CN114896689A - Ship rapidity teaching method and system based on resistance map - Google Patents
Ship rapidity teaching method and system based on resistance map Download PDFInfo
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Abstract
The invention discloses a ship rapidity teaching method and a ship rapidity teaching system based on a resistance map, which belong to the field of ship experiment teaching, wherein the method is used for obtaining resistance maps of a series of ship types under different ship type parameters on the basis of existing resistance data of each ship type; during teaching, a student inputs a target ship type parameter, and obtains the resistance of the target ship type ship during navigation through a resistance map matched with the target ship type parameter so as to obtain an effective power curve of the target ship type ship; then inputting host parameters and parameters related to the propulsion coefficient, converting the host power according to the propulsion coefficient to obtain an effective power value, substituting the effective power value into an effective power curve to obtain an estimated navigational speed, further completing model selection of the target ship-type propeller, and drawing a propeller. The resistance-based ship knowledge point series-connection teaching method is used for performing series-connection teaching on ship knowledge points based on the resistance map, completes training and practice of ship-engine propeller matching, improves understanding and application capability of students to knowledge, and is good in teaching effect.
Description
Technical Field
The invention belongs to the field of ship experiment teaching, and particularly relates to a ship rapidity teaching method and system based on a resistance map.
Background
The linear design of the ship is a system engineering, and needs to consider both stationarity and rapidity, and also maneuverability and wave resistance, wherein the rapidity is the most core performance, and directly influences the practicability and economy of the ship. The ship rapidity mainly comprises two parts of resistance performance and propulsion performance, the contents of the two parts are important components in a special core course of the ship, and the two major chapters of ship resistance and ship propulsion are shared. The learning of the rapid knowledge is particularly important, and both subsequent deep construction and related work are required to be deeply understood and skillfully mastered.
The experiment teaching of resistance-open water-self-navigation is carried out with ship model towing tank laboratory cooperation boats and ships model, screw model to current boats and ships tachypless teaching experiment more, because it needs to use trailer system to test the teaching in-process, and trailer system is big to the place demand, construction cost is high, and the colleges and universities that are equipped with boats and ships class specialty are generally just one set of trailer system, so the experiment teaching process is many to use the experiment of student's sight and mole to be the main, and student's participation is poor.
Therefore, it is necessary to research a ship rapid teaching method and system to improve student participation, inspire students' thinking about core problems in the ship design phase, and improve innovation and practice capabilities.
Disclosure of Invention
The invention provides a ship rapidity teaching method and system based on a resistance map, aiming at solving the technical problems of large site requirement, high construction cost, poor student participation and poor teaching effect of the traditional ship rapidity teaching experiment.
In order to achieve the above object, according to one aspect of the present invention, the following technical solutions are provided:
a ship rapidity teaching method based on a resistance map comprises the following steps:
(S1) setting parameters of a target ship type during teaching, acquiring the resistance of the target ship type during navigation through a resistance map matched with the parameters of the target ship type, converting the resistance to obtain the effective power of the target ship type at different navigation speeds, and fitting to obtain an effective power curve; the resistance map is a map which is pre-established according to the existing resistance data of each ship type and is used for reflecting the resistance of the ship during navigation under different ship type parameters;
(S2) setting host parameters including host power and propulsion coefficient related parameters of the target ship type, calculating to obtain a propulsion coefficient according to the propulsion coefficient related parameters, converting the host power according to the propulsion coefficient to obtain an effective power value of the target ship type, and substituting the effective power value into the effective power curve to obtain the corresponding speed, namely the estimated speed of the target ship type; finishing propeller model selection according to the target ship model parameters and the estimated navigational speed; the model selection of the target ship type propeller comprises the following steps: determining main parameters including propeller diameter, pitch ratio and disk surface ratio;
(S3) according to the propeller model selection, finishing the drawing of the propeller blade section parameter table and the propeller blade profile shape chart.
Preferably, in the step (S1), the resistance map is plotted with volume fourier number as abscissa and unit displacement resistance as ordinate; the volume Fourier number
Comprises the following steps:
wherein V is the ship navigation speed, and g is the gravity acceleration;
is the volume of water to be drained by the vessel,
Δ is the displacement, ρ is the density of water;
the unit displacement resistance is R/. DELTA, wherein R is the resistance of the ship when sailing.
