A method of designing a biomimetic fan using a combination of porous media and wave front configuration

Abstract

The present application relates to a kind of bionic fan design method of porous medium and wave front configuration combination in the technical field of aero-engine fan aerodynamic noise control.First, the leading edge line of the stator blade of benchmark fan is designed wave front configuration, as porous medium wave front.Second, the leading edge of benchmark blade is scaled to tailing edge along arc line, and a new leading edge benchmark line is obtained, and the solid wave front is designed according to the new benchmark line.The bionic stator blade based on the combination of porous medium and wave front configuration is obtained by combining the porous medium wave front and the solid wave front, and the bionic stator blade is installed on the fan according to the installation mode of benchmark stator blade, which combines the noise reduction characteristics of porous medium and wave front, proposes the bionic fan with the bionic combination configuration of porous medium wave front and solid wave front.Compared with single bionic configuration fan, the noise suppression effect of fan is significantly enhanced, and the noise of combination configuration is further reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine fan aerodynamic noise control, and particularly relates to a bionic fan design method combining a porous medium and a wave front edge configuration. BACKGROUND

[0002] With the rapid development of the aviation transportation industry, aircraft noise has become one of the important technical problems that the aviation industry is generally concerned about, and aircraft noise is closely related to flight safety, environmental protection, and people's livelihood. Since the 1970s, aircraft noise has been included in the airworthiness certification process as a mandatory index for entering the market. Civil aviation engine noise, especially fan noise as the main noise source of the engine, has received widespread attention and in-depth research from global aviation research institutions. In order to meet the rapidly developing aviation transportation market in the future and to continuously improve the requirements of environmental protection and healthy living, the International Civil Aviation Organization has put forward increasingly stringent aircraft airworthiness noise standards.

[0003] The noise of an aero turbine has always been the focus of attention of aircraft noise. Research on turbine noise is constantly being carried out, and at present, research on reducing turbine noise has entered a bottleneck period, and traditional noise control methods have no way to further reduce noise. The development of bionics provides a new way of thinking for noise control. At present, the bionic noise control theory of the turbine mainly has two sources: the owl with "super-quiet" flight capability and the beluga whale with "super-maneuverable" movement capability. The structure similar to "porous medium" can be observed in the wings of the owl, which contributes significantly to the silent flight of the owl. According to the structure observed in the wings of the owl, a "porous medium" bionic noise reduction configuration is proposed. The leading edge of the pectoral fin of the beluga whale has a protruding feature, and the protruding feature of the leading edge contributes significantly to the flexible swimming of the beluga whale in water. According to this feature, a "wave leading edge" bionic noise reduction configuration is proposed. A large number of documents have proved that the two bionic configurations can effectively suppress turbine noise.

[0004] It can be known from the prior art that it is difficult to further reduce noise efficiently through a single bionic configuration. In the research on the cylinder-airfoil, it is found that the wave leading edge is more effective in suppressing broadband noise, and the porous leading edge is more effective in suppressing single-tone noise. The porous wave leading edge has a significant inhibitory effect on single-tone noise and broadband noise, which shows that the combination design of the porous medium and the wave leading edge can retain the advantages of the wave leading edge and the porous medium in noise suppression. However, there are obvious differences between the fan blade and the airfoil. Compared with the airfoil, the fan blade has strong three-dimensionality. Therefore, there is currently a lack of a method for integrally designing a porous wave leading edge combined configuration and applying it to a fan. SUMMARY

[0005] The present application aims at avoiding the shortcomings of the prior art and providing a bionic fan with a combination of porous media and wave front configuration, the present application combines the noise reduction characteristics of porous media and wave front configuration, and proposes a bionic fan with a combination of porous wave front and solid wave front configuration, so that the noise suppression effect of bionic design on the fan is further enhanced.

