阅读说明：本技术 一种船用带制流板舵舵效的计算方法 (Method for calculating rudder effect of marine rudder with flow control plate ) 是由 程嘉欢 赵德亮 杨洪刚 林佩剑 于 2019-11-13 设计创作，主要内容包括：一种船用带制流板舵舵效的计算方法。本发明通过分解复杂模型,立足现有试验结果,适当处理边界条件的手段,较为便捷计算带制流板舵的舵效,为设计初期阶段计算舵效提供一种便捷、灵活的计算方法。本发明共分为五个步骤,步骤1为建立坐标系,步骤2为计算舵叶舵效,步骤3为计算制流板水动力,步骤4为计算带制流板舵在均匀来流中的舵效,步骤5为引入尾流效果进行调整。本发明于现有的计算方法相比,有以下优点：考虑了船体伴流和螺旋桨尾流的影响,使得准确性满足设计过程的要求；计算过程较CFD方法大为简化,提高设计效率,降低工作强度；计算方法覆盖范围较广,使用灵活,适用于设计初期方案不断调整的情况；不需要进行专项试验,节约成本。(A method for calculating the rudder effect of a rudder with a flow control plate for a ship. According to the invention, by decomposing the complex model, based on the existing test result and a means of properly processing the boundary conditions, the rudder effect of the rudder with the flow control plate is calculated more conveniently, and a convenient and flexible calculation method is provided for calculating the rudder effect in the initial stage of design. The method is divided into five steps, wherein the step 1 is to establish a coordinate system, the step 2 is to calculate the rudder effect of the rudder blade, the step 3 is to calculate the hydrodynamic force of the flow control plate, the step 4 is to calculate the rudder effect of the rudder with the flow control plate in the uniform incoming flow, and the step 5 is to introduce the wake effect for adjustment. Compared with the existing calculation method, the method has the following advantages: the influence of ship wake flow and propeller wake flow is considered, so that the accuracy meets the requirement of the design process; compared with a CFD method, the calculation process is greatly simplified, the design efficiency is improved, and the working intensity is reduced; the calculation method has wide coverage range and flexible use, and is suitable for the condition of continuously adjusting the scheme at the initial stage of design; and a special test is not needed, so that the cost is saved.)

1. A method for calculating rudder effect of a rudder with a flow control plate for a ship is characterized by comprising the following steps:

step 1: regarding the rudder with the flow control plate as a whole, and establishing a calculation coordinate system of the rudder in a stern flow field; the whole rudder is divided into a rudder blade and two flow control plates, and respective sub-coordinate systems are respectively established;

step 2: calculating the lift and torque of the rudder blade body under uniform incoming flow;

and step 3: calculating the hydrodynamic force of the flow making plate under uniform incoming flow by using the plate friction resistance;

and 4, step 4: according to the existing test results, the problem of hydrodynamic interference between the rudder blade and the flow control plate is solved, and the lift and the torque with the flow control plate are solved;

and 5: clearing boundary conditions; and correcting the wake flow of the propeller and the wake flow of the ship body, and calculating the rudder effect of the flow control plate in the stern flow field.

2. The method for calculating the rudder effect of the marine rudder with the flow control plate according to claim 1, wherein the step 1 is to establish two sets of three primary and secondary coordinate systems of the whole rudder, the rudder blade and the flow control plate respectively; the propeller and the rudder with the flow control plate are positioned in an uneven flow field of a stern, and the propeller shaft of the propeller is horizontal, so that a space rectangular coordinate system O-XYZ is established; the origin O of the coordinate system is established at the intersection point of the propeller shaft of the propeller and the reference line of the propeller, and the X axis is the extension line of the propeller shaft and points to the rear of the propeller; the Y axis is vertical upwards; the Z axis is determined by a right hand rule; then, splitting the rudder with the flow making plates into rudder blades and 2 flow making plates, and respectively establishing a sub-coordinate system; for the rudder blade, the establishment principle of a coordinate system o-xyz is as follows: the intersection point of the section of the origin o in the rudder spreading chord and the rudder axis; the y axis is superposed with the rudder axis and the direction is vertical and upward; the x axis is parallel to the chord length of the rudder and the direction is backward; the z-axis satisfies the right hand rule; for the flow control plate, a coordinate system o-xyz is established on the XOY section of the flow control plate, wherein an origin o is positioned in the middle of the front edge of the flow control plate, an x axis points to the stern, a y axis is vertically upward, and a z axis meets the right-hand rule.

