A Parametric Design Method for Helicopter Particle Separators

Abstract

This invention discloses a parametric design method for a helicopter particle separator. The method first sets control points at key locations and constructs the central body contour of the separator using a cubic Hermite interpolation polynomial with weighted terms. Next, based on the cross-sectional areas of key locations such as the separator inlet, bifurcation, and throat, the outer wall surface of the core region and part of the bifurcation profile are derived. Subsequently, by adding control points again and combining the cubic Hermite interpolation polynomial with weighted terms, a complete outer wall surface contour curve is generated. Simultaneously, the bifurcation curve is designed using circular arcs and tangents. This method not only meets the structural design requirements of the particle separator but also precisely controls the changing trend of its internal pressure gradient and supports flexible adjustment of key geometric parameters, thereby achieving efficient parametric design and optimization of the particle separator.

Description

Technical Field

[0001] This invention relates to the field of aircraft design, specifically to a parametric design method for helicopter particle separators. Background Technology

[0002] As a vertical takeoff and landing aircraft, helicopters frequently operate in various complex environments. When helicopters operate in particulate-rich environments such as deserts and seas, especially during takeoff and landing when the engine is near full power, they typically ingest large amounts of high-inertia particulate matter. If no protective measures are taken, these particles can cause severe damage to the engine, such as corrosion of compressor blades, leading to reduced engine power and, in severe cases, engine blade stall; the cooling channels of turbine blades can easily become clogged by particles, causing turbine blade overheating; and even engine failure in mid-air. Therefore, developing an effective air intake system protection device is particularly important for better protecting helicopter engines.

[0003] Inertial particle separators, with their advantages of high airflow per unit area, low drag, easy integration with engines, and minimal pressure distortion, are expected to be widely used in helicopter intake protection. Currently, research on efficient design methods for particle separators is scarce, and existing methods often struggle to simultaneously address structural constraints, aerodynamic performance, and parametric adjustment requirements. Therefore, developing an efficient design method for helicopter particle separators is particularly important. Summary of the Invention

[0004] Purpose of the Invention: The purpose of this invention is to provide a parametric design method for helicopter particle separators. This method achieves parametric design of helicopter particle separators by rationally arranging control points, optimizing the angles of key position surfaces, and controlling the area of ​​key cross-sections, thus taking into account the structural constraints, aerodynamic performance, and parametric adjustment requirements of the helicopter particle separator.

[0005] Technical Solution: To achieve the above objectives, the present invention provides a parameterized design method for a helicopter particle separator, comprising the following steps:

[0006] 1) Based on the structural constraints and dimensional specifications of the particle separator, establish control points for the central body and pre-set the slope of the central body contour curve at each control point;

[0007] 2) Construct a cubic Hermite interpolation polynomial curve and introduce a weight term; adjust the curve shape by adjusting the weight factors in the weight term;

[0008] 3) Using the cubic Hermite interpolation polynomial with weighted terms constructed in step 2), the control points determined in step 1) are connected in series to draw the outline of the central body of the helicopter particle separator.

[0009] 4) Locate the positions of the outer wall surfaces at the inlet and outlet of the particle separator, and determine the cross-sectional area at the throat position; following the predetermined area change law, deduce the outer wall surface profile at the key position in reverse; then, using the cubic Hermite interpolation polynomial with weighted terms constructed in step 2), smoothly connect the outer wall surface profile at the key position with the positions at the inlet and outlet, and finally complete the overall design of the outer wall surface of the helicopter particle separator.

[0010] 5) Based on the geometric characteristics of the particle separator outlet, determine the endpoint position of the main channel outlet and design the cross-sectional area at the bifurcation point in combination with the flow parameters; according to the correspondence between the outlet area and the bifurcation area, deduce the profile of the lower wall of the particle separator; the front end of the bifurcation point uses arcs and tangents to achieve a smooth transition, and at the same time, determine the control point of the upper wall endpoint of the bifurcation point according to the size of the throat and the sweeping air channel outlet, and make a smooth connection through the cubic Hermite interpolation polynomial with weighted terms in step 2), and finally complete the profile design of the bifurcation point.

