CN103332288B - Edge strip at trailing edge of airplane and design method thereof - Google Patents

Abstract

A side bar at the trailing edge of an aircraft main wing and a design method thereof. The side surface of the leading edge of the side strip is bonded to the side surface of the aircraft main wing trailing edge, and the upper surface of the side strip transitions smoothly with the upper surface of the aircraft main wing, and the lower surface of the side strip transitions smoothly with the lower surface of the aircraft main wing , so that the airflow can flow smoothly through the edge strip. When the inner flap is retracted, the lower surface of the side strip is attached to the upper surface of the inner flap. In the present invention, the side strips are installed on the main wing of the aircraft and correspond to the inner flaps to adjust the slot width G _f and the overlap O _f of the trailing edge flaps. Trailing edge flaps flow separation, improving the aerodynamic performance of the aircraft in takeoff/landing conditions.

Description

A side strip at the trailing edge of an aircraft main wing and its design method

technical field

The invention relates to the field of aircraft design, in particular to a side strip installed at the trailing edge of an aircraft main wing and a design method thereof.

Background technique

Large aircraft require high available lift due to high wing loads and low flying speeds during takeoff/landing. Modern aircraft obtain high usable lift mainly through the following methods: increasing wing camber, increasing wing area, flow control, etc. Increasing the camber of the wing is the most common method, which is mainly achieved by the deflection of the trailing edge flap. The greater the deflection angle of the trailing edge flaps, the more the wing camber changes and generally the higher the available lift for the aircraft. However, the deflection angle available for trailing edge flaps is limited. When the trailing edge flap is in a state of large deflection, the peak pressure coefficient of the trailing edge flap head is very high, and it is easy to induce flow separation on the upper surface of the trailing edge flap, resulting in loss of lift, reducing the takeoff/landing performance of the aircraft, and even possibly Circumstances arise where the aircraft takeoff/landing requirements cannot be met.

In order to control the flow separation in the large deflection state of the trailing edge flap and improve the take-off/landing performance of the aircraft, a large number of active/passive flow control technologies have been researched at home and abroad. For example, installing vortex generators on the upper surface of the trailing edge flap, slotting on the upper surface of the trailing edge flap for blowing/suction, installing plasma actuators, laying MEMS actuators, etc., can all achieve certain results. However, these technologies generally have disadvantages such as harsh conditions of use, damage to the original structure of the flap, need for additional energy input, complex auxiliary mechanisms, and high maintenance costs, which limit the practical application of engineering.

Contents of the invention

In order to overcome the deficiencies in the prior art such as harsh service conditions, damage to the original structure of the flap, need for additional energy input, complex auxiliary mechanisms, and high maintenance costs, the present invention proposes a side strip at the trailing edge of the main wing of the aircraft and its design method.

The side bar at the trailing edge of the main wing of the aircraft proposed by the present invention, the side bar is installed on the main wing of the aircraft and corresponds to the inner flap, so as to adjust the slot width G _f and the slot overlap O _f of the trailing edge flap. When the trailing edge flap is highly deflected, the flow separation of the trailing edge flap is controlled to improve the aerodynamic performance of the aircraft in the takeoff/landing state.

The trailing edge of the side strip is arc-shaped; the spanwise length l of the side strip is the same as the spanwise length L of the flap in the aircraft, and the width at both ends of the side strip is 25% of the maximum width D of the side strip; The width at the symmetrical plane in the length direction is the widest, and the maximum width D of the side strip is 0.5% of the spanwise length l of the side strip; between the two ends of the arc-shaped trailing edge of the side strip and the widest point of the side strip Smooth connections using spline interpolation. The thickness of the joint between the side strip and the trailing edge of the main wing of the aircraft is the same as that of the trailing edge of the main wing of the aircraft, and the profile of the upper surface and the lower surface of the side strip is the same as that of the matched aircraft main wing.

The side surface of the leading edge of the side strip is bonded to the side surface of the aircraft main wing trailing edge, and the upper surface of the side strip is smoothly transitioned to the upper surface of the aircraft main wing, and the lower surface of the side strip is connected to the lower surface of the aircraft main wing. Smooth transitions to allow airflow to flow smoothly over the side strips. When the inner flap is retracted, the lower surface of the side strip is attached to the upper surface of the inner flap.

The present invention also proposes a method for designing side strips at the trailing edge of the main wing of the aircraft, the specific process of which is:

Step 1, determine the lift of the aircraft. Using the numerical simulation method of solving the Reynolds average N-S equation, calculate the flight speed V=68m/s, and the flow field of the aircraft in the range of a=0°～20°. Use formula (1) to get the aircraft lift coefficient Cl at each angle of attack.

Cl=(F _y *cosa-F _x *sina)/(0.5*ρ*V ² *S); (1)

Among them: F _y is the component force of the total aerodynamic force of the whole aircraft in the y direction; F _x is the component force of the total aerodynamic force of the whole aircraft in the x direction; a is the incoming flow angle of attack; ρ is the air density; Flight speed; S is the reference area of the aircraft.

