Rapid modeling and simulation method for centrifugal fan based on wing blade model

Abstract

The invention belongs to the field of design of industrial centrifugal fans, and particularly relates to a rapid modeling and simulation method for a centrifugal fan based on a wing blade model. The centrifugal fan is divided into six parts, namely a volute part, an impeller, a space shape of a central cavity of the impeller, a space shape defined by the impeller and the volute, a current collector and a space shape of a gap between the current collector and the impeller, so that the actual geometric structure of the centrifugal fan can be quickly and accurately obtained, and structured grids of all parts of the centrifugal fan can be obtained; simulation resources are reduced, simulation precision and modeling accuracy are improved at the same time, the universality of centrifugal fan modeling and simulation is achieved, the method can be used for centrifugal fan mechanism analysis or optimization design, manpower cost input is greatly reduced, and repeated work is avoided.

Description

Technical Field

[0001] The invention belongs to the field of industrial centrifugal fan design, and in particular relates to a centrifugal fan rapid modeling and simulation method based on a wing blade model. Background Art

[0002] As the most widely used type of fan, the centrifugal fan is the core machine and main energy-consuming equipment for conveying gas medium in many industrial components. As the core component of the ventilation system, the centrifugal fan is not only widely used in military fields such as power generation and metallurgy, but also in household fields such as range hoods and air conditioners. Therefore, researching and improving centrifugal fans and improving their working efficiency are of great significance to energy conservation.

[0003] As a kind of impeller machine, the centrifugal fan has rotating parts and stationary parts, and its internal structure is complex. Generally speaking, it is composed of three major parts: impeller, collector and volute. At present, the design and optimization of centrifugal fans are mainly based on numerical simulation. However, there are tiny structures such as the gap between the collector and the impeller inside the centrifugal fan, which brings many difficulties to the modeling of the centrifugal fan and the meshing in the numerical simulation process. In order to improve the efficiency of modeling and simulation, the existing centrifugal fan design ignores the structure such as the gap between the collector and the impeller in the modeling process, adopts a simplified model, and even adopts unstructured meshes in the simulation process for the convenience of meshing.

[0004] In addition, due to the limited design and processing levels, most of the existing fan blades are straight blades. However, the gap structure between the collector and the impeller has a significant impact on the overall performance of the centrifugal fan. Simplifying the model will inevitably introduce errors and reduce the simulation accuracy. At the same time, unstructured grids require more grids to achieve the same accuracy, and the number of grids is proportional to the calculation cost, which undoubtedly increases the calculation cost. In addition, the calculation accuracy of unstructured grids also needs to be studied. Although straight blades are easy to process, their high-efficiency range is narrow and their efficiency is low. Airfoil blades are not only generally more efficient but also have a wide high-efficiency range. However, due to the large number of airfoil blade modeling parameters and complex modeling, their application is limited. Summary of the invention

[0005] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a centrifugal fan rapid modeling and simulation method based on a wing blade model, which is based on a centrifugal fan model, an airfoil blade shaping method and a grid partitioning strategy, thereby improving the simulation accuracy and efficiency.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a centrifugal fan rapid modeling and simulation method based on a wing blade model, comprising the following steps:

[0007] Step 1: Establish a centrifugal fan model, define and constrain the shape and size of the impeller, collector, and volute of the centrifugal fan, as well as the gap between the collector and the impeller;

[0008] Step 2: Based on the centrifugal fan model, the airfoil blade modeling method is used to shape the leading edge, trailing edge, upper and lower surfaces of the impeller blade in turn, and a centrifugal fan impeller blade model based on the airfoil blade is established, thereby defining and constraining the shape and size of the impeller blade;

[0009] Step 3: Output the three-dimensional geometric bodies of the centrifugal fan's volute, impeller, collector, the gap space shape between the collector and the impeller, the central cavity space shape of the impeller, and the space shape surrounded by the impeller and the volute, and perform structured meshing on the three-dimensional geometric bodies to obtain the computational mesh of the centrifugal fan model;

[0010] Step 4: Use the computational grid of the centrifugal fan model to perform fluid mechanics simulation.

[0011] Furthermore, the step 1 specifically includes:

[0012] Step 11: Determine the shape of the impeller:

[0013] The impeller is an arc-shaped front disk, and the impeller inlet diameter is D0; the distance between the front end point of the impeller front disk and the impeller back plate is the impeller inlet height b1; the distance between the rear end point of the impeller front disk and the impeller back plate is the impeller outlet height b2; the front end point and the rear end point of the impeller front disk are used as an arc, and the radius of the arc is the impeller front disk radius R0; given the unique dimensions of the impeller inlet height b1, the impeller outlet height b2, the impeller front disk radius R0 and the impeller inlet diameter D0, the complete constraint of the impeller is achieved;

[0014] Step 12: Determine the shape of the current collector:

[0015] The collector is a conical arc collector. The first section of the collector is a conical surface. The angle between the generatrix of the conical surface and the direction perpendicular to the axis is the collector convergence angle. The second section is an arc surface, which is tangent to the conical surface. The end point of the arc is used as a tangent line. The angle between the tangent line and the direction perpendicular to the axis is the expansion angle of the collector. ; Given the collector convergence angle and collector expansion angle Unique size, i.e. achieving full constraint of the current collector;

[0016] Step 13: Determine the clearance between the collector and the impeller:

[0017] The collector extends into the central cavity of the impeller, and a gap is formed between the collector and the impeller. The axial distance of the collector extending into the impeller is the axial gap between the collector and the impeller. The circumferential distance between the collector outlet and the inner wall of the impeller front disk is the circumferential clearance between the collector and the impeller. ; Given axial clearance and circumferential clearance Unique size, i.e. achieving full constraint of collector and impeller clearance;

[0018] Step 14: Determine the volute shape:

[0019] The inner wall profile of the volute is a logarithmic spiral line, which is drawn by the equilateral basis method and is similar to the Archimedean spiral line. Therefore, the outlet opening A of the volute is determined first, and then a square with a side length of a=A / 4 is made with the center of the impeller to obtain an equilateral base square. Then, with the four corners of the equilateral base square as the center, arcs are made with radii R1, R2, R3 and R4 respectively to obtain the inner wall profile of the volute, where:

[0020] ,

[0021] ,

[0022] ,

[0023] ,

[0024] After obtaining the inner wall profile of the volute, determine the volute outlet and volute tongue geometry, and the volute outlet length C is:

[0025] ,

[0026] The radius of the arc at the tip of the snail tongue is r ’ , the value is:

[0027] ,

[0028] The value of the clearance t between the volute tongue and the impeller is:

[0029] ,

[0030] Where D2 is the blade outlet diameter; by defining the outlet opening A of the volute, the distance t between the volute tongue and the impeller, the outlet length C of the volute and the radius r of the volute tongue ’ , given a unique dimension, that is, to realize the constraint of the volute profile, and at the same time define the width B of the volute, that is, to realize the axial constraint of the volute.

[0031] Furthermore, the step 2 specifically includes:

[0032] Step 21: Determine the upper and lower intersection points of the leading edge circle and the trailing edge circle of the impeller blade:

[0033] The impeller blade is a single arc blade, that is, the mid-arc line is an arc. Therefore, the chord length b is first determined by a straight line, and circles are made with the two end points of the chord length b as the center, and the radii are and , respectively denoted as the leading edge circle and the trailing edge circle; a straight line perpendicular to the chord length b is drawn at the centers of the leading edge circle and the trailing edge circle, and the straight line has an upper intersection point and a lower intersection point with the leading edge circle and the trailing edge circle respectively;

[0034] Step 22: Determine the impeller blade curve control circle:

[0035] On the chord length b of the impeller blade, the point with a distance a from the center of the leading edge circle is taken as the maximum thickness position, and a straight line is drawn perpendicular to the chord length b from the maximum thickness position, and a radius r is drawn on the straight line. control Make a circle, record it as the curve control circle;

[0036] Step 23: Complete the upper surface modeling of the impeller blades:

[0037] The upper surface is shaped by a second-order Bezier curve. The second-order Bezier curve is constrained by two control lines. Specifically, two Bezier curve control lines are made through the upper intersection point of the leading edge circle and the upper intersection point of the trailing edge circle. First, the two Bezier curve control lines are made tangent to the curve control circle to form a Bezier curve. Then, the formed Bezier curve is made tangent to the leading edge circle and the trailing edge circle to complete the shape of the upper surface of the blade.

[0038] Step 24: Complete the lower surface modeling of the impeller blade:

[0039] The lower surface is shaped by a second-order Bezier curve, which is constrained by three control points. Specifically, first, the lower intersection point of the leading edge circle, the lower intersection point of the trailing edge circle, and the intersection point of the curve control circle and the straight line perpendicular to the chord length are used as the three control points of the second-order Bezier curve to form a Bezier curve. Then, the formed Bezier curve is tangent to the leading edge circle and the trailing edge circle to complete the shaping of the lower surface of the blade.

[0040] Step 25: Determine the center arc of the impeller blade:

[0041] Find the largest inscribed circle between the upper and lower surfaces of the blade. The diameter of the inscribed circle is the maximum thickness. , draw a three-point arc from the center of the leading edge circle, the center of the trailing edge circle and the center of the inscribed circle, which is the median arc;

[0042] Step 26: Determine the impeller blade inlet and outlet airflow angles:

[0043] Take the centrifugal fan model coordinate origin as the center, make a circle tangent to the leading edge circle, the diameter of the circle is the blade inlet diameter D1, make a tangent line tangent to the leading edge circle at the tangent point of the two circles, make a tangent line of the middle arc at the center of the leading edge circle, the angle formed by the tangent line of the middle arc and the tangent line of the leading edge circle is the inlet airflow angle ;

[0044] Similarly, with the centrifugal fan model coordinate origin as the center, make a circle tangent to the trailing edge circle. The diameter of the circle is the blade outlet diameter D2. Make a tangent line tangent to the trailing edge circle at the tangent point of the two circles. Make a tangent to the mid-arc line at the center of the trailing edge circle. The angle formed by the tangent of the mid-arc line and the tangent of the trailing edge circle is the outlet airflow angle. ;

[0045] Given the inlet airflow angle , outlet airflow angle , Maximum thickness , the distance a between the maximum thickness position and the center of the leading edge circle, and the radius of the leading edge circle , the radius of the trailing edge circle And the only dimension of the blade chord length b is to achieve complete constraint of the blade shape.

[0046] Furthermore, the step three is specifically as follows:

[0047] Step 31: Based on the shape of the volute of the centrifugal fan model, the volute consists of a central cylindrical surface, an outlet and an outer wall surface, wherein the diameter of the central cylindrical surface is 1.05 times the diameter D2 of the impeller blade outlet, and the three-dimensional volute is simplified into a two-dimensional volute to reduce the complexity of volute modeling; the central cylindrical surface of the volute is connected to the space shape surrounded by the impeller and the volute, and the outlet of the volute is connected to the atmosphere; then, a grid is divided on the two-dimensional volute to obtain a calculation grid of the volute;

[0048] Step 32: The impeller is composed of an impeller inlet, an outlet, blades, an impeller front disk and an impeller back plate; the impeller inlet is connected to the central cavity space of the impeller; the impeller outlet is connected to the space shape surrounded by the impeller and the volute, and then the impeller inlet, outlet, blades, impeller front disk and impeller back plate are meshed to obtain the calculation mesh of the impeller;

[0049] Step 33: The collector is a truncated cone structure. The upper surface of the truncated cone of the collector is the inlet of the centrifugal fan and is connected to the atmosphere. The lower surface of the truncated cone of the collector is the outlet of the collector and is connected to the shape of the central cavity space of the impeller. Then, the collector is meshed to obtain the calculation mesh of the collector.