Preferably, in step (S1), the formula for obtaining the effective power of the target ship model at different sailing speeds through the resistance conversion is as follows:
in the formula, P E Is the active power.
Preferably, the existing resistance data of each ship model is converted into the resistance data of a real ship from the experimental data of a ship model towing tank, or the existing resistance data of the real ship;
the target ship type parameters comprise the ship length, the model width, the draught, the inclined lift angle, the static inclination angle, the square coefficient and the displacement of the target ship type; the parameters of the main machine also comprise the number of the main machines and the rotating speed of the main machines, and the parameters related to the propulsion coefficient comprise thrust reduction, wake fraction, mechanical transmission efficiency, relative rotation efficiency and open water efficiency;
the model selection of the target ship type propeller is specifically as follows: and selecting first parameters including the propeller type and the blade number of the propeller according to the target ship type parameter and the estimated navigational speed, and determining the main parameters through a propeller spectrum according to the first parameters.
Preferably, the step (S3) is specifically: and according to the main parameters, performing secondary development on the AutoCAD by taking VB language as a tool to finish drawing the section parameter table and the blade profile shape chart of the propeller blade.
According to another aspect of the invention, the following technical scheme is also provided:
a ship rapidity teaching system based on a resistance map comprises:
the resistance map module is used for pre-establishing a map for reflecting the resistance of the ship during navigation under different ship type parameters according to the existing resistance data of each ship type; the existing resistance data of each ship model is converted into the resistance data of a real ship from the experimental data of a ship model towing tank, or the existing resistance data of the real ship;
the ship type input module is used for inputting target ship type parameters during teaching;
the resistance performance estimation module is used for acquiring the resistance of the target ship type during navigation through a resistance map matched with the target ship type parameters input by the ship type input module, obtaining the effective power of the target ship type at different navigation speeds through the resistance conversion, and further fitting to obtain an effective power curve;
the propeller model selection module is used for setting host parameters including host power and propulsion coefficient related parameters of the target ship model, calculating to obtain a propulsion coefficient according to the propulsion coefficient related parameters, converting the host power according to the propulsion coefficient to obtain an effective power value of the target ship model, and substituting the effective power value into the effective power curve to obtain a corresponding navigational speed, namely an estimated navigational speed of the target ship model; finishing propeller model selection according to the target ship model parameters and the estimated navigational speed; the model selection of the target ship type propeller comprises the following steps: determining main parameters including propeller diameter, pitch ratio and disk surface ratio;
and the propeller plotting module is used for finishing drawing the propeller blade section parameter table and the propeller blade outline shape chart according to the propeller model selection.
Preferably, in the resistance map module,
the resistance map is drawn by taking volume Fourier number as a horizontal coordinate and taking unit displacement resistance as a vertical coordinate; the volume Fourier number
Comprises the following steps:
in which V isThe ship sailing speed g is the gravity acceleration;
is the volume of water to be drained by the vessel,
Δ is the displacement, ρ is the density of water;
the unit displacement resistance is R/. DELTA, wherein R is the resistance of the ship when sailing.
Preferably, in the resistance map module, the formula for obtaining the effective power of the target ship type at different navigational speeds through the conversion of the resistance is as follows:
in the formula, P E Is the active power.
Preferably, in the above system, the existing resistance data of each ship model is converted from ship model towing tank experimental data into resistance data of an actual ship, or existing resistance data of an actual ship;
the target ship type parameters comprise the ship length, the model width, the draught, the inclination angle, the static inclination angle, the square coefficient and the displacement of the target ship type; the parameters of the main machine also comprise the number of the main machines and the rotating speed of the main machines, and the parameters related to the propulsion coefficient comprise thrust reduction, wake fraction, mechanical transmission efficiency, relative rotation efficiency and open water efficiency;
the model selection of the target ship type propeller is specifically as follows: and selecting first parameters including the propeller type and the blade number of the propeller according to the target ship type parameter and the estimated navigational speed, and determining the main parameters through a propeller spectrum according to the first parameters.