[0011] 6) The three parts of the profile are spliced ​​together: the central body, the outer wall, and the bifurcation. The meridional plane of the particle separator is designed, and the three-dimensional geometric model of the helicopter particle separator is constructed by generating a rotating body structure. Finally, the overall design of the particle separator is realized.

[0012] Furthermore, in step 2), a cubic Hermite interpolation polynomial curve is established. The function form of the cubic Hermite interpolation polynomial curve is as follows:

[0013]

[0014] Where x0 and y0 represent the coordinates of the starting point, x1 and y1 represent the coordinates of the ending point, m0 is the slope of the starting point, and m1 is the slope of the ending point; add a weight term. t is the weight parameter; the final function is in the form F(x) = H3(x) + W(x).

[0015] Further, in step 1), based on the structural constraints and dimensional specifications of the particle separator, control points [P0, P1, P2, P3, P4, P5, P6] are established for the design center body. Among them, P0 is the starting point of the center body, P1 is the starting point of the first area transition region of the center body, P2 is the location of the center body in the throat of the particle separator, P3 is the vertex of the center body, P4 is the end point of the third area transition region, P5 is the control point of the center body at the bifurcation of the main channel, and P6 is the end point of the center body. The slope of the center body contour curve at each control point [K0, K1, K2, K3, K4, K5, K6] is also determined.

[0016] Furthermore, in step 3), based on the cubic Hermite interpolation polynomial function relationship with weighted terms established in step 2), the control points [P0, P1, P2, P3, P4, P5, P6] determined in step 1), combined with their corresponding slopes [K0, K1, K2, K3, K4, K5, K6], are smoothly connected. The weight parameter t of each curve segment is adjusted to change the shape of that curve segment. Subsequently, the generated curves L... P0P1 ,L P1P2 ,L P2P3 ,L P3P4 ,L P4P5 ,L P5P6 The parts are then spliced ​​together to form the complete central body contour curve L_ZXT=[L P0P1 ,L P1P2 ,L P2P3 ,L P3P4 ,L P4P5 ,L P5P6 Complete the geometric design of the central body.

[0017] Further, in step 4), based on the geometric constraints of the outer wall of the particle separator, the coordinates of the starting position W0 of the outer wall and the slope of its profile are determined. The areas of the key sections P1_W1, P3_3, P4_W4, and the throat P2_W2 are determined according to aerodynamic performance requirements. W1, W2, W3, and W4 are the intersection points of the straight lines connecting the tangents at points P1, P2, P3, and P4 on the vertical center curve to the outer wall. Subsequently, according to the specified area variation law, the areas at the intermediate sections of the four sections are smoothly transitioned, and the outer wall curve L is calculated using the area formula. W1W2 L W2W3 L W3W4 Based on the dimensions of the downstream scavenging volute of the particle separator, the outer contour endpoint P6 is designed, and a transition point P5 adapted to the shape of the outer contour is provided between P4 and P6. The other parts are smoothly connected using the cubic Hermite interpolation polynomial method with weighted terms as described in step 2), generating curve L. W0W1 L W4W5 L W5W6 Finally, connect the curves in sequence to generate the outer wall curve L_WZ = [L W0W1 L W1W2 L W2W3 L W3W4 L W4W5 L W5W6 Complete the geometric design of the outer wall surface.

[0018] Furthermore, in step 5), the cross-sectional area of ​​the particle separator at the bifurcation is designed based on the flow information, and the profile L of the lower wall of the particle separator at the bifurcation is derived by combining the relationship between the outlet area and the bifurcation area. F0F1 The leading edge of the bifurcation is designed with a smooth connection achieved through an arc and its tangent, generating curve L. F2F3 Simultaneously, based on the dimensions of the particle separator throat and the scavenging volute, control point F5 is determined on the upper wall of the bifurcation point. Control point F4 is added between points F3 and F5. Then, using the cubic Hermite interpolation polynomial method with weighted terms (as described in step 2), the control points are smoothly connected to generate curve L. F1F2 ,L F3F4 ,L F4F5 Finally, the curves are connected in sequence to generate the outer wall curve L_FZK = [L F0F1 L F1F2 L F2F3 L F3F4 L F4F5 Complete the geometric design of the bifurcation point.