3. The method for calculating the rudder effect of the marine rudder with flow control plates according to claim 2, wherein the step 2 adopts a labeling algorithm in the current ship design specification to calculate the rudder effect of the rudder blade in the uniform incoming flow:

T＝FR (2)

in the formulae (1) and (2), F_LThe lift force of the rudder when the rudder is full, T the torque of the rudder when the rudder is full, A the area of the rudder blade and V_dThe speed of the ship and the arm moment. K₁、K₂、K₃Is a coefficient; wherein, K₁＝b²/A_tB is the average height of the rudder blade, A_tThe sum of the areas of the rudder and a rudder post/rudder horn in the average height range of the rudder blade; k₂Selecting according to the section form of the rudder blade, wherein the China Classification society has corresponding specified coefficients for the section form of the commonly used rudder blade; k₃The rudder-oar relationship and the oar form are selected from a data sheet of China Classification; after the full rudder effect is obtained, the rudder effect under each rudder angle can be obtained according to the profile performance curve; after the rudder effect of the rudder blade is obtained through calculation, the lift coefficient and the torque coefficient of the rudder blade can be obtained through calculation: c_L’、C_M’；

4. The method for calculating the rudder effect of the marine rudder with the flow control plates according to claim 3, wherein the flow control plates in the step 3 are higher in the Re number of the stern flow field, so that the boundary layer of the surfaces of the flow control plates is turbulent, and the method is solved on the basis of a momentum integral equation of the Karman boundary layer; taking the x direction as an example, the flow control plate is arranged at the incoming flow U_XIn the specification, δ is the thickness of the boundary layer at a distance x from the front edge of the flow control plate, and the x-direction hydrodynamic force per unit width from the front edge of the flow control plate to the x is as follows:

in the formula (4), u_xIs the flow velocity in the boundary layer, and because

Thus, it is possible to provide

In the formula (6), θ represents the momentum loss thickness. Substituting equation (6) into (5), integrate along the length/of the flow control plate, and note: when x is 0, theta is 0, and when x is l, theta is theta_lThe x-direction hydrodynamic force of unit width is obtained as follows:

considering that the flow control plate is a geometric flat plate with a finite aspect ratio, when the velocity distribution in the boundary layer is assumed, the scale effect and the geometric similarity need to be considered; therefore, the method adopts the Houss formula to calculate C_fx；

In the formula (9), Re is a Reynolds number. F can be obtained by the following equations (7) to (9)_X，f_ZThe solving method of (1) is the same as that of (1), and the Hours formula is also adopted to calculate C_Z。

5. The method for calculating the rudder effect of the marine rudder with flow control plates according to claim 3, wherein the step 4 adopts public coupling test data between the flow control plates and the rudder blades, and calculates the rudder effect of the rudder with flow control plates in the uniform incoming flow more intuitively according to the calculation results of the step 2 and the step 3.

6. The method for calculating rudder effect of marine rudder with flow control plates according to claim 3, wherein the calculation in the step 4 is performed by using dimensionless hydrodynamic coefficients as calculation objects.

7. The method for calculating the rudder effect of the marine rudder with the flow control plates according to the claim 2, wherein in the step 5, the wake flow of the ship body and the wake flow of the propeller participate in the calculation in a mode of correcting the induced speed, so that the rudder effect of the rudder with the flow control plates in the wake flow is obtained.

