JP2019200752A - Wake flow field design method, wake flow field design system, and ship considering wake flow field - Google Patents

Abstract

To provide a wake flow field design method capable of realizing overall optimization of hull, stern appendages, and propellers, a wake flow field design system, and ship considering the wake flow field.SOLUTION: The design method of wake flow field which is generated at the stern of a ship. Wake flow field for at least one of hull, stern appendages, and propellers is analyzed on the basis of a hull form/wake flow field database that links pre-built hull form and wake flow field, and a wake flow field suitable for at least one of stern appendages and propellers is designed.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a wake field design method, a wake field design system, and a ship that considers a wake field.

  Conventionally, the design of the stern wake distribution induced by the hull form (the wake field generated at the stern of a ship) has been difficult to implement only by trial and error based on the empirical rules of skilled engineers, and as shown in FIG. In addition, the stern appendages and propellers were designed to be dependent on the hull. Therefore, a hull suitable for stern appendages and propellers was not designed, and overall optimization based on mutual interference among hulls, propellers, and energy-saving appendages was not performed.

By the way, Patent Document 1 discloses a ship design program that generates design data indicating the shape of a ship floating in a fluid, a calculation grid creation tool that converts design data into grid data, and a calculation condition setting program that generates conditions. , A flow field calculation program that simulates the flow field of the fluid that the ship is navigating based on the grid data and its conditions, and a ship that derives the hydrodynamic performance of the fluid acting on the ship based on the flow field A ship design apparatus including a performance evaluation program and a visualization tool for displaying hydrodynamic performance on a display device is disclosed.
Further, Patent Document 2 discloses parameters indicating the flow field characteristics of a hull form obtained from integral values at the bow and stern portions of the amount of change in pressure coefficient obtained by calculating a double model flow around the hull, and a stern Using the parameters representing the increase in resistance due to the secondary flow and the geometrical shape parameters of the hull form, a regression equation for estimating the shape influence coefficient is created, and the viscous resistance of the enlarged ship that estimates the viscous resistance using the estimated regression equation An estimation method is disclosed.
Further, in Patent Document 3, a stern fin is provided at the stern of the ship to stop and rectify the downflow, and in the presence of the stern fin, the working flow field at the stern duct installation position in front of the propeller is measured or analyzed. Measure and analyze the working flow field at the rudder fin installation position on the left and right sides of the rudder in the presence of the stern fin and stern duct in the presence of the stern fin and stern duct. A design method for a stern structure is disclosed in which a ladder fin is designed and provided so as to have the highest power reduction effect in a working flow field.

Japanese Patent Laid-Open No. 2004-9858 JP 2001-133891 A JP 2006-347285 A

The distribution shape of the stern wake is deeply related to the improvement of the effect of energy-saving adjuncts, the improvement of propeller efficiency and the reduction of cavitation, but there has been no way to realize the overall optimization of the hull, stern adjuncts, and propellers. Not proposed.
Patent Document 1 describes a flow field calculation program for simulating another flow field indicating the pressure and flow velocity of a fluid being navigated by another ship, but the hull, stern appendage, and propeller are described. It does not realize the overall optimization.
In addition, Patent Document 2 describes that an estimated regression equation is created by using the measurement results of 58 tank tests of the shape influence coefficient (1 + K) in a full load state as a database. It does not realize overall optimization of products and propellers.
Further, in Patent Document 3, since the stern duct and the ladder fin are designed to be dependent on the hull, a hull suitable for an energy-saving additive is not designed. That is, it does not realize overall optimization of the hull, stern appendages, and propellers.

  Therefore, an object of the present invention is to provide a wake field design method, a wake field design system, and a ship that takes into account the wake field, which realizes the overall optimization of the hull, stern appendages, and propellers.

A wake field design method corresponding to claim 1 is a wake field design method generated at a stern of a ship, wherein a wake field for at least one of a hull, a stern appendage, and a propeller is preliminarily constructed. The wake field is analyzed based on the hull form / wake field database in which the hull form and the wake field are linked, and the wake field suitable for at least one of the stern appendage and the propeller is designed.
According to the first aspect of the present invention, it is easy to associate the hull (hull form) with the wake field, and it is possible to design a hull suitable for a stern appendage and a propeller. Achieves overall propeller optimization.

According to the second aspect of the present invention, the design of the wake field is made by selecting a ship type data close to the target wake field based on the ship shape / wake field database and obtaining a target wake field. Is generated.
According to the present invention described in claim 2, it is possible to easily design a hull form suitable for a stern appendage and a propeller.

The present invention described in claim 3 is characterized in that a plurality of hull form data close to a target wake field is selected and averaged to generate a hull form from which a target wake field can be obtained.
According to the present invention described in claim 3, it is possible to design a hull form suitable for a stern appendage and a propeller more efficiently and accurately.

The invention according to claim 4 is characterized in that at least one of the stern appendage and the propeller is designed after generating a hull form capable of obtaining a target wake field.
According to the fourth aspect of the present invention, it is possible to perform detailed design of the stern appendage and the propeller after generating the hull form, and the overall optimization of the hull, stern appendage and propeller can be performed with higher accuracy. It can be carried out.

The present invention according to claim 5 constructs an optimum wake field database suitable for at least one of a stern appendage and a propeller based on the hull form / wake field database, and uses the optimum wake field database to make a hull. The wake field suitable for at least one of the stern appendage and the propeller is selected in consideration of the above-mentioned constraints.
According to the fifth aspect of the present invention, the optimum wake field targeted by the stern appendage and the propeller can be obtained using the optimum wake field database in accordance with the constraint conditions of the hull.

