CN104573265A - Method for optimizing aerodynamic performance of ring-sail parachute - Google Patents

Abstract

The invention relates to a method for optimizing aerodynamic performance of a ring-sail parachute. The method includes steps of acquiring canopy pressure intensity distribution, parachute cord joint force curve and steady outline fire of the ring-sail parachute under an assigned working condition, judging the steady state start time moment and the steady state period of the ring-sail parachute according to the parachute cord joint force curve, dividing a ring-sail parachute canopy into a plurality of concentric ring groups according to gradient width positions and calculating effective pressure difference of the inner surface and the outer surface of the canopy respectively, and finally decreasing ventilation of the maximum level of the effective pressure difference and increasing ventilation of the minimum level of the effective pressure by adjusting the local structure to obtain a new ring-sail parachute structure, calculating fluid-structure interaction again and evaluating the aerodynamic performance of the new structure, and repeatedly iterating till to obtain the optimal object. On the premise of not changing the integral structure of the ring-sail parachute, the aerodynamic performance of the ring-sail parachute is optimized.

Description

A kind of method that ringsail parachute aeroperformance is optimized

Technical field

The invention belongs to spacecraft parachute technology field, relate to a kind of method ringsail parachute aeroperformance is optimized based on technology of numerical simulation.Ringsail parachute aeroperformance comprises resistance coefficient and stability.

Background technology

Ringsail parachute because of have high reliability feature and by a large amount of aerodynamic decelerator for realizing the various spacecraft such as guided missile, unmanned plane, its configuration can be summarized with " perforate+circumferential weld+sail ": canopy top is apical pore, middle and upper part is circumferential weld structure, and the remainder near shirt rim is sail structure.Apical pore, circumferential weld and sail structure moon teeth space provide vent canopy amount for canopy, ensure that the stability of system; Sail structure, while raising canopy drag efficiency, improves the reliability of ringsail parachute.Because the parameter of ringsail parachute complex structure, control profile is more, the design result obtained according to design specifications has certain discreteness, and aeroperformance also has larger optimization space.The close-loop feedback of optimizing process needs performance assessment component, and parachute aeroperformance assessment in the past can only be realized by actual loading test modes such as air-drop, wind-tunnel, and the test period is long, cost is high, and it is more difficult to carry out closed-loop optimization, and accuracy is low, complicated operation; A kind of optimization method of present urgent need, makes the aeroperformance optimizing ringsail parachute on the basis not changing ringsail parachute overall configuration.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide a kind of method ringsail parachute aeroperformance is optimized based on technology of numerical simulation, utilize the local structure parameter of numerical simulation result of calculation to ringsail parachute to adjust, the basis not changing ringsail parachute overall configuration is optimized the aeroperformance of ringsail parachute.

Technical solution of the present invention is:

The method that ringsail parachute aeroperformance is optimized, comprises step as follows:

(1) extract umbrella rope joint forces time history curve, from t=0, search first cyclic curve section along time shaft positive dirction, this section of curve initial time estimated value is t _std=t _std0, time span estimated value is T _f=T _f0, get the time average of this section of curve, be designated as get [t _std+ T _f, t _std+ 2T _f] time average of segment of curve, be designated as if

$\frac{|\stackrel{\‾}{F_b}-\stackrel{\‾}{F_a}|}{\stackrel{\‾}{F_a}}\≤5\%$

Then think current t _stdnamely be that ringsail parachute enters the initial time of section steady-state period and section cycle steady-state period is T _fand enter step (2), otherwise get T _f=AT _fdouble counting above formula is until meet above formula condition, if if T in computation process _fvalue is greater than B times of T _f0, then T is refetched _f=T _f0, and make t _std=t _std+ T _f, continue to calculate until meet above formula condition;

(2) if umbrella rope joint forces time history curve comprises at least D constant time range, then step (3) is entered, otherwise according to T _fextend enough numerical simulation durations and re-start numerical simulation calculating to meet the demands, and enter step (3);

(3) judge that aeroperformance is the need of optimization, optimize if do not need, then enter step (9), otherwise calculate umbrella rope joint forces incoming flow durection component at t=[t _std, t _std+ DT _f] time average in interval with the maximum pendulum angle θ of ringsail parachute axis within D steady-state period _max, and will be scaled the resistance coefficient C of ringsail parachute _d;

(4) the average pressure reduction of the every ring of ringsail parachute and effective projected area is obtained;