Preferably, the propeller drawing module is used for carrying out secondary development on AutoCAD by taking VB language as a tool according to the main parameters to complete drawing of the propeller blade section parameter table and the propeller blade outline shape diagram.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
1. the ship rapidity teaching method and the ship rapidity teaching system based on the resistance map, which are provided by the invention, are based on the existing resistance data of each ship type according with the actual engineering, and the resistance maps of a series of ship types under different ship type parameters (different main scales and different displacement working conditions) are obtained; the method comprises the following steps that students input target ship type parameters during teaching, a system automatically compares the target ship type parameters in a resistance map according to the target ship type parameters, the resistance of a target ship type ship during navigation is obtained through the resistance map matched with the target ship type parameters, the effective power of the target ship type at different navigation speeds is obtained through conversion of the resistance, and an effective power curve is obtained through fitting; then inputting host parameters and parameters related to the propulsion coefficient, converting the host power according to the propulsion coefficient to obtain an effective power value, substituting the effective power value into the power curve to obtain the corresponding speed, namely the estimated speed, so as to complete the model selection of the target ship-type propeller and determine main parameters such as the diameter of the propeller, the pitch ratio, the plate surface ratio and the like; the propeller mapping is then performed according to the main parameters. The ship model ship.
2. According to the ship rapidity teaching method and system based on the resistance map, the resistance map is drawn by taking volume Fourier number as an abscissa and taking unit displacement resistance as an ordinate, so that the resistance characteristics of ships in navigation under different ship type parameters can be reflected simply and accurately, the ship resistance characteristics displayed by the resistance map can be obtained according to target ship type parameters input by students in teaching, the resistance of the ships in navigation of the target ship type can be obtained according to the resistance map, and effective power curves of the target ship type at different navigation speeds can be obtained through the resistance conversion; the teaching efficiency is effectively improved, so that students can directly and clearly master and understand knowledge points of resistance experiment data and resistance performance through autonomous learning, and the teaching effect is improved.
3. According to the ship rapidity teaching method and system based on the resistance map, the propeller model selection module determines main parameters such as propeller diameter, pitch ratio and plate surface ratio through the existing propeller spectrum (B type, AU type, MAU type and the like) after selecting parameters such as propeller model, effective power, host machine parameter, estimated target ship model navigational speed and propeller model, completes calculation of the main parameters of the propeller, performs AutoCAD secondary development based on VB language by contrasting the propeller map, and completes drawing of the propeller map. The teaching system is designed based on model test data, is high in practicability and concise in interface, is high in interactivity, can stimulate the thinking ability of students as an auxiliary tool for classroom teaching, improves knowledge understanding, and has a positive effect on improving the innovation ability of the students.
Drawings
FIG. 1 is a flow chart of a method for teaching rapidity of a ship based on a resistance map according to a preferred embodiment of the present invention;
FIG. 2 is a block diagram of a ship rapid teaching system based on a resistance map according to a preferred embodiment of the present invention;
FIG. 3 is a diagram illustrating an interface of the system for teaching ship rapidity based on a resistance map according to the preferred embodiment of the present invention;
FIG. 4 is an example of the results of a calculation of a propeller design in a preferred embodiment of the present invention;
FIG. 5 is an example of a resistance map in a preferred embodiment of the invention;
FIG. 6(a) is a table of propeller elements generated by the ship's rapid teaching system based on a resistance map according to the preferred embodiment of the present invention;
FIG. 6(b) is a propeller specification generated by the ship tachy metry system based on a resistance map in accordance with the preferred embodiment of the present invention;
FIG. 6(c) is a table of propeller type values generated by the ship's rapid teaching system based on a resistance map in accordance with the preferred embodiment of the present invention;
FIG. 6(d) is a cross-sectional view of a propeller generated by the ship's rapid teaching system based on a resistance map according to the preferred embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides a ship rapidity teaching method and system based on a resistance map, which are based on test accumulated data or real ship data of a ship model towing tank laboratory, obtain the resistance maps of series ships under different ship type parameters by classifying different ship type data, integrate knowledge points such as resistance, navigational speed estimation, propeller design and the like in the whole teaching process, finish the ship rapidity experimental teaching such as training and practice of ship-engine propeller matching and the like, and improve the understanding and application capability of students to knowledge.
As shown in fig. 1, the ship rapidity teaching method based on the resistance map provided by the embodiment of the invention includes the following steps:
step 1, establishing resistance maps of serial ship types under different ship type parameters (different main scales and different displacement working conditions) based on the existing resistance data of each ship type. In particular, the amount of the solvent to be used,
the resistance map is used for reflecting the resistance of the ship during navigation under different ship type parameters.