[0050] Step 34: The gap space shape between the collector and the impeller is a hollow cylindrical structure, the outer surface of the hollow cylinder of the gap space shape is the inner wall surface of the impeller front disk; the inner surface of the hollow cylinder of the gap space shape is the outer wall surface of the collector; the lower surface of the hollow cylinder of the gap space shape is connected to the upper surface of the central cavity space shape of the impeller; the upper surface of the hollow cylinder of the gap space shape is connected to the space shape surrounded by the impeller and the volute, and then the gap space shape is meshed to obtain the calculation mesh of the gap space shape;

[0051] Step 35: The central cavity space shape of the impeller is a truncated cone structure. The upper surface of the truncated cone of the central cavity space shape of the impeller is connected to the collector and the gap space shape; the lower surface of the truncated cone of the central cavity space shape of the impeller is the inner wall surface of the impeller back plate; the truncated cone side surface of the central cavity space shape of the impeller is connected to the inlet of the impeller, and then the central cavity space shape of the impeller is meshed to obtain the calculation mesh of the central cavity space shape of the impeller;

[0052] Step 36: The space shape enclosed by the impeller and the volute is the space shape formed between the impeller, the collector and the volute, and then the space shape enclosed by the impeller and the volute is divided into grids to obtain a calculation grid of the space shape enclosed by the impeller and the volute.

[0053] The beneficial effects of the present invention are as follows: the present invention provides a method for rapid modeling and simulation of a centrifugal fan based on a wing blade model, which realizes rapid and accurate acquisition of the actual geometric structure of the centrifugal fan based on centrifugal fan modeling, a wing blade modeling method, and a grid partitioning strategy, greatly improving the accuracy of modeling, and the platform is suitable for modeling any type of industrial centrifugal fan;

[0054] Among them, the grid block strategy adopted by the method of the present invention simplifies the grid division topology, making it easier to obtain the structured grids of each component of the centrifugal fan, thereby reducing simulation resources and improving simulation accuracy;

[0055] The blade modeling method realizes the modeling and modeling of centrifugal fan airfoil blades, significantly improves the fan performance, and realizes the versatility of centrifugal fan modeling and simulation. It is subsequently used for centrifugal fan mechanism analysis or optimal design, greatly reducing labor cost investment and avoiding repetitive work. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the three-dimensional geometry of various parts of the centrifugal fan in a specific example of the present invention;

[0057] Figure 2 is a schematic diagram of the cross-sectional structure of an impeller and a collector in a specific example of the present invention;

[0058] Figure 3is a parametric schematic diagram of the volute in a specific example of the present invention;

[0059] Figure 4 It is a schematic diagram of the blade shape in a specific example of the present invention;

[0060] Figure 5 It is a schematic diagram of the volute structure in a specific example of the present invention;

[0061] FIG6 is a schematic diagram of the impeller structure in a specific example of the present invention;

[0062] Figure 7 It is a schematic diagram of the calculation grid of the model of each part of the centrifugal fan in the specific example of the present invention;

[0063] Figure 8 It is a velocity distribution cloud diagram at 50% blade height of a centrifugal fan in a specific example of the present invention.

[0064] In the figure, 1. volute; 2. impeller; 3. collector; 4. shape of the space between collector and impeller; 5. shape of the space of the central cavity of the impeller; 6. shape of the space surrounded by the impeller and volute; 1-1. central cylindrical surface; 1-2. volute outlet; 1-3. outer wall of volute; 2-1. impeller front disk; 2-2. impeller back plate; 2-3. blades; 2-4. impeller inlet; 2-5. impeller outlet. DETAILED DESCRIPTION

[0065] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0066] In order to achieve the above object, the present invention provides the following specific implementation methods:

[0067] Example 1: Figure 1-8 As shown, a rapid modeling and simulation method for a centrifugal fan based on a wing blade model comprises the following steps:

[0068] Step 1: Establish a centrifugal fan model, define and constrain the shape and size of the impeller 2, collector 3, and volute 1 of the centrifugal fan, and the gap between the collector 3 and the impeller 2;

[0069] The specific steps are:

[0070] Step 11: Determine the shape of impeller 2:

[0071] The impeller 2 is an arc-shaped front disk, and the inlet diameter of the impeller 2 is D0; the distance between the front end point of the impeller front disk 2-1 and the impeller back plate 2-2 is the impeller inlet height b1; the distance between the rear end point of the impeller front disk 2-1 and the impeller back plate 2-2 is the impeller outlet height b2; the front end point and the rear end point of the impeller front disk 2-1 are used as an arc, and the radius of the arc is the radius R0 of the impeller front disk 2-1; given the unique dimensions of the impeller inlet height b1, the impeller outlet height b2, the impeller front disk radius R0 and the impeller inlet diameter D0, the complete constraint of the impeller 2 is achieved;

[0072] Step 12: Determine the shape of current collector 3:

[0073] The collector 3 is a conical arc collector. The first section of the collector 3 is a conical surface. The angle between the generatrix of the conical surface and the direction perpendicular to the axis is the collector convergence angle. The second section is an arc surface, which is tangent to the conical surface. The end point of the arc is used as a tangent line. The angle between the tangent line and the direction perpendicular to the axis is the expansion angle of the collector. ; Given the collector convergence angle and collector expansion angle Unique size, i.e. achieving full confinement of the current collector 3;

[0074] Step 13: Determine the clearance between collector 3 and impeller 2:

[0075] The collector 3 extends into the central cavity of the impeller 2, and a gap is formed between the collector 3 and the impeller 2. The axial distance of the collector 3 extending into the impeller 2 is the axial gap between the collector 3 and the impeller 2. The circumferential distance between the outlet of the collector 3 and the inner wall of the impeller front disk 2-1 is the circumferential clearance between the collector 3 and the impeller 2 ; Given axial clearance and circumferential clearance Unique size, i.e. achieving full constraint of the clearance between collector 3 and impeller 2;

[0076] Step 14: Determine the shape of the volute 1:

[0077] The inner wall profile of the volute 1 is a logarithmic spiral line, which is drawn by the equilateral basis method and is similar to the Archimedean spiral line. Therefore, the outlet opening A of the volute 1 is determined first, and then a square with a side length of a=A / 4 is made with the center of the impeller 2, that is, an equilateral base square is obtained, and then arcs are made with radii R1, R2, R3 and R4 with the four corners of the equilateral base square as the center, respectively, to obtain the inner wall profile of the volute 1, where:

[0078] ,

[0079] ,

[0080] ,

[0081] ,

[0082] After obtaining the inner wall profile of the volute 1, the outlet of the volute 1 and the geometry of the volute tongue are determined, and the outlet length C of the volute 1 is taken as:

[0083] ,

[0084] The radius of the arc at the tip of the snail tongue is r ’ , the value is:

[0085] ,

[0086] The value of the clearance t between the volute tongue and the impeller is:

[0087] ,

[0088] Where D2 is the blade outlet diameter; by defining the outlet opening A of the volute 1, the distance t between the volute tongue and the impeller 2, the outlet length C of the volute 1 and the radius r of the volute tongue ’ , given a unique dimension, that is, to realize the constraint of the volute 1 profile, and at the same time define the width B of the volute 1, that is, to realize the axial constraint of the volute 1.

[0089] Step 2: Based on the centrifugal fan model, the airfoil blade modeling method is used to shape the leading edge, trailing edge, upper and lower surfaces of the impeller blade in turn, and a centrifugal fan impeller blade model based on the airfoil blade is established, thereby defining and constraining the shape and size of the impeller blade;

[0090] The specific steps are:

[0091] Step 21: Determine the upper and lower intersection points of the leading edge circle and the trailing edge circle of the impeller blade of impeller 2:

[0092] The impeller blade is a single arc blade, that is, the mid-arc line is an arc. Therefore, the chord length b is first determined by a straight line, and circles are made with the two end points of the chord length b as the center, and the radii are and , respectively denoted as the leading edge circle and the trailing edge circle; a straight line perpendicular to the chord length b is drawn at the centers of the leading edge circle and the trailing edge circle, and the straight line has an upper intersection point and a lower intersection point with the leading edge circle and the trailing edge circle respectively;

[0093] Step 22: Determine the impeller blade curve control circle:

[0094] On the chord length b of the impeller blade, the point with a distance a from the center of the leading edge circle is taken as the maximum thickness position, and a straight line is drawn perpendicular to the chord length b from the maximum thickness position, and a radius r is drawn on the straight line. control Make a circle, record it as the curve control circle;

[0095] Step 23: Complete the upper surface modeling of the impeller blades:

[0096] The upper surface is shaped by a second-order Bezier curve. The second-order Bezier curve is constrained by two control lines. Specifically, two Bezier curve control lines are made through the upper intersection point of the leading edge circle and the upper intersection point of the trailing edge circle. First, the two Bezier curve control lines are made tangent to the curve control circle to form a Bezier curve. Then, the formed Bezier curve is made tangent to the leading edge circle and the trailing edge circle to complete the shape of the upper surface of the blade.

[0097] Step 24: Complete the lower surface modeling of the impeller blade:

[0098] The lower surface is shaped by a second-order Bezier curve, which is constrained by three control points. Specifically, first, the lower intersection point of the leading edge circle, the lower intersection point of the trailing edge circle, and the intersection point of the curve control circle and the straight line perpendicular to the chord length are used as the three control points of the second-order Bezier curve to form a Bezier curve. Then, the formed Bezier curve is tangent to the leading edge circle and the trailing edge circle to complete the shaping of the lower surface of the blade.

[0099] Step 25: Determine the center arc of the impeller blade:

[0100] Find the largest inscribed circle between the upper and lower surfaces of the blade. The diameter of the inscribed circle is the maximum thickness. , draw a three-point arc from the center of the leading edge circle, the center of the trailing edge circle and the center of the inscribed circle, which is the median arc;

[0101] Step 26: Determine the impeller blade inlet and outlet airflow angles:

[0102] Take the centrifugal fan model coordinate origin as the center, make a circle tangent to the leading edge circle, the diameter of the circle is the blade inlet diameter D1, make a tangent line tangent to the leading edge circle at the tangent point of the two circles, make a tangent line of the middle arc at the center of the leading edge circle, the angle formed by the tangent line of the middle arc and the tangent line of the leading edge circle is the inlet airflow angle ;

[0103] Similarly, with the centrifugal fan model coordinate origin as the center, make a circle tangent to the trailing edge circle. The diameter of the circle is the blade outlet diameter D2. Make a tangent line tangent to the trailing edge circle at the tangent point of the two circles. Make a tangent to the mid-arc line at the center of the trailing edge circle. The angle formed by the tangent of the mid-arc line and the tangent of the trailing edge circle is the outlet airflow angle. ;

[0104] Given inlet airflow angle , outlet airflow angle , Maximum thickness , the distance a between the maximum thickness position and the center of the leading edge circle, and the radius of the leading edge circle , the radius of the trailing edge circle And the only dimension of the blade chord length b is to achieve complete constraint of the blade shape.

[0105] Step 3, outputting the three-dimensional geometric bodies of the volute 1, the impeller 2, the collector 3, the gap space shape 4 between the collector 3 and the impeller 2, the central cavity space shape 5 of the impeller 2, and the space shape 6 surrounded by the impeller 2 and the volute 1 of the centrifugal fan, and performing structured meshing on the three-dimensional geometric bodies, that is, obtaining the computational mesh of the centrifugal fan model;

[0106] The specific steps are:

[0107] Step 31: Based on the shape of the volute 1 of the centrifugal fan model, the volute 1 consists of a central cylindrical surface 1-1, an outlet 1-2 and an outer wall surface 1-3, wherein the diameter of the central cylindrical surface is 1.05 times the diameter D2 of the blade outlet of the impeller 2, and the three-dimensional volute 1 is simplified into a two-dimensional volute 1 to reduce the complexity of the modeling of the volute 1; the central cylindrical surface 1-1 of the volute 1 is connected to the space shape 6 surrounded by the impeller 2 and the volute 1, and the outlet 1-2 of the volute 1 is connected to the atmosphere; then, a grid is divided on the two-dimensional volute 1 to obtain a calculation grid of the volute 1;