The present invention according to claim 6 is characterized in that a hull form is generated in consideration of a hull constraint.
According to the sixth aspect of the present invention, the stern appendage and the hull form that realizes the wake field suitable for the propeller can be generated in consideration of the hull constraints, so the hull, the stern appendage, and the propeller can be generated. Overall optimization can be performed with higher accuracy.

The present invention as set forth in claim 7 sets the hull constraint conditions, performs statistical analysis of the wake field against the constraint conditions based on the hull form / wake field database, and wake field statistical data under the constraint conditions It is characterized by obtaining.
According to the present invention as set forth in claim 7, even when the ship type information is unknown or the wake field cannot be estimated, the optimum effect is generally obtained for any ship under a certain constraint condition. It is possible to design stern appendages and propellers. For example, it is possible to design optimal stern appendages and propellers by estimating wake fields for existing ships whose detailed design information is unknown and for new ships where flow field analysis cannot be performed due to budget.

The present invention according to claim 8 is characterized in that at least one optimum design of a stern appendage and a propeller under constraint is performed based on wake field statistical data.
According to the present invention as set forth in claim 8, even if the ship type information is unknown or the wake field cannot be estimated, the wake field statistical data is used to determine which It is possible to design stern appendages and propellers that are generally optimal for ships.

The present invention according to claim 9 is characterized in that the wake field in the hull form / wake field database is a flow field having nodes with little change in flow even if the hull form changes.
According to the ninth aspect of the present invention, the entire hull, stern appendage, and propeller can be optimized using a flow field having nodes. For example, the stern appendage and the propeller are allowed to face a node with little change in flow, and the performance can be improved.

The wake field design system corresponding to claim 10 is a wake field design system generated at the stern of a ship, wherein the condition input means inputs a condition for at least one of a hull, a stern appendage, and a propeller. Ship type / wake field database means that stores data that links the hull form and wake field, and wake field that analyzes the wake field based on the data of the ship type / wake field database means for the input conditions And a wake field design means for designing the wake field based on the analysis result of the wake field, and a wake field output means for outputting the design result of the wake field. To do.
According to the present invention described in claim 10, it is easy to associate the hull (hull form) with the wake field, and a hull suitable for the stern appendage and the propeller can be designed. Achieves overall propeller optimization.

In the present invention according to claim 11, the wake field analysis means selects the hull form data close to the target wake field based on the hull form / wake field database means, and the wake field is determined according to the selected hull form data. The design means generates a hull form from which a target wake field can be obtained.
According to the present invention described in claim 11, it is possible to easily design a hull form suitable for a stern appendage and a propeller.

According to the twelfth aspect of the present invention, the design of the wake field in the wake field design means is obtained by averaging a plurality of ship shape data close to the target wake field to obtain a ship shape that can obtain a target wake field. It is characterized by generating.
According to the present invention described in claim 12, it is possible to design a hull form suitable for a stern appendage and a propeller more efficiently and accurately.

In the wake field design means according to the thirteenth aspect of the present invention, the wake field design means performs at least one design of the stern appendage and the propeller after generating the hull form from which the target wake field is obtained. It is characterized by that.
According to the present invention as set forth in claim 13, it is possible to perform detailed design of the stern appendage and the propeller after generating the hull form, and the overall optimization of the hull, stern appendage and propeller can be performed with higher accuracy. It can be carried out.

A ship considering a wake field corresponding to claim 14 is a ship considering a wake field using a wake field design method, and a stern appendage and a propeller for which the wake field is designed. Equipped with at least one of the above.
According to the fourteenth aspect of the present invention, it is possible to provide a ship that realizes the entire optimization of the hull, the stern appendage, and the propeller.

The present invention according to claim 15 is characterized in that a duct is used as the stern appendage, and the fluctuation range of the inflow angle of the wake field flow with respect to the duct is set to 25 ° or less.
According to the present invention described in claim 15, the energy saving effect by the duct can be further enhanced in consideration of the wake field.

The present invention according to claim 16 is characterized in that the range in which the inflow angle is 25 ° or less is at least in the range of 0 ° to 90 ° at the upper intersection of the longitudinal center line of the duct.
According to the sixteenth aspect of the present invention, the duct can face the range of the inflow angle that has a large effect as the wake field, and the energy saving effect by the duct can be enhanced efficiently.

The present invention according to claim 17 is characterized in that a duct is used as the stern appendage and the opening angle of the duct corresponding to the wake field is set to -3 ° or more and 14 ° or less.
According to the present invention as set forth in claim 17, the duct can be allowed to face a range of a large opening angle as a wake field, and the energy saving effect by the duct can be further enhanced.

The present invention according to claim 18 is characterized in that the propeller suppresses the fluctuation rate of the circumferential distribution of the flow of the wake field with respect to the propeller surface to 0.4 or less.
According to the eighteenth aspect of the present invention, the propeller efficiency can be further increased in consideration of the wake field.

The present invention according to claim 19 is characterized in that the range in which the fluctuation rate of the circumferential distribution of the flow of the wake field is suppressed to 0.4 or less is a position of 60% to 100% of the propeller radius. .
According to the nineteenth aspect of the present invention, since the fluctuation rate in a range where the effect as a propeller is large can be suppressed, the propeller efficiency can be efficiently increased.

The present invention according to claim 20 is characterized in that the wake field is improved by enlarging the bottom of the hull near S.S.2.0.
According to the 20th aspect of the present invention, the stern vertical vortex can be strengthened and the center thereof can be lowered to the same height as the propeller shaft core, and the wake field can be improved.

  According to the wake field designing method of the present invention, it becomes easy to associate the hull (hull form) with the wake field, and a hull suitable for a stern appendage and a propeller can be designed. Achieves overall propeller optimization.