The existing ship model resistance data is converted into the resistance data of the real ship from the ship model towing tank experimental data, or the existing real ship resistance data comprises main scale parameters such as ship model, ship length, ship width, draught, displacement, square coefficient, prismatic coefficient and the like, and resistance data corresponding to different navigational speeds. If the basic data is ship model data, converting the basic data into a real ship to finish resistance map drawing; and if the basic data is real ship data, the basic data is directly used.
And (3) directly drawing a resistance map for the ship types covered by the existing resistance data of all ship types. For the ship types which are not covered by the existing ship type resistance data, the resistance map can be obtained by linear interpolation according to the ship types or ship type parameter data with similar ship types.
In the embodiment of the invention, the resistance spectrum is drawn by taking volume Fourier number as a horizontal coordinate and resistance of unit displacement as a vertical coordinate; the volume Fourier number
Comprises the following steps:
wherein V is the ship navigation speed, and g is the gravity acceleration;
is the volume of water to be drained by the vessel,
Δ is the displacement, ρ is the density of water;
the unit displacement resistance is R/. DELTA, wherein R is the resistance of the ship when sailing.
And (3) on the basis that the resistance map is established in the step 1, performing the following steps 2-4 in teaching.
And 2, in the teaching process, a student sets a target ship type parameter, sets the target ship type parameter during teaching, obtains the resistance of the target ship type ship during navigation through a resistance map matched with the target ship type parameter, obtains the effective power of the target ship type at different navigation speeds through the resistance conversion, and further obtains an effective power curve through fitting.
Specifically, the formula for obtaining the effective power of the target ship type at different navigational speeds through the conversion of the resistance of the target ship type during navigation is as follows:
in the formula, P E Is the active power.
Step 3, the students set host parameters including host power and related parameters of a propulsion coefficient of the target ship type, calculate the propulsion coefficient according to the related parameters of the propulsion coefficient, convert the host power according to the propulsion coefficient to obtain an effective power value of the target ship type, and substitute the effective power value into the effective power curve to obtain the corresponding navigational speed, namely the estimated navigational speed of the target ship type; finishing propeller model selection according to the target ship model parameters and the estimated navigational speed; the model selection of the target ship type propeller comprises the following steps: the main parameters including propeller diameter, pitch ratio and disk ratio are determined. In particular, the amount of the solvent to be used,
the parameters of the main machine also comprise the number of the main machines and the rotating speed of the main machines, and the parameters related to the propulsion coefficient comprise thrust decrement, wake fraction, mechanical transmission efficiency, relative rotation efficiency and open water efficiency.
And converting the host power according to the propulsion coefficient to obtain the effective power value of the target ship type:
P E ＝P S ·P.C
P.C＝η S ·η G ·η r ·η 0 ·η H
in the formula, P E Is the effective power; p S Is the host power; P.C is the propulsion coefficient; eta S ·η G Mechanical transmission efficiency; eta r Relative rotational efficiency; eta 0 Of propellers for open water efficiencyInherent characteristics, after the propeller is selected, the open water efficiency performance is determined; eta H For hull efficiency; t and w are respectively thrust deduction and wake fraction;
the model selection of the target ship type propeller is specifically as follows: and selecting first parameters including the propeller type and the blade number of the propeller according to the target ship type parameter and the estimated navigational speed, and determining the main parameters through a propeller spectrum according to the first parameters. The specific process of propeller termination design will be described below with reference to a design example:
knowing the host power P S 541kw, 950r/min of main engine speed, 11kn of estimated designed navigational speed V and effective power curve, selecting MAU type propeller with 4 number of blades, and calculating to obtain the required propeller disk surface ratio A according to the related formula E /A 0 The MAU4-40 and MAU4-50 maps were then selected for design based on the ratio of disc sizes at 0.385, with the specific steps calculated in table 1.
TABLE 1 calculation Table for Propeller termination design
The results of the calculations in Table 1 are plotted in FIG. 4, with the speed V on the abscissa and P on the abscissa E P/D, D and eta 0 Is the ordinate. Curve P in the figure TE And curve P E The intersection point of the two is the propeller to be obtained, and the main parameters of the obtained propeller are shown in table 2.
