Volute complex flow channel parametric modeling method and transport characteristic evaluation method and device

Abstract

The invention provides a volute complex flow channel parameterization modeling method and a transportation characteristic evaluation method and device, and the method comprises the steps: S1, obtaining the center lines of a flow channel, setting a plurality of control points between the starting point and the end point of each center line, and building a Bezier curve of each center line according to the starting point, the end point and each control point; s2, according to the curvature control relation and the continuity control relation between the control points, constructing a runner feature control tree; and S3, adjusting the CAD model and the CFD simulation model according to the adjustment of the control parameters, and carrying out flow characteristic distribution analysis according to the CFD simulation model until the volute complex flow channel meets the design requirements. The method provided by the invention is beneficial to rapid design of the type of products, and the design cycle of the products is effectively shortened. And in addition, aiming at the wide application trend of additive manufacturing in the type of products, the method has good universality and can be popularized and applied to product design of similar structural forms.

Description

Technical Field

[0001] The present invention belongs to the technical field of complex flow channel forward design for additive manufacturing, and specifically relates to a parametric modeling method for vortex complex flow channels and a method and device for evaluating transport characteristics. Background Art

[0002] The high power-to-weight ratios required by advanced equipment and the advent of the intelligent, automated, and digital age are driving increasingly stringent requirements for servo valves. These demands primarily focus on miniaturization, high integration, fast response, high power-to-weight ratios, low power consumption, and high reliability. In recent years, servo valve technology has advanced rapidly, driven by the continuous advancements in materials technology, control theory, and machining techniques. While achieving compact size and light weight, servo valves offer outstanding capabilities in flow rate, dynamics, and high cutting forces. They are gradually finding their way into cutting-edge fields such as aerospace, precision robotics, and high-end industrial equipment.

[0003] Current hydraulic valve bodies are usually manufactured using subtractive manufacturing. Due to the limitations of the subtractive manufacturing process, the internal flow channels within the hydraulic manifold block are usually composed of right-angle intersections and many blind holes. In addition, the arrangement of dense channels in a limited space will lead to significant pressure loss and hinder the smooth flow of the fluid. Therefore, this structural complexity leads to considerable energy loss during the service life of the cross-pipe structure, which has an adverse effect on the fluid flow performance. Additive manufacturing is an effective means to improve the power-to-weight ratio of hydraulic products and perform lightweight product design. The servo valve housing prepared by additive manufacturing under the same index requirements can reduce the weight by more than 30%, which is because a conformal flow channel structure with a minimum outer envelope curve can be used. However, this also means an increase in the difficulty and complexity of product design. The conformal flow channel structure has a vortex feature, which is difficult to prevent using traditional CAD design, with a long cycle and poor controllability. Therefore, it is necessary to carry out rapid prototyping technology and supporting integrated simulation method technology research. The main problems to be solved are as follows: 1) When designing complex structures for additive manufacturing, the design process suffers from poor controllability. This is particularly true for three-dimensional conformal flow channels with vortex characteristics. Existing design methods rely solely on manual parameter adjustment, point-to-point adjustment, and then sweep forming, resulting in low design efficiency and an inability to precisely control flow channel curvature. This significantly prolongs product design cycles, impacts project schedules, and undermines the goal of rapid, frequent product design.

[0004] 2) The verification and evaluation method is immature, and it is necessary to establish a complete evaluation method for the transport characteristics of this type of flow channel to support the low pressure loss design of the flow channel. Summary of the Invention

[0005] The present invention provides a parametric modeling method for vortex-shaped complex flow channels and a method and device for evaluating transport characteristics. It studies the design method of a high-integration vortex-shaped channel for a hydraulic servo valve and implements parametric modeling of this type of flow channel to achieve effective control of its key features. In order to evaluate the transport characteristics of the valve channel, a relatively complete evaluation method is constructed based on a CFD simulation model for the valve channel. The simulation model includes a basic flow model, a Schnerr-Sauer cavitation model, and a turbulence model. This method can be used to study and analyze the influence of major characteristics such as the change in flow channel curvature on its transport characteristics, providing a reliable reference for the low-pressure-loss forward design of this type of flow channel prepared by additive manufacturing.

[0006] A first aspect of the present invention provides a parametric modeling method for a vortex-shaped complex flow channel and a method for evaluating transport characteristics, comprising: S1: Obtain the center line of each flow channel in the vortex complex flow channel, set multiple control points between the starting point and the end point of each center line, and establish the Bezier curve of each center line according to the starting point, the end point, and the control points; S2: Constructing a flow channel feature control tree based on the curvature control relationship and continuity control relationship between each control point. The flow channel feature control tree includes control parameters for flow channel morphology adjustment. S3: Adjust the CAD model and CFD simulation model according to the adjustment of the control parameters. Perform flow characteristic distribution analysis based on the CFD simulation model until the vortex complex flow channel meets the design requirements.