Technical Field

The invention relates to a method for calculating the rudder effect of a marine rudder with a flow control plate, and belongs to the technical field of ship outfitting devices.

Background

Today, ship designs place increasingly higher demands on the rudder. On the one hand, the demand of ships for maneuverability is increasing, and there is an urgent need to improve the steering efficiency in all aspects. On the other hand, the sensitivity of the ship to the on-body resistance is in contradiction with the traditional mode of increasing the steering effect by increasing the steering area. Nowadays, the potentiality excavation of traditional rudder is almost exhausted, and this form of rudder of installing system flow board has been proposed abroad for a long time, has gained unusual effect, is worth very much domestic reference. The rudder with the flow control plate is characterized in that the flow control plate is arranged on a traditional rudder body in order to improve the fluid performance of the rudder, and the flow control plate cuts off the washing flow of two wing tips of the rudder plate to improve the pressure distribution on the surface of the rudder body, so that the effects of improving the rudder effect, improving the operating performance, reducing the total resource occupation and the like are achieved. The accurate calculation of the rudder effect of the rudder with the flow control plate relates to the analysis of the problems of a large amount of fluid and even multiphase fluid, and is difficult to solve, complex in flow, large in workload and not suitable for the calculation and judgment of the initial design stage.

The main content of the rudder effect calculation is to calculate the lift and the torque of the rudder. At present, the calculation of the rudder effect of the rudder with flow control plates at home and abroad mainly focuses on the following two methods: 1) by utilizing a CFD calculation method, the overall flow field model of the stern is established for solving, the workload is large and complex, and personnel are required to have higher fluid mechanics calculation level. 2) The lift and torque of the rudder plate are directly measured by using a method of a water tank test. The method is simple, accurate, time-consuming and labor-consuming, requires a large investment cost, and can only be applied to a specific scheme. At present, a calculation method which is simple and convenient and considers the actual condition of the stern incoming flow is not available.

Disclosure of Invention

The invention provides a method for calculating the rudder effect of a marine rudder with a flow control plate aiming at the defects of the prior art. According to the invention, by decomposing the complex model, based on the existing test result and a means of properly processing the boundary conditions, the rudder effect of the rudder with the flow control plate is calculated more conveniently, and a convenient and flexible calculation method is provided for calculating the rudder effect in the initial stage of design.

In order to solve the technical problem, the invention is realized by the following steps:

step 1: regarding the rudder with the flow control plate as a whole, and establishing a calculation coordinate system of the rudder in a stern flow field; and the whole rudder is divided into a rudder blade and two flow control plates, and respective sub-coordinate systems are respectively established.

Step 2: and (4) calculating the lift and torque of the rudder blade body under uniform incoming flow.

And step 3: and calculating the hydrodynamic force of the flow control plate under uniform incoming flow by using the plate frictional resistance.

And 4, step 4: according to the existing test results, the problem of hydrodynamic interference between the rudder blade and the flow control plate is solved, and the lift and the torque with the flow control plate are solved.

And 5: and clearing the boundary conditions. Correcting the induced propeller wake flow and the hull wake flow, and calculating the rudder effect of the flow control plate in the stern flow field

Compared with the existing calculation method, the method has the following advantages: the influence of ship wake flow and propeller wake flow is considered, so that the accuracy meets the requirement of the design process; compared with a CFD method, the calculation process is greatly simplified, the design efficiency is improved, and the working intensity is reduced; the calculation method has wide coverage range and flexible use, and is suitable for the condition of continuously adjusting the scheme at the initial stage of design; and a special test is not needed, so that the cost is saved.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:

FIG. 1 is a schematic diagram of a global coordinate system in an embodiment of the invention;

FIG. 2 is a schematic view of a rudder blade coordinate system in an embodiment of the present invention;