TABLE 2 Propeller principal parameters
And 4, carrying out secondary development on the AutoCAD by taking VB language as a tool according to the obtained main parameters of the diameter, the disk surface ratio, the pitch ratio and the like of the propeller, and completing drawing of the section parameter table of the propeller blade and the profile shape chart of the propeller blade.
As shown in fig. 2, the ship rapid teaching system based on the resistance map provided by the invention comprises: the system comprises a resistance map module 101, a ship type input module 102, a resistance performance estimation module 103, a propeller model selection module 104 and a propeller map module 105.
The resistance map module 101 is used for classifying the data of different ship types based on the existing resistance data of each ship type, and is used for obtaining the resistance maps of a series of ship types under different ship type parameters (different main dimensions and different displacement working conditions).
The resistance map is used for reflecting the resistance of the ship in navigation under different ship type parameters.
The existing ship model resistance data is converted into the resistance data of the real ship from the ship model towing tank experimental data, or the existing real ship resistance data comprises main scale parameters such as ship model, ship length, ship width, draught, displacement, square coefficient, prismatic coefficient and the like, and resistance data corresponding to different navigational speeds. If the basic data is ship model data, converting the basic data into a real ship to finish resistance map drawing; and if the basic data is real ship data, the basic data is directly used.
And (3) directly drawing a resistance map for the ship types covered by the existing resistance data of all ship types. For the ship types which are not covered by the existing ship type resistance data, the resistance map can be obtained by linear interpolation according to the ship types or ship type parameter data with similar ship types.
The ship type input module 102 is used for receiving parameters of a target ship type, and students select the ship type and input main parameters including parameters such as ship length, model width, draught, square coefficient and water displacement in the teaching process.
The resistance performance estimation module 103 is used for estimating resistance data of the target ship type, acquiring the resistance of the target ship type during navigation through a resistance map matched with the parameters of the target ship type, obtaining the effective power of the target ship type at different navigation speeds through the resistance conversion, and further fitting to obtain an effective power curve.
Specifically, in the teaching process, students select a ship type, input the main scale and the load working condition of the ship type, and then obtain the input effective power of the target ship type at different navigational speeds by inquiring the corresponding ship type resistance map.
The propeller model selection module 104 is used for students to input host parameters including host power, thrust reduction, wake flow fraction, mechanical transmission efficiency and relative rotation efficiency of a target ship model, obtain a propulsion coefficient according to the input parameters, further convert the host power to obtain an effective power value of the target ship model, and substitute the effective power value into the effective power curve to obtain a corresponding navigational speed, namely an estimated navigational speed of the target ship model; and finishing propeller model selection according to the target ship model parameters and the estimated navigational speed.
Specifically, after obtaining an effective power curve of a target ship model at different sailing speeds, a student inputs host parameters such as host power, host number and host rotating speed, inputs propulsion coefficient related parameters such as thrust derating, wake flow fraction, relative rotating efficiency and mechanical transmission efficiency by combining with ship model characteristics, obtains the propulsion coefficient of the system according to the input parameters, automatically converts the host power to obtain an effective power value of the target ship model, and substitutes the effective power value into the effective power curve to obtain a corresponding sailing speed, namely an estimated sailing speed of the target ship model;
and the student selects a first parameter comprising the propeller type and the blade number of the propeller according to the target ship type parameter and the estimated navigational speed, and determines main parameters such as the diameter, the pitch ratio and the plate surface ratio of the propeller according to the first parameter through an existing propeller spectrum (B type, AU type, MAU type and the like).
And the propeller drawing module 105 carries out secondary development on the AutoCAD by taking VB language as a tool according to the obtained main parameters of the propeller diameter, the disk surface ratio, the pitch ratio and the like, and finishes drawing the propeller blade section parameter table and the propeller blade outline shape chart.
The specific implementation of each module may refer to the description in the method embodiment, and the embodiment of the present invention will not be repeated.
The process of how the ship rapidity teaching is realized by the ship rapidity teaching system based on the resistance map is specifically described below by combining examples.
As shown in fig. 3, after the resistance performance original data accumulation and the map interpolation are completed, the resistance performance original data accumulation and the map interpolation enter an experiment teaching interface, for example, a deep V-shaped speed boat type, information such as the length, the width, the displacement, the inclination angle, the static inclination angle and the like of a target boat can be input on a boat type input interface, and the information basically determines the appearance and the main performance indexes of the target boat.