[0019] Furthermore, in step 6), the three parts of the profiles—the central body, the outer wall, and the bifurcation—are spliced ​​together to complete the design of the meridional plane of the particle separator; and a rotating body structure is generated around the central axis, thereby fully constructing the three-dimensional geometric model of the helicopter particle separator and finally realizing the overall design of the particle separator.

[0020] Furthermore, in step 4), the outer wall curve L is calculated by using the area formula. W1W2 L W2W3 L W3W4 The process is as follows:

[0021] Establish the relationship between cross-sectional area and channel height L:

[0022] S(i)=π*L(i)(Y zxt (i)+L(i)*cos(theta(i))

[0023] Where Y zxt (i) is the ordinate of the i-th point on the specified curve on the central body; theta(i) is the slope at the i-th point on the specified curve on the central body; S(i) is the area of ​​the i-th cross section; and L(i) is the flow channel height of the i-th cross section.

[0024] L(i) is calculated iteratively using Newton's iteration method;

[0025] The points on the corresponding outer wall surface profile are calculated using the following formula:

[0026] X W (i)=Xzxt (i)+L(i)*cos(90-theta(i))

[0027] Y W (i)=Y zxt (i)+L(i)*sin(90-theta(i))

[0028] Where X W (i) represents the x-coordinate of point i on the curve of the outer wall surface, Y... W (i) is the ordinate of point i on the curve of the outer wall surface.

[0029] Furthermore, in step 5), the specific method for designing the leading edge position of the bifurcation using arcs and tangents is as follows:

[0030] Based on the specific requirements of the particle separator design, determine the center position (x) of the arc. c ,y c ); and the positions of the two tangent points (x t1 ,y t1 ), (x t2 ,y t2 The positions of the two tangent points are represented as follows:

[0031] x t1 =x c +Rcos(theta1)

[0032] y t1 =y c +Rcos(theta1)

[0033] x t2 =x c +Rcos(theta2)

[0034] y t2 =y c +Rcos(theta2)

[0035] Where R is the radius of the circle, and theta1 and theta2 are the angle values ​​of the positions of the tangent points on the circle;

[0036] Calculate the other endpoints (x) of the two tangent lines corresponding to the two points of tangency. t11 ,y t11 ) and (x t22 ,y t22 The formula for calculating the coordinates of ) is:

[0037] x t11 =x t1 -n1cos(theta1+90)

[0038] yt11 =y t1 -n1sin(theta1+90)

[0039] x t22 =x t2 -n2cos(theta2+90)

[0040] y t22 =y t2 -n2sin(theta2+90)

[0041] Where n1 and n2 are the lengths of the two tangents, respectively; generating curve L stc1 [(x t1 ,y t1 ), (x t11 ,y t11 )] and curve L stc2 [(x t2 ,y t2 ), (x t22 ,y t22 )];

[0042] Points on the circular arc are generated using the following formula:

[0043] theta(j)=theta1+(theta(2)-theta(1))*C(j)

[0044] Where theta(j) is the angle of the j-th point on the arc on the circle, C is a function with a range of [0,1] and uniform distribution, and C(j) is the j-th value of this function; x cir (j) is the x-coordinate of the j-th point on the arc, y cir (j) is the ordinate of the j-th point on the arc; generate curve L stc2 [x cir ,y cir ];

[0045] The three curves are spliced ​​together to generate the bifurcation leading edge curve L. F2F3 The two endpoints of the curve are named F2 and F3, respectively.

[0046] Furthermore, in step 5), the cubic Hermite interpolation polynomial method with weighted terms from step 2) is used to smoothly connect the control points as follows:

[0047] Connect F1 and F2 to generate a curve. Subsequently, based on the size and location of the scavenging airway outlet, the control point F5 at the outlet position of the bifurcation is determined. To allow for more flexible design, a control point F4 is added between F3 and F5. Its specific location can be determined according to specific design requirements. Then, connect points F3 and F4. At this point, substitute the x and y coordinates of F3 into the formula F(x) in step 2), and substitute the x and y coordinates of F4 into the formula F(x), and substitute the slope of F3 into the formula m0 and the slope of F4 into the formula m1. This yields the curve L connecting F3 and F4. F3F4 Using the same method, connect points F4 and F5 to generate a curve. Finally Perform splicing to generate the bifurcation curve.