FIG. 3 is a schematic diagram of a flow control plate coordinate system according to an embodiment of the present invention;

fig. 4 is a schematic view of a hydrodynamic calculation of a flow control plate according to an embodiment of the present invention;

FIG. 5 is a schematic view of a flow plate with different geometric dimensions according to an embodiment of the present invention;

fig. 6 shows a rudder with damper C having λ of 1.67 according to an embodiment of the present invention_L/C_L' test pattern;

fig. 7 shows a rudder with damper C having λ of 1.67 according to an embodiment of the present invention_M/C_M' test pattern;

the same or similar reference numbers in the drawings identify the same or similar elements.

Detailed Description

The invention is further elucidated with reference to the drawing. The preferred embodiments of the present invention are provided only to help illustrate the present invention and not to limit the scope of the present invention. The preferred embodiments of the present invention are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents. After reading the description of the invention, one skilled in the art can make various changes and modifications to the invention, and such equivalent changes and modifications also fall into the scope of the invention defined by the claims.

Now, the method for calculating the rudder effect of the marine rudder with flow control plates according to the invention will be described in detail.

In the step 1, the propeller and the rudder with the flow control plate are positioned in the uneven flow field of the stern, and the propeller shaft of the propeller is horizontal, so that a space rectangular coordinate system O-XYZ is established. The origin O of the coordinate system is established at the intersection point of the propeller shaft of the propeller and the reference line of the propeller, and the X axis is the extension line of the propeller shaft and points to the rear of the propeller; the Y axis is vertical upwards; the Z axis is determined by the right hand rule, see in particular FIG. 1. Then, the rudder with the flow control plates is split into rudder blades and 2 flow control plates, and sub-coordinate systems are respectively established. For the rudder blade, the establishment principle of a coordinate system o-xyz is as follows: the intersection point of the section of the origin o in the rudder spreading chord and the rudder axis; the y axis is superposed with the rudder axis and the direction is vertical and upward; the x axis is parallel to the chord length of the rudder and the direction is backward; the z-axis satisfies the right hand rule, see in particular fig. 2. For the flow control plate, a coordinate system o-xyz is established on the XOY section, wherein the origin o is located in the middle of the front edge of the flow control plate, the x axis points to the stern, the y axis is vertical upwards, and the z axis meets the right-hand rule, which is specifically shown in fig. 3.

In the step 2, the rudder effect of the rudder blade in the uniform incoming flow is calculated according to the 2 nd article of Steel Ship entry and construction Specification.

T＝FR (2)

In the formulae (1) and (2), F_LThe lift force of the rudder when the rudder is full, T the torque of the rudder when the rudder is full, A the area of the rudder blade and V_dThe speed of the ship and the arm moment. K₁、K₂、K₃Are coefficients. Wherein, K₁＝b²/A_tB is the average height of the rudder blade, A_tIs the sum of the areas of the rudder and the rudder post/rudder horn within the average height of the rudder blade. K₂The section form of the rudder blade is selected according to the section form of the rudder blade, and China Classification corporation has corresponding specified coefficients for the commonly used section form of the rudder blade. K₃The rudder-oar relationship and the form of the oar are selected from the data sheet of classification society of China. After the full rudder effect is obtained, the rudder effect under each rudder angle can be obtained according to the profile performance curve.

After the rudder effect of the rudder blade is obtained through calculation, the lift coefficient and the torque coefficient of the rudder blade can be obtained through calculation: c_L’、C_M’。