The length of the V-shaped boat is 26.79 m, and the widths of the V-shaped boat are 4.58 m, 5.42 m and 6.63 m respectively. The boat is provided with a sharp bilge type bow, all cross sections are V-shaped, the bow is sharp, the inclined angle is large, the angle is continuously reduced and smoothly transited into the boat, the transverse inclined angle beta (13 degrees, 16 degrees and 20 degrees) in the boat is continuously reduced and transited towards the stern until the stern approaches to zero.
Table 3 shows the ship type parameters of 4.58 m width, the inclined angles are respectively 13 degrees, 16 degrees and 20 degrees, three draft angles of 45t, 55t and 65t are respectively arranged under each inclined angle, and each draft angle has a static inclination angle of 0 degree and 0.5 degree (tail inclination). Tables 4 and 5 show ship type parameters for ship widths of 5.42 meters and 6.63 meters, respectively, each ship width including similar combinations of lift, displacement, and static trim conditions as in table 3. Three sets of ship widths, three sets of inclined lifting angles, three sets of water displacement and two sets of static inclination angles are combined into 54 sets of working conditions, the navigational speed range of each set of working conditions is 15-39 kn, and the navigational Fourier number Fn range is 1.229-3.194.
Table 3 beam B-4.58 meter ship type parameters
Table 4 beam B-5.42 m ship type parameter
TABLE 5 Width B ═ 6.63 m ship type parameter
After the student finishes the ship type input, the effective power output by clicking can obtain the effective power estimation of the real ship at different navigational speeds through linear interpolation of the map.
The conversion from the model resistance to the real ship effective power adopts Froude's Method [10] The resistance R of the ship model t Divided into frictional resistance R f And residual resistance R r Dimensionless ship model drag coefficient C t Divided into coefficient of friction resistance C f And coefficient of residual resistance C r The Froude method considers that the residual resistance coefficients of the actual ship and the model are equal, and the frictional resistance coefficient is calculated by adopting a 1957-ITTC formula, wherein the formula is as follows:
actual ship total drag coefficient:
C ts ＝C fs +C rs +ΔC f ＝C fs +(C tm -C fm )+ΔC f (2)
wherein C is ts Is the total drag coefficient, C, of a real ship fs And C rs Coefficient of friction resistance and coefficient of residual resistance, C, of a real ship tm And C fm Respectively, the total resistance coefficient and the frictional resistance coefficient of the model, Delta C f The roughness is used for supplementing and pasting the coefficient, the experimental experience of a laboratory on the model treatment of the yacht type is combined, and the Delta C f Take 0.2X 10 -3 。
The total resistance of the real ship:
effective power:
V s is the real ship sailing speed; s S Is the ship wet surface area; rho S Is the fluid density.
For the yacht, the resistance map can be drawn by volume Fourier number and unit displacement resistance, wherein the volume Fourier number
Comprises the following steps:
wherein V is the sailing speed of the ship, i.e. the sailing speed V of the real ship s In meters per second; g is the acceleration of the gravity and,
is the volume of water to be drained by the vessel,
the unit is cubic meters.
Δ is the displacement, ρ represents the density of water, and ρ is in kilograms per cubic meter. Dimensional analysis
Is a dimensionless quantity.
Taking 54 pieces of resistance data of all working conditions as volume Fourier number according to abscissa
The ordinate is R/delta to draw a test result curve chart, wherein R is the resistance of the ship during navigation, namely the total resistance R of the real ship ts Fig. 5 shows the results of the test with the width B of 4.58 m and the water discharge Δ of 45t, and it can be seen that 9 result charts shown in fig. 5 were obtained in total after all the test results were completed, and the acquisition of the map data was completed.
And further sequentially inputting information such as the number of main engines, the power of the main engines, the rotating speed of the main engines, the reduction ratio of a gear box, thrust reduction, wake fraction, mechanical transmission efficiency, relative rotation efficiency, seawater density, the immersion depth of a propeller shaft, the number of propeller blades and the like into a propeller model selection interface, wherein most of the information can have an approximate estimation range by combining with a target ship model, for example, the thrust reduction t range is 0.06-0.15, the wake fraction w range is 0.1-0.18, the relative rotation efficiency can be initially 1, the shafting efficiency is 0.95-1 and the like.