[0048] Beneficial Effects: The parametric design method proposed in this invention, by introducing a cubic Hermite interpolation polynomial with weighted terms, combined with back-calculation and smooth connection techniques for key geometric parameters, can not only meet the structural design requirements of particle separators but also precisely control their internal flow field characteristics (such as pressure gradient variation trends). It also supports flexible adjustment of key geometric parameters, balancing the structural constraints, aerodynamic performance, and parametric adjustment needs of helicopter particle separators. This method provides an efficient solution for the design and optimization of helicopter particle separators. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of a typical particle separator flow channel structure.

[0050] Figure 2 This is the weighted cubic interpolation polynomial curve used in this invention.

[0051] Figure 3 This is the curve representing the control area change pattern used in this invention.

[0052] Figure 4 This is a schematic diagram of the leading edge generation of the bifurcation port of the particle separator of the present invention.

[0053] Figure 5 This is a schematic diagram of the meridional plane generation of the particle separator of the present invention.

[0054] Figure 6 This is a schematic diagram of the final three-dimensional model of the particle separator generated by this invention. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0056] A typical particle separator flow channel structure is as follows: Figure 1 As shown (for visual clarity, the main body of the particle separator is shown in cross-section), it includes a central body, an outer wall, and a bifurcation. The main flow channel between the bifurcation and the central body is connected to the engine, and the scavenging flow channel formed between the bifurcation and the outer wall is connected to the scavenging volute.

[0057] Based on the basic configuration of this particle separator, this invention provides a parametric design method for a helicopter particle separator, which can adjust the local shape of the particle separator based on the basic configuration to achieve the required design requirements. The design method of this invention includes the following steps:

[0058] 1) Based on the structural constraints and dimensional specifications of the particle separator, establish control points [P0, P1, P2, P3, P4, P5, P6] for the design center body. Here, P0 is the starting point of the particle separator center body, P1 is the starting point of the first area transition region of the center body, P2 is the location of the center body at the throat of the particle separator, P3 is the vertex of the center body, P4 is the end point of the third area transition region of the center body, P5 is the control point at the bifurcation point of the main channel, and P6 is the end point of the particle separator center body. Based on actual design requirements and experience, pre-determine the slope of the center body contour curve at each control point [K0, K1, K2, K3, K4, K5, K6] to provide accurate initial conditions for the subsequent geometric design of the center body.

[0059] 2) Construct a cubic Hermite interpolation polynomial curve, with the following functional form:

[0060]

[0061] Where x0, y0 represent the coordinates of the starting point of the curve, x1, y1 represent the coordinates of the ending point of the curve, m0 is the slope of the starting point, m1 is the slope of the ending point, and x is the x-coordinate of the cubic Hermite interpolation polynomial curve. Additionally, a weight term is added after the curve function. Where t is the weighting parameter; the final function of the curve has the form F(x) = H3(x) + W(x). This function can smoothly connect given the two endpoints and their slopes, and can change the trend of the curve by adjusting the weighting parameter, such as... Figure 2 As shown.

[0062] 3) Using the cubic Hermite interpolation polynomial function relationship with weighted terms established in step 2), the control points [P0, P1, P2, P3, P4, P5, P6] determined in step 1) are smoothly connected with their corresponding slopes [K0, K1, K2, K3, K4, K5, K6]. Taking the segment from P0 to P1 as an example, the x and y coordinates of P0 are substituted into the formula F(x) in step 2), and the x and y coordinates of P1 are substituted into F(x), x1 and y1. The slope K1 at P1 is substituted into the formula m0 at F(x), and the slope K2 at P2 is substituted into the formula m1 at F(x). This yields the curve L connecting P0 and P1. P0P1 Furthermore, based on actual design requirements, the weighting parameter t of the curve is adjusted to achieve flexible control over the curve's shape. Subsequently, the curve segments L generated through the above steps are... P0P1 ,L P1P2 ,L P2P3 ,L P3P4 ,L P4P5 ,L P5P6 And then spliced ​​together to finally form the complete central body contour curve L_ZXT=[L P0P1 ,L P1P2 ,L P2P3 ,L P3P4 ,L P4P5 ,L P5P6 ].