  The design of the wake field is based on the selection of the hull form data close to the target wake field based on the hull form / wake field database, and when generating a hull form that provides the target wake field, A hull form suitable for stern appendages and propellers can be designed easily.

  In addition, when multiple hull form data close to the target wake field are selected and averaged to generate a hull form that provides the target wake field, the stern appendages and propellers can be more efficiently and accurately used. It is possible to design a hull form suitable for.

  In addition, after creating the hull form that can obtain the target wake field, when designing at least one of the stern appendage and propeller, the detailed design of the stern adjunct and propeller should be made after the hull form is created. This makes it possible to optimize the hull, stern appendages, and propellers more accurately.

  In addition, based on the hull form and wake field database, an optimal wake field database suitable for at least one of the stern appendages and propellers is constructed, and the optimal wake field database is used to consider the hull constraints. When selecting the wake field suitable for at least one of the stern appendage and propeller, the optimum wake field database is used and the optimum target of the stern appendage and propeller is selected according to the hull constraints. Wake field can be obtained.

  In addition, when generating a hull form that takes into account the hull constraints, a hull form that realizes a wake field suitable for stern appendages and propellers can be generated taking into account the hull restrictions, so the hull and stern additions can be generated. The overall optimization of the object and the propeller can be performed with higher accuracy.

  In addition, when hull constraint conditions are set, statistical analysis of the wake field against the constraint conditions is performed based on the hull form / wake field database, and wake field statistical data under the constraint conditions is obtained, the hull form Even if the information is unknown or the wake field cannot be estimated, it is possible to design stern appendages and propellers that are generally optimally effective for any ship under certain constraints. . For example, it is possible to design optimal stern appendages and propellers by estimating wake fields for existing ships whose detailed design information is unknown and for new ships where flow field analysis cannot be performed due to budget.

  In addition, when designing at least one of the stern appendages and propellers under constraint conditions based on the wake field statistical data, the hull form information is unknown or the wake field is estimated. Even if this is not possible, it is possible to design stern appendages and propellers that are generally optimally effective for any ship under certain constraints, based on wake field statistical data.

  In addition, if the wake field in the hull form / wake field database is a flow field having nodes with little change in flow even if the ship type changes, the hull and stern addition are used using the flow field having nodes. The entire optimization of the product and the propeller can be performed. For example, the stern appendage and the propeller are allowed to face a node with little change in flow, and the performance can be improved.

  Further, according to the wake field design system of the present invention, it is easy to associate the hull (hull form) with the wake field, and a hull suitable for a stern appendage and a propeller can be designed. , And overall optimization of the propeller is realized.

  The wake field analysis means selects the hull form data close to the target wake field based on the hull form / wake field database means, and the wake field design means sets the target according to the selected hull form data. When generating a hull form capable of obtaining a wake field, it is possible to easily design a hull form suitable for a stern appendage and a propeller.

  In addition, the design of the wake field in the wake field design means is more effective when generating a ship type that can obtain a target wake field by averaging a plurality of ship shape data close to the target wake field. A hull form suitable for stern appendages and propellers can be designed efficiently and accurately.

  Also, the wake field design in the wake field design means is to create a hull form when designing a stern appendage and at least one of the propellers after generating a hull form to obtain the target wake field. After that, the detailed design of the stern appendage and the propeller can be performed, and the entire hull, stern appendage, and propeller can be optimized more accurately.

  Moreover, according to the ship which considered the wake field of this invention, the ship which implement | achieved the whole optimization of a hull, a stern appendage, and a propeller can be provided.

  In addition, when a duct is used as the stern appendage and the fluctuation range of the inflow angle of the wake field flow with respect to the duct is 25 ° or less, the energy saving effect by the duct can be further enhanced in consideration of the wake field. it can.

  Further, the range in which the inflow angle is 25 ° or less is at least within the range of 0 ° to 90 ° of the upper intersection of the longitudinal center line of the duct. The energy saving effect by the duct can be enhanced efficiently.

  In addition, when a duct is used as the stern appendage and the opening angle of the duct corresponding to the wake field is set to -3 ° or more and 14 ° or less, the duct is allowed to face a range of a large opening angle as the wake field. The energy saving effect by the duct can be further enhanced.

  Further, the propeller can further increase the propeller efficiency in consideration of the wake field when the variation rate of the circumferential distribution of the wake field flow with respect to the propeller surface is suppressed to 0.4 or less.

  Further, the range in which the fluctuation rate of the circumferential distribution of the wake field flow is suppressed to 0.4 or less is a range in which the effect of the propeller is large when the propeller radius is 60% or more and 100% or less. Since the rate can be suppressed, the propeller efficiency can be increased efficiently.

  In addition, when the ship's bottom near SS 2.0 is enlarged to improve the wake field, the stern vertical vortex should be strengthened and its center lowered to the same height as the propeller shaft. And wake field can be improved.

The block diagram of the wake field design system by this embodiment of this invention Figure showing an example of ship type (S.S.1.0) stored in the ship type database A figure showing an example of the ship type (stern profile) stored in the ship type database Figure showing an example of accompanying flow field database (propeller surface wake distribution) A figure that summarizes the flow velocity distribution in the axial direction for all the flow field data of the 2730 individual hull form for each propeller radius position. The figure which shows distribution of the inflow angle to the duct wing cross section of the wake field data of all the ship types of 2730 individuals Flow chart showing accompanying flow field design method Flow chart showing the design method of the wake field as the target Diagram showing the wake distribution designed in the same way Comparison of the original ship and the generated ship (S.S.1.0) Comparison chart of the original ship and the generated ship (stern profile) The flowchart which shows the wake field design method by other embodiment of this invention A figure showing the state of the tank test using the original ship type The figure which shows the state of the aquarium test using the generated hull form Diagram showing wake distribution measured by prototype ship Figure showing the measured wake distribution of the generated ship type (system output ship type) Diagram showing the distribution of the inflow angle in the circumferential direction to the duct blade section in the original ship type Diagram showing the distribution of the inflow angle in the circumferential direction to the duct blade section in the generated hull form Illustration of duct inflow angle α Illustration of duct position θ Diagram showing energy saving effect of generated ship type compared with original ship type Diagram showing the flow direction distribution of the axial velocity of the original ship type Diagram showing the flow direction distribution of the generated ship's axial flow velocity Flow chart showing conventional hull, stern appendage, and propeller design method Schematic diagram of the wake design system studied in previous research