In the step 3, the hydrodynamic force of the flow control plate is calculated by using a plate frictional resistance calculation formula. Because the Re number of the stern flow field of the flow control plate is higher, the boundary layer on the surface of the flow control plate is turbulent flow, and the method solves the problem on the basis of the momentum integral equation of the Karman boundary layer. Taking the x direction as an example, the flow control plate is arranged at the incoming flow U_XWhere δ is the thickness of the boundary layer at a distance x from the leading edge of the flow control plate (see fig. 4), the x-direction hydrodynamic force per unit width in a section from the leading edge of the flow control plate to x is:

in the formula (4), u_xIs the flow velocity in the boundary layerAnd due to

Thus, it is possible to provide

In the formula (6), θ represents the momentum loss thickness. Substituting equation (6) into (5), integrate along the length/of the flow control plate, and note: when x is 0, theta is 0, and when x is l, theta is theta_lThe x-direction hydrodynamic force of unit width is obtained as follows:

considering that the flow control plate is a geometric flat plate with a finite aspect ratio, when the velocity distribution in the boundary layer is assumed, both the scale effect and the geometric similarity need to be considered. Therefore, the method adopts the Houss formula to calculate C_fx。

In the formula (9), Re is a Reynolds number. F can be obtained by the following equations (7) to (9)_X，f_ZThe solving method of (1) is the same as that of (1), and the Hours formula is also adopted to calculate C_Z。

In step 4, the hydrodynamic coefficient of the entire rudder with the damper is obtained based on the already-disclosed test results and the already-completed calculation. Rudders of this type are typically symmetrical profile flaps with an aspect ratio of no more than 2. The currently published research has already carried out experimental research on rudders with flow control plates with aspect ratios of 0.5-2, and the rudders have data of dimensionless influence coefficients of the flow control plates with different geometric dimensions on the hydrodynamic force of the rudders. For ship rudder, the aspect ratio is usually 1.4-1.8, the invention adopts the test results of the aspect ratio lambda being 1, 1.67 and 2 as the calculation basis after internal difference. Fig. 5 is a schematic diagram of the flow control plates with different geometrical dimensions, which respectively represent a plurality of typical situations that the flow control plates are almost consistent with the cross section size of the rudder blade to the oblong limit. Geometric dimension of the flow control plate is as a dimensionless effective width h_e' means.

In the formula (10), h_eThe effective width is defined as A' as the average area of the flow control plate on one side, A as the average area of the rudder cross section, and b as the chord length. The geometric dimensions of the test flow control plate adopted by the invention are shown in the table 1, and the flow control plates with other geometric parameters can be subjected to interpolation calculation according to the test data of the typical conditions.

TABLE 1 geometric parameters of flow control plates

Fig. 6 and 7 show dimensionless influence coefficients of flow control plates with different geometric dimensions on rudder hydrodynamic force in a rudder test with flow control plates with an aspect ratio λ of 1.67. En route, C_L、C_MThe lift and torque coefficients of the rudder with the flow control plate; c_L’、C_M' is the lift and torque coefficient of the rudder blade without the flow plate.

In the step 5, the hydrodynamic force of the rudder with the flow control plate is finally obtained by introducing boundary conditions of the propeller wake flow and the hull wake flow in the form of correction of the current speed in front of the rudder. Wherein, the correction of the ship wake flow to the incoming flow speed is expressed as:

U_Rω＝U(1-ω_R) (11)

in the formula (11), U is the ship speed; omega_RCoefficient of wake flow, omega, at the rudder of a ship_R＝(0.7C_b-0.08)c。C_bIs the square coefficient of the ship, and c is the position coefficient. The rudder is arranged on the centerline plane, and c is 1.0; when rudders are arranged on both sides, C ═ C_b+0.15。

On the basis of the ship wake flow, the correction of the incoming flow speed by the propeller wake flow is expressed as follows:

U_RP＝U_Rω+ku_∞＝U_P[ε+k(u_∞/U_P-1)](12)

in the formula (12), the advancing speed U of the propeller_P＝(1-ω_P)U，ω_PIs the wake coefficient at the propeller; e ═ 1- ω_R)/(1-ω_P) (ii) a k is a coefficient between 0.5 and 1; u. of_∞For the flow velocity of the propeller after acceleration and flowing to the position at infinity behind the propeller, the method adopts the following formula to calculate:

in formula (13), K_TIs the thrust coefficient of the propeller, J_PIs the advance speed coefficient. For rudder of ship, the rudder area S in the wake of the propeller_PBy U_RPFor incoming velocity, the rudder area (S-S) outside the wake of the propeller_P) By U_RIs the incoming flow velocity. Lift and torque P of rudder with flow control plate_LM may be represented as:

in the formula (14), b_P、b_RRespectively the average chord length of the inner rudder and the outer rudder of the propeller wake flow.