[0006] To achieve the above-mentioned object, the technical scheme adopted by the present application is as follows: a bionic fan design method with a combination of porous media and wave front configuration, characterized by comprising the following steps:

[0007] Step 1: extracting the geometric data of the reference fan stator blade;

[0008] Step 2: designing the wave front configuration blade with the leading edge line of the reference fan stator blade, and selecting the region between the leading edge line and the region 30% chord length away from the leading edge line as the porous media wave front region;

[0009] Step 3: scaling the leading edge of the reference blade along the arc by 20% chord length to the trailing edge to obtain a new leading edge reference line, and designing the solid wave front blade according to the reference line to obtain the solid of the bionic combination blade;

[0010] Step 4: combining the porous media wave front region in Step 2 and the blade solid obtained in Step 3, and then filling the porous media between the porous media wave front and the solid to obtain the bionic stator blade with a combination of porous media and wave front configuration;

[0011] Step 5: mounting the bionic stator blade with a combination of porous media and wave front configuration on the axial fan according to the mounting mode of the reference stator blade to obtain a bionic stator blade row, and then mounting the rotor blade row on the fan to obtain a bionic fan with a combination of porous media and wave front configuration.

[0012] In the first step, the geometric data of the reference fan stator blade is extracted by the following method:

[0013] Firstly, select a stator blade of a fan, establish a three-dimensional coordinate system with chord direction as x-axis, span direction as y-axis, and vertical to xy plane as z-axis, divide the reference fan stator blade into n sections along the span direction, n=l / 10, l is the span length of the blade, and 10 is 10mm, i.e. take n sections of the blade at intervals of 10mm; divide the section airfoil into pressure surface curve and suction surface curve according to the leading edge point and trailing edge point through the camber line of each section airfoil, discretize the pressure surface curve, suction surface curve and camber line, and the selection rule of the points is to ensure that the airfoil regenerated according to the points is the same as the original airfoil, and the number of data points of the pressure surface, suction surface and camber line is also required to be the same, and the coordinates of the points are extracted.

[0014] The second step of designing the wave front configuration blade specifically includes the following steps:

[0015] (1) According to the extracted data point coordinates, find the corresponding blade section spanwise coordinates, the spanwise coordinates of each section data point are the same, according to the spanwise coordinates, interpolation is carried out between the spanwise adjacent sections, so as to obtain more spanwise position section pressure surface, suction surface and camber line data, so that the generated wave front line is smooth, the number of spanwise sections is determined according to the wavelength W of the wave front configuration, the number m of wave front configurations on the blade is obtained from the spanwise length l and the wavelength W, m = l / W, at least 4 sections are divided in a wavelength, so the number of spanwise sections is: N = m x k = lk / W, k ≥ 4;

[0016] (2) According to the cosine function to generate the wave type front edge, the chord length of the wave type front edge of the blade spanwise section is calculated as follows:

[0017]

[0018] Wherein, A is the amplitude of the wave front configuration, W is the wavelength of the wave front configuration; z is the spanwise coordinate of the section blade, c is the chord length of the reference blade, c z is the chord length of the wave front configuration blade;

[0019] (3) According to the calculated new chord length of the section blade, the point coordinate transformation of the wave front blade is as follows:

[0020]

[0021] Wherein, x w , y w , x B , y B are the horizontal coordinates and vertical coordinates of the data points of the wave front blade airfoil and the reference fan blade airfoil respectively, x max , y max represent the horizontal coordinates and vertical coordinates corresponding to the maximum thickness position of the airfoil, z is the spanwise coordinate of the section blade, c is the chord length of the reference blade, c z is the chord length of the wave front configuration blade; thus the wave peak, wave and wave trough three characteristic section airfoils of the wave front airfoil are generated;

[0022] (4) Stack all the newly generated section airfoils in the spanwise direction to obtain the conventional wave front configuration blade, install the conventional wave front configuration blade on the fan according to the installation mode of the reference stator blade, and obtain the conventional wave front configuration bionic fan.

[0023] The third step of designing the wave front configuration blade of the entity part specifically includes the following steps:

[0024] (1) Determine the position of the leading edge line of the blade entity, determine the leading edge point of each cross-section airfoil according to the data points of the extracted cross-section, form the leading edge line of the blade by the leading edge point of each cross-section blade, scale the leading edge line of the reference blade by 20% chord length, obtain the scaled blade leading edge line, scale the coordinates of the point from the leading edge point to the position of the maximum thickness of the airfoil, and the scaling transformation of the coordinates is as follows:

[0025]

[0026]

[0027] Wherein, x new , y new are the coordinates of the scaled leading edge airfoil, n is the scaling ratio, which is 0.2, x B , y B are the horizontal and vertical coordinates of the data points of the reference fan airfoil, x max , y max represent the horizontal and vertical coordinates corresponding to the position of the maximum thickness of the airfoil, and c is the chord length of the reference blade.