(4a) according to the diverse location of each trapezoidal width in gores, ringsail parachute canopy is divided into different canopy rings by top to shirt rim by trapezoidal width sequence number; Remember that the time average of every ring canopy blade unit inside and outside differential pressure curve within D cycle is Δ P _{i, ele}, then the average pressure differential deltap P of the every ring of ringsail parachute _ifor { Δ P _{i, ele}arithmetic mean:

$\mathrm{\Δ}{P}_i=\frac{\mathrm{\Σ\Δ}{P}_{i,\mathrm{ele}}}{n_i}$

Wherein i is width sequence number, gets positive integer, and ele is unit number, n _iit is the canopy blade unit sum that i-th canopy ring comprises;

(4b) remember that the area vector of each canopy blade unit is S _ele, incoming flow direction vector is r _ele, then the effective projected area S of canopy ring in down-flowing incoming direction plane _ifor:

S _i＝∑S _ele·r _ele；

(5) effective pressure differential deltap P of every ring is calculated _ei:

ΔP _ei＝ΔP _i×S _i；

(6) according to the difference adjustment ringsail parachute partial structurtes size of the effective pressure reduction of every ring:

Adjustment mode is as follows:

(6a) the width sequence number { m} of the canopy ring at maximum effective pressure reduction place is found; By reducing canopy circumferential weld, the mode that reduces moon teeth space width or change low Air permenbility material reduces the Air permenbility Δ W of maximum effective pressure reduction in gores relevant position _l; The value of m is less than or equal to i;

(6b) find minimum effective pressure reduction place canopy ring width sequence number n}, and by increase seam wide, increase moon teeth space width or the mode of changing high Air permenbility material increases the Air permenbility Δ W of minimum effective pressure reduction in gores relevant position _mif minimum differntial pressure is distributed near apical pore, then increase apical pore diameter; The value of n is less than or equal to i;

(7) check Parachute area and Air permenbility, if meet following formula, enter step (8), otherwise reduce parameter adjustment increment in step (6), again calculate until meet the demands according to the following formula, and enter step (8);

$\frac{|\mathrm{\Δ}{W}_m-\mathrm{\Δ}{W}_l|}{W}\≤20\%;$

Wherein, W is total Air permenbility of ringsail parachute structure before this suboptimization;

(8) re-start simulation calculation according to the ringsail parachute structural parameters after optimization, and enter the iteration optimization that step (1) starts next step; Ringsail parachute structural parameters after described optimization be canopy circumferential weld after step (6) adjustment, the moon teeth space width and the low Air permenbility material of replacing;

(9) terminate.

A in step (1) gets 1.05; B in described step (1) gets 1.5.

D in step (2) gets 5.

In step (3) meet in following two conditions any one, aeroperformance does not need to optimize:

The iterative computation that a iterative computation that () is optimized is optimized after reaching the predetermined number of times upper limit terminates;

(b) target setting resistance coefficient value C _dwwith permission maximum pendulum angle θ _{max, w}if meet following formula iterative computation and stop simultaneously;

$\left\{\begin{array}{c}{C}_D\≥C_{\mathrm{Dw}}\\ {\mathrm{\θ}}_{\max }\≤{\mathrm{\θ}}_{\max ,w}\end{array}\right..$

The moon teeth space width and the low Air permenbility material of replacing of the canopy circumferential weld of the change in step (6), change, as the variable parameter in optimizing process, in Optimized Iterative computation process, the parameter increase of each step is not more than 5% of raw parameter value.

The present invention's beneficial effect is compared with prior art:

(1) the canopy aerodynamic characteristic evaluation index (effective pressure reduction) of the present invention's proposition, can reflect that local canopy aerodynamic decelerator performance is strong and weak more accurately, the present invention optimizes the aeroperformance of ringsail parachute on the basis not changing ringsail parachute overall configuration, closed-loop optimization can be carried out, substantially increase accuracy, simple to operate, be easy to realize, the test period is short simultaneously, cost is low.

(2) the present invention carries out umbrella structural adjustment according to the effective Pressure difference distribution of ringsail parachute canopy, to canopy resistance coefficient and stability lifting directly, effectively, to avoid in traditional ringsail parachute design process the properties of product that are that cause because parameter is too numerous and diverse and to fluctuate the problem that cannot effectively control.