Step 2, determine the separation range of the trailing edge flap and the pressure coefficient distribution of the trailing edge flap. Determine the incoming flow angle of attack a=8°, draw the surface limit streamline on the surface of the inner flap; the intersection line of the surface limit streamline is the separation line of the inner flap. At the position where the distance from the separation line to the leading edge of the inner flap is the shortest, the spanwise section of the inner flap is made, and the intersection line of the section and the inner flap is the inner flap profile at the spanwise position. Take out the pressure coefficient Cp on the profile surface and the geometric coordinates (x, y) of the profile surface, and obtain the relationship diagram between the pressure coefficient Cp and the profile abscissa x. The pressure coefficient Cp is defined as:

Cp=(Pressure-Preference)/(0.5*ρ*V ² ); (2)

Among them: Pressure is the pressure on each coordinate point of the inner flap profile at the spanwise section; Preference is the reference pressure, which is the standard atmospheric pressure.

Step 3, determine the spanwise length of the side strips. Obtain the inner flap separation line according to step 2, within the spanwise start and end range of the inner flap separation line, follow the principle that the spanwise start and end positions of the side strips are consistent with the spanwise start and end positions of the inner flap separation line , to determine the spanwise length of the strip.

Step 4, determine the value range of the maximum width of the side bar. The spanwise position of the shortest distance between the separation line of the inner flap and the leading edge of the inner flap is defined as the position of the maximum width D of the side bar.

Step 5, determine the width of both ends of the side strip. The width of both ends of the side strip is 20-30% of the maximum width D of the side strip.

Step 6, check the influence of the side strips on the lift of the aircraft. The maximum width D=D _max of the strip. According to the maximum width D of the side strip determined in step 4 and step 5 and the widths at both ends of the side strip, the side strip is constructed by the spline interpolation method, and the side strip is added to the trailing edge of the main wing of the aircraft. Using the numerical simulation method of solving the Reynolds average NS equation, calculate the flight speed V=68m/s, and the flow field of the aircraft in the range of a=0°～20°. Use formula (1) to get the aircraft lift coefficient Cl at each angle of attack.

When the maximum width of the side strip D=D _max , and the incoming flow angle of attack a=0°～20°, if the maximum lift coefficient Cl _max of the aircraft ≥ before the side strip is installed, the maximum width D of the side strip meets the design requirements, and the end side strip design; if the maximum lift coefficient Cl _max of the aircraft < before adding the side strips, then the maximum width D of the side strips does not meet the aerodynamic requirements, and it is necessary to reduce the maximum width D of the side strips, continue with the side strip design, and go to step 7.

Step 7, determine the target pressure coefficient. Add an increment Δ to the minimum pressure coefficient Cp _min1 of the inner flap profile obtained in step 2 to obtain a new minimum pressure coefficient Cp _min2 ; Cp _min2 is the target pressure coefficient.

Step 8, adjust the maximum width of the side bar. The adjustment amount of the maximum width D of the side bar is recorded as ΔD. The value range of ΔD is [0, D _max ]. The width at both ends of the side strip is still taken as 20-30% of the maximum width D of the side strip. The adjusted maximum width of the side bar D=D _max -ΔD. The side strips are constructed by the spline interpolation method, and the side strips are added to the trailing edge of the main wing of the aircraft. Using the numerical simulation method of solving the Reynolds average NS equation, the flow field of the aircraft with the flight speed V=68m/s and the incoming flow angle of attack a=8° is calculated. Using the same method as step 2, obtain the minimum pressure coefficient Cp _{min_ΔD} of the inner flap profile at the spanwise position where the maximum width D of the side strip is located. The difference between it and the target pressure coefficient ΔCp=Cp _min2 −Cp _{min_ΔD} .

Step 9, determine the maximum width of the side bar corresponding to the target pressure coefficient. According to the size of ΔCp obtained in step 8, use the formula (3) to determine the new value of the adjustment amount ΔD of the maximum width D of the side bar. Then, repeat step 8 of constructing side strips, solving flow field and obtaining ΔCp until |ΔCp _i+1 /Cp _min2 |≤0.05.

Formula (3) is:

ΔD _i+1 =ΔD _i /(1-k*ΔCp _i /D _max ); (3)

Among them: ΔD _i is the adjustment amount of the maximum width of the i-th side strip; ΔD _i+1 is the adjustment amount of the maximum width of the i+1-th side strip; ΔCp _i is the target pressure coefficient Cp _min2 and the i-th side strip The difference between the minimum pressure coefficient Cp _{min_ΔDi} of the inner flap profile corresponding to the maximum width adjustment; D _max is the upper limit of the maximum width of the side strip determined by structural constraints; k is the relaxation factor, which is used to control the adjustment ΔD _{i+ 1} size. The said i is the number of adjustments of the maximum width of the side bar.

