CN104898286A - Method for reducing IV shock wave interference heat load and wave impedance by using laser - Google Patents

Abstract

The invention provides a method for controlling IV shock wave interference to reduce heat load and wave impedance through use of the technology of loading a breakdown flow field with laser energy to form quasi-static wave. The method comprises a step of pre-estimating the position and strength of IV shock wave interference, a step of shaping a laser beam into a light sheet, a step of forming quasi static wave, and a step of controlling IV shock wave interference to achieve heat insulation and impedance reduction. In the first step, an NS equation is solved and a flow field is numerically simulated, or wind tunnel test is carried out according to the Mach and Renault similarity criterion, and whether IV shock wave interference occurs in the flow field and the position and strength of IV shock wave interference are judged; in the second step, a laser beam is shaped into a light sheet by using multiple reflector and lens combinations; in the third step, the size, position and frequency of laser energy injection are optimized to form quasi static wave; and in the fourth step, the quasi static wave and the IV shock wave interference interact with each other, arch shock wave is distorted, quasi static wave is formed near the surface of a blunt body, and thus, integration of heat insulation and impedance reduction is realized.

Description

A kind of laser reduces IV type Shock wave interaction heat and carries the method with wave resistance

Technical field

The invention belongs to Flowing Main-Control control field, is a kind of device for reducing hot year of supersonic and hypersonic aircraft and wave resistance.

Background technology

Shock wave interaction is also a kind of common phenomenon at supersonic and hypersonic in-flight, and especially the IV type of oblique shock wave and bow shock disturbs, and has deep effect to aircraft performance.Nineteen sixty-eight, Edney, according to the difference of incident shock and bow shock relative position, determines 6 kinds of dissimilar interference, wherein type i V creates supersonic speed injection, be flowing in during this sprays and compress efficiently, tangent or bumps against with leading edge, significant ballast and heat year is created on blunt body surface.The research of A.Wieting show the surge pressure that produces when there is IV type Shock wave interaction and hot-fluid be 20-40 when only having bow shock doubly, and with free-stream Mach number and the rising of the incident angle of attack, the reduction of specific heat ratio and raising.High heat is carried and is proposed acid test to Flight Vehicle Design, and IV type Shock wave interaction is normally unstable, can produce unstable thermal stress, which has limited the serviceable life of lip.

Some numerical value and experimental study has been carried out in the world at present for laser energy deposition control IV type Shock wave interaction.(the Adelgren such as the R.G.Adelgren of state university of New Jersey, R., Yan, H., Elliott, G., et al.Localized Flow Control by Laser Energy Deposition Applied to Edney IV Shock Impingement and Intersecting Shocks [C] .AIAA, 2003-0031.) carry out the experiment being punctured air control IV type Shock wave interaction by single-pulse laser, schlieren have taken the impact of laser energy on IV type Shock wave interaction, measurement shows that surge pressure reduces by 30%, demonstrate feasibility laser being used for supersonic flows control.(the Kandala R such as the R.Kandala of University of Minnesota, Candler G V.Numerical Studies of Laser-Induced Energy Deposition for Supersonic Flow Control [J] .AIAA Journal.2004,42 (11): 2266-2275.) calculate in the fluid of Mach 3.45, laser energy injects the impact on IV type Shock wave interaction, result shows that laser changes IV type Shock wave interaction structure, particular moment pressure and hot-fluid significantly reduce, return to initial state subsequently.(the H.Yan such as H.Yan, D.Gaitonde.Control of Edney IV Interaction by Energy Pulse [C] .44th Aerospace Sciences Meeting and Exhibit, Nevada.AIAA, 2006-0562.) numerical evaluation laser energy injects the impact on IV type Shock wave interaction, result shows that the injection of energy can significantly change fluid field pressure and Temperature Distribution, and the ballast and the heat that effectively reduce aircraft surface are carried.

The laser controlling IV type Shock wave interaction employee's card carried out both at home and abroad understands the feasibility of the method, but laser energy injection mode is all confined to monopulse at present, and controlling object is carry with heat for reducing ballast, reduction wave resistance is not taken into account.

Summary of the invention

The object of this invention is to provide a kind of based on reducing IV type Shock wave interaction while laser energy injection hot year and the method for wave resistance.The present invention proposes Gao Zhongying laser energy to puncture the quasistatic ripple that incoming flow formed first and interacts with IV type Shock wave interaction, and gives the optimum choice scheme of laser parameter and injection phase, reduction wave resistance while reducing heat year.The shaped laser bundle that the present invention proposes is sheet light and the method focused on, and provides possible technique approach for controlling two dimensional surface IV type Shock wave interaction.It is heat insulation that the present invention can be applicable to supersonic and hypersonic aircraft drag reduction.

