CN100497092C - Backpack S-shaped inlet channel - Google Patents

Abstract

The present invention discloses a knapsack type S-shaped air inlet passage, a lip opening inner shape is the quarter oblong. The upper section of an air inlet lip opening, the two lateral sections of the lip opening and the lower section of the lip opening are different oblong equations. The centerline of a diffuser is a novel centerline form which approximately changes with rapid front and slow back, and one centerline with highest total pressure recovery coefficient is selected from the centerline with rapid front and slow back and the centerline with equivalently rapid and slow degree. Based on the rapid front and slow back on-way area changing principle, the on-way area changing principle of the diffuser is designed to obtain one centerline with the highest total pressure recovery coefficient from the rapid front and slow back on-way area changing principle and the on-way area changing principle with equivalently rapid and slow degree. The present invention has good pneumatic characteristic and high total pressure recovery coefficient, and the steady-state distortion index is at the small quantity grade, which is in favor of improving the inner flow characteristic of the S-shaped air inlet passage and can effectively reduces the shape resistance of an airplane.

Description

A kind of Backpack S-shaped inlet channel

Technical field

The invention belongs to the pneumatic design field of unmanned plane, be specifically related to a kind of designing technique that is applicable to the inlet channel of unmanned plane combustion chamber.

Background technology

Unmanned plane is widely used in campaign and the scouting of strategy level, supervision, target positioning, target is injured numerous areas such as assessment, electronic countermeasure, communication repeating.Its outstanding feature is the flying height height, and airborne period is long, and mission payload is big.Stealth is basic demand of modern advanced military aircraft design-calculated, and inlet channel is an important component part that realizes the unmanned plane stealth.If inlet channel is stealthy bad, the face exposure of engine blower and turbine is among the radar line of sight of incident, and that is tantamount to, and flash light impinges upon on the glittering gate panel in night, and it is all difficult to want not see.

In the aircraft propulsion system particularly inlet channel partly be a strong scattering source, the pipeline of inlet channel may cause strong radar returns, and the radar incident wave reflects strong echo by straight inlet channel from air compressor.Position after inlet channel is installed in fuselage back and leans on, there is significant impact in the fuselage flow field to inlet characteristic, so will reasonably determine forebody shape and inlet channel interior conduit shape at design phase, both are complementary, make inlet channel inflow point can obtain uniform flow field, satisfy the requirement of inlet channel and engine design.The inlet channel design divides about two parts, and " lining " is meant admission port with interior this section to driving engine, and for stealthy, this section should be crooked to some extent, and the driving engine front is not directly exposed among the radar line of sight of incident; " outward " is meant admission port itself, and this requires to be avoided the separation of boundary layer plate as far as possible, and it is out of square to reach admission port lip and working direction (generally being assumed to topmost radar incident direction), if possible, even avoids separation of boundary layer.The S shape inlet channel of compact conformation is a kind of design form that will adopt in the unmanned plane design.Its shortcoming is that total pressure recovery is low, air-flow degree of irregularity and turbulence level are big, thereby can cause reducing driving engine (aircraft) performance and engine stall margin, this is because the restriction of the shape of S shape inlet channel own and air inlet characteristics determine, certainly will exist inlet channel outlet total pressure recovery lower, bigger problem distorts.

Summary of the invention

Main purpose of the present invention is the layout characteristics according to unmanned plane, and a kind of short diffusion, big offset distance, Backpack S-shaped inlet channel are provided, and it is low to solve S shape inlet channel outlet total pressure recovery, and big problem distorts.By CFD emulation, analysis, revise formal parameter targetedly, optimize profile.

For reaching above purpose, the technical solution used in the present invention is as follows:

1) shape is adopted 1/4 elliptical shape in the lip, and cross section, admission port lip top, lip two lateral sections, lip lower section are got different elliptic equations, and the elliptic equation that get in cross section, lip top is:

$\frac{x^2}{{22}^2}+\frac{y^2}{{72}^2}=1,$

The elliptic equation that get lip two lateral sections is:

$\frac{x^2}{{26}^2}+\frac{y^2}{{72}^2}=1,$

The elliptic equation that the lip lower section is got is:

$\frac{x^2}{{30}^2}+\frac{y^2}{{72}^2}=1,$

In the formula, x, y are respectively horizontal stroke, the ordinate of putting on the cross section; The lip exterior cross-section adopts NACA-1 series inlet channel shape;