After the i+1th adjustment, the relationship is as follows:

ΔCp _i+1 =Cp _min2 -Cp _{min_ΔDi+1} ; (4)

In the formula (4): Cp _{min_ΔDi+1} is the minimum value of the pressure coefficient of the inner flap profile corresponding to the adjustment of the maximum width of the side bar for the i+1th time; ΔCp _i+1 is the target pressure coefficient and the i+1th time The adjustment amount of the maximum width of the side strip corresponds to the difference of the minimum pressure coefficient of the inner flap profile.

When |ΔCp _i+1 /Cp _min2 |≤0.05, end the adjustment and go to step 10.

Step 10, check the influence of the side strips on the lift of the aircraft. Using the numerical simulation method of solving the Reynolds average N-S equation, calculate the flight speed V=68m/s, and the flow field of the aircraft in the range of a=0°～20°. Use formula (1) to get the aircraft lift coefficient Cl at each angle of attack.

If the maximum value of the aircraft lift coefficient Cl _max ≥ before the addition of side strips, then the maximum width D of the side strips meets the design requirements, and the design of the side strips ends; if the maximum value of the aircraft lift coefficient Cl _max < before the addition of side strips, the target pressure coefficient Cp _min2 Unreasonable, the value of the increment Δ is too large, adjust the increment Δ to 90% of the original increment, and then re-enter step 7 to continue the design of the side strips. The increment Δ is the pressure coefficient of the inner flap profile Increment of minimum value Cp _min1 .

In the present invention, by installing side strips at the trailing edge of the main wing of an aircraft, the seam parameters of the trailing edge flaps are significantly changed. Repair the overlapping amount O1 of the trailing edge flap slot before using the side strip to the overlapping amount O2 of the trailing edge flap slot after using the side strip; and O1 is a negative value, and O2 is a positive value. As the overlapping amount O2 of the trailing edge flap slot after using the strip is repaired to a positive value, the width G1 of the trailing edge flap slot before using the strip is changed to the width G2 of the trailing edge flap slot after using the strip, And G2<G1. The effect of this change in the slot parameters is that the main wing of the aircraft suppresses the flow on the upper surface of the trailing edge flap, the peak value of the pressure coefficient of the trailing edge flap decreases, and the reverse pressure gradient decreases. The flow separation on the upper surface is effectively controlled, the flow quality of the flap is improved, the lift force is increased, and the aerodynamic performance of the aircraft in the takeoff/landing state is improved.

Compared with prior art, the effect that the present invention obtains shows in the following aspects:

1. The side strips can effectively improve the aerodynamic performance of the aircraft in the takeoff/landing state. Only one side strip is added to the trailing edge of the main wing of an aircraft to effectively control the flow separation on the inner flap, so that the lift force at each angle of attack is significantly improved, especially the angle of attack α=8°～12° In the most common state of aircraft takeoff/landing, the lift force is increased by about 4%, which effectively improves the takeoff/landing performance of the aircraft.

2. The side strips are installed on the rear edge of the main wing of the aircraft by bonding, which avoids the problem of destroying the original structure of the aircraft. It is especially suitable for the improved design of existing aircraft, and it is easy to install and maintain, and has strong engineering practicability.

3. The side strips effectively alleviate the contradiction between the maximum lift and the available lift in the most common state of takeoff/landing. Since the deflection of the trailing edge flap is mainly designed to ensure the maximum lift force, it is easy to cause the most common state of takeoff/landing of the aircraft with an angle of attack α=8°～12°, and the trailing edge flap will appear flow separation. The use of side strips can cure the flow separation of the trailing edge flaps at the most commonly used angles of attack for aircraft takeoff/landing under the premise of ensuring the maximum lift, and avoid reducing the trailing edge flap deflection in order to prevent the separation of the trailing edge flaps, resulting in maximum The issue of lift loss.

4. The trailing edge of the main wing of a large aircraft is generally designed in the form of a spoiler. Therefore, the side strip is installed at the trailing edge of the main wing. On the one hand, it can be used to control the flow separation of the trailing edge flap and improve the aerodynamic performance of the aircraft in the takeoff/landing state; On the other hand, it can increase the area of the spoiler and improve the efficiency of the spoiler.

Description of drawings

Accompanying drawing 1 is the application schematic diagram of side bar on the main wing of certain aircraft;

Accompanying drawing 2 is the partially enlarged view of the aircraft wing with additional side strips;

Accompanying drawing 3 is a schematic diagram of the positional relationship between the side bar and the main wing of the aircraft and the trailing edge flap;

Accompanying drawing 4 is a schematic diagram of the parameters of the trailing edge flap slot for side strip adjustment;

Accompanying drawing 5 is the schematic diagram of the increasing effect of the side bar;

Accompanying drawing 6 is the flow chart of side bar design of the present invention;

Accompanying drawing 7 is a schematic diagram of the aerodynamic decomposition of the whole machine; wherein: F _x is the component force of the total aerodynamic force of the whole machine in the x direction, F _y is the component force of the total aerodynamic force of the whole machine in the y direction, and F _lift is the component force of the total aerodynamic force of the whole machine in the y direction. Lift, F _drag is the overall drag.