The present invention describes and estimates IV type Shock wave interaction generation position and intensity, and implementation is as follows:

(1) flow field state around numerical simulation aircraft.Solving NS equation, is ideal gas or non-equilibrium gas according to incoming flow stagnation temperature determination gas model, is with reference to building and dividing computing grid, with true incoming flow conditions for foundation is determined to calculate starting condition and incoming flow parameter with aircraft configurations.According to the temperature of result of calculation, pressure distribution and wave system structure, determine whether IV type Shock wave interaction occurs, position and intensity occur.

(2) in laboratory conditions, according to Mach and reynolds analogue criterion, design aircraft scale model carries out wind tunnel test, judges whether IV type Shock wave interaction occurs and position occurs according to schlieren or shadow picture.

It is sheet light that the present invention describes shaped laser bundle, and implementation is as follows:

(1) utilize high reflective mirror reflection lasering beam, make beam center by predetermined laser energy deposition position;

(2) utilize recessed cylindrical mirror laser beam to be expanded, make circular laser beam become elongated oval shape;

(3) utilize rectangular slot to limit oval-shaped laser bundle, slit length is set to the cover width of IV type Shock wave interaction, after determining slit length, determine slit width, and its index is ensure that as far as possible many laser energies pass through slit;

(4) utilize convex cylindrical mirror to converge sheet light, focus at flow field ad-hoc location and puncture incoming flow.

The present invention establishes laser sheet optical and focuses on the method puncturing supersonic speed or Hypersonic Flow Field formation quasistatic ripple, and gives the optimum choice of laser parameter, and implementation is as follows:

(1) puncture place system of selection: IV type Shock wave interaction upstream is apart from diameter place, 2 to 3 times, blunt body surface;

(2) laser output power size system of selection: the incoming flow enthalpy H of 0.2 to 0.6 times, H=ρ _∞c _pt _∞v _∞(2R) ², wherein c _pfor specific heat at constant pressure, R is blunt body radius, ρ _∞, T _∞and V _∞be respectively free flow density, temperature and speed;

(3) laser frequency system of selection: select laser frequency according to speed of incoming flow, the point source explosion ripple that single-pulse laser is caused merges formation quasistatic ripple.

The present invention gives quasistatic ripple that laser the causes method for the heat insulation drag reduction of IV type Shock wave interaction, implementation is as follows:

(1) first quasistatic ripple interacts with the oblique shock wave in IV type Shock wave interaction, and produce transmit shock, transmit shock and bow shock interact, and temporarily defines relatively high pressure and heat flux regions on blunt body surface;

(2) quasistatic ripple and bow shock interact, and bow shock distorts, and lift-off distance increases, and blunt body near surface forms rarefaction wave simultaneously, produces adverse pressure gradient;

(3) along with lasting injection and the quasistatic wave direction downstream travel of pulse laser, the region that is affected of bow shock expands gradually, and blunt body surface peak hot-fluid and wave resistance significantly decline, the flow field structure that final formation is basicly stable.

Accompanying drawing explanation

Fig. 1 is for illustrating IV type Shock wave interaction wave system structural drawing of the present invention;

Fig. 2 is for realizing of the present invention light shaping index path;

Fig. 3 is that the point source explosion ripple that laser of the present invention causes merges formation quasistatic ripple figure;

Fig. 4 is quasistatic ripple of the present invention and IV type Shock wave interaction interaction diagram;

Fig. 5 is for realizing experimental provision layout of the present invention.

Advantage of the present invention is

1) two-dimensional laser energy injection mode, is convenient to control two-dimensional flow field.IV type Shock wave interaction two dimension often, adopts sheet light shaping light path to be planar configuration by focusing laser energy, focuses on the quasistatic ripple producing approximate two dimension after puncturing, be convenient to flowing and control.

2) energy injection size, position and frequency controllability are strong.Laser response is fast, and controllability is strong.By regulating laser instrument to export energy model, can for different incoming flow conditions, the optimization of the control device of realization.

3) heat insulation drag reduction integration.Utilize the interaction of quasistatic ripple and bow shock, produce rarefaction wave at blunt body near surface, effectively reduce blunt body surface heat and carry, quasistatic ripple changes the aerodynamic configuration of blunt body simultaneously, bow shock changes the structure of similar oblique shock wave into, and wave resistance significantly reduces.