[0028] (2), with the scaled leading edge airfoil as the new reference airfoil, repeat steps (1), (2) and (3) in step two, stack all the new cross-section airfoils in the spanwise direction to generate the entity wavy leading edge blade.

[0029] The fourth step of designing the biomimetic stator blade combined with the porous medium and the wavy leading edge configuration comprises: taking the part of the wavy leading edge configuration obtained in step two near the 30% chord length of the leading edge as the porous medium leading edge region, combining the porous medium wavy leading edge and the entity wavy leading edge configuration, and filling the porous medium between the porous medium wavy leading edge and the entity wavy leading edge, so as to obtain the biomimetic stator blade combined with the porous medium and the wavy leading edge configuration.

[0030] The fifth step of designing the biomimetic fan combined with the porous medium and the wavy leading edge configuration comprises: installing the biomimetic stator blade combined with the porous medium and the wavy leading edge configuration in the fan according to the installation mode of the reference stator to obtain the biomimetic stator blade row based on the combination of the porous medium and the wavy leading edge configuration, and then installing the rotor blade row in the fan to obtain the biomimetic fan combined with the porous medium and the wavy leading edge configuration.

[0031] The application has the following beneficial effects: the bionic fan based on the combination of the porous medium and the wave front configuration can further reduce the noise of the bionic fan based on the combination of the porous medium and the wave front configuration by adjusting the structural parameters of the bionic configuration, such as the wavelength and amplitude of the wave front configuration and the porosity of the porous medium, and adjusting the relative spanwise positions between the porous wave front and the solid wave front, the bionic fan breaks through the limitation of the noise reduction ability of a single bionic configuration, and further enhances the noise suppression effect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a design flowchart of the application;

[0033] Figure 2 It is a wave front peak, wave and wave trough profile schematic diagram of the application;

[0034] Figure 3 It is a wave front configuration bionic fan structure schematic diagram in the prior art;

[0035] Figure 4 It is a wave front configuration bionic stator blade structure schematic diagram in the prior art;

[0036] Figure 5 It is a reference blade front edge line and scaled front edge line structure schematic diagram of the application;

[0037] Figure 6 It is a bionic blade schematic diagram of the application;

[0038] Figure 7 It is a bionic stator blade row schematic diagram of the application;

[0039] Figure 8 It is a bionic fan schematic diagram of the application;

[0040] Figure 9 It is a comparison schematic diagram of the single tone noise result of the application and the prior art.

[0041] In the figure, 1, wave peak profile; 2, wave profile; 3, wave trough profile; 4, conventional wave front blade; 5, reference blade front edge line; 6, scaled blade front edge line; 7, porous medium area; 8, solid area; 9, bionic stator blade based on the combination of the porous medium and the wave front configuration. DETAILED DESCRIPTION

[0042] The principles and characteristics of the application are described below in combination with the drawings, the examples are only used to explain the application, and are not used to limit the scope of the application.

[0043] In order to achieve the above object, the present application provides the following specific embodiment: as Figure 1 A biomimetic fan design method combining porous medium and wave front configuration, as shown in the figure, characterized in that it comprises the following steps:

[0044] Step 1: Extract the geometric data of the reference fan stator blade;

[0045] Step 2: Design wave front configuration blades with the leading edge line of the reference fan stator blade, and select the area between the leading edge line and the 30% chord length from the leading edge line as the wave front area of the porous medium;

[0046] Step 3: Scale the leading edge of the reference blade along the arc by 20% of the chord length to the trailing edge to obtain a new leading edge reference line, and design solid wave front blades according to this reference line to obtain the solid of the biomimetic combined blade;

[0047] Step 4: Combine the wave front area of the porous medium in Step 2 and the blade solid obtained in Step 3, and then fill the porous medium between the wave front of the porous medium and the solid to obtain the biomimetic stator blade 9 combining porous medium and wave front configuration;

[0048] Step 5: Install the biomimetic stator blade 9 combining porous medium and wave front configuration on the axial fan according to the installation method of the reference stator blade to obtain a biomimetic stator blade row, and then install the rotor blade row on the fan to obtain a biomimetic fan combining porous medium and wave front configuration.