(3) the present invention effectively can revise the homologous series umbellate form resistance coefficient deviation produced because of size difference, and versatility strengthens greatly, provides cost savings, and has been applied in the important flying apsaras model of China.

Accompanying drawing explanation

Fig. 1 is process flow diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is further described in detail.

First by numerical simulation, (numerical simulation is calculated as the fluid structurecoupling simulation calculation of carrying out ringsail parachute in the present invention, canopy circumferential weld, the low Air permenbility material of month teeth space width and replacing and the emulation experiment duty parameter of outside input, the parameters such as algorithm parameters are as numerical simulation input parameter computation year), export ringsail parachute and specify the canopy unit pressure time history curve under operating mode, umbrella rope joint forces time history curve, ringsail parachute axis pivot angle time history curve and ringsail parachute stable state are full of outer shape file, then carry out ringsail parachute stable state initial time according to umbrella knot point force curve judge and choose steady-state period, and then ringsail parachute canopy is divided into multiple concentric ring group according to trapezoidal width position and calculates the respective effective pressure reduction of canopy surfaces externally and internally.Effective pressure reduction directly characterizes the contribution of canopy unit to ringsail parachute resistance coefficient, and Air permenbility has considerable influence to the stability of ringsail parachute on the one hand, also adjustable local canopy, to the utilization factor of effective pressure reduction, therefore reduces by the mode of adjustment canopy partial structurtes and increases effective pressure reduction Air permenbility that is comparatively large and smaller part position to control to improve ringsail parachute resistance coefficient or stability while certain limit at the overall Air permenbility of guarantee respectively on the other hand.After completing primary structure adjustment, need to re-start ringsail parachute numerical simulation and calculate and the aeroperformance assessing new construction, to confirm the effect of optimization of structural adjustment to ringsail parachute aeroperformance.The object optimizing ringsail parachute aeroperformance can be reached by the above-mentioned flow process that iterates.

As shown in Figure 1, a kind of method that ringsail parachute aeroperformance is optimized, comprises step as follows:

(1) extract umbrella rope joint forces time history curve, from t=0, search first cyclic curve section along time shaft positive dirction, this section of curve initial time estimated value is t _std=t _std0, time span estimated value is T _f=T _f0, get the time average of this section of curve, be designated as get [t _std+ T _f, t _std+ 2T _f] time average of segment of curve, be designated as if

$\frac{|\stackrel{\‾}{F_b}-\stackrel{\‾}{F_a}|}{\stackrel{\‾}{F_a}}\≤5\%$

Then think current t _stdnamely be that ringsail parachute enters the initial time of section steady-state period and section cycle steady-state period is T _fand enter step (2), otherwise get T _f=1.05T _fdouble counting above formula is until meet above formula condition, if if T in computation process _fvalue is greater than 1.5 times of T _f0, then T is refetched _f=T _f0, and make t _std=t _std+ T _f, continue to calculate until meet above formula condition;

Step (1) is actual, and what carry out is the judgement of Numerical Simulation Results validity.

(2) if umbrella rope joint forces time history curve comprises at least 5 constant time ranges, then step (3) is entered, otherwise according to T _fextend enough numerical simulation durations and re-start numerical simulation calculating to meet the demands, and enter step (3);

(3) judge that aeroperformance is the need of optimization, optimize if do not need, then enter step (9), otherwise calculate umbrella rope joint forces incoming flow durection component at t=[t _std, t _std+ DT _f] time average in interval (calculating by numerical simulation the umbrella rope joint forces time history curve exported to obtain) and the maximum pendulum angle θ of ringsail parachute axis within D steady-state period _max(calculating by numerical simulation the ringsail parachute axis pivot angle time history curve exported to obtain), and will according to following formula be scaled the resistance coefficient C of ringsail parachute _d:

$C_D=\frac{{\stackrel{\‾}{F}}_D}{q{S}_0}$

Wherein, q is incoming flow dynamic pressure, S ₀for canopy apparent area, these two parameters are the input parameter of simulation calculation.