And clicking to output propeller parameters after the parameters are input, and completing propeller design, wherein the output parameters comprise propeller diameter, pitch ratio, disc surface ratio and estimated navigational speed of the ship under the designed propeller.
After the propeller parameter selection is completed, information such as the size of the propeller, the propeller turning direction, the material and the weight is further selected, and a propeller is plotted, in this case, the propeller plotting effect is as shown in fig. 6(a) -6 (d), the plotting information includes propeller element information, propeller technical requirements, a propeller type value table and a propeller section diagram, wherein fig. 6(a) is the propeller element table, fig. 6(b) is the propeller technical requirements, fig. 6(c) is the propeller type value table, and fig. 6(d) is the propeller section diagram.
The embodiment of the invention provides a ship rapidity teaching method and a ship rapidity teaching system based on a resistance map, which are characterized in that a series ship-shaped water pool test result or a real ship test result is classified, sorted and linearly interpolated to complete the design of the series ship-shaped resistance map, students autonomously input ship-shaped parameters, then obtain effective power through the resistance map, input parameters such as thrust derating, accompanying current fraction, relative rotation efficiency and mechanical transmission efficiency, estimate design navigational speed after selecting host power and rated rotation speed and complete propeller design to obtain parameters such as propeller diameter, disc surface ratio and pitch ratio, and perform secondary development on AutoCAD by taking VB language as a tool to complete the drawing of a propeller blade profile parameter table and a propeller blade profile shape chart. The resistance map is established based on the existing ship resistance data, the ship rapid teaching knowledge points are organically fused, the knowledge points of resistance experiment, real ship speed estimation, propeller model selection and propeller design are connected in series, the system learning and mastering of knowledge veins of resistance performance, propulsion performance and ship engine propeller matching of students are realized, each student can independently complete learning, the understanding of knowledge is strengthened, the application capability of the knowledge is improved, the practicability is high, and the teaching effect is good.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A ship rapidity teaching method based on a resistance map is characterized by comprising the following steps:
(S1) setting parameters of a target ship type during teaching, acquiring the resistance of the target ship type during navigation through a resistance map matched with the parameters of the target ship type, converting the resistance to obtain the effective power of the target ship type at different navigation speeds, and fitting to obtain an effective power curve; the resistance map is a map which is pre-established according to the existing resistance data of each ship type and is used for reflecting the resistance of the ship during navigation under different ship type parameters;
(S2) setting host parameters including host power and propulsion coefficient related parameters of the target ship type, calculating to obtain a propulsion coefficient according to the propulsion coefficient related parameters, converting the host power according to the propulsion coefficient to obtain an effective power value of the target ship type, and substituting the effective power value into the effective power curve to obtain the corresponding navigational speed, namely the estimated navigational speed of the target ship type; finishing propeller model selection according to the target ship model parameters and the estimated navigational speed; the model selection of the target ship type propeller comprises the following steps: determining main parameters including propeller diameter, pitch ratio and disk surface ratio;
(S3) according to the propeller model selection, finishing the drawing of the propeller blade section parameter table and the propeller blade profile shape chart.
2. The resistance map-based ship rapid teaching method according to claim 1, wherein in the step (S1), the ship is taughtThe resistance map is drawn by taking volume Fourier number as a horizontal coordinate and taking unit displacement resistance as a vertical coordinate; the volume Fr ▽ Comprises the following steps:
wherein V is the ship navigation speed, and g is the gravity acceleration; v is the volume of water displaced by the ship, Δ ═ Δ ρ, Δ is the displacement, ρ is the density of the water;
the unit displacement resistance is R/. DELTA, wherein R is the resistance of the ship when sailing.
3. The method for rapid teaching of ships according to claim 2, wherein in step (S1), the formula for obtaining the effective power of the target ship type at different speeds by the resistance conversion is:
in the formula, P E Is the active power.