[0049] The method for extracting the geometric data of the reference fan stator blade in the first step is:

[0050] First, select a stator blade of a fan, establish a three-dimensional coordinate system with chordwise as x-axis, spanwise as y-axis, and perpendicular to xy-plane as z-axis, divide the reference fan stator blade into n sections along the spanwise, n = l / 10, l is the spanwise length of the blade, and 10 is 10 mm, i.e. take n sections of the blade at intervals of 10 mm; divide the section airfoil into pressure surface and suction surface curves according to the leading edge point and trailing edge point through the camber line of each section airfoil; discretize the pressure surface curve, suction surface curve and camber line, and the selection rule of the points is to ensure that the airfoil regenerated according to the points is the same as the original airfoil, and the number of data points of the pressure surface, suction surface and camber line is also the same, and the coordinates of the points are extracted.

[0051] The method for designing wave front configuration blades in the second step comprises the following steps:

[0052] (1) According to the extracted data point coordinates, the spanwise coordinates of the corresponding blade section are found, the spanwise coordinates of the data points of each section are the same, and according to the spanwise coordinates, interpolation is carried out between the spanwise adjacent sections, so as to obtain the pressure surface, suction surface and mean camber line data of more spanwise position sections, so that the generated wave front line is smooth, and the number of spanwise sections is determined according to the wavelength W of the wave front configuration, the number m of wave front configurations on the blade is obtained from the spanwise length l and the wavelength W, m = l / W, at least 4 sections are divided in one wavelength, so the number of spanwise sections is: N = m x k = lk / W, k ≥ 4;

[0053] (2) According to the cosine function, the wave-shaped front edge is generated, and the chord length of the wave-shaped front edge of the biomimetic blade spanwise section is calculated as follows:

[0054]

[0055] Wherein, A is the amplitude of the wave front configuration, W is the wavelength of the wave front configuration, A selected in the embodiment is 20% of c, and W is 10% of c; z is the spanwise coordinate of the section blade, c is the chord length of the reference blade, and c z is the chord length of the wave front configuration blade;

[0056] (3) According to the calculated new chord length of the section airfoil, the point coordinates of the wave front airfoil are transformed as follows:

[0057]

[0058] Wherein, x w , y w , x B , y B are the horizontal coordinates and vertical coordinates of the data points of the wave front blade airfoil and the reference fan airfoil, respectively, x max , y max represent the horizontal coordinates and vertical coordinates corresponding to the maximum thickness position of the airfoil, respectively, z is the spanwise coordinate of the section blade, c is the chord length of the reference blade, and c z is the chord length of the wave front configuration blade; as shown in Figure 2 , three characteristic section airfoils of wave crest 1, wave middle 2 and wave trough 3 of the wave front airfoil are generated;

[0059] (4) Stack all the newly generated section airfoils in the spanwise direction to obtain a conventional wave front blade 4, and install the conventional wave front blade on the fan according to the installation mode of the reference stator blade to obtain a conventional wave front configuration biomimetic fan, as shown in Figure 3 and 4 ;

[0060] The wave front configuration blade of the designed entity part in the third step specifically comprises the following steps:

[0061] (1) Determine the position of the leading edge line of the blade body. Based on the data points of the extracted cross sections, determine the leading edge point of each cross section of the blade. The leading edge line of the blade is formed by the leading edge point of each cross section of the blade. Scale the leading edge line 5 of the reference blade by 20% of the chord length to obtain the scaled leading edge line 6 of the blade. Scale the coordinates of the points from the leading edge point to the maximum thickness of the blade. The scaling transformation of the coordinates is as follows:

[0062]

[0063] Where, x new y new Here are the leaf shape coordinates after scaling the leading edge, where n is the scaling ratio (0.2), and x... B y B These are the x and y coordinates of the data points for the baseline fan blade profile, respectively. max y max These represent the x and y coordinates corresponding to the position of maximum blade thickness, respectively, where c is the chord length of the reference blade; generally, the scaling should not exceed the position of maximum blade thickness.