[0007] Optionally, the vortex complex flow channel includes a main flow channel and a branch flow channel; The Bezier curve of the main channel is expressed by the M-order equation, and the Bezier curve of the branch channel is expressed by the m-order equation; M and m are positive integers; the value of M is greater than m.

[0008] Optionally, the continuous control relationship includes: the positions of each control point on the same flow channel change along with the adjustment of the control parameter; and / or, When the control parameters on the main channel are adjusted and changed, the control points of the branch channels connected to the main channel also change accordingly.

[0009] Optionally, flow characteristic distribution including pressure, volume fraction and velocity.

[0010] A second aspect of the present invention provides a parametric modeling method for a vortex-shaped complex flow channel and a transport characteristics evaluation device, comprising: The curve creation module is used to obtain the center line of each flow channel in the vortex complex flow channel, set multiple control points between the starting point and the end point of each center line, and create the Bezier curve of each center line based on the starting point, the end point, and the control points; A flow channel feature control tree establishment module is used to construct a flow channel feature control tree based on the curvature control relationship and continuity control relationship between each control point. The flow channel feature control tree includes control parameters for flow channel morphology adjustment. The adjustment module is used to adjust the CAD model and CFD simulation model according to the adjustment of the control parameters, and perform flow characteristic distribution analysis based on the CFD simulation model until the vortex complex flow channel meets the design requirements.

[0011] Optionally, the vortex complex flow channel includes a main flow channel and a branch flow channel; The Bezier curve of the main channel is expressed by the M-order equation, and the Bezier curve of the branch channel is expressed by the m-order equation; M and m are positive integers; the value of M is greater than m.

[0012] Optionally, the continuous control relationship includes: the positions of each control point on the same flow channel change along with the adjustment of the control parameter; and / or, When the control parameters on the main channel are adjusted and changed, the control points of the branch channels connected to the main channel also change accordingly.

[0013] Optionally, flow characteristic distribution including pressure, volume fraction and velocity.

[0014] The present invention provides a parametric modeling method for complex vortex flow channels and a method and device for evaluating transport characteristics, forming a forward design method and parametric modeling method for highly integrated vortex-shaped channels prepared by additive manufacturing of advanced hydraulic servo valves. This type of flow channel can effectively improve the power-to-weight ratio of the product and is a relatively advanced servo valve design technology. The method proposed in the present invention effectively improves the design efficiency of the special-shaped structure and constructs a relatively effective characteristic evaluation method for the structure. The method proposed in the present invention is beneficial to the rapid design of this type of product and effectively shortens the design cycle of the product. In addition, in view of the widespread application trend of additive manufacturing in this type of product, this method has good universality and can be extended to the design of products with similar structural forms. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the valve body and flow channel integrated design structure; Figure 2 Schematic diagram of the flow channel parametric modeling method based on Bezier curve; Figure 3 Design scheme of control point correlation for flow channel parametric modeling and schematic diagram of control law relationship tree; Figure 4 This is a schematic diagram of the flow channel mesh division results; Figure 5a This is the example model 1; Figure 5b This is the second example model; Figure 5c This is the example model three; Figure 6a The stress analysis results for the example model; Figure 6b The volume fraction analysis results of the example model; Figure 6c The speed analysis results of the example model are shown in Figure 2. DETAILED DESCRIPTION

[0016] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0017] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific arrangement and method proposed below, but rather encompasses any improvements, replacements, and modifications to structures, methods, and devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessary ambiguity in the present invention.

[0018] The present invention provides a parametric modeling method for a vortex-shaped complex flow channel and a transport characteristics evaluation method, comprising: S1: Obtain the center line of each flow channel in the vortex complex flow channel, set multiple control points between the starting point and the end point of each center line, and establish the Bezier curve of each center line according to the starting point, the end point, and the control points; S2: Constructing a flow channel feature control tree based on the curvature control relationship and continuity control relationship between each control point. The flow channel feature control tree includes control parameters for flow channel morphology adjustment. S3: Adjust the CAD model and CFD simulation model according to the adjustment of the control parameters. Perform flow characteristic distribution analysis based on the CFD simulation model until the vortex complex flow channel meets the design requirements.

[0019] Optionally, the vortex complex flow channel includes a main flow channel and a branch flow channel; The Bezier curve of the main channel is expressed by the M-order equation, and the Bezier curve of the branch channel is expressed by the m-order equation; M and m are positive integers; the value of M is greater than m.

[0020] Optionally, the continuous control relationship includes: the positions of each control point on the same flow channel change along with the adjustment of the control parameter; and / or, When the control parameters on the main channel are adjusted and changed, the control points of the branch channels connected to the main channel also change accordingly.