Embodiment

Now in conjunction with the accompanying drawings and embodiments the method for laser energy for reducing hot year of IV type Shock wave interaction and wave resistance is described in further detail by the present invention.Fig. 1 gives the present invention the IV type Shock wave interaction wave system structural drawing that will control.

Implementation of the present invention is as follows: analysing in depth on the basis that IV type Shock wave interaction affects aircraft performance, proposes a kind of heat insulation drag reduction method injected based on laser energy.The present invention is divided into four steps, namely determines that IV type Shock wave interaction position and intensity step, laser beam reshaping are sheet light step, quasistatic ripple forming step and the heat insulation step of drag reduction.Specific embodiments is as follows:

Step one, estimate IV type Shock wave interaction position and intensity occur

This step is completed by numerical evaluation and wind tunnel test two kinds of methods.Governing equation is the compressible Navier-Stokes equation of conservation form unsteady flo w:

$\frac{\∂Q}{\∂t}+\frac{\∂F}{\∂x}+\frac{\∂G}{\∂y}+\frac{\∂H}{\∂z}=\frac{{\∂F}_v}{\∂x}+\frac{{\∂G}_v}{\∂y}+\frac{{\∂H}_v}{\∂z}+S$

Wherein Q is conserved quantity, and F, G, H are without sticky (convection current) flux term, F _v, G _v, H _vfor viscosity (dissipation) flux term, every expression is as follows:

$Q=\left[\begin{array}{c}\mathrm{\ρ}\\ \mathrm{\ρu}\\ \mathrm{\ρv}\\ \mathrm{\ρw}\\ \mathrm{\ρE}\end{array}\right]F=\left[\begin{array}{c}\mathrm{\ρu}\\ \mathrm{\ρuu}+p\\ \mathrm{\ρvu}\\ \mathrm{\ρwu}\\ \mathrm{\ρEu}+\mathrm{pu}\end{array}\right]G=\left[\begin{array}{c}\mathrm{\ρv}\\ \mathrm{\ρuv}\\ \mathrm{\ρvv}+p\\ \mathrm{\ρwv}\\ \mathrm{\ρEv}+\mathrm{pv}\end{array}\right]H=\left[\begin{array}{c}\mathrm{\ρw}\\ \mathrm{\ρuw}\\ \mathrm{\ρvw}\\ \mathrm{\ρww}+p\\ \mathrm{\ρEw}+\mathrm{pw}\end{array}\right]$

$S=\left[\begin{array}{c}0\\ 0\\ \mathrm{\ρ\Ωw}\\ -\mathrm{\ρ\Ωv}\\ 0\end{array}\right]F_v=\left[\begin{array}{c}0\\ {\mathrm{\τ}}_{\mathrm{xx}}\\ {\mathrm{\τ}}_{\mathrm{yx}}\\ {\mathrm{\τ}}_{\mathrm{zx}}\\ {\mathrm{\β}}_x\end{array}\right]G_v=\left[\begin{array}{c}0\\ {\mathrm{\τ}}_{\mathrm{xy}}\\ {\mathrm{\τ}}_{\mathrm{yy}}\\ {\mathrm{\τ}}_{\mathrm{zy}}\\ {\mathrm{\β}}_y\end{array}\right]H_v=\left[\begin{array}{c}0\\ {\mathrm{\τ}}_{\mathrm{xz}}\\ {\mathrm{\τ}}_{\mathrm{yz}}\\ {\mathrm{\τ}}_{\mathrm{zz}}\\ {\mathrm{\β}}_z\end{array}\right]$

Wherein

$\left\{\begin{array}{c}{\mathrm{\τ}}_{\mathrm{xx}}=2{\mathrm{\μu}}_x+\mathrm{\λ}(u_x+v_y+w_z)\\ {\mathrm{\τ}}_{\mathrm{yy}}=2{\mathrm{\μv}}_y+\mathrm{\λ}(u_x+v_y+w_z)\\ {\mathrm{\τ}}_{\mathrm{zz}}=2{\mathrm{\μw}}_z+\mathrm{\λ}(u_x+v_y+w_z)\\ {\mathrm{\τ}}_{\mathrm{xy}}={\mathrm{\τ}}_{\mathrm{yx}}=\mathrm{\μ}(u_y+v_x)\\ {\mathrm{\τ}}_{\mathrm{yz}}={\mathrm{\τ}}_{\mathrm{zy}}=\mathrm{\μ}(v_z+w_y)\\ {\mathrm{\τ}}_{\mathrm{zx}}={\mathrm{\τ}}_{\mathrm{xz}}=\mathrm{\μ}(u_z+w_x)\end{array}\right.$