Accompanying drawing 8 is the flow characteristics of the inner flap before installing side strips;

Accompanying drawing 9 is a schematic diagram of adjusting the minimum value of the pressure coefficient of the inner flap profile;

Accompanying drawing 10 is the flow characteristics of the inner flap after adding the edge strip;

Accompanying drawing 11 is the comparison of the pressure coefficient distribution of the inner flap profile before/after the side strip is added. in:

1. Leading edge slat; 2. Aircraft main wing; 3. Trailing edge flap; 4. Side strip; 5. Inner flap; 6. Outer flap; 7. Limit streamline of inner flap surface; 8. Inner flap Wing separation line; 9. Pressure coefficient distribution before adding side strips; 10. Pressure coefficient distribution after adding side strips.

Detailed ways

As shown in accompanying drawing 1, accompanying drawing 2. This embodiment is a side strip installed at the trailing edge of the main wing of the aircraft, and the side strip 4 is located at the position corresponding to the main wing 2 and the inner flap 5 of the aircraft. By installing side strips 4 on the trailing edge of the main wing 2 of the aircraft, the slot width G _f and slot overlap O _f of the trailing edge flap can be adjusted, and the trailing edge flap can be controlled under the state of large deflection of the trailing edge flap. Flow separation for improved aerodynamic performance in takeoff/landing conditions.

As shown in Figure 3. The side strip 4 used for a certain aircraft is a strip plate made of aluminum alloy, and one side surface of the side strip 4 is arc-shaped, and the arc-shaped side surface is used as the back of the side strip 4 edge. The spanwise length l of the side strip 4 is the same as the spanwise length L of the aircraft inner flap 5, and the width at both ends of the side strip 4 is 25% of the maximum width D of the side strip 4; The width of the side strip 4 is the widest, and the maximum width D of the side strip 4 is 0.5% of the spanwise length l of the side strip 4; Smooth connection by strip interpolation. The thickness of the place where the side strip 4 is matched with the rear edge of the aircraft main wing 2 is the same as the thickness of the aircraft main wing 2 trailing edge, and the profile of the upper surface and the lower surface of the side strip 4 is consistent with that of the matched aircraft main wing 2. The profile is the same.

The edge strip 4 is installed at the rear edge of the main wing 2 of the aircraft, and the position of the edge strip 4 corresponds to the position of the inner flap 5 . The side surface of the front edge of the side strip 4 is connected with the side surface of the aircraft main wing 2 trailing edge by bonding, and the upper surface of the side strip 4 and the upper surface of the aircraft main wing 2 are smoothly transitioned, and the side strip 4 The lower surface of the lower surface and the lower surface of the main wing 2 of the aircraft transition smoothly, so that the airflow can flow through the side strips 4 smoothly. When the inner flap 5 is retracted, the lower surface of the edge strip 4 is attached to the upper surface of the inner flap 5 .

Accompanying drawing 4 has provided the principle that the side bar of this embodiment is used to adjust the slot parameter of trailing edge flap. It can be seen from attached drawing 4 that by installing side strips on the trailing edge of the main wing of an aircraft, the seam parameters of the trailing edge flaps have changed significantly, and the seam overlap O1 of the trailing edge flaps before the strips will be used The repair is the overlapping amount O2 of the trailing edge flap slot after using the side strip; the overlapping amount O1 of the trailing edge flap slot before using the side strip is a negative value, and the overlapping amount of the trailing edge flap slot after using the side strip O2 is a positive value. As the overlapping amount O2 of the trailing edge flap slot after using the strip is repaired to a positive value, the width G1 of the trailing edge flap slot before using the strip is changed to the width G2 of the trailing edge flap slot after using the strip, And G2<G1.

It can be seen from the schematic diagram of the lift-increasing effect of the side strips in Figure 5 that after the side strips are installed on the trailing edge of the main wing of an aircraft, the lift force at each angle of attack is significantly increased. Especially the most commonly used angle of attack α=8°～12° in the takeoff/landing state of the aircraft, and the lift force increases by about 4%, which will effectively improve the takeoff/landing performance of the aircraft.

Accompanying drawing 8, accompanying drawing 10 and accompanying drawing 11 disclose the physical mechanism that the main wing trailing edge strip of this embodiment improves the aerodynamic performance of aircraft take-off/landing state.