[0063] 4) Based on the geometric and structural constraints of the outer wall of the particle separator, determine the coordinates of the initial position W0 of the outer wall and the slope K of the curve. W0 Based on aerodynamic requirements, the areas of key sections P1W1, P3W3, P4W4, and the throat P2W2 are determined. W1, W2, W3, and W4 are the intersection points of the straight lines connecting the tangents at points P1, P2, P3, and P4 on the vertical centerline curve to the outer wall surface. Then, according to the specified area variation law, the areas at the intermediate sections of the four sections are smoothly transitioned, with the area transition curve selected as follows:

[0064] y = (-1 - 0.5n)x 4 +nx 3 +(2-0.5n)x 2

[0065] Where x is the x-coordinate and y is the y-coordinate, as shown in the figure. Figure 3 As shown; n is a parameter controlling the trend of the curve, which can make the curve transition from steep to gentle, to a balance of steep and gentle, or from gentle to steep, and its value range is [0,1]. Figure 3 As shown.

[0066] The area transition formula between two adjacent transition sections is shown below:

[0067] S j =S s +(S s -S e )*y(j)

[0068] Where S s S is the initial cross-sectional area. e S is the area of ​​the terminating cross section. j Let y(j) be the area of ​​the j-th cross section between the two cross sections, and y(j) be the ordinate of the j-th point on the transition curve.

[0069] Then, based on the area of ​​each cross section and the curves L2, L3, and L4 on the central body, the outer wall curve L is calculated. W1W2 L W2W3 L W3W4 The solution method is as follows:

[0070] The process of reversing the curve of the outer wall is as follows:

[0071] 1. Establish the relationship between cross-sectional area and channel height L:

[0072] S(i)=π*L(i)(Y zxt (i)+L(i)*cos(theta(i))

[0073] Where Y zxt (i) is the ordinate of the i-th point on the specified curve (e.g., the curve from P0 to P1) on the central body; theta(i) is the slope at the i-th point on the specified curve on the central body; S(i) is the area of ​​the i-th cross section; and L(i) is the flow channel height of the i-th cross section.

[0074] 2. Calculate L(i) iteratively using Newton's iteration method.

[0075] 3. Calculate the points on the corresponding profile lines on the outer wall surface, using the following formula:

[0076] X W (i)=X zxt (i)+L(i)*cos(90-theta(i))

[0077] Y W (i)=Y zxt (i)+L(i)*sin(90-theta(i))

[0078] Where X W (i) Specifies the x-coordinate of a point on the outer wall surface using a curve (e.g., the curve from W1 to W2), Y W(i) specifies the ordinate of a point on the curve of the outer wall surface.

[0079] Curve L was generated using the methods described above. W1W2 L W2W3 L W3W4 Connect W0 and W1 using the method in step 2). Substitute the x and y coordinates of W0 into the formula F(x) in step 2), and the x and y coordinates of W1 into F(x), respectively. Substitute the slope of W0 into F(x) and the slope of W1 into F(x) again, respectively, to obtain the curve L connecting W0 and W1. W0W1 Based on actual design requirements, the weighting parameter t of the curve is adjusted to achieve flexible control of the curve shape. Then, according to the dimensions of the downstream scavenging volute of the particle separator, the endpoint W6 of the outer wall is designed, and the transition point W5 is designed between W4 and W6. Using the same method as when connecting W0 and W1, curve L is generated by connecting W4 and W5, and W5 and W6. W4W5 L W5W6 Finally, connect the curves in sequence to generate the outer wall curve L_WZ = [L W0W1 L W1W2 L W2W3 L W3W4 L W4W5 L W5W6 ].