The distribution shape of the stern wake is deeply related to the improvement of the effect of energy saving adjuncts, the improvement of propeller efficiency and the reduction of cavitation. For example, the energy-saving effect of a duct-type energy-saving additive is strongly influenced by the circumferential distribution of the angle (inflow angle) of the flow flowing into the duct blade cross section.
The present inventor first researched a new hull form design method (wake design system) that enables the design of the intended wake distribution, and confirmed the theoretical effectiveness of the wake design system by cross-validation. confirmed.
The outline of the wake design system examined in this study is shown in FIG. Unlike the conventional ship form database analysis example, the wake design system does not organize the ship form by ship form parameters (for example, the inclination angle of the C _p curve, etc.), but simply manages it by ID, so its flexibility and expandability are high. It has characteristics.
As a result, data of other ship types can coexist, and unlike the past, past design heritage can be coexisted and utilized in the database. Further, since the ship type is managed by the ID, it is possible to avoid a lack of information due to the parameterization of the ship type.
In addition, in the wake design system examined in this study, the wake distribution and ship type database (ship type / flow field database) are analyzed by a method based on the k-nearest neighbor method which is one of machine learning methods. In addition, since the wake design system can drop machine learning problem settings into a relatively simple solution space, it is less necessary to apply a machine learning method that is more complicated than the k-nearest neighbor method. It was found that an effective database analysis can be performed.
The wake field analysis of FIG. 25 will be described. The similarity (Euclidean distance) between the input wake and the wake on the database is calculated by the following equation (1) from the target input wake distribution data and the wake data of the hull form / flow field database.
Using the Euclidean distance obtained by Equation (1) as an evaluation function, three similar wakes are identified from the ship shape / flow field database, three ship types having similar wakes are identified, and the three ship types are identified as Euclidean distances (d ₁ , d ₂ , d ₃ ) and hull shape blending using the weighting coefficient (α _i ) calculated by the following equation (2) to mechanically obtain the hull shape that realizes the target input wake distribution.

Hereinafter, the wake field design method, the wake field design system, and the ship taking into account the wake field according to the embodiment of the present invention obtained in this study will be described.
FIG. 1 is a block diagram of a wake field design system according to this embodiment.
The wake field design system includes condition input means 10, ship shape / wake field database means 20, wake field analysis means 30, wake field design means 40, and wake field output means 50.

The condition input means 10 is, for example, a keyboard, a touch panel, a mouse or the like, and the user inputs a condition for at least one of the hull, stern appendage, and propeller to the wake field design system using the condition input means 10. .
The ship shape / wake field database means 20 stores data in which the ship shape and the wake field are linked (associated).

In the present embodiment, a ship type / wake field database of 2730 individuals is constructed in the ship type / wake field database means 20 for a general cargo ship of 749 gross tons. The wake field was estimated by using the RaNS solver NAGISA developed by the National Maritime Research Institute (MARI), National Maritime Research Institute (MARI), and disclosed by the inventors. “Yasuo Ichinose, Yusuke Tahara, Kenichi Kume: Construction and Evaluation of Ship Type Database for Coastal Ships with Restriction on Gross Tonnage—Development of Prototypes for 749 Gross General Tonnage Cargo Ships— No. 26, pp.51-62, 2017. "(Reference 1) The calculation was carried out with a structural grid of 1.8 million cells on both sides. In applying the turbulent flow model, several turbulent flow models of EASM kω, SST kω, and Modified SA are compared and compared with the results of the tank test of the original ship type (MS No.869) in Reference 1. As a result of considering the robustness of the ship, Modified SA (Cvor = 20) is applied to the creation of the hull form / wake field database. As the calculation grid, a grid equivalent to that of Reference 1 is adopted, and the uncertainty of the calculation grid has an uncertainty level appropriate for the present invention according to Reference 1.
The ship type / wake field database means 20 is characterized by its high degree of freedom and high expandability because the ship type data and wake field data are not managed by ship type parameters and wake field data, but simply managed by ID. Although it is possible to apply complex machine learning techniques to database analysis, it has been confirmed that the simple technique created in this study is rather useful.
The hull form / wake field database means 20 facilitates the correspondence between the hull (hull form) and the wake field, so that the entire hull, stern appendages, and propellers can be optimized, including existing ships. It can be used for various purposes such as analysis of ship wake field and construction of secondary optimal flow field database for flow field analysis suitable for stern appendages and propellers.
FIG. 2 is a view showing an example of a ship type (SS1.0) stored in the ship type database, and FIG. 3 is a view showing an example of a ship type (stern profile) stored in the ship type database.
The hull form database has practically the same amount of water as the original hull form. As shown in the hull form examples in FIGS. 2 and 3, the stern frame line, stern profile, stern crossing area curve (hereinafter referred to as C _p curve), This is a group of 2730 hulls having different hull shapes with different tendency to fall off shoulders. In addition, since this ship type database has the same main item, the propeller of the same propeller diameter and installation position is assumed.