Meet any one in following two conditions, aeroperformance does not need to optimize:

The iterative computation that a iterative computation that () is optimized is optimized after reaching the predetermined number of times upper limit terminates;

(b) target setting resistance coefficient value C _dwwith permission maximum pendulum angle θ _{max, w}if meet following formula iterative computation and stop simultaneously;

$\left\{\begin{array}{c}{C}_D\≥C_{\mathrm{Dw}}\\ {\mathrm{\θ}}_{\max }\≤{\mathrm{\θ}}_{\max ,w}\end{array}\right..$

(4) the average pressure reduction of the every ring of ringsail parachute and effective projected area is obtained;

(4a) according to the diverse location of each trapezoidal width in gores, ringsail parachute canopy is divided into different canopy rings by top to shirt rim by trapezoidal width sequence number; Remember that the time average of every ring canopy blade unit inside and outside differential pressure curve within D cycle is Δ P _{i, ele}(calculating by numerical simulation the canopy unit pressure time history curve exported to obtain), then the average pressure differential deltap P of the every ring of ringsail parachute _ifor { Δ P _{i, ele}arithmetic mean:

$\mathrm{\Δ}{P}_i=\frac{\mathrm{\Σ\Δ}{P}_{i,\mathrm{ele}}}{n_i}$

Wherein i is width sequence number, gets positive integer, and ele is unit number, n _iit is the canopy blade unit sum that i-th canopy ring comprises;

(4b) remember that the area vector of each canopy blade unit is S _ele, incoming flow direction vector is r _ele, then the effective projected area S of canopy ring in down-flowing incoming direction plane _ifor:

S _i＝∑S _ele·r _ele；

(5) effective pressure differential deltap P of every ring is calculated _ei:

ΔP _ei＝ΔP _i×S _i；

(6) according to the difference adjustment ringsail parachute partial structurtes size of the effective pressure reduction of every ring:

Adjustment mode is as follows:

(6a) the width sequence number { m} of the canopy ring at maximum effective pressure reduction place is found; By reducing canopy circumferential weld, the mode that reduces moon teeth space width or change low Air permenbility material reduces the Air permenbility Δ W of maximum effective pressure reduction in gores relevant position _l; The value of m is less than or equal to i;

(6b) find minimum effective pressure reduction place canopy ring width sequence number n}, and by increase seam wide, increase moon teeth space width or the mode of changing high Air permenbility material increases the Air permenbility Δ W of minimum effective pressure reduction in gores relevant position _mif minimum differntial pressure is distributed near apical pore, then increase apical pore diameter; The value of n is less than or equal to i;

The moon teeth space width and the low Air permenbility material of replacing of the canopy circumferential weld changed, change, as the variable parameter in optimizing process, in Optimized Iterative computation process, the parameter increase of each step is not more than 5% of raw parameter value.

(7) check Parachute area and Air permenbility, if meet following formula, enter step (8), otherwise reduce parameter adjustment increment in step (6), again calculate until meet the demands according to the following formula, and enter step (8);

$\frac{|\mathrm{\Δ}{W}_m-\mathrm{\Δ}{W}_l|}{W}\≤20\%;$

Wherein, W is total Air permenbility of ringsail parachute structure before this suboptimization;

(8) re-start simulation calculation according to the ringsail parachute structural parameters after optimization, and enter the iteration optimization that step (1) starts next step; Ringsail parachute structural parameters after optimization be canopy circumferential weld after step (6) adjustment, the moon teeth space width and the low Air permenbility material of replacing.

The present invention has been applied in the great models such as the space flight goddess in the moon, and achieves good.

The content be not described in detail in instructions of the present invention belongs to the known technology of professional and technical personnel in the field.

Claims (5)

1. the method that is optimized of ringsail parachute aeroperformance, is characterized in that step is as follows:

(1) extract umbrella rope joint forces time history curve, from t=0, search first cyclic curve section along time shaft positive dirction, this section of curve initial time estimated value is t _std=t _std0, time span estimated value is T _f=T _f0, get the time average of this section of curve, be designated as get [t _std+ T _f, t _std+ 2T _f] time average of segment of curve, be designated as if

$\frac{|\stackrel{\‾}{F_b}-\stackrel{\‾}{F_a}|}{\stackrel{\‾}{F_a}}\≤5\%$

Then think current t _stdnamely be that ringsail parachute enters the initial time of section steady-state period and section cycle steady-state period is T _fand enter step (2), otherwise get T _f=AT _fdouble counting above formula is until meet above formula condition, if if T in computation process _fvalue is greater than B times of T _f0, then T is refetched _f=T _f0, and make t _std=t _std+ T _f, continue to calculate until meet above formula condition;

(2) if umbrella rope joint forces time history curve comprises at least D constant time range, then step (3) is entered, otherwise according to T _fextend enough numerical simulation durations and re-start numerical simulation calculating to meet the demands, and enter step (3);