[0021] Optionally, flow characteristic distribution including pressure, volume fraction and velocity.

[0022] For example, the vortex geometry model of a certain type of servo valve is as follows: Figure 1 As shown, this model uses additive manufacturing and is integrated with the valve body. This manufacturing method can reduce the volume by 30%. This method was validated for this flow channel, resulting in three test cases.

[0023] Step 1: Before conducting a detailed performance study on the flow channel structure, it is necessary to parameterize the structure. In this study, Bezier curves are used to describe the centerline of the flow channel, which is the main characteristic control parameter of the flow channel, such as Figure 2 As shown in the figure, the Bezier curve corresponds to a mathematical curve in a two-dimensional plane. Due to its simple control and ability to handle smooth curves, it has begun to be used in local path planning for autonomous vehicles. By setting the start and end points of the curve and adding a varying number of control points between these endpoints, the direction and curvature of the curve can be controlled by changing the coordinates of these control points. The Bezier function is shown below, where 𝑃0, 𝑃1,…, 𝑃𝑛 are the control points.

[0024] (1) The fifth-order and third-order equations are: (2) (3) Figure 2 The following is a three-dimensional diagram of the structure under study and a diagram of the centerline group structure. In the figure, curves A and B represent the centerlines of the main channels, and curves C, D, E, F, G, and H represent the centerlines of the connecting channels. The expression group of curves formed using Bezier curves is as follows: (4) (5) Where: t As parameters, , by controlling tBy increasing the value from 0 to 1, a Bezier curve can be drawn.

[0025] Step 2: Construct the flow channel feature control tree to form a parametric modeling control point correlation design scheme to achieve dimensionality reduction of complex flow channel control problems, such as Figure 3 shown.

[0026] In the figure, CCR is the curvature control relationship, which ensures that the curvature of the flow channel is reasonable when adjusting the flow channel. CGR is the continuity control relationship, which ensures that the flow channel has good continuity when adjusting the flow channel.

[0027] Each CCR contains a linked control law for the changes of two control points. This solution reduces the control parameters for adjusting the flow channel shape to eight, while also uniformly controlling the curvature of the internal flow channel. As a result, the control parameters of the combined flow channel are further reduced to three.

[0028] Step 3: Create a CFD simulation model to evaluate the structural characteristics. The meshing of the computational domain is performed with a preference for high smoothness using the "Mesh" command in Workbench. The mesh is generated using an automatic method, and the mesh results are as follows: Figure 4 As shown in the figure, each surface is configured according to the flow rules. Initially, the settings are configured for the fixed surface (wall) and the inlet / outlet interface. The calculation model selected is: Schnerr-Sauer cavitation model, standard k-ε, and standard wall function. Subsequently, the fluid characteristic parameters are set. With the above details, the CFD solution model is established and configured. The relevant governing equations are as follows: The mass conservation equation, also known as the continuity equation, states that for a control volume within a flow field, its surface is called the control surface. The momentum conservation equation states that the rate of change of momentum of a control volume within a flow field with respect to time is equal to the sum of the external forces acting on the control volume. The mass conservation equation and momentum conservation equation are expressed as follows: (6) (7) Where ρ is the fluid density, uᵢ, u j and u k is the fluid velocity in the i, j, and k directions; p is the pressure on the fluid element; ρgᵢ is the gravitational force in the i direction; Fᵢ is the external object force in the i direction; x i , x j , x k is the coordinate system coordinate; τᵢ j is the stress tensor, expressed as follows: (8) Where, μ is the viscosity, for Kronecker delta function.

[0029] (9) (10) Where, 、 and is the turbulence model coefficient.

[0030] Step 4: Figure 5a 、 5b Figures 5c and 5c show three channel design options, designated Design a, Design b, and Design c, which are compared as follows. Designs b and c are the CAD modeling results of Design a with modified curvature. Design b results from expanding the centerline of the main channel, while Design c results from modifying the curvature of the connecting channel centerline. The fluid transport characteristics of the flow channel will be studied in detail. Figure 6a 、 6b Figures 6 and 6c show the flow characteristic distributions of different design schemes, including pressure, volume fraction, and velocity. Overall, the differences between Design a and Design b are small. Compared with Design a, the flow velocity of Design b is lower. For Design c, the pressure near the inlet area of ​​the connecting channel is relatively high. In addition, as the local flow velocity increases, more cavitation areas appear in the curved portion of the connecting channel. Although the change in the curvature of the main channel has a slight effect on the pressure loss results, increasing the curvature will increase the volume of the valve body, which is not conducive to the lightweight design of the product.