2) a highest line of centers of total pressure recovery coefficient between the slow suitable line of centers of line of centers in anxious back before the diffuser line of centers is got with emergency, described diffuser line of centers relaxes in inflow point than the slow line of centers in anxious back before described, and wherein, the slow line of centers in preceding anxious back satisfies equation:

$Y=\mathrm{\ΔY}[{3\left(\frac{X}{L}\right)}^4-8{\left(\frac{X}{L}\right)}^3+6{\left(\frac{X}{L}\right)}^2],$

Improve rear center's line and satisfy equation:

$Y=\mathrm{\ΔY}[{4\left(\frac{X}{L}\right)}^5-7{\left(\frac{X}{L}\right)}^4+{\left(\frac{X}{L}\right)}^3+4{\left(\frac{X}{L}\right)}^2],$

In the formula, on behalf of the ordinate of diffuser line of centers, eccentric throw, X that Δ Y represents diffuser, Y represent the abscissa of diffuser line of centers, and L represents the length of diffuser;

3) before diffuser is got along journey area change rule anxious back slow along journey area change rule and emergency quite along a highest line of centers of total pressure recovery coefficient between the journey area change rule, wherein, the slow rule along the journey area change in preceding anxious back satisfied equation:

$\frac{A}{A_1}=(\frac{A_2}{A_1}-1)[-{3\left(\frac{X}{L}\right)}^4+4{\left(\frac{X}{L}\right)}^3]+1,$

Improve the back diffuser and satisfy equation along journey area change rule:

$\frac{A}{A_1}=(\frac{A_2}{A_1}-1)[{2\left(\frac{X}{L}\right)}^5-3{\left(\frac{X}{L}\right)}^4-{\left(\frac{X}{L}\right)}^3+2{\left(\frac{X}{L}\right)}^2]+1,$

A represents diffuser along journey area, A in the formula ₁Represent the inlet-duct area of diffuser, A ₂Represent the diffuser exit sectional area, X represents the abscissa of diffuser line of centers, and L represents the length of diffuser.

The invention has the advantages that:

(1) utilize a kind of Backpack S-shaped inlet channel of the present invention, empirical evidence has aerodynamic characteristic preferably, and total pressure recovery coefficient is higher, and the steady-state distortion index is on the less magnitude, can satisfy need of real project.

(2) the S shape inlet channel diffuser line of centers equation after the improvement and favourable to the inner flowing characteristic that improves S shape inlet channel along journey area change rule proof.

(3) a kind of Backpack S-shaped inlet channel of the present invention is subjected to covering of body, can reduce inlet channel to electromagnetic scattering, thereby reduces the RCS of aircraft.

(4) a kind of Backpack S-shaped inlet channel of the present invention merges mutually with body, can effectively reduce the type resistance of aircraft.

Description of drawings

Fig. 1 is a kind of Backpack S-shaped inlet channel schematic cross-section of the present invention;

Fig. 2 is a diffuser line of centers form scheme drawing;

Fig. 3 restrains scheme drawing for diffuser gas along Cheng Bianhua;

Fig. 4 is a kind of S shape of the present invention inlet channel outlet total pressure recovery collection of illustrative plates.

Among the figure:

2 lips, two lateral sections, cross section, 1 lip top, 3 lip lower section, 4 diffuser line of centerss

The anxious line of centers in slow back before the suitable line of centers 8 of slow line of centers 6 improvement rear center line 7 emergencies in anxious back before 5

9 preceding anxious backs are slow to be restrained along the journey area change along journey area change rule 10 improvement back diffusers

11 emergencies are quite suddenly restrained along the journey area change along journey area change rule 12 preceding slow backs

The specific embodiment

The present invention is described in further detail below in conjunction with accompanying drawing.

A kind of Backpack S-shaped inlet channel of the present invention, one-body molded, as shown in Figure 1.

1) shape is adopted 1/4 elliptical shape in the lip, consider the influence of the big angle of attack of aircraft low speed and crosswind, different elliptic equations is got in cross section, admission port lip top 1, lip two lateral sections 2, lip lower section 3 cross sections, in fact different elliptic equations is exactly different import contraction ratio, and the elliptic equation that get in cross section, lip top 1 is:

$\frac{x^2}{{22}^2}+\frac{y^2}{{72}^2}=1,$

The elliptic equation that get lip two lateral sections 2 is:

$\frac{x^2}{{26}^2}+\frac{y^2}{{72}^2}=1,$

The elliptic equation that lip lower section 3 is got is:

$\frac{x^2}{{30}^2}+\frac{y^2}{{72}^2}=1;$

The lip exterior cross-section adopts NACA-1 series inlet channel profile.