[0080] 5) Based on the size of the particle separator's main outlet, set a control point F0 at the bifurcation outlet location. Based on the flow rate information, design the cross-sectional area of ​​the particle separator at the bifurcation (i.e., the cross-sectional area of ​​the particle separator between point P5 on the central body and point F1 on the bifurcation). Then, based on the outlet area and this area, calculate the first curve from the main outlet of the particle separator to the bifurcation. The other endpoint of the curve is named F1. The method for generating the curve is the same as the method for calculating the outer wall profile from the area in step 4); then, the leading edge position of the bifurcation is designed using arcs and tangents, such as... Figure 4 As shown, the specific method is as follows:

[0081] 1. Based on the specific requirements of the particle separator design, determine the center position (x) of the arc. c ,y c ); and the positions of the two tangent points (x t1 ,y t1 ), (x t2 ,y t2 The positions of the two tangent points can be represented as follows:

[0082] x t1 =xc +Rcos(theta1)

[0083] y t1 =y c +Rcos(theta1)

[0084] x t2 =x c +Rcos(theta2)

[0085] y t2 =y c +Rcos(theta2)

[0086] Where R is the radius of the circle, and theta1 and theta2 are the angle values ​​of the positions of the tangent points on the circle.

[0087] 2. Calculate the other endpoints (x) of tangent 1 and tangent 2. t11 ,y t11 ) and (x t22 ,y t22 The formula for calculating the coordinates of ) is:

[0088] x t11 =x t1 -n1cos(theta1+90)

[0089] y t11 =y t1 -n1sin(theta1+90)

[0090] x t22 =x t2 -n2cos(theta2+90)

[0091] y t22 =y t2 -n2sin(theta2+90)

[0092] Where n1 and n2 are the lengths of tangent 1 and tangent 2, respectively; generate curve L stc1 [(x t1 ,y t1 ), (x t11 ,y t11 )] and curve L stc2 [(x t2 ,y t2 ), (x t22 ,y t22 )).

[0093] 3. Use the following formula to generate points on the circular arc:

[0094] theta(j)=theta1+(theta(2)-theta(1))*C(j)

[0095] Where theta(j) is the angle of the j-th point on the arc on the circle, C is a function with a range of [0,1] and uniform distribution, and C(j) is the j-th value of this function; x cir (j) is the x-coordinate of the j-th point on the arc, y cir (j) is the ordinate of the j-th point on the arc; generate curve L stc2 [x cir ,y cir ].

[0096] 4. Combine the three curves to generate the leading edge curve of the bifurcation point. The two endpoints of the curve are named F2 and F3, respectively.

[0097] Connect F1 and F2 using the formula in step 2) to generate curve L. F1F2 Subsequently, based on the size and location of the scavenging airway outlet, the control point F5 at the outlet position of the bifurcation is determined. To allow for more flexible design, a control point F4 is added between F3 and F5. Its specific location can be determined according to specific design requirements. Then, the method in step 2) is used to connect points F3 and F4. At this time, the x and y coordinates of F3 are substituted into the formula F(x) in step 2), and the x and y coordinates of F4 are substituted into the formula F(x), x1 and y1. The slope of F3 is substituted into the formula F(x), m0, and the slope of F4 is substituted into the formula F(x), m1. The curve L connecting F3 and F4 can then be obtained. F3F4 Using the same method, connect points F4 and F5 to generate a curve. Finally Perform splicing to generate the bifurcation curve.

[0098] 6) The profiles of the central body, outer wall, and bifurcation point are spliced ​​together to complete the design of the meridional plane of the particle separator; its schematic diagram is shown below. Figure 5 As shown, the structure is rotated around the central axis to generate a rotating body structure, thereby fully constructing the three-dimensional geometric model of the helicopter particle separator, ultimately realizing the overall design of the particle separator. The three-dimensional model of the particle separator is as follows: Figure 6 As shown.