[0064] (2) Using the scaled-down blade profile as the new reference blade profile, repeat steps (1), (2), and (3) in step two to stack all the new cross-sectional blade profiles in the spanwise direction to generate a solid wave leading edge blade.

[0065] The fourth step involves designing a biomimetic stator blade based on a combination of porous media and a wave leading edge configuration. Specifically, this includes: using the 30% chord length portion of the wave leading edge configuration obtained in step two as the porous media leading edge region; combining the porous media wave leading edge and the solid wave leading edge configuration; and filling the space between the porous media wave leading edge and the solid wave leading edge with porous media. This yields the biomimetic stator blade 9, a combination of porous media and a wave leading edge configuration. In this embodiment, the porosity of the porous media is selected to be 0.8, and the average pore diameter is 0.0022 mm. Figure 6 The figure shows a cross-sectional view of a biomimetic composite blade. Through the cross-section of the biomimetic blade based on the combination of porous media and wave leading edge configuration, it can be seen that the dark part of the leading edge of the blade is the porous media region 7, and the blank part behind it is the solid region 8. After the porous media comes into contact with the solid part of the blade, the porous media continues to extend to the 30% chord length position.

[0066] The fifth step, which involves designing a biomimetic fan combining porous media and a wave-leading edge configuration, specifically includes: Figure 7 As shown, by installing the biomimetic stator blade 9, which combines porous media and wave leading edge configuration, into the fan according to the mounting method of the reference stator, a biomimetic stator blade row based on the combination of porous media and wave leading edge configuration can be obtained, such as... Figure 8The rotor blade rows are then installed on the fan to obtain the biomimetic fan based on the combination of porous medium and wave front configuration.

[0067] As Figure 9 The single tone noise sound power of the reference fan, the conventional wave front configuration fan and the biomimetic fan based on the combination of porous medium and wave front configuration proposed by the present application in the embodiment is shown. As can be seen from the figure, the sound power column chart of the first three orders of BPF of the fan is shown. The wave front blade reduces the sound power of the reference blade. The biomimetic blade based on the combination of porous medium and wave front further reduces the noise sound power.