From the pressure coefficient distribution given in Figure 11, it can be seen that when the Mach number Ma=0.20 and the angle of attack α=8°, the peak value of the pressure coefficient Cp of the inner flap profile reaches -3.4. The high peak pressure coefficient of the inner flap will form a strong reverse pressure gradient near the peak pressure coefficient, increasing the risk of separation of the inner flap, which can also be confirmed from the flow characteristics of the inner flap in Figure 8.

The peak value of the pressure coefficient of the trailing edge flap is high, which is rooted in the unreasonable seam parameters between the main wing and the trailing edge flap. The upwash effect of the external airflow is too strong. However, after the side strips are installed on the trailing edge of the main wing of the aircraft, the overlapping amount O _f of the slots of the trailing edge flaps increases, the width G _f of the slots of the trailing edge flaps decreases, and the restraining effect of the main wing on the trailing edge flaps is obviously strengthened .

The distribution of the pressure coefficient in Figure 11 shows that after the side strips are installed on the trailing edge of the main wing of the aircraft, the peak value of the pressure coefficient of the inner flap profile drops significantly from the original -3.4 to -2.5, which effectively weakens the reverse pressure gradient , the flow characteristics of the inner flap are also improved, the separation of the upper surface of the inner flap disappears, and the ideal adhesion flow characteristics are regained, as shown in Figure 10.

The improvement of the flow characteristics of the inner flaps makes the air flow velocity around the wings of the aircraft faster, which is reflected in the distribution of the pressure coefficients in Figure 11, which means that the peak pressure coefficients of the main wings and leading edge slats of the aircraft increase, and the circulation increases, thus effectively making up for the The lift loss of the inner flaps increases the total lift and improves the aerodynamic performance of the aircraft in takeoff/landing conditions.

Present embodiment also proposes a kind of design method of described side bar, concrete process is:

Step 1, determine the lift of the aircraft. Using the numerical simulation method of solving the Reynolds average N-S equation, calculate the flight speed V=68m/s, and the flow field of the aircraft in the range of a=0°～20°. Using formula (1), the lift coefficient Cl of the aircraft at each angle of attack is obtained.

Cl=(F _y *cosa-F _x *sina)/(0.5*ρ*V ² *S); (1)

Among them: F _y is the component force of the total aerodynamic force of the whole aircraft in the y direction; F _x is the component force of the total aerodynamic force of the whole aircraft in the x direction; a is the incoming flow angle of attack; ρ is the air density; Flight speed; S is the reference area of the aircraft. See accompanying drawing 7 for the aerodynamic decomposition of the whole machine.

Step 2, determine the separation range of the trailing edge flap and the pressure coefficient distribution of the trailing edge flap. Due to the takeoff/landing status of the aircraft, the most commonly used angle of attack is around a=8°. Therefore, determine the incoming flow angle of attack a=8°, use the Tecplot graphics processing software to import the flow field results calculated in step 1, and draw the surface limit streamline 7 on the surface of the inner flap 5, as shown in Figure 8 . The intersection line of the surface limiting streamlines 7 is the separation line 8 of the inner flap 5 . After the inner flap separation line 8 is obtained, the spanwise section of the inner flap 5 is made at the shortest distance from the separation line 8 to the leading edge of the inner flap 5, and the intersection line of the section and the inner flap 5 is the spanwise position The inner flap profile at . Take out the pressure coefficient Cp on the profile surface and the geometric coordinates (x, y) of the profile surface to obtain the relationship diagram between the pressure coefficient Cp and the abscissa x coordinate of the profile surface, as shown in Figure 9. In this embodiment, the shortest distance from the inner flap separation line 8 to the leading edge of the inner flap 5 is at the symmetrical plane of the inner flap 5 in the spanwise longitudinal direction. The pressure coefficient Cp is defined as:

Cp=(Pressure-Preference)/(0.5*ρ*V ² ); (2)

Among them: Pressure is the pressure on each coordinate point of the inner flap profile at the spanwise section; Preference is the reference pressure, which is the standard atmospheric pressure.

Step 3, determine the spanwise length of the side strips. According to step 2, the inner flap separation line 8 is obtained. Within the start and end range of the inner flap separation line 8 along the span direction, the start and end positions of the side strips along the span direction are consistent with the start and end positions of the inner flap separation line along the span direction. Based on the principle, determine the spanwise length of the side strip 4. In this embodiment, since the separation line 8 runs through the entire spanwise direction of the inner flap 5 , as shown in FIG. 8 , the spanwise length l of the edge strip 4 is the same as the spanwise length L of the inner flap 5 .

Step 4, determine the value range of the maximum width of the side bar. The spanwise position of the shortest distance between the inner flap separation line 8 and the leading edge of the inner flap 5 is defined as the position where the maximum width D of the side bar is located. Because the profiles of the upper surface and the lower surface of the side bar 4 in this embodiment are the same as the profile of the matched aircraft main wing 2 . On a real aircraft, the minimum thickness of the main airfoil should not be less than 4 mm, which determines the upper limit D _max of the maximum width D of the side strip. In this embodiment, the upper limit D _max of the maximum width D of the side bars determined by structural constraints is 0.8%l. Therefore, the value range of the maximum width D of the side bar 4 in this embodiment is [0, D _max ].