[0031] The present invention aims at the complex flow channel structure of the servo valve with vortex characteristics. The present invention forms a relatively complete parameterized modeling method. The Bezier curve is used to describe the center line of the flow channel, which is the main characteristic control parameter of the flow channel, such as Figure 2 As shown. Through this method, a mapping relationship between this type of complex structure and the mathematical model is constructed, and parametric modeling is realized. The present invention forms a more convenient forming method for this type of flow channel structure. By adjusting the position of each control point, the characteristics of the flow channel can be quickly adjusted. The traditional design method is to change the curve position by pulling the UG internal curve fitting control point. Since this type of flow channel is composed of multiple sections of special-shaped flow channels, it is difficult to ensure the continuity of the flow channel while actually adjusting one curve. Therefore, other curves need to be adjusted at the same time, and the forming efficiency of the three-dimensional structure is low. Through this method, the continuity change relationship when the structure changes can be constructed based on the algorithm level. While adjusting a section of the flow channel, the connection position of other flow channels can be guaranteed to change accordingly, which greatly improves the convenience of correcting the structure. The present invention constructs a relatively complete transport characteristic evaluation method and a transport characteristic simulation model, including a flow model, a turbulence model and a cavitation model. Calculations in this way can provide evaluation values ​​to guide the design of the flow channel.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other, and the various embodiments may refer to and quote each other.

[0033] The above-described embodiments merely represent preferred embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and the scope of protection of the present invention is not limited thereto. Any person skilled in the art will readily conceive of various equivalent modifications or substitutions within the technical scope disclosed herein, and such modifications or substitutions should be encompassed within the scope of protection of the present invention.

Claims

1. A parametric modeling method for a vortex-shaped complex flow channel and a transport characteristics evaluation method, characterized in that: include: S1: Obtain the center line of each flow channel in the vortex complex flow channel, set multiple control points between the starting point and the end point of each center line, and establish the Bezier curve of each center line according to the starting point, the end point, and the control points; S2: Constructing a flow channel feature control tree based on the curvature control relationship and continuity control relationship between each control point. The flow channel feature control tree includes control parameters for flow channel morphology adjustment. S3: Adjust the CAD model and CFD simulation model according to the adjustment of the control parameters. Perform flow characteristic distribution analysis based on the CFD simulation model until the vortex complex flow channel meets the design requirements.

2. The parametric modeling method for vortex complex flow channel and the transport characteristics evaluation method according to claim 1 are characterized in that: The vortex complex flow channel includes the main flow channel and the branch flow channel; The Bezier curve of the main channel is expressed by the M-order equation, and the Bezier curve of the branch channel is expressed by the m-order equation; M and m are positive integers; the value of M is greater than m.

3. The parametric modeling method for vortex complex flow channel and the transport characteristics evaluation method according to claim 2 are characterized in that: The continuous control relationship includes: the positions of each control point on the same flow channel change with the adjustment of the control parameters; and / or, When the control parameters on the main channel are adjusted and changed, the control points of the branch channels connected to the main channel also change accordingly.

4. The parametric modeling method for complex vortex flow channels and the transport characteristics evaluation method according to claim 1 are characterized in that: Flow characteristic distribution including pressure, volume fraction, and velocity.

5. A parametric modeling method for a vortex-shaped complex flow channel and a transport characteristics evaluation device, characterized in that: include: The curve creation module is used to obtain the center line of each flow channel in the vortex complex flow channel, set multiple control points between the starting point and the end point of each center line, and create the Bezier curve of each center line based on the starting point, the end point, and the control points; A flow channel feature control tree establishment module is used to construct a flow channel feature control tree based on the curvature control relationship and continuity control relationship between each control point. The flow channel feature control tree includes control parameters for flow channel morphology adjustment. The adjustment module is used to adjust the CAD model and CFD simulation model according to the adjustment of the control parameters, and perform flow characteristic distribution analysis based on the CFD simulation model until the vortex complex flow channel meets the design requirements.

6. The parametric modeling method for complex vortex flow channels and the transport characteristics evaluation device according to claim 5, characterized in that: The vortex complex flow channel includes the main flow channel and the branch flow channel; The Bezier curve of the main channel is expressed by the M-order equation, and the Bezier curve of the branch channel is expressed by the m-order equation; M and m are positive integers; the value of M is greater than m.

7. The parametric modeling method for complex vortex flow channels and the transport characteristics evaluation device according to claim 6, characterized in that: The continuous control relationship includes: the positions of each control point on the same flow channel change with the adjustment of the control parameters; and / or, When the control parameters on the main channel are adjusted and changed, the control points of the branch channels connected to the main channel also change accordingly.

8. The parametric modeling method for complex vortex flow channels and the transport characteristics evaluation device according to claim 5, characterized in that: Flow characteristic distribution including pressure, volume fraction, and velocity.

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