[0068] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of designing a biomimetic fan using a combination of porous media and wave front configuration, characterized by, The method comprises the following steps: The first step is to extract the geometric data of the reference fan stator blade, and the extraction method is: Select a stator blade of a fan, establish a three-dimensional coordinate system with the chord direction as the x-axis, the span as the y-axis, and the axis perpendicular to the xy-plane as the z-axis, and divide the reference fan stator blade along the span into... n A cross section, n = l / 10, l The spanwise length of the blade is 10 mm, meaning the blade is measured at 10 mm intervals. n Each section of the airfoil is divided into pressure surface and suction surface curves based on the leading / tail edge points and the mid-curve of each section. The pressure surface curve, suction surface curve, and mid-curve are discretized into points. The selection of points follows the rule that the number of points must ensure that the regenerated airfoil is the same as the original airfoil, and that the number of data points for the pressure surface, suction surface, and mid-curve is the same. The coordinates of the points are then extracted. The second step is to design a wave front edge configuration blade based on the leading edge line of the reference fan stator blade, and the region between the leading edge line and the 30% chord length away from the leading edge line is selected as the porous medium wave front edge region, and the specific steps are as follows: (1) According to the extracted data point coordinates, the spanwise coordinates of the corresponding blade section are found, and the spanwise coordinates of each section are the same. According to the spanwise coordinates, interpolation is carried out between the spanwise adjacent sections, so as to obtain more spanwise position section pressure surface, suction surface and camber line data, so that the generated wave front line is smooth, and the number of spanwise sections is according to the wavelength of the wave front configuration W Decided by the spanwise length l And the wavelength W The number of wave front configurations on the blade m , m = l / W At least divided into 4 sections in a wavelength, so the number of spanwise sections is: N = m * k = l * k / W, k >= 4; (2) The wave-shaped front edge is generated according to the cosine function, and the chord length of the wave-shaped front edge is calculated as follows: （1）， wherein, A is an amplitude of the wave front configuration, W is a wavelength of the wave front configuration; z is a spanwise coordinate of the cross-sectional blade, c is a chord length of the reference blade, c z is a chord length of the wave front configuration blade; (3) According to the calculated new chord length of the cross-sectional blade profile, the point coordinates of the wave-shaped front edge profile are transformed as follows: （2）， （3）， wherein, x w , y w , x B , y B are the abscissa and ordinate of the data points of the wave leading edge blade airfoil and the reference fan blade airfoil, respectively, x max , y max denote the abscissa and ordinate of the maximum thickness position of the blade airfoil, respectively, z is the spanwise coordinate of the cross-sectional blade, c is the chord length of the reference blade, c z is the chord length of the wave leading edge configured blade; from which three characteristic cross-sectional blade airfoils of the wave peak (1), wave mid (2) and wave trough (3) of the wave leading edge airfoil are generated; (4) Stack all the newly generated cross-sectional blade profiles in the spanwise direction to obtain a conventional wave-shaped front edge blade (4), install the conventional wave-shaped front edge blade on the fan according to the installation mode of the reference stator blade, and obtain a conventional wave-shaped front edge configuration bionic fan; The third step is to scale the leading edge of the reference blade along the arc by 20% of the chord length to obtain a new leading edge reference line, and design a solid wave-shaped front edge blade based on the reference line to obtain a solid bionic combination blade, and the specific steps are as follows: (1) Determine the position of the blade solid front edge line, determine the leading edge point of each cross-sectional blade profile according to the data points of the extracted cross section, and form the leading edge line of the blade by the leading edge point of each cross-sectional blade profile. Scale the leading edge line (5) of the reference blade by 20% of the chord length to obtain the scaled leading edge line (6) of the blade, and scale the point coordinates from the leading edge point to the maximum thickness position of the blade profile. The coordinate scaling transformation is as follows: （4）， （5）， wherein, x new , y new is the coordinate of the leading edge scaled airfoil, n is the scale ratio, and is 0.2, x B , y B are the abscissa and ordinate of the data points of the reference fan airfoil, respectively, x max , y max respectively represent the abscissa and ordinate corresponding to the maximum thickness position of the airfoil, c is the chord length of the reference blade. (2) Take the leading edge scaled blade profile as a new reference blade profile, repeat steps (1), (2) and (3) in step two, and stack all the new cross-sectional blade profiles in the spanwise direction to generate a solid wave-shaped front edge blade; The fourth step is to combine the porous medium wave front edge region in the second step and the blade solid obtained in the third step, and then fill the porous medium between the porous medium wave front edge and the solid to obtain a bionic stator blade (9) combined with the porous medium and the wave front edge configuration, and the specific steps are as follows: The 30% chord length part of the wave front edge configuration obtained in the second step is selected as the porous medium front edge region, the porous medium wave front edge and the solid wave front edge configuration part are combined, and the porous medium is filled between the porous medium wave front edge and the solid wave front edge to obtain a bionic stator blade (9) combined with the porous medium and the wave front edge configuration; The fifth step is to install the bionic stator blade (9) combined with the porous medium and the wave front edge configuration on the axial fan according to the installation mode of the reference stator blade to obtain a bionic stator blade row, and then install the rotor blade row on the fan to obtain a bionic fan combined with the porous medium and the wave front edge configuration.

2. A method of designing a biomimetic fan using a combination of porous media and wave front configuration as claimed in claim 1, wherein, The fifth step of designing a bionic fan combined with the porous medium and the wave front edge configuration is as follows: install the bionic stator blade (9) combined with the porous medium and the wave front edge configuration on the fan according to the installation mode of the reference stator to obtain a bionic stator blade row based on the porous medium and the wave front edge configuration, and then install the rotor blade row on the fan to obtain a bionic fan based on the porous medium and the wave front edge configuration.

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