Step 5, determine the width of both ends of the side strip. The width of both ends of the side strip 4 is 20-30% of the maximum width D of the side strip, so as to facilitate the bonding of the side strip 4 and the rear edge of the main wing 2 and ensure the bonding strength. In this embodiment, the width at both ends of the side strip 4 is taken as 25% of the maximum width D of the side strip.

Step 6, check the influence of the side strips on the lift of the aircraft. The maximum width D=D _max of the strip. According to the maximum width D of the side bar 4 determined in step 4 and step 5 and the width at both ends of the side bar 4, the side bar 4 is constructed by the spline interpolation method, and the side bar 4 is added to the main wing trailing edge 2 of the aircraft. Using the numerical simulation method of solving the Reynolds average NS equation, calculate the flight speed V=68m/s, and the flow field of the aircraft in the range of a=0°～20°. Use formula (1) to get the aircraft lift coefficient Cl at each angle of attack.

When the maximum width of the side strip D=D _max , and the incoming flow angle of attack a=0°～20°, if the maximum lift coefficient Cl _max of the aircraft ≥ before the side strip is installed, the maximum width D of the side strip meets the design requirements, and the end side strip design; if the maximum lift coefficient Cl _max of the aircraft < before adding the side strips, then the maximum width D of the side strips does not meet the aerodynamic requirements, and it is necessary to reduce the maximum width D of the side strips, continue with the side strip design, and go to step 7.

Step 7, determine the target pressure coefficient. Add an increment Δ to the minimum pressure coefficient Cp _min1 of the inner flap profile obtained in step 2 to obtain a new minimum pressure coefficient Cp _min2 , as shown in Fig. 9 . Cp _min2 is called the target pressure coefficient. In this embodiment, when no side strips are installed, the minimum value of the profile pressure coefficient Cp _min1 of the inner flap 5 obtained in step 2 =-3.4, and the increment Δ=0.9 is taken to obtain the target pressure coefficient Cp _min2 =-2.5 .

Step 8, adjust the maximum width of the side bar. The adjustment amount of the maximum width D of the side bar is recorded as ΔD. The value range of ΔD is [0, D _max ]. In this embodiment, when adjusting for the first time, ΔD=0.2D _max is taken, and the width at both ends of the side bar is still taken as 25% of the maximum width D of the side bar. The adjusted maximum width of the side bar D=D _max -ΔD. The side strips are constructed by the spline interpolation method, and the side strips are added to the trailing edge of the main wing of the aircraft. Using the numerical simulation method of solving the Reynolds average NS equation, the flow field of the aircraft with the flight speed V=68m/s and the incoming flow angle of attack a=8° is calculated. Using the same method as step 2, the minimum value Cp _{min_ΔD} of the profile pressure coefficient of the inner flap 5 at the spanwise position where the maximum width D of the side strip is located is obtained. The difference between it and the target pressure coefficient ΔCp=Cp _min2 −Cp _{min_ΔD} .

Step 9, determine the maximum width of the side bar corresponding to the target pressure coefficient. According to the size of ΔCp obtained in step 8, use the formula (3) to determine the new value of the adjustment amount ΔD of the maximum width D of the side bar. Then, repeat step 8 of constructing side strips, solving flow field and obtaining ΔCp until |ΔCp _i+1 /Cp _min2 |≤0.05.

Formula (3) is:

ΔD _i+1 =ΔD _i /(1-k*ΔCp _i /D _max ); (3)

Among them: ΔD _i is the adjustment amount of the maximum width of the i-th side strip; ΔD _i+1 is the adjustment amount of the maximum width of the i+1-th side strip; ΔCp _i is the target pressure coefficient Cp _min2 and the i-th side strip The difference between the minimum pressure coefficient Cp _{min_ΔDi} of the inner flap profile corresponding to the maximum width adjustment; D _max is the upper limit of the maximum width of the side strip determined by structural constraints; k is the relaxation factor, which is used to control the adjustment ΔD _{i+ 1} , this embodiment takes k=0.005. The said i is the number of adjustments of the maximum width of the side bar.

After the i+1th adjustment, the relationship is as follows:

ΔCp _i+1 =Cp _min2 -Cp _{min_ΔDi+1} ; (4)

In the formula (4): Cp _{min_ΔDi+1} is the minimum value of the pressure coefficient of the inner flap profile corresponding to the adjustment of the maximum width of the side bar for the i+1th time; ΔCp _i+1 is the target pressure coefficient and the i+1th time The adjustment amount of the maximum width of the side strip corresponds to the difference of the minimum pressure coefficient of the inner flap profile.