[0108] Step 32: The impeller 2 is composed of the inlet 2-4, outlet 2-5, blades 2-3, impeller front disk 2-1 and impeller back plate 2-2 of the impeller 2; the inlet 2-4 of the impeller 2 is connected to the central cavity space shape 5 of the impeller 2; the outlet 2-5 of the impeller 2 is connected to the space shape 6 surrounded by the impeller 2 and the volute 1, and then the inlet 2-4, outlet 2-5, blades 2-3, impeller front disk 2-1 and impeller back plate 2-2 of the impeller 2 are meshed to obtain the calculation mesh of the impeller 2;

[0109] Step 33: the collector 3 is a truncated cone structure. The upper surface of the truncated cone of the collector 3 is the inlet of the centrifugal fan and communicates with the atmosphere; the lower surface of the truncated cone of the collector 3 is the outlet of the collector 3 and connects with the central cavity space shape 5 of the impeller 2. Then, the collector 3 is meshed to obtain a calculation mesh of the collector 3.

[0110] Step 34: the gap space shape 4 between the collector 3 and the impeller 2 is a hollow cylindrical structure, the outer surface of the hollow cylinder of the gap space shape 4 is the inner wall surface of the impeller front disk 2-1; the inner surface of the hollow cylinder of the gap space shape 4 is the outer wall surface of the collector 3; the lower surface of the hollow cylinder of the gap space shape 4 is connected to the upper surface of the central cavity space shape 5 of the impeller 2; the upper surface of the hollow cylinder of the gap space shape 4 is connected to the space shape 6 surrounded by the impeller and the volute, and then the gap space shape 4 is divided into a grid to obtain a calculation grid of the gap space shape 4;

[0111] Step 35: the central cavity space shape 5 of the impeller 2 is a truncated cone structure, the truncated cone upper surface of the central cavity space shape 5 of the impeller 2 is connected to the collector 3 and the gap space shape 4; the truncated cone lower surface of the central cavity space shape 5 of the impeller 2 is the inner wall surface of the impeller back plate 2-2; the truncated cone side surface of the central cavity space shape 5 of the impeller 2 is connected to the inlet 2-4 of the impeller 2, and then the central cavity space shape 5 of the impeller 2 is meshed to obtain the calculation mesh of the central cavity space shape 5 of the impeller 2;

[0112] Step 36: The spatial shape 6 enclosed by the impeller 2 and the volute 1 is the spatial shape formed between the impeller 2, the collector 3 and the volute 1, and then the spatial shape 6 enclosed by the impeller and the volute is divided into a grid to obtain a calculation grid of the spatial shape 6 enclosed by the impeller 2 and the volute 1.

[0113] Step 4: Use the computational grid of the centrifugal fan model to perform fluid mechanics simulation.

[0114] The final simulation results are post-processed and analyzed, which can be used for flow mechanism research or optimization design.

[0115] In order to further illustrate the technical scheme and technical effects of the present invention, the present invention provides the following specific examples:

[0116] Specific example: The implementation includes the following steps:

[0117] S01, establishing a centrifugal fan model, the model includes an impeller 2, a collector 3, and a volute 1 of the centrifugal fan;

[0118] S02. Determine the shape of impeller 2:

[0119] Impeller 2 uses an arc-shaped front disk, and the inlet diameter of impeller 2 is D0, in this case D0=360mm; the distance between the front end point of the impeller front disk 2-1 and the impeller back plate 2-2 is the impeller inlet height b1, in this case b1=442.7mm; the distance between the rear end point of the impeller front disk 2-1 and the impeller back plate 2-2 is the impeller outlet height b2, in this case b2=267mm; the front end point and the rear end point of the impeller front disk 2-1 are used as an arc, and the arc radius is the impeller front disk radius R0, in this case R0=200mm. By defining the impeller inlet height b1, the impeller outlet height b2, the impeller front disk radius R0 and the impeller inlet radius D0, a unique dimension is given, that is, the complete constraint of impeller 2 is achieved, such as Figure 2 shown.

[0120] S03. Determine the shape of the current collector 3:

[0121] The collector 3 is a conical arc collector. The first section of the collector 3 is a conical surface. The angle between the generatrix of the conical surface and the direction perpendicular to the axis is the collector convergence angle. , in this case =40.42°; the second section is an arc surface, which is tangent to the conical surface. The end point of the arc is used as a tangent line. The angle between the tangent line and the straight line perpendicular to the axis is the collector expansion angle. , in this case =53.58°. By defining the collector convergence angle and collector expansion angle , given a unique size, the full constraint of collector 3 is achieved, as Figure 2 shown.

[0122] S04. Determine the gap between the collector 3 and the impeller 2:

[0123] The collector 3 extends into the central cavity of the impeller 2, and forms a gap with the impeller 2. The axial distance of the collector 3 extending into the impeller 2 is the axial gap between the collector 3 and the impeller 2. , in this case =7.9mm; the circumferential distance between the outlet of collector 3 and the inner wall of impeller front disk 2-1 is the circumferential clearance between collector 3 and impeller 2 , in this case =7.7mm. By defining the axial clearance and circumferential clearance , given a unique size, that is, to achieve complete constraint on the gap between the collector 3 and the impeller 2, such as Figure 2 shown.

[0124] S05, such as Figure 3 As shown, determine the shape of the volute 1:

[0125] The inner wall profile of the volute 1 is a logarithmic spiral line, which is drawn by the equilateral basis method and is similar to the Archimedean spiral line. Therefore, the first thing to determine is the volute outlet opening A, which is A=900mm in this example; then, a square with a side length of a=A / 4 is made with the center of the impeller to obtain an equilateral base square, and then arcs are made with radii R1, R2, R3 and R4 with the four corners of the base square as the center to obtain the volute inner wall profile. D2 is the blade outlet diameter, which is D2=1000mm in this example, where:

[0126] ,

[0127] ,

[0128] ,

[0129] ,

[0130] In this example, R1=520mm, R2=647mm, R3=768mm, R4=888mm. After obtaining the inner wall profile, the volute outlet and volute tongue geometry are determined, and the volute outlet length C is taken as:

[0131] ,

[0132] In this case, C=810mm, the arc radius of the tip of the snail tongue r ’ , the value is:

[0133] ,

[0134] In this example, r' = 45mm, and the clearance t between the volute tongue and the impeller is:

[0135] ,

[0136] In this example, t=60mm. By defining the volute width B, the radius of the volute tongue r', the distance between the volute tongue and the impeller t, and the volute outlet opening A, a unique dimension is given, which means that the complete constraint of the volute 1 profile is achieved; the volute width B is defined, which means that the axial constraint of the volute 1 is achieved. In this example, the volute width is 665mm.