Claims

1. A parametric design method for a helicopter particle separator, characterized in that, Includes the following steps: 1) Based on the structural constraints and dimensional specifications of the particle separator, establish control points for the central body and pre-set the slope of the central body contour curve at each control point; 2) Construct a cubic Hermite interpolation polynomial curve and introduce a weight term; adjust the curve shape by adjusting the weight factor in the weight term; 3) Using the cubic Hermite interpolation polynomial with weights constructed in step 2), the control points determined in step 1) are connected in series to draw the outline of the central body of the helicopter particle separator. 4) Locate the positions of the outer wall surfaces at the inlet and outlet of the particle separator, and determine the cross-sectional area of ​​the throat. Following the predetermined area variation law, derive the outer wall profile at the key positions in reverse. Then, using the cubic Hermite interpolation polynomial with weighted terms constructed in step 2), smoothly connect the outer wall profile at the key positions with the positions at the inlet and outlet, and finally complete the overall design of the outer wall surface of the helicopter particle separator. 5) Based on the geometric characteristics of the particle separator outlet, determine the endpoint position of the main channel outlet, and design the cross-sectional area at the bifurcation point in combination with the flow parameters; based on the correspondence between the outlet area and the bifurcation point area, deduce the profile of the lower wall of the particle separator. The front end of the bifurcation is smoothly transitioned using arcs and tangents. At the same time, the control points of the upper wall endpoints of the bifurcation are determined based on the dimensions of the throat and the outlet of the sweeping air passage. The bifurcation profile design is then completed by using a cubic Hermite interpolation polynomial with weighted terms in step 2). 6) The three parts of the profile are spliced ​​together: the central body, the outer wall, and the bifurcation. The meridional plane of the particle separator is designed, and the three-dimensional geometric model of the helicopter particle separator is constructed by generating a rotating body structure. Finally, the overall design of the particle separator is realized.

2. The parametric design method for a helicopter particle separator according to claim 1, characterized in that, In step 2), a cubic Hermite interpolation polynomial curve is established. The function form of the cubic Hermite interpolation polynomial curve is as follows: Where x0, y0 represent the coordinates of the starting point, x1, y1 represent the coordinates of the ending point, m0 is the slope of the starting point, and m1 is the slope of the ending point; add weight terms. t is the weight parameter; the final function has the following form: .

3. The parametric design method for a helicopter particle separator according to claim 2, characterized in that, In step 1), based on the structural constraints and dimensional specifications of the particle separator, control points [P0, P1, P2, P3, P4, P5, P6] are established for the design center body. Among them, P0 is the starting point of the center body, P1 is the starting point of the first area transition region of the center body, P2 is the location of the center body in the throat of the particle separator, P3 is the vertex of the center body, P4 is the end point of the third area transition region, P5 is the control point of the center body at the bifurcation of the main channel, and P6 is the end point of the center body. The slope of the center body contour curve at each control point [K0, K1, K2, K3, K4, K5, K6] is also determined.

4. The parameterized design method for a helicopter particle separator according to claim 3, characterized in that, In step 3), based on the cubic Hermite interpolation polynomial function relationship with weighted terms established in step 2), the control points [P0, P1, P2, P3, P4, P5, P6] determined in step 1), along with their corresponding slopes [K0, K1, K2, K3, K4, K5, K6], are smoothly connected. The weight parameter t of each curve segment is adjusted to change the shape of that curve segment. Subsequently, the generated curves L... P0P1 ,L P1P2 ,L P2P3 ,L P3P4 ,L P4P5 ,L P5P6 The parts are then spliced ​​together to form the complete central body contour curve L_ZXT=[ L P0P1 ,L P1P2 ,L P2P3 ,L P3P4 ,L P4P5 ,L P5P6 Complete the geometric design of the central body.

5. The parametric design method for a helicopter particle separator according to claim 4, characterized in that, Step 4) Based on the geometric constraints of the particle separator's outer wall, determine the coordinates of the initial position W0 of the outer wall and the slope of its profile. Then, based on aerodynamic performance requirements, determine the areas of the key sections P1_W1, P3_3, P4_W4, and the throat P2_W2. W1, W2, W3, and W4 are the intersection points of the straight lines connecting the tangents at points P1, P2, P3, and P4 on the vertical center curve to the outer wall. Subsequently, according to the specified area variation pattern, smoothly transition the areas at the intermediate sections of the four sections, and use the area formula to inversely calculate the outer wall curve L. W1W2 L W2W3 L W3W4 Based on the dimensions of the downstream scavenging volute of the particle separator, the outer contour endpoint P6 is designed, and a transition point P5 adapted to the shape of the outer contour is provided between P4 and P6. The other parts are smoothly connected using the cubic Hermite interpolation polynomial method with weighted terms in step 2), generating curve L. W0W1 L W4W5 L W5W6 Finally, connect the curves in sequence to generate the outer wall curve L_WZ=[L W0W1 L W1W2 L W2W3 L W3W4 L W4W5 L W5W6 Complete the geometric design of the outer wall surface.