2) diffuser line of centers 4 designs rule of thumb, are at first set three kinds of line of centers variation patterns, the slow line of centers 5 in anxious back, the suitable line of centers 7 of emergency, the anxious line of centers 8 in preceding slow back before being respectively, and wherein, the slow line of centers 5 in preceding anxious back satisfies equation:

$Y=\mathrm{\ΔY}[{3\left(\frac{X}{L}\right)}^4-8{\left(\frac{X}{L}\right)}^3+6{\left(\frac{X}{L}\right)}^2],$

The suitable line of centers 7 of emergency satisfies equation:

$Y=\mathrm{\ΔY}[{3\left(\frac{X}{L}\right)}^2-2{\left(\frac{X}{L}\right)}^3],$

The anxious line of centers 8 in preceding slow back satisfies equation:

$Y=\mathrm{\ΔY}[{-3\left(\frac{X}{L}\right)}^4+4{\left(\frac{X}{L}\right)}^3],$

Mainly be unlikely to from considering aspect the lower wall surface separation after curved then from enter second at air-flow, air inlet characteristics in conjunction with big offset distance, on the slow line of centers 5 in preceding anxious back, the suitable line of centers of emergency 7 bases, revise equation coefficients, a highest line of centers of total pressure recovery coefficient between the slow suitable line of centers 7 of line of centers 5 in anxious back before getting with emergency, draw a kind of new line of centers form near gradualization of preceding anxious back, promptly improve rear center's line 6, the difference that line of centers 5 is delayed in it and preceding anxious back is that import comparatively relaxes, and it satisfies equation:

$Y=\mathrm{\ΔY}[{4\left(\frac{X}{L}\right)}^5-7{\left(\frac{X}{L}\right)}^4+{\left(\frac{X}{L}\right)}^3+4{\left(\frac{X}{L}\right)}^2],$

The concrete form that improves rear center's line 6 and the slow line of centers 5 in preceding anxious back, the suitable line of centers 7 of emergency, the anxious line of centers 8 in preceding slow back as shown in Figure 2.In the above-mentioned equation, on behalf of the ordinate of diffuser line of centers, eccentric throw, X that Δ Y represents diffuser, Y represent the abscissa of diffuser line of centers, and L represents the length of diffuser.

3) diffuser is along the design of journey area change rule, rule of thumb, at first set three kinds of diffusers along journey area change rule variation pattern, anxious back is slow quite anxious along journey area change rule 12 along journey area change rule 11, preceding slow back along journey area change rule 9, emergency before being respectively, wherein, preceding anxious back is slow satisfies equation along journey area change rule 9:

$\frac{A}{A_1}=(\frac{A_2}{A_1}-1)[-{3\left(\frac{X}{L}\right)}^4+4{\left(\frac{X}{L}\right)}^3]+1,$

Emergency quite satisfies equation along journey area change rule 11:

$\frac{A}{A_1}=(\frac{A_2}{A_1}-1)[2{\left(\frac{X}{L}\right)}^2-{2\left(\frac{X}{L}\right)}^3]+1,$

Preceding slow back is anxious satisfies equation along journey area change rule 12:

$\frac{A}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="C200710304700E00081.png,C200710304700E00082.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}=(\frac{A_2}{A_1}-1)[-3{\left(\frac{X}{L}\right)}^4+4{\left(\frac{X}{L}\right)}^3]+1,$

Consider mainly that then the variation of the diffuser angle of flare should relax in order to avoid in the diffuser air-flow to occur separating as far as possible as far as possible,, should not carry out excessive air-flow along the journey diffusion especially at the diffuser exit place.For on finite length, reaching required diffusion value, have only increase slightly inflow point along the journey diffusion, slow in preceding anxious back for this reason along on the basis of journey area change rule 9, revise equation coefficients, anxious back is slow before getting quite restrain along journey area change rule and emergency along the journey area change between a highest line of centers of total pressure recovery coefficient, form a kind of new diffuser along journey area change rule, promptly improve the back diffuser along journey area change rule 10, it satisfies equation:

$\frac{A}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="C200710304700E00081.png,C200710304700E00082.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}=(\frac{A_2}{A_1}-1)[{2\left(\frac{X}{L}\right)}^5-3{\left(\frac{X}{L}\right)}^4-{\left(\frac{X}{L}\right)}^3+2{\left(\frac{X}{L}\right)}^2]+1,$

It and preceding anxious back are slow along journey area change rule 9, emergency quite along the anxious concrete parameter along journey area change rule 12 of journey area change rule 11, preceding slow back as shown in Figure 3.In the above-mentioned equation, A represents diffuser along journey area, A ₁Represent the inlet-duct area of diffuser, A ₂Represent the diffuser exit sectional area, X represents the abscissa of diffuser line of centers, and L represents the length of diffuser.

By the setting of above-mentioned geometric shape parameter, utilize the moulding of CAD (computer aided design) software, the outside drawing of formation is as shown in Figure 1.This Backpack S-shaped inlet channel model that CAD (computer aided design) is finished imports in the CFD software, carry out the Backpack S-shaped inlet channel numerical simulation of flow field, this Backpack S-shaped inlet channel exit flow field collection of illustrative plates, as shown in Figure 4, the left side is outlet total pressure recovery coefficient isoline, and the right is the exit velocity streamline.Calculating the outlet total pressure recovery coefficient from figure is 96.5%, and distortion index is 0.12 to satisfy the actual requirement of engineering fully.

Claims (1)

1, a kind of Backpack S-shaped inlet channel is one-body molded, it is characterized in that, this inlet channel satisfies:

(1) for the lip part, shape is adopted 1/4 elliptical shape in the lip, and cross section, admission port lip top, lip two lateral sections, lip lower section are got different elliptic equations; The elliptic equation that get in cross section, described lip top is $\frac{x^2}{{22}^2}+\frac{y^2}{{72}^2}=1,$ The elliptic equation that get lip two lateral sections is $\frac{x^2}{{26}^2}+\frac{y^2}{{72}^2}=1,$ The elliptic equation that the lip lower section is got is $\frac{x^2}{{30}^2}+\frac{y^2}{{72}^2}=1,$ In the formula, x, y are respectively horizontal stroke, the ordinate of putting on the cross section;

(2) for inlet channel diffuser line of centers, a highest line of centers of total pressure recovery coefficient between the slow suitable line of centers of line of centers in anxious back before getting with emergency, described diffuser line of centers relaxes in inflow point than the slow line of centers in anxious back before described; The slow line of centers in anxious back satisfies equation before described $Y=\mathrm{\&Delta;Y}[3{\left(\frac{X}{L}\right)}^4-8{\left(\frac{X}{L}\right)}^3+6{\left(\frac{X}{L}\right)}^2],$ Described diffuser line of centers satisfies equation $Y=\mathrm{\&Delta;Y}[4{\left(\frac{X}{L}\right)}^5-7{\left(\frac{X}{L}\right)}^4+{\left(\frac{X}{L}\right)}^3+4{\left(\frac{X}{L}\right)}^2],$ In the formula, on behalf of the ordinate of diffuser line of centers, eccentric throw, X that Δ Y represents diffuser, Y represent the abscissa of diffuser line of centers, and L represents the length of diffuser;

(3) for the inlet channel diffuser along journey area change rule, anxious back is slow before getting quite restrain along journey area change rule and emergency along the journey area change between a highest line of centers of total pressure recovery coefficient; Anxious back is slow before described satisfies equation along journey area change rule $\frac{A}{A_1}=(\frac{A_2}{A_1}-1)[-3{\left(\frac{X}{L}\right)}^4+{4\left(\frac{X}{L}\right)}^3]+1,$ Described inlet channel diffuser satisfies equation along journey area change rule $\frac{A}{A_1}=(\frac{A_2}{A_1}-1)[2-{\left(\frac{X}{L}\right)}^5-3{\left(\frac{X}{L}\right)}^4-{\left(\frac{X}{L}\right)}^3+2{\left(\frac{X}{L}\right)}^2]+1,$ In the formula, A represents diffuser along journey area, A ₁Represent the inlet-duct area of diffuser, A ₂Represent the diffuser exit sectional area, X represents the abscissa of diffuser line of centers, and L represents the length of diffuser.

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