[0137] S06, such as Figure 4 As shown, determine the upper and lower intersection points of the leading edge circle and the trailing edge circle of the impeller 2 blade:

[0138] The impeller 2 blade adopts a single arc blade shape, that is, the mid-arc line is an arc. Therefore, the chord length b is first determined by a straight line. In this example, b=297mm. Circles are made with the two ends of the chord length b as the center, and the radii are the leading edge radius and trailing edge radius , in this case = =3mm, respectively recorded as the leading edge circle and the trailing edge circle. Draw a straight line perpendicular to the chord length b at the center of the leading edge circle and the trailing edge circle, and the straight line will have an upper intersection point and a lower intersection point with the leading edge circle and the trailing edge circle respectively.

[0139] S07, such as Figure 4 As shown, determine the impeller 2 blade curve control circle:

[0140] On the impeller blade chord length b, take the point with a distance a from the center of the leading edge circle as the maximum thickness position. In this example, a=156mm. Draw a straight line perpendicular to the chord length b with the maximum thickness position as the maximum thickness position. Make a circle, record it as the curve control circle, in this example =28mm.

[0141] S08, such as Figure 4 As shown, the upper surface modeling of the impeller 2 blade is completed:

[0142] The upper surface is shaped using a second-order Bezier curve. The second-order Bezier curve is constrained by two control lines. Specifically, two Bezier curve control lines are made through the upper intersection point of the leading edge circle and the upper intersection point of the trailing edge circle. First, the two Bezier curve control lines are made tangent to the curve control circle to form a Bezier curve. Then, the formed Bezier curve is made tangent to the leading edge circle and the trailing edge circle to complete the shape of the upper surface of the blade.

[0143] S09, such as Figure 4 As shown, the lower surface modeling of the impeller 2 blade is completed:

[0144] The lower surface is shaped using a second-order Bezier curve, which is constrained by three control points. Specifically, first, the lower intersection point of the leading edge circle, the lower intersection point of the trailing edge circle, and the intersection point of the curve control circle and the straight line perpendicular to the chord length are used as the three control points of the second-order Bezier curve to form a Bezier curve. Then, the formed Bezier curve is tangent to the leading edge circle and the trailing edge circle to complete the shaping of the lower surface of the blade.

[0145] S10. Determine the mid-arc line of the impeller 2 blade:

[0146] Find the largest inscribed circle between the upper and lower surfaces of the blade. The diameter of the inscribed circle is the maximum thickness. , in this case =18mm. Draw a three-point arc from the center of the leading edge circle, the center of the trailing edge circle and the center of the inscribed circle, which is the median arc.

[0147] S11. Determine the inlet airflow angle and outlet airflow angle of the impeller 2 blade:

[0148] Take the centrifugal fan model coordinate origin as the center, and make a circle tangent to the leading edge circle. The diameter of the circle is the blade inlet diameter D1. In this example, D1=730mm. Make a tangent line tangent to the leading edge circle at the tangent point of the two circles; make a tangent to the mid-arc line at the center of the leading edge circle. The angle formed by the tangent of the mid-arc line and the tangent of the leading edge circle is the inlet airflow angle. , in this case =24.27°;

[0149] Similarly, with the centrifugal fan model coordinate origin as the center, make a circle tangent to the trailing edge circle. The diameter of the circle is the blade outlet diameter D2. In this example, D2=1000mm. Make a tangent line tangent to the trailing edge circle at the tangent point of the two circles. Make a tangent to the mid-arc line at the center of the trailing edge circle. The angle formed by the tangent of the mid-arc line and the tangent of the trailing edge circle is the outlet airflow angle. , in this case =29.22°.

[0150] S12, such as Figure 1 , Figure 5 As shown in FIG7 , the shape of the volute 1 based on the centrifugal fan model is composed of the central cylindrical surface 1-1, the outlet 1-2 and the outer wall surface 1-3 of the volute. Among them, the diameter of the central cylindrical surface is 1.05 times the diameter D2 of the impeller 2 blade outlet, simplifying the three-dimensional volute into a two-dimensional volute, reducing the complexity of the volute modeling; the central cylindrical surface 1-1 of the volute 1 is connected to the space shape 6 surrounded by the impeller and the volute. The outlet 1-2 of the volute 1 is connected to the atmosphere; then the grid is divided on the two-dimensional volute to obtain the calculation grid of the volute 1.

[0151] S13, such as Figure 1 , Figure 6 and Figure 7 As shown, the impeller 2 is composed of the inlet 2-4, outlet 2-5, blades 2-3, impeller front disk 2-1 and impeller back plate 2-2 of the impeller 2; the inlet 2-4 of the impeller 2 is connected to the central cavity space shape 5 of the impeller; the outlet 2-5 of the impeller 2 is connected to the space shape 6 surrounded by the impeller and the volute, and then the inlet 2-4, outlet 2-5, blades 2-3, impeller front disk 2-1 and impeller back plate 2-2 of the impeller 2 are meshed to obtain the calculation mesh of the impeller 2.

[0152] S14, such as Figure 1 , Figure 7 As shown, the collector 3 is a truncated cone structure. The upper surface of the truncated cone of the collector 3 is the inlet of the centrifugal fan, which is connected to the atmosphere; the lower surface of the truncated cone of the collector 3 is the outlet of the collector, which is connected to the central cavity space shape 5 of the impeller, and then the collector 3 is divided into a grid to obtain the calculation grid of the collector 3.