6. The parametric design method for a helicopter particle separator according to claim 5, characterized in that, In step 5), the cross-sectional area of ​​the particle separator at the bifurcation is designed based on the flow information. Then, by combining the relationship between the outlet area and the bifurcation area, the profile L of the lower wall of the particle separator at the bifurcation is derived. F0F1 The leading edge of the bifurcation is designed with a smooth connection achieved through an arc and its tangent, generating curve L. F2F3 Simultaneously, based on the dimensions of the particle separator throat and the scavenging volute, control point F5 is determined on the upper wall of the bifurcation point. Control point F4 is added between points F3 and F5. Then, using the cubic Hermite interpolation polynomial method with weighted terms (as described in step 2), the control points are smoothly connected to generate curve L. F1F2 ,L F3F4 ,L F4F5 Finally, the curves are connected in sequence to generate the outer wall curve L_FZK=[L F0F1 L F1F2 L F2F3 L F3F4 L F4F5 Complete the geometric design of the bifurcation point.

7. The parametric design method for a helicopter particle separator according to claim 6, characterized in that, In step 6), the three parts of the profile are spliced ​​together: the central body, the outer wall, and the bifurcation. This completes the design of the meridional plane of the particle separator. The structure is then rotated around the central axis to generate a rotating body structure, thereby fully constructing the three-dimensional geometric model of the helicopter particle separator and ultimately realizing the overall design of the particle separator.

8. The parametric design method for a helicopter particle separator according to claim 5, characterized in that, In step 4), the outer wall curve L is calculated by using the area formula. W1W2 L W2W3 L W3W4 The process is as follows: Establish the relationship between cross-sectional area and channel height L: in Specify the ordinate of the i-th point on the curve on the central body; Specify the angle of the i-th point on the curve on the central body. Let be the area of ​​the i-th cross section. Let be the flow channel height of the i-th cross-section; Using Newton's iteration method Perform iterative calculations; The points on the corresponding outer wall surface profile are calculated using the following formula: in Specify the x-coordinate of point i on the curve of the outer wall surface. Specify the ordinate of point i on the curve of the outer wall surface.

9. The parametric design method for a helicopter particle separator according to claim 6, characterized in that, In step 5), the specific method for designing the leading edge position of the bifurcation using arcs and tangents is as follows: Based on the specific requirements of the particle separator design, determine the position of the center of the arc. , ); and the positions of the two tangent points ( , ), ( , The positions of the two tangent points are represented as follows: Where R is the radius of the circle, and theta1 and theta2 are the angle values ​​of the positions of the points of tangency on the circle; Calculate the other endpoints of the two tangent lines corresponding to the two points of tangency. , )and( , The formula for calculating the coordinates of ) is: Where n1 and n2 are the lengths of the two tangents, respectively; generate curve [( , ), ( , )] and curve [( , ), ( , )]; Points on the circular arc are generated using the following formula: in Let be the angle of the j-th point on the arc on the circle, and let C be a function with a range of [0,1] and uniform distribution. This is the j-th value of the function; Let x be the x-coordinate of the j-th point on the arc. Let be the ordinate of the j-th point on the arc; Generate curve [ , ]; The three curves are spliced ​​together to generate the leading edge curve of the bifurcation. The two endpoints of the curve are named F2 and F3, respectively.

10. The parametric design method for a helicopter particle separator according to claim 9, characterized in that, In step 5), the cubic Hermite interpolation polynomial method with weighted terms from step 2) is used to smoothly connect the control points as follows: Connect F1 and F2 to generate a curve. Subsequently, based on the size and location of the scavenging airway outlet, the control point F5 at the outlet position of the bifurcation is determined. To allow for more flexible design, a control point F4 is added between F3 and F5. Its specific location can be determined according to specific design requirements. Then, connect points F3 and F4. At this point, substitute the x and y coordinates of F3 into the formula F(x) in step 2), and substitute the x and y coordinates of F4 into the formula F(x), and substitute the slope of F3 into the formula m0 and the slope of F4 into the formula m1. This yields the curve L connecting F3 and F4. F3F4 Using the same method, connect points F4 and F5 to generate a curve. Finally, , , , , Perform splicing to generate the bifurcation curve. =[ , , , , ].

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