β _x＝uτ _xx+vτ _yx+wτ _zx-q _x

β _y＝uτ _xy+vτ _yy+wτ _zy-q _y

β _z＝uτ _xz+vτ _yz+wτ _zz-q _z

Under perfect gas supposition, gas meets following state equation

p＝ρRT

$\mathrm{\ρe}=\frac{p}{\mathrm{\γ}-1}$

E is specific internal energy, than being:

$E=e+\frac{1}{2}(u^2+v^2+w^2)=\frac{p}{(\mathrm{\γ}-1)\mathrm{\ρ}}+\frac{1}{2}(u^2+v^2+w^2)$

In above expression formula, ρ, (u, v, w), p, T, e represent the interior energy of three speed components, pressure, temperature and unit masses of density, rectangular coordinate system (x, y, z) respectively; E, E, γ, μ are expressed as the interior energy of unit mass, total energy, specific heats of gases ratio and coefficient of viscosity.If incoming flow stagnation temperature is higher than 1000K, then stationary point gas may exist and dissociates, then select non-equilibrium gas equation.

For wind tunnel test, then design processing aircraft scale model and wind-tunnel incoming flow parameter, design considerations is Mach and reynolds analogue criterion, and this work is mature technology, repeats no more.

Step 2, be sheet light by laser beam reshaping

Fig. 2 gives laser beam reshaping and the concrete grammar focused on.First utilize high reflective mirror (2) reflection lasering beam (1), make beam center by predetermined laser energy deposition position; Recycle recessed cylindrical mirror (3) laser beam is expanded, make circular laser beam become elongated oval shape; Then utilize rectangular slot (4) to limit oval-shaped laser bundle, slit length is set to the cover width of IV type Shock wave interaction, after determining slit length, determine slit width, and its index is ensure that as far as possible many laser energies pass through slit; Finally utilize convex cylindrical mirror (5) to converge sheet light, focus at flow field ad-hoc location and form high laser power density deposition region (6), puncture incoming flow.

Step 3, sheet light focused on puncture incoming flow, form quasistatic ripple

Fig. 3 gives multiple point source explosion ripple and merges the process forming quasistatic ripple, and concrete steps are:

(1) measurement obtains blunt body diameter D, locates focused laser energy, puncture incoming flow and form point source explosion ripple in IV type Shock wave interaction upstream apart from blunt body surface 2D to 3D;

(2) defining incoming flow enthalpy is: H=ρ _∞c _pt _∞v _∞d ², wherein c _pfor freely flowing specific heat at constant pressure, ρ _∞, T _∞and V _∞be respectively free flow density, temperature and speed; Laser power definition is: W=Qf, wherein Q is single-pulse laser energy, and f is laser frequency, and the system of selection of laser output power size is W=0.2H ~ 0.6H.

(3) selection of laser frequency f is the key factor that quasistatic ripple is formed.N-th pulsed laser energy punctures incoming flow and forms a point source explosion ripple, and point source explosion ripple moves with freely flowing to downstream while expansion; Meanwhile, (n+1)th pulsed laser energy punctures freely to flow and also produces point source explosion ripple, the translational speed of part for the downstream of this point source explosion ripple is higher than the speed of the n-th point source explosion corrugated upstream part, therefore, according to free stream velocity and point source explosion ripple speed of expansion, adjustment laser frequency f, just can realize catching up with merging between point source explosion ripple, and final formation is similar to the quasistatic wave structure of oblique shock wave.

Step 4, quasistatic ripple and IV type Shock wave interaction interact, and reduce heat and carry and wave resistance

Fig. 4 gives multiple quasistatic ripple control IV type Shock wave interaction drag reduction heat insulation design sketch, and Fig. 5 gives the testing program for shock tunnel, and concrete steps are:

(1) when incidence arrives shock tube (7) low pressure end face, trigger pip is inputted digital delay signal generator (9) as 0 moment by pressure transducer (8).When flow field is stablized, digital delay signal generator (9) trigger laser (10) Output of laser, by wind-tunnel window (11) and sheet light shaping light path (12), in flow field, assigned address punctures incoming flow.

(2) supersonic speed or hypersonic inlet flow conditions are determined by Rafael nozzle (13), IV type Shock wave interaction to interact simulation by tiltedly splitting oblique shock wave that (14) produce and the bow shock that blunt body (15) produces, testpieces is arranged in vacuum chamber (