(3) judge that aeroperformance is the need of optimization, optimize if do not need, then enter step (9), otherwise calculate umbrella rope joint forces incoming flow durection component at t=[t _std, t _std+ DT _f] time average in interval with the maximum pendulum angle θ of ringsail parachute axis within D steady-state period _max, and will be scaled the resistance coefficient C of ringsail parachute _d;

(4) the average pressure reduction of the every ring of ringsail parachute and effective projected area is obtained;

(4a) according to the diverse location of each trapezoidal width in gores, ringsail parachute canopy is divided into different canopy rings by top to shirt rim by trapezoidal width sequence number; Remember that the time average of every ring canopy blade unit inside and outside differential pressure curve within D cycle is Δ P _{i, ele}(pressure time curve), the then average pressure differential deltap P of the every ring of ringsail parachute _ifor { Δ P _{i, ele}arithmetic mean:

$\mathrm{\Δ}{P}_i=\frac{\mathrm{\Σ\Δ}{P}_{i,\mathrm{ele}}}{n_i}$

Wherein i is width sequence number, gets positive integer, and ele is unit number, n _iit is the canopy blade unit sum that i-th canopy ring comprises;

(4b) remember that the area vector of each canopy blade unit is S _ele, incoming flow direction vector is r _ele, then the effective projected area S of canopy ring in down-flowing incoming direction plane _ifor:

S _i＝∑S _ele·r _ele；

(5) effective pressure differential deltap P of every ring is calculated _ei:

ΔP _ei＝ΔP _i×S _i；

(6) according to the difference adjustment ringsail parachute partial structurtes size of the effective pressure reduction of every ring:

Adjustment mode is as follows:

(6a) the width sequence number { m} of the canopy ring at maximum effective pressure reduction place is found; By reducing canopy circumferential weld, the mode that reduces moon teeth space width or change low Air permenbility material reduces the Air permenbility Δ W of maximum effective pressure reduction in gores relevant position _l; The value of m is less than or equal to i;

(6b) find minimum effective pressure reduction place canopy ring width sequence number n}, and by increase seam wide, increase moon teeth space width or the mode of changing high Air permenbility material increases the Air permenbility Δ W of minimum effective pressure reduction in gores relevant position _mif minimum differntial pressure is distributed near apical pore, then increase apical pore diameter; The value of n is less than or equal to i;

(7) check Parachute area and Air permenbility, if meet following formula, enter step (8), otherwise reduce parameter adjustment increment in step (6), again calculate until meet the demands according to the following formula, and enter step (8);

$\frac{|\mathrm{\Δ}{W}_m-\mathrm{\Δ}{W}_l|}{W}\≤20\%;$

Wherein, W is total Air permenbility of ringsail parachute structure before this suboptimization;

(8) re-start simulation calculation according to the ringsail parachute structural parameters after optimization, and enter the iteration optimization that step (1) starts next step; Ringsail parachute structural parameters after described optimization be canopy circumferential weld after step (6) adjustment, the moon teeth space width and the low Air permenbility material of replacing;

(9) terminate.

2. the method that is optimized of a kind of ringsail parachute aeroperformance according to claim 1, is characterized in that: the A in described step (1) gets 1.05; B in described step (1) gets 1.5.

3. the method that is optimized of a kind of ringsail parachute aeroperformance according to claim 1, is characterized in that: the D in described step (2) gets 5.

4. the method that is optimized of a kind of ringsail parachute aeroperformance according to claim 1, is characterized in that: in described step (3) meet in following two conditions any one, aeroperformance does not need to optimize:

The iterative computation that a iterative computation that () is optimized is optimized after reaching the predetermined number of times upper limit terminates;

(b) target setting resistance coefficient value C _dwwith permission maximum pendulum angle θ _{max, w}if meet following formula iterative computation and stop simultaneously;

$\left\{\begin{array}{c}{C}_D\≥C_{\mathrm{Dw}}\\ {\mathrm{\θ}}_{\max }\≤{\mathrm{\θ}}_{\max ,w}\end{array}\right..$

5. the method that is optimized of a kind of ringsail parachute aeroperformance according to claim 1, it is characterized in that: the moon teeth space width and the low Air permenbility material of replacing of the canopy circumferential weld of the change in described step (6), change, as the variable parameter in optimizing process, in Optimized Iterative computation process, the parameter increase of each step is not more than 5% of raw parameter value.