Taking the forms of the rudder and the mother ship described in tables 2 and 3 as examples, the rudder effect of the rudder at each rudder angle is calculated by referring to the present invention.

TABLE 2 example parameters of rudders with dampers

Geometric form	Rectangular rudder	Rudder blade chord length	1.3m
				Section plane	NACA0018	Area of rudder blade	2.8m2
Aspect ratio of rudder blade	1.67	Number of flow-making plates	2
				Rudder height	2.2m	Flow-making plate form	V type

TABLE 3 mother vessel example environmental parameters

Speed U	28kn	Diameter of propeller	3.5m
				Square coefficient Cb	0.50	Rotational speed of propeller	250r/min
Area S of rudder in wake flowP	1.8m2	Coefficient of thrust KT	0.20
				Screw moment of propeller	5.2m	Coefficient of advance JP	0.97

Firstly, according to the step 1 and the parameters in the table 2, establishing a whole coordinate system with a flow control plate and a rudder by referring to fig. 1; and (4) splitting the rudder blade and the upper and lower flow control plates, and respectively establishing respective sub-coordinate systems. Secondly, according to the step 2, a flow-around flow field model of the rudder body under the condition of uniform inflow is established, and the hydrodynamic coefficient of the rudder blade is calculated by using a surface element method, and the result can be shown in table 4.

TABLE 4 hydrodynamic coefficient of uniform inflow rudder blade

Steering angle (°)	2.5	5	10	15	17.5	20
							CL’	0.096	0.197	0.366	0.481	0.452	0.460
CM’	0.0036	0.0069	0.0088	0.0092	0.0085	0.0087

Then, according to the step 3, a flow field model of the uniform inflow throttling plate is established, and the hydrodynamic coefficient of a single throttling plate is solved on the basis of the momentum integral equation of the karman boundary layer, and the result is shown in table 5.

TABLE 5 hydrodynamic coefficients of a single flow control plate under uniform incoming flow

Steering angle (°)	2.5	5	10	15	17.5	20
							Cx(×103)	2.365	2.366	2.370	2.378	2.383	2.389
Cz(×103)	4.863	4.857	3.596	3.322	3.227	3.148

Next, according to the step 4, the hydrokinetic coefficient of the entire rudder with baffles flowing down uniformly is obtained, and the specific results are shown in table 6.

TABLE 6 hydrodynamic coefficient of rudder with damper plate under uniform incoming flow

Steering angle (°)	2.5	5	10	15	17.5	20
							CL’	0.170	0.250	0.559	0.633	0.621	0.451
CM’	0.0056	0.0070	0.0095	0.0129	0.0136	0.0072

And finally, according to the step 5, introducing the hull wake flow and the propeller wake flow to obtain the rudder effect of the rudder with the flow control plates and the rudder, and referring to a table 7.

Water power of rudder with flow control plate under tail flow of table 7

Angle of attack (°)	2.5	5	10	15	17.5	20
							PL(kN)	44.8	65.9	147.4	166.9	163.8	118.9
M(kN*m)	17.7	22.1	30.0	40.8	43.1	22.8

Therefore, the method can calculate the hydrodynamic force of the rudder with the flow control plate more simply, is more accurate than the traditional empirical formula algorithm, is more convenient and faster than the CFD algorithm, has lower cost than the test method, and is suitable for scheme selection and adjustment in the initial design stage.