4. The resistance-map-based ship rapidity teaching method according to claim 3, wherein the existing resistance data of each ship model is converted into resistance data of a real ship from ship model towing tank experimental data, or the existing resistance data of the real ship;
the target ship type parameters comprise the ship length, the model width, the draught, the inclined lift angle, the static inclination angle, the square coefficient and the displacement of the target ship type; the parameters of the main machine also comprise the number of the main machines and the rotating speed of the main machines, and the parameters related to the propulsion coefficient comprise thrust reduction, wake fraction, mechanical transmission efficiency, relative rotation efficiency and open water efficiency;
the model selection of the target ship type propeller is specifically as follows: and selecting first parameters including the propeller type and the blade number of the propeller according to the target ship type parameter and the estimated navigational speed, and determining the main parameters through a propeller spectrum according to the first parameters.
5. The resistance map-based ship quickness teaching method according to claim 1 or 2, wherein the step (S3) is specifically: and according to the main parameters, performing secondary development on the AutoCAD by taking VB language as a tool to finish drawing the section parameter table and the blade profile shape chart of the propeller blade.
6. A ship rapidity teaching system based on a resistance map is characterized by comprising:
the resistance map module is used for pre-establishing a map for reflecting the resistance of the ship during navigation under different ship type parameters according to the existing resistance data of each ship type; the existing resistance data of each ship model is converted into the resistance data of a real ship from the experimental data of a ship model towing tank, or the existing resistance data of the real ship;
the ship type input module is used for inputting target ship type parameters during teaching;
the resistance performance estimation module is used for acquiring the resistance of the target ship type during navigation through a resistance map matched with the target ship type parameters input by the ship type input module, obtaining the effective power of the target ship type at different navigation speeds through the resistance conversion, and further fitting to obtain an effective power curve;
the propeller model selection module is used for setting host parameters including host power and related parameters of a propulsion coefficient of the target ship model, calculating the propulsion coefficient according to the related parameters of the propulsion coefficient, converting the host power according to the propulsion coefficient to obtain an effective power value of the target ship model, and substituting the effective power value into the effective power curve to obtain the corresponding navigational speed, namely the estimated navigational speed of the target ship model; finishing propeller model selection according to the target ship model parameters and the estimated navigational speed; the model selection of the target ship type propeller comprises the following steps: determining main parameters including propeller diameter, pitch ratio and disk surface ratio;
and the propeller plotting module is used for finishing drawing the propeller blade section parameter table and the propeller blade outline shape chart according to the propeller model selection.
7. The resistance map-based ship rapid teaching system of claim 6, wherein in the resistance map module,
the resistance map is drawn by taking volume Fourier number as a horizontal coordinate and taking unit displacement resistance as a vertical coordinate; the volume Fr ▽ Comprises the following steps:
wherein V is the ship sailing speed, and g is the gravity acceleration; v is the volume of water displaced by the ship, Δ ═ Δ ρ, Δ is the displacement, ρ is the density of the water;
the unit displacement resistance is R/. DELTA, wherein R is the resistance of the ship when sailing.
8. The system according to claim 7, wherein the formula for obtaining the effective power of the target ship type at different sailing speeds through the resistance conversion in the resistance map module is as follows:
in the formula, P E Is the active power.
9. The system for teaching ship rapidity based on resistance map according to claim 8, wherein the existing resistance data of each ship model is converted into the resistance data of a real ship from the experimental data of a ship model towing tank, or the existing resistance data of the real ship;
the target ship type parameters comprise the ship length, the model width, the draught, the inclined lift angle, the static inclination angle, the square coefficient and the displacement of the target ship type; the parameters of the main machine also comprise the number of the main machines and the rotating speed of the main machines, and the parameters related to the propulsion coefficient comprise thrust reduction, wake fraction, mechanical transmission efficiency, relative rotation efficiency and open water efficiency;
the model selection of the target ship type propeller is specifically as follows: and selecting first parameters including the propeller type and the blade number of the propeller according to the target ship type parameter and the estimated navigational speed, and determining the main parameters through a propeller spectrum according to the first parameters.
10. The system for rapid teaching of ships according to claim 6 or 7, wherein the propeller mapping module is used for performing secondary development on AutoCAD by using VB language as a tool according to the main parameters to complete the drawing of the propeller blade profile parameter table and the propeller blade profile shape chart.
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| CN116776464A (en) * | 2023-06-09 | 2023-09-19 | 武汉理工大学 | Method and system for generating profile pedigree of specific-route river-sea direct container ship |
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