FIG. 4 is a diagram showing an example of a wake field database (a wake distribution on a propeller surface). FIG. 4 (a) shows a case of a hull of ID030001 and FIG. 4 (b) shows a case of a hull of ID030003. FIG. 4C shows the case of ID030005, and FIG. 4D shows the case of ID030006. As shown in FIG. 4, the constructed hull form and wake field database is a database that is very varied, especially focusing on the strength of the stern vertical vortex.
FIG. 5 is a diagram in which the flow velocity distribution in the axial direction is summarized for each propeller radius position for all the flow field data of the ship shape of 2730 individuals, and FIG. 5 (a) shows the case of FIG. 5 (b) when R = 0.7R. ) Is for R = 1.0R.
Here, the horizontal axis of FIG. 5 indicates the circumferential position where the propeller TOP position is 0, and r = 0.7R is a graph at the 70% propeller radial position. From FIG. 5, it can be seen that the axial flow velocity distribution of 2730 individuals changes in the vicinity of the 70 ° position as a node. This axial velocity distribution fluctuates from node to node because the hull database of this time has a wide range of changes compared to the hull shape change in actual design, and the center position of the stern vertical vortex is the upward flow from the bottom of the ship. Inferring from the fact that it is generally located only above the propeller shaft, it can be assumed that this phenomenon can be applied to general uniaxial skeg vessels with a constant displacement.
Since the wake field in the hull form / wake field database is a flow field having nodes with little change in flow even if the ship type changes, the hull, stern appendage, and The entire propeller can be optimized. The existence of a knot is a new finding that was discovered as a result of analyzing all wake field data of 2730 individual hulls. For example, the stern appendages and propellers face a knot with little change in flow, and We can expect improvement.

The energy-saving effect of the duct-type energy-saving additive is strongly influenced by the circumferential distribution of the angle (flow angle) of the flow flowing into the duct blade cross section. For this reason, if the inflow angle in the circumferential direction can be improved by the hull form, the energy-saving effect of the adjunct will be improved and the total fuel consumption will be reduced. For ducts with the same opening angle in the circumferential direction from the viewpoint of work, the higher the opening angle, the higher the inflow angle into the duct blade cross section from 0 ° to 80 °, the higher the energy saving effect. I know that The hull form in which the inflow angle to the duct blade cross section is almost constant is obtained mechanically by the wake field design system of this embodiment.
FIG. 6 is a diagram showing the distribution of the inflow angle to the wing section of the wake field data of all 2730 individual ship types. In FIG. 6, nodes can be confirmed near the 20 ° position and the 90 ° position. The nodes near the 20 ° position are considered to be formed by the influence of the position of the stern vertical vortex described above. On the other hand, at 90 ° position, the evaluation axis of the inflow angle coincides with the transverse direction of the hull. Therefore, the nodes near the 90 ° position are caused by the fact that a strong lateral flow is not formed in the straight flow field of the uniaxial skeg type with a constant drainage amount. it is conceivable that. As described above, it is obtained as a new finding that there is a node with respect to the inflow angle. For example, it can be expected that the stern appendage and the propeller face the node with little change in flow to improve the performance.

  The conventional database targeted the ship type and the final result, horsepower, and the integral value, which is the resistance self-propelled element, but the ship type and wake field database of the present invention is in the middle of the ship type and the integral value. It is a new database that links the wake field including knowledge and ship form.

The wake field analysis means 30 is previously constructed in the hull form / wake field database means 20 for at least one condition regarding the hull, stern appendage, and propeller input by the user using the condition input means 10. The wake field is analyzed based on the database.
The wake field design means 40 designs the wake field based on the analysis result of the wake field by the wake field analysis means 30.
The wake field output means 50 outputs the design result of the wake field by the wake field design means 40 to a screen or paper.

Further, the wake field analysis means 30 selects the hull form data close to the target wake field based on the database constructed in the hull form / wake field database means 20.
The wake field design means 40 generates a hull form from which a target wake field can be obtained according to the hull form data selected by the wake field analysis means 30.
In this way, the design of the wake field is based on the selection of the hull form data close to the target wake field based on the hull form / wake field database and generating a hull form that provides the target wake field. It is possible to easily design a hull form suitable for a stern appendage and a propeller.

Further, the wake field design in the wake field design means 40 generates a ship form that can obtain a target wake field by averaging a plurality of ship form data close to the target wake field.
In this way, by selecting multiple hull form data close to the target wake field and averaging them to generate a hull form that can obtain the target wake field, the stern appendage can be more efficiently and accurately A hull shape suitable for a propeller can be designed.

In addition, the wake field in the wake field design means 40 is designed to generate at least one of a stern appendage and a propeller after generating a hull form capable of obtaining a target wake field.
In this way, after generating the hull form that can obtain the target wake field, by designing at least one of the stern appendage and the propeller, the detailed design of the stern adduct and the propeller is generated after generating the hull form. This makes it possible to optimize the entire hull, stern appendages, and propellers with higher accuracy.

The wake design system using ship hull blending described above can be used to generate a hull form that provides a target wake field. This wake design system is also characterized in that the similarity between the target wake field and the wake field data in the database is evaluated by the “Euclidean distance”. Since the wake field is usually 1080-dimensional data represented by 360 velocity components, it is generally very difficult to efficiently parameterize the similarity in a low dimension. However, the parameterization by the “Euclidean distance” is a very efficient parameterization that can evaluate the similarity of the wake field and the hull form in a low dimension. Thereby, it is possible to greatly reduce the calculation cost in the analysis of the database.
Furthermore, new ship type data that is not in the ship form / wake field database can be generated by blending (averaging) the selected ship types with the weight of “Euclidean distance”. As a result, it is possible to obtain a hull form that induces exactly the same wake as the desired wake rather than simply extracting data from the database.