When |ΔCp _i+1 /Cp _min2 |≤0.05, end the adjustment and go to step 10.

Step 10, check the influence of the side strips on the lift of the aircraft. Using the numerical simulation method of solving the Reynolds average N-S equation, calculate the flight speed V=68m/s, and the flow field of the aircraft in the range of a=0°～20°. Using formula (1), the lift coefficient Cl of the aircraft at each angle of attack is obtained.

If the maximum value of the aircraft lift coefficient Cl _max ≥ before the installation of the side strips, the side strips meet the design requirements, and the design of the side strips is completed; if the maximum value of the aircraft lift coefficient Cl _max < before the installation of the side strips, it means that the target pressure coefficient Cp _min2 is unreasonable , the value of the increment Δ is too large, adjust the increment Δ to 90% of the original increment, and then re-enter step 7 to continue the design of the side strips. The increment Δ is the increment of the minimum pressure coefficient Cp _min1 of the inner flap profile.

Claims (3)

1. the edge strip at aircraft main wing trailing edge place, described edge strip is arranged on the main wing section trailing edge of aircraft wing, and corresponding with interior wing flap, to adjust the seam road width G of trailing edge flap _fwith seam trace overlap amount O _f, under the large degree of bias state of trailing edge flap, control trailing edge flap flow separation, improve and take off/the aeroperformance of landing state; It is characterized in that, the trailing edge of described edge strip is arc; The exhibition of this edge strip is identical to length L with the exhibition of wing flap in aircraft to length l, and the width at described edge strip two ends is 20 ~ 30% of edge strip maximum width D; Edge strip exhibition is the widest to the width at length direction plane of symmetry place, for edge strip exhibition is to 0.5% of length l; Be smoothly connected with spline method between the two ends of edge strip arc trailing edge and described edge strip the widest part; Described edge strip is identical with the thickness of this aircraft main wing trailing edge with the thickness of aircraft main wing trailing edge cooperation place, and the upper surface of described edge strip is all identical with the profile of aircraft main wing joined together with the profile of lower surface.

2. the edge strip at a kind of aircraft main wing trailing edge place as claimed in claim 1, it is characterized in that, the side surface of described edge strip leading edge is bonding with the side surface of aircraft main wing trailing edge, and the upper surface smooth transition of the upper surface of edge strip and aircraft main wing, the lower surface of described edge strip and the lower surface smooth transition of aircraft main wing, smoothly flow through edge strip to enable air-flow; When interior wing flap is packed up, the lower surface of edge strip and the upper surface of interior wing flap are fitted.

3. a method of designing for the edge strip at aircraft main wing trailing edge place as claimed in claim 1, it is characterized in that, detailed process is:

Step 1, determines the lift of aircraft; Utilize the method for numerical simulation solving average Navier-Stokes equation, calculate flying speed V=68m/s, the aircraft flow field within the scope of incoming flow angle of attack a=0 ° ~ 20 °; Airplane ascensional force coefficient Cl under utilizing formula (1) to obtain each angle of attack;

Cl＝(F _y*cosa-F _x*sina)/(0.5*ρ*V ²*S)； (1)

Wherein: F _ythe total component of aerodynamic force in y direction of full machine; F _xthe total component of aerodynamic force in x direction of full machine; A is the incoming flow angle of attack; ρ is density of air; V is the flying speed of aircraft; S is the reference area of aircraft;

Step 2, determines that the pressure coefficient distribution of scope and the trailing edge flap be separated occurs trailing edge flap; Determine incoming flow angle of attack a=8 °, draw limiting streamline of surface in interior flap surface; The meld line of limiting streamline of surface is the defiber of interior wing flap; In the distance the shortest position of defiber to interior wing flap leading edge, in doing, the exhibition of wing flap is to section, and the intersection of section and interior wing flap is this exhibition to wing flap profile in position; Take out the geometric coordinate (x, y) of pressure coefficient Cp in this profile and profile, obtain the graph of a relation of pressure coefficient Cp and profile abscissa x; Pressure coefficient Cp is defined as:

Cp＝(Pressure-Preference)/(0.5*ρ*V ²)； (2)

Wherein: Pressure is that exhibition is to the pressure in each coordinate points of wing flap profile at section place; Preference is reference pressure, gets standard atmosphere;

Step 3, determines that the exhibition of edge strip is to length; Obtain interior wing flap defiber according to step 2, described interior wing flap defiber along exhibition to start-stop within the scope of, according to edge strip along exhibition to start-stop position and interior wing flap defiber edge open up to the principle of start-stop position consistency, determine that the exhibition of edge strip is to length;

Step 4, determines the span of edge strip maximum width; The exhibition of interior wing flap defiber and the most weakness of interior wing flap leading edge distance is defined as the position of edge strip maximum width D to position;