[0153] S15, such as Figure 1 , Figure 7 As shown, the gap space shape 4 between the collector and the impeller is a hollow cylindrical structure, the outer surface of the hollow cylinder of the gap space shape 4 is the inner wall surface of the impeller front disk 2-1; the inner surface of the hollow cylinder of the gap space shape 4 is the outer wall surface of the collector 3; the lower surface of the hollow cylinder of the gap space shape 4 is connected to the upper surface of the central cavity space shape 5 of the impeller; the upper surface of the hollow cylinder of the gap space shape 4 is connected to the space shape 6 surrounded by the impeller and the volute, and then the gap space shape 4 is divided into a grid to obtain the calculation grid of the gap space shape 4.

[0154] S16, such as Figure 1 , Figure 7As shown, the central cavity space shape 5 of the impeller is a truncated cone structure, and the truncated cone upper surface of the central cavity space shape 5 of the impeller is connected to the collector 3 and the gap space shape 4; the truncated cone lower surface of the central cavity space shape 5 of the impeller is the inner wall surface of the impeller back plate 2-2; the truncated cone side surface of the central cavity space shape 5 of the impeller is connected to the inlet of the impeller 2, and then the central cavity space shape 5 of the impeller is divided into a grid to obtain the calculation grid of the central cavity space shape 5 of the impeller.

[0155] S17, such as Figure 1 , Figure 7 As shown, the space shape 6 surrounded by the impeller and the volute is the space shape formed between the impeller 2, the collector 3 and the volute 1, and then the space shape 6 surrounded by the impeller and the volute is divided into a grid to obtain a calculation grid of the space shape 6 surrounded by the impeller and the volute.

[0156] S18. Using the computational grid of the centrifugal fan model, a fluid mechanics simulation is performed. Part of the simulation results are shown in FIG8 .

[0157] Specifically, Figure 8 This is a velocity distribution cloud diagram at 50% blade height after fluid mechanics simulation using the computational grid of the centrifugal fan model. It can be seen that the flow is very continuous, and the actual flow conditions inside the centrifugal fan are truly restored. Post-processing analysis of the simulation results can be used for subsequent flow mechanism analysis or optimization design.

[0158] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A rapid modeling and simulation method for a centrifugal fan based on a wing blade model, characterized in that: The following steps are involved: Step 1: Establish a centrifugal fan model, define and constrain the shape and size of the impeller, collector, and volute of the centrifugal fan, as well as the gap between the collector and the impeller; Step 2: Based on the centrifugal fan model, the airfoil blade modeling method is used to shape the leading edge, trailing edge, upper and lower surfaces of the impeller blade in turn, and a centrifugal fan impeller blade model based on the airfoil blade is established, thereby defining and constraining the shape and size of the impeller blade; Step 3: Output the three-dimensional geometric bodies of the centrifugal fan's volute, impeller, collector, the gap space shape between the collector and the impeller, the central cavity space shape of the impeller, and the space shape surrounded by the impeller and the volute, and perform structured meshing on the three-dimensional geometric bodies to obtain the computational mesh of the centrifugal fan model; Step 4: Use the computational grid of the centrifugal fan model to perform fluid mechanics simulation.

2. The centrifugal fan rapid modeling and simulation method based on the wing blade model according to claim 1 is characterized in that: The step 1 specifically includes: Step 11: Determine the shape of the impeller: The impeller is an arc-shaped front disk, and the impeller inlet diameter is D0; the distance between the front end point of the impeller front disk and the impeller back plate is the impeller inlet height b1; the distance between the rear end point of the impeller front disk and the impeller back plate is the impeller outlet height b2; the front end point and the rear end point of the impeller front disk are used as an arc, and the radius of the arc is the impeller front disk radius R0; given the unique dimensions of the impeller inlet height b1, the impeller outlet height b2, the impeller front disk radius R0 and the impeller inlet diameter D0, the complete constraint of the impeller is achieved; Step 12: Determine the shape of the current collector: The collector is a conical arc collector. The first section of the collector is a conical surface. The angle between the generatrix of the conical surface and the direction perpendicular to the axis is the collector convergence angle. The second section is an arc surface, which is tangent to the conical surface. The end point of the arc is used as a tangent line. The angle between the tangent line and the direction perpendicular to the axis is the expansion angle of the collector. ; Given the collector convergence angle and collector expansion angle Unique size, i.e. achieving full constraint of the current collector; Step 13: Determine the clearance between the collector and the impeller: The collector extends into the central cavity of the impeller, and a gap is formed between the collector and the impeller. The axial distance of the collector extending into the impeller is the axial gap between the collector and the impeller. The circumferential distance between the collector outlet and the inner wall of the impeller front disk is the circumferential clearance between the collector and the impeller. ; Given axial clearance and circumferential clearance Unique size, i.e. achieving full constraint of collector and impeller clearance; Step 14: Determine the volute shape: The inner wall profile of the volute is a logarithmic spiral line, which is drawn by the equilateral basis method and is similar to the Archimedean spiral line. Therefore, the outlet opening A of the volute is determined first, and then a square with a side length of a=A / 4 is made with the center of the impeller to obtain an equilateral base square. Then, with the four corners of the equilateral base square as the center, arcs are made with radii R1, R2, R3 and R4 respectively to obtain the inner wall profile of the volute, where: ， ， ， ， After obtaining the inner wall profile of the volute, determine the volute outlet and volute tongue geometry, and the volute outlet length C is: ， The radius of the arc at the tip of the snail tongue is r ’ , the value is: ， The value of the clearance t between the volute tongue and the impeller is: ， Where D2 is the blade outlet diameter; by defining the outlet opening A of the volute, the distance t between the volute tongue and the impeller, the outlet length C of the volute and the radius r of the volute tongue ’ , given a unique dimension, that is, to realize the constraint of the volute profile, and at the same time define the width B of the volute, that is, to realize the axial constraint of the volute.