FIG. 7 is a flowchart showing the wake field designing method according to the present embodiment.
First, a target wake field suitable for the selected stern appendage and propeller is designed (S1: Step 1).
After step 1, a plurality of hull form data close to the target wake field is selected based on a previously built hull form / wake field database (S2: step 2).
After step 2, a plurality of selected ship type data is averaged (blended) to generate a ship type that provides a target wake field (S3: step 3).
Thereafter, the hull form generated in step 3 is finely corrected (S4: step 4).
After step 4, the stern appendage and propeller selected in step 1 are designed for fine correction and determination of the mounting angle to the hull (S5: step 5).
After step 5, whether or not the overall optimization by the hull, stern appendage, and propeller for the ship satisfies the target performance is confirmed by analysis or test (S6: step 6).
If it is determined in step 6 that the target performance is satisfied, the designed hull form, stern appendage, and propeller results are output (S7: step 7).
On the other hand, if it is determined in step 6 that the target performance is not satisfied, the process returns to step 4 to make a fine correction of the hull form.

FIG. 8 is a flowchart showing a target wake field design method.
First, based on the data related to stern appendages and propellers and the hull form and wake field database constructed in advance, the stern appendages and flow fields suitable for propellers are analyzed, and at least one of stern appendages and propellers is analyzed. First, an optimum wake field database suitable for the above is constructed (S11: Step 11).
After step 11, the hull constraints are applied to the optimal wake field database constructed in advance, and the target wake field suitable for the stern appendage and the propeller is selected (S12: step 12). The hull constraint conditions include the ship type, main length such as the length, width, and draft of the hull.
In this way, an optimal wake field database suitable for at least one of stern appendages and propellers is constructed based on the hull form / wake field database, and the hull constraints are considered using the optimal wake field database. In addition, by selecting the wake field suitable for at least one of the stern appendages and propellers, the optimal wake field database is used and the stern appendages and propeller targets are set according to the hull constraints. An optimal wake field can be obtained.
In addition, by generating a hull form that takes into account the hull constraints, it is possible to generate a hull form that realizes a wake field that is suitable for a stern appendage and a propeller in consideration of the hull constraints. , And overall optimization of the propeller can be performed with higher accuracy.

In this embodiment, the target wake field is designed for the purpose of improving the energy saving effect of the adjunct by improving the circumferential inflow angle to the duct blade cross section and reducing cavitation by reducing the circumferential fluctuation of the axial wake. did.
In order to achieve these two objectives, the duct best flow field (data with the smallest variance of the variation in the circumferential direction of the inflow angle in the design range from 0 ° to 80 °) and the cavity best flow field (0. The target wake field was designed by selecting two of the data of the smallest difference between the maximum value and the minimum value of the axial flow velocity in 7R, and blending (averaging) the two wake fields. . FIG. 9 is a diagram showing the designed wake distribution. In FIG. 9, the numerical values are made dimensionless by the ship speed, and U = 1.0 is the ship speed. In order to improve the circumferential inflow angle to the duct blade section, the center of the stern vertical vortex has the same height as the propeller shaft.

Further, in this embodiment, the hull form that generates the target wake field is generated by using the designed target wake field as an input. The generated hull form (system output hull form) is a newly generated hull form / wake field database created by blending three hull forms with similarities (Euclidean distance in Equation (1)) with the designed wake field. The difference between the original ship type and the generated ship type is 0.02%.
FIG. 10 is a comparison diagram (SS1.0) between the prototype ship and the generated ship type, and FIG. 11 is a comparison diagram (stern profile) between the prototype ship and the generated ship type. In order to lower the center of the stern vertical vortex to the same height as the propeller shaft center, the stern separation line is moved to the stern side, so a so-called shoulder-pumped C _p- curve hull form is created that has a drainage amount behind the stern. I originally expected it to happen. However, the generated hull form is S.D. S. Was hull with C _p curve of a small so-called shoulder-clad cross-sectional area at 1.0.
The reason for this can be explained from the hull surface pressure distribution and the critical streamline of the prototype ship and the generated ship shape shown in FIGS. That is, S. of the hull. S. By increasing the bottom of the ship near 2.0 and improving the wake field, the negative pressure region that can be made here is strengthened, and the stern vertical vortex is strengthened by creating a streamline with a strong reverse pressure gradient. Can be lowered to the same height as the propeller shaft core, and the wake field can be improved.
Note that “SS” is the length between the perpendiculars (captain) L. P. P. Stern vertical line when the total is 10 P. The position from is shown. That is, “SS 1.0” is the stern perpendicular line A.S. P. To perpendicular length L. P. P. Is “S.S.2.0” is the stern perpendicular line A.S. P. To perpendicular length L. P. P. It is a position 20% ahead.

  By considering a wake field using the wake field design method of the present embodiment, and a ship equipped with at least one of a stern appendage and a propeller that have designed the wake field, It is possible to provide a ship that realizes overall optimization of the hull, stern appendages, and propellers.

FIG. 12 is a flowchart showing a wake field designing method according to another embodiment of the present invention.
The wake field design method according to the present embodiment is an optimum stern appendage and propeller design method when hull or flow field information is unknown. When retrofitting a stern appendage to an existing ship, the hull form information is often unknown. In addition, there are many cases where the flow field cannot be estimated due to budget constraints even in new ships. By using the wake field design method according to the present embodiment in such a case, there is generally an optimum effect for any ship under a certain constraint condition from the statistical analysis result based on the hull form / wake field database. Stern appendages and propellers can be designed.
First, hull constraint conditions are determined (S21: step 21).
After step 21, based on the hull form / wake field database constructed in advance, statistical analysis of the wake field with respect to the determined hull constraint conditions is performed to obtain wake field statistical data under the constraint conditions (S22: Step 22).
After step 22, based on the wake field statistical data, at least one optimum design of the stern appendage and the propeller under constraint is performed (S23: step 23).
As a result, even if the ship type information is unknown or the wake field cannot be estimated, it is generally optimal for any ship under certain constraints based on the wake field statistical data. There are stern appendages and propellers that can be designed. For example, it is possible to design optimal stern appendages and propellers by estimating wake fields for existing ships whose detailed design information is unknown and for new ships where flow field analysis cannot be performed due to budget.

