6. The pod driver as claimed in claim 5, characterized in that the processing unit is configured to determine whether the obtained pressure is smaller than or equal to a preset threshold and, when it determines that the obtained pressure is smaller than or equal to the preset threshold, determine that cavitation will occur in the liquid,
wherein the threshold is greater than or equal to the critical pressure under which cavitation occurs in a liquid around the pressure sensing device.
7. The pod driver as claimed in claim 6, characterized in that the pod driver further comprises:
an alarm unit (770) , connected to the processing unit, wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send an alarm command to the alarm unit so that the alarm unit gives the alarm.
8. The pod driver as claimed in claim 6, characterized in that the processing unit is connected to a driving control system (10) that is used to control a ship mounted with the pod driver,
wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for adjusting the driving of the ship to the driving control system, thereby adjusting the driving of the ship.
9. The pod driver as claimed in claim 8, characterized in that the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for propeller speed regulation to a propeller speed regulation module (11) comprised by the driving control system, thereby decreasing the rotation speed of the propeller.
10. The pod driver as claimed in claim 9, characterized in that the processing unit is configured to, if the driving control system is in rudder deflection mode, when it determines that cavitation will occur in the liquid, send a rudder angle control command to a rudder angle control module (13) comprised by the driving control system, thereby decreasing the rudder angle or decreasing the rotation speed of the rudder.
11. A cavitation monitoring system, characterized in that the cavitation monitoring system comprises:
a pressure sensing device (710) , disposed on the surface of the rudder body of the pod driver and configured to sense pressure of a liquid on the surface of the rudder body; and a processing unit (750) , configured to, based on output from the pressure sensing device, obtain the pressure of a liquid around the pressure sensing device and determine whether the obtained pressure is smaller than or equal to a preset threshold, wherein when the processing unit determines that the obtained pressure is smaller than or equal to the preset threshold, it determines that cavitation will occur in the liquid,
the threshold being greater than or equal to the critical pressure under which cavitation occurs in a liquid around the pressure sensing device.
12. The cavitation monitoring system as claimed in claim 11, characterized in that the rudder body comprises a frontal edge, wherein the pressure sensing device is disposed on the surface of the frontal edge of the rudder body.
13. The cavitation monitoring system as claimed in claim 11, characterized in that the pressure sensing device comprises a plurality of pressure sensors, wherein the plurality of pressure sensors are respectively disposed on the surface of either side of the rudder body.
14. The cavitation monitoring system as claimed in claim 13, characterized in that a plurality of pressure sensors among the plurality of pressure sensors that are disposed on the surface of one of the two sides of the rudder body comprise one or more main pressure sensors and one or more secondary pressure sensors, wherein a secondary pressure sensor is configured to start when a main pressure sensor stops.
15. The cavitation monitoring system as claimed in claim 11, characterized in that the cavitation monitoring system further comprises:
an alarm unit (770) , connected to the processing unit, wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send an alarm command to the alarm unit so that the alarm unit gives the alarm.
16. The cavitation monitoring system as claimed in claim 11, characterized in that the processing unit is connected to a driving control system (10) that is used to control the driving of a ship mounted with the pod driver,
wherein the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for adjusting the driving of the ship to the driving control system, thereby adjusting the driving of the ship.
17. The cavitation monitoring system as claimed in claim 16, characterized in that the processing unit is configured to, when it determines that cavitation will occur in the liquid, send a command for propeller speed regulation to a propeller speed regulation module (11) comprised by the driving control system, thereby decreasing the rotation speed of the propeller .
18. The cavitation monitoring system as claimed in claim 16, characterized in that the processing unit is configured to, if the driving control system is in rudder deflection mode, when it determines that cavitation will occur in the liquid, send a rudder angle control command to a rudder angle control module (13) comprised by the driving control system, thereby decreasing the rudder angle or decreasing the rotation speed of the rudder.
PCT/EP2019/070781 2018-08-01 2019-08-01 Cavitation monitoring system and pod driver WO2020025753A1 (en)

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CN201810866885.1A CN110789698A (en) 2018-08-01 2018-08-01 Cavitation monitoring system and pod drive
CN201810866885.1 2018-08-01

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