3. The centrifugal fan rapid modeling and simulation method based on the wing blade model according to claim 1 is characterized in that: The step 2 specifically includes: Step 21: Determine the upper and lower intersection points of the leading edge circle and the trailing edge circle of the impeller blade: The impeller blade is a single arc blade, that is, the mid-arc line is an arc. Therefore, the chord length b is first determined by a straight line, and circles are made with the two end points of the chord length b as the center, and the radii are and , respectively denoted as the leading edge circle and the trailing edge circle; a straight line perpendicular to the chord length b is drawn at the centers of the leading edge circle and the trailing edge circle, and the straight line has an upper intersection point and a lower intersection point with the leading edge circle and the trailing edge circle respectively; Step 22: Determine the impeller blade curve control circle: On the chord length b of the impeller blade, a point at a distance a from the center of the leading edge circle is taken as the maximum thickness position, and a straight line is drawn perpendicular to the chord length b from the maximum thickness position. control Make a circle, record it as the curve control circle; Step 23: Complete the upper surface modeling of the impeller blades: The upper surface is shaped by a second-order Bezier curve. The second-order Bezier curve is constrained by two control lines. Specifically, two Bezier curve control lines are made through the upper intersection point of the leading edge circle and the upper intersection point of the trailing edge circle. First, the two Bezier curve control lines are made tangent to the curve control circle to form a Bezier curve. Then, the formed Bezier curve is made tangent to the leading edge circle and the trailing edge circle to complete the shape of the upper surface of the blade. Step 24: Complete the lower surface modeling of the impeller blade: The lower surface is shaped by a second-order Bezier curve, which is constrained by three control points. Specifically, first, the lower intersection point of the leading edge circle, the lower intersection point of the trailing edge circle, and the intersection point of the curve control circle and the straight line perpendicular to the chord length are used as the three control points of the second-order Bezier curve to form a Bezier curve. Then, the formed Bezier curve is tangent to the leading edge circle and the trailing edge circle to complete the shaping of the lower surface of the blade. Step 25: Determine the center arc of the impeller blade: Find the largest inscribed circle between the upper and lower surfaces of the blade. The diameter of the inscribed circle is the maximum thickness. , draw a three-point arc from the center of the leading edge circle, the center of the trailing edge circle and the center of the inscribed circle, which is the median arc; Step 26: Determine the impeller blade inlet and outlet airflow angles: Take the centrifugal fan model coordinate origin as the center, make a circle tangent to the leading edge circle, the diameter of the circle is the blade inlet diameter D1, make a tangent line tangent to the leading edge circle at the tangent point of the two circles, make a tangent line of the middle arc at the center of the leading edge circle, the angle formed by the tangent line of the middle arc and the tangent line of the leading edge circle is the inlet airflow angle ; Similarly, with the centrifugal fan model coordinate origin as the center, make a circle tangent to the trailing edge circle. The diameter of the circle is the blade outlet diameter D2. Make a tangent line tangent to the trailing edge circle at the tangent point of the two circles. Make a tangent to the mid-arc line at the center of the trailing edge circle. The angle formed by the tangent of the mid-arc line and the tangent of the trailing edge circle is the outlet airflow angle. ; Given the inlet airflow angle , outlet airflow angle , Maximum thickness , the distance a between the maximum thickness position and the center of the leading edge circle, and the radius of the leading edge circle , the radius of the trailing edge circle And the only dimension of the blade chord length b is to achieve complete constraint of the blade shape.

4. The centrifugal fan rapid modeling and simulation method based on the wing blade model according to any one of claims 1 to 3, characterized in that: The step three is specifically as follows: Step 31: Based on the shape of the volute of the centrifugal fan model, the volute consists of a central cylindrical surface, an outlet and an outer wall surface, wherein the diameter of the central cylindrical surface is 1.05 times the diameter D2 of the impeller blade outlet, and the three-dimensional volute is simplified into a two-dimensional volute to reduce the complexity of volute modeling; the central cylindrical surface of the volute is connected to the space shape surrounded by the impeller and the volute, and the outlet of the volute is connected to the atmosphere; then, a grid is divided on the two-dimensional volute to obtain a calculation grid of the volute; Step 32: The impeller is composed of an impeller inlet, an outlet, blades, an impeller front disk and an impeller back plate; the impeller inlet is connected to the central cavity space of the impeller; the impeller outlet is connected to the space shape surrounded by the impeller and the volute, and then the impeller inlet, outlet, blades, impeller front disk and impeller back plate are meshed to obtain the calculation mesh of the impeller; Step 33: The collector is a truncated cone structure. The upper surface of the truncated cone of the collector is the inlet of the centrifugal fan and is connected to the atmosphere. The lower surface of the truncated cone of the collector is the outlet of the collector and is connected to the shape of the central cavity space of the impeller. Then, the collector is meshed to obtain the calculation mesh of the collector. Step 34: The gap space shape between the collector and the impeller is a hollow cylindrical structure, the outer surface of the hollow cylinder of the gap space shape is the inner wall surface of the impeller front disk; the inner surface of the hollow cylinder of the gap space shape is the outer wall surface of the collector; the lower surface of the hollow cylinder of the gap space shape is connected to the upper surface of the central cavity space shape of the impeller; the upper surface of the hollow cylinder of the gap space shape is connected to the space shape surrounded by the impeller and the volute, and then the gap space shape is meshed to obtain the calculation mesh of the gap space shape; Step 35: The central cavity space shape of the impeller is a truncated cone structure. The upper surface of the truncated cone of the central cavity space shape of the impeller is connected to the collector and the gap space shape; the lower surface of the truncated cone of the central cavity space shape of the impeller is the inner wall surface of the impeller back plate; the truncated cone side surface of the central cavity space shape of the impeller is connected to the inlet of the impeller, and then the central cavity space shape of the impeller is meshed to obtain the calculation mesh of the central cavity space shape of the impeller; Step 36: The space shape enclosed by the impeller and the volute is the space shape formed between the impeller, the collector and the volute, and then the space shape enclosed by the impeller and the volute is divided into grids to obtain a calculation grid of the space shape enclosed by the impeller and the volute.

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