When a duct is used as the stern appendage, the duct having the optimum effect for any ship preferably has a duct inflow angle design range of 5 ° to 20 °, preferably 12 ° to 18 °. The following range is more preferable, and the range of 14 ° to 18 ° is most preferable.
In addition, since the angle of attack of the wings of the duct is preferably about 6 ° to 8 °, the opening angle of the duct corresponding to the wake field is preferably -3 ° to 14 °, and preferably 4 ° to 12 °. It is more preferable that the angle be 6 ° or more and 12 ° or less. Thereby, a duct can be made to face in the range of the large opening angle which is effective as a wake field, and the energy-saving effect by a duct can be improved further.

  As described above, the wake field for at least one of the hull, stern appendage, and propeller is analyzed based on the hull form / wake field database in which the hull form and the wake field are linked in advance. By designing a wake field suitable for at least one of the propellers, it becomes easy to associate the hull (hull form) with the wake field, and a hull suitable for the stern appendage and the propeller can be designed. , Hull, stern appendages, and overall propeller optimization.

  In order to verify the effectiveness of the wake design system according to the present invention, a large model ship with a captain of 6.8 m was created for the original ship type (MS No.869) and the generated ship type (MS No.875). In the water tank, wake measurement and propulsion performance confirmation tests were conducted. FIG. 13 is a diagram showing a state of the aquarium test using the original hull form, and FIG. 14 is a diagram showing a state of the aquarium test using the generated hull form.

FIG. 15 is a diagram showing the measured wake distribution of the prototype ship, and FIG. 16 is a diagram showing the measured wake distribution of the generated ship type (system output ship type). The center of the stern vertical vortex generated as expected has been lowered to the same height as the propeller shaft compared to the original ship.
FIG. 17 is a diagram showing the distribution of the circumferential inflow angle to the duct wing cross section in the original hull form, FIG. 18 is a diagram showing the distribution of the circumferential inflow angle to the duct wing cross section in the generated hull form, and FIG. FIG. 20 is an explanatory view of the inflow angle α, FIG. 20 is an explanatory view of the duct position θ, and FIG. 21 is a view showing the energy saving effect of the generated ship shape in comparison with the original ship shape.
17 and 18 show the distribution of the inflow angle in the circumferential direction on the duct blade cross section in comparison with the calculation results. According to the design purpose, the generated hull form has a smaller variation in the inflow angle in the circumferential direction in the design range of 0 ° to 80 ° as compared with the original hull form. As a result, as shown in Table 1 and FIG. 21, the duct horsepower reduction effect (Energy savings), which was 1.9% in the prototype ship, was 4.1% (1.0-678 / 708 in Table 1). The energy saving effect of the duct was improved as designed. In addition, the generated hull form is barely equipped with no duct, and requires more horsepower at 0.4% the same hull speed than the original hull form, but due to improved energy saving effect of the duct, Duct 6 deg with the same opening angle is reduced. 1.9% compared to the mounted state, 2.2% horsepower reduction confirmed with the Duct 8deg designed for the wake distribution of the generated ship form, and the hull form and the adjuncts that were intended for the design Total horsepower reduction by combining the two. From these design results, the effectiveness of the present invention was confirmed.

In this way, the fluctuation in the circumferential direction of the inflow angle to the duct induced by the hull can be improved. As a result, a duct having a constant opening angle in the circumferential direction is generally a problem of workability, and a stable thrust is obtained in the circumferential direction, so that an energy saving effect is enhanced.
The fluctuation range of the inflow angle of the wake field flow with respect to the duct is preferably 25 ° or less, more preferably 20 ° or less, and most preferably 15 ° or less. Thereby, the energy saving effect by the duct can be further enhanced in consideration of the wake field.
Further, the range in which the inflow angle is 25 ° or less is preferably at least in the range of 0 ° or more and 90 ° or less of the upper intersection of the longitudinal center line of the duct, and is in the range of 0 ° or more and 80 ° or less. Is more preferable, and most preferably within a range of 10 ° to 80 °. Thereby, a duct can be made to face the range of an inflow angle with a large effect as a wake field, and the energy-saving effect by a duct can be heightened efficiently.

Next, the circumferential fluctuation reduction of the axial wake for the purpose of reducing cavitation will be described. FIG. 22 is a diagram showing the flow direction distribution of the axial velocity of the original ship type, and FIG. 23 is a diagram showing the flow direction distribution of the generated axial velocity of the ship type.
22 and 23 show the flow direction distributions of the axial velocity of the original hull form and the generated hull form in comparison with the calculation results, respectively. The intended minimization of the difference between the maximum value and the minimum value of the axial flow velocity at 0.7R has been realized. However, in the aquarium test results, the increase in flow velocity from 0 ° to 20 ° and the deceleration near 120 ° tend to be the same, but the results of the aquarium test results are not as expected. . However, this indicates that the CFD calculation for constructing the flow field database needs to be performed under conditions with higher accuracy than the number of grids, etc. in order to apply it to the propeller design aimed at reducing cavitation. It is not a structural problem of the design system, but can be solved easily.