Step 5, determines the width at edge strip two ends; The width at described edge strip two ends is 20 ~ 30% of edge strip maximum width D;

Step 6, checks edge strip to the impact of airplane ascensional force; The maximum width D=D of described edge strip _max; The maximum width D of edge strip determined according to step 4 and step 5 and the width at edge strip two ends, construct edge strip by spline method, and edge strip is attached to the main wing trailing edge place of aircraft; Utilize the method for numerical simulation solving average Navier-Stokes equation, calculate flying speed V=68m/s, the aircraft flow field within the scope of incoming flow angle of attack a=0 ° ~ 20 °, the lift coefficient Cl under utilizing formula (1) to obtain each angle of attack;

As edge strip maximum width D=D _max, and incoming flow angle of attack a=0 ° ~ 20 °, if airplane ascensional force coefficient maxim Cl _max>=install edge strip additional before, then edge strip maximum width D meets design requirement, terminate edge strip design; If airplane ascensional force coefficient maxim Cl _maxbefore < installs edge strip additional, then edge strip maximum width D does not meet pneumatic requirement, needs the maximum width D reducing edge strip, proceeds edge strip design, enters step 7;

Step 7, determines goal pressure coefficient; The pressure coefficient minimum value Cp of wing flap profile in being obtained by step 2 _min1add an increment Delta, obtain new pressure coefficient minimum value Cp _min2; Cp _min2for goal pressure coefficient;

Step 8, the maximum width of adjustment edge strip; The adjustment amount of edge strip maximum width D is designated as Δ D; The span of Δ D is [0, D _max]; The width at edge strip two ends is still taken as 20 ~ 30% of edge strip maximum width D; Edge strip maximum width D=D after adjustment _max-Δ D; Utilize spline method to obtain the edge strip after have adjusted maximum width, and be attached to the main wing trailing edge of aircraft; Utilize the method for numerical simulation solving average Navier-Stokes equation, calculate flying speed V=68m/s, the aircraft flow field that the incoming flow angle of attack is a=8 °; Utilize the method identical with step 2, obtain the pressure coefficient minimum value Cp of edge strip maximum width D place exhibition to wing flap profile in position _{min_ Δ D}; The difference DELTA Cp=Cp of itself and goal pressure coefficient _min2-Cp _{min_ Δ D};

Step 9, determines the edge strip maximum width that goal pressure coefficient is corresponding; According to the size of the Δ Cp obtained by step 8, formula (3) is utilized to determine the new value of the adjustment amount Δ D of edge strip maximum width D; Then, repeat the structure edge strip of step 8, flow field calculation and acquisition Δ Cp process, until | Δ Cp _i+1/ Cp _min2|≤0.05;

Formula (3) is:

ΔD _i+1＝ΔD _i/(1-k*ΔCp _i/D _max)； (3)

Wherein: Δ D _iit is the adjustment amount of the edge strip maximum width of i-th time; Δ D _i+1it is the adjustment amount of the edge strip maximum width of the i-th+1 time; Δ Cp _ifor goal pressure coefficient Cp _min2wing flap surface pressure coefficient minimum value Cp in corresponding with i-th edge strip maximum width adjustment amount _{min_ Δ Di}difference; D _maxfor the upper limit of the maximum width of edge strip determined by structural constraint; K is relaxation factor, for controlling adjustment amount Δ D _i+1size; Described i is the adjustment number of times of edge strip maximum width; After the i-th+1 time adjustment, there is following relational expression:

ΔCp _i+1＝Cp _min2-Cp _{min_ΔDi+1}； (4)

In formula (4): Cp _{min_ Δ Di+1}it is the interior wing flap surface pressure coefficient minimum value that the adjustment amount of the edge strip maximum width of the i-th+1 time is corresponding; Δ Cp _i+1for goal pressure coefficient corresponding with the adjustment amount of the edge strip maximum width of the i-th+1 time in the difference of wing flap surface pressure coefficient minimum value;

When | Δ Cp _i+1/ Cp _min2| when≤0.05, terminate adjustment, enter step 10;

Step 10, checks edge strip to the impact of airplane ascensional force; Utilize the method for numerical simulation solving average Navier-Stokes equation, calculate flying speed V=68m/s, the aircraft flow field within the scope of incoming flow angle of attack a=0 ° ~ 20 °; Utilize formula (1), obtain each angle of attack and to get off the plane lift coefficient Cl; If airplane ascensional force coefficient maxim Cl _max>=install edge strip additional before, then edge strip maximum width D meets design requirement, terminate edge strip design; If airplane ascensional force coefficient maxim Cl _maxbefore < installs edge strip additional, goal pressure Cp is described _min2unreasonable, increment Delta value is bigger than normal, increment Delta is adjusted to 90% of former increment, then reenters step 7, proceeds the design of edge strip; Described increment Delta is the pressure coefficient minimum value Cp of interior wing flap profile _min1increment.