Thus, cavitation of the propeller can be reduced. Reducing cavitation solves noise and vibration problems. Further, by reducing cavitation, the allowable range of the propeller development area ratio can be further reduced, which contributes to improvement of propeller efficiency.
The variation rate of the circumferential distribution of the wake field flow with respect to the propeller surface is preferably suppressed to 0.4 or less, more preferably to 0.3 or less, and most preferably to 0.2 or less. Thereby, the propeller efficiency can be further increased in consideration of the wake field.
The range in which the fluctuation rate of the circumferential distribution of the wake field flow is suppressed to 0.4 or less is preferably 60% to 100% of the propeller radius, and 70% to 90%. More preferably, it is more preferably 70% or more and 80% or less. Thereby, since the fluctuation rate in a range where the effect is large as a propeller can be suppressed, the propeller efficiency can be increased efficiently.

As described above, the present invention uses the wake field design method or wake field design system that enables the design of the intended wake field, and improves the energy saving effect and cavitation of the stern appendage such as a duct type energy saving appendage. The wake distribution that contributes to the reduction can be improved.
By improving the energy saving effect of the stern appendage, the total horsepower reduction of the hull form and stern appendage is achieved.
In addition to the duct, the stern appendage includes all devices that contribute to energy saving, such as fins and valves provided in the rudder, fins provided in front of the propeller, and torsion rudder.

According to the present invention, it is easy to associate the hull (hull form) with the wake field, and it is possible to design a hull suitable for the stern appendage and the propeller, and to optimize the entire hull, stern appendage, and propeller. Realize.
In addition, the present invention realizes the visualization of craftsmen's knowledge, and has the advantage of enabling hull form design while understanding the wake field over the hull form design technique combining conventional CFD and optimization techniques. It can be used for decision making by the hull designer.

10 Condition input means 20 Hull form / wake field database means 30 Wake field analysis means 40 Wake field design means 50 Wake field output means

Claims (20)

  A method for designing a wake field generated at the stern of a ship, in which a wake field for at least one of a hull, a stern appendage, and a propeller is linked to a wake field constructed in advance and a wake field. A wake field design method characterized by analyzing the data based on a database and designing the wake field suitable for at least one of the stern appendage and the propeller.   The design of the wake field is to select a hull form data close to the target wake field based on the hull form / wake field database and generate a hull form from which the target wake field can be obtained. The wake field designing method according to claim 1, wherein   The wake field design according to claim 2, wherein a plurality of the ship form data close to the target wake field are selected and averaged to generate the ship form from which the target wake field is obtained. Method.   The wake field according to claim 2 or 3, wherein at least one of the stern appendage and the propeller is designed after generating the hull form capable of obtaining the target wake field. Design method.   Based on the hull form / wake field database, an optimum wake field database suitable for at least one of the stern appendage and the propeller is constructed, and the constraint conditions of the hull are determined using the optimum wake field database. The wake field design method according to claim 1, wherein the wake field suitable for at least one of the stern appendage and the propeller is selected in consideration.   The wake field design method according to claim 5, wherein the hull form is generated in consideration of constraints of the hull.   Setting constraints on the hull, performing statistical analysis of the wake field on the constraints based on the hull form / wake field database, and obtaining wake field statistical data under the constraints The wake field designing method according to claim 1, wherein   The wake field design method according to claim 7, wherein at least one optimum design of the stern appendage and the propeller under the constraint condition is performed based on the wake field statistical data. .   9. The wake field in the hull form / wake field database is a flow field having nodes with little change in flow even when the hull form changes. Wake field design method described in 1.   A design system for a wake field generated at the stern of a ship, which stores condition input means for inputting a condition for at least one of a hull, a stern appendage, and a propeller, and data that links a hull form and a wake field. Hull form / wake field database means, wake field analysis means for analyzing the wake field based on the data of the hull form / wake field database means for the input conditions, and analysis of the wake field A wake field design system comprising: wake field design means for designing the wake field based on a result; and wake field output means for outputting the design result of the wake field.   The wake field analysis means performs selection of ship type data close to the target wake field based on the ship form / wake field database means, and according to the selected ship type data, the wake field design means includes: The wake field design system according to claim 10, wherein a hull form capable of obtaining the target wake field is generated.   The design of the wake field in the wake field design means is to average the plurality of ship shape data close to the target wake field to generate the ship shape that can obtain the target wake field. The wake field design system according to claim 11.   The design of the wake field in the wake field design means is characterized in that after the hull form that provides the target wake field is generated, at least one of the stern appendage and the propeller is designed. The wake field design system according to claim 11 or 12.   A ship considering a wake field using the wake field design method according to any one of claims 1 to 9, wherein the stern appendage has designed the wake field, and A ship that takes into account the wake field, which is equipped with at least one propeller.   The ship considering the wake field according to claim 14, wherein a duct is used as the stern appendage, and a fluctuation range of an inflow angle of the wake field flow with respect to the duct is set to 25 ° or less.   The wake field according to claim 15, wherein the range in which the inflow angle is 25 ° or less is at least the range of 0 ° to 90 ° at the upper intersection of the longitudinal center line of the duct. Ship.   The duct according to any one of claims 14 to 16, wherein a duct is used as the stern appendage, and an opening angle of the duct corresponding to the wake field is set to -3 ° or more and 14 ° or less. A ship that takes into account the wake field.   18. The wake according to claim 14, wherein the propeller suppresses a variation rate of a circumferential distribution of the wake field flow with respect to a propeller surface to 0.4 or less. A ship that takes into account the field.   19. The companion according to claim 18, wherein the range in which the fluctuation rate of the circumferential distribution of the flow of the wake field is suppressed to 0.4 or less is a position that is 60% or more and 100% or less of the radius of the propeller. A ship that considers the flow field. The wake field according to any one of claims 14 to 19, wherein the wake field is improved by enlarging a bottom portion of the hull near S.S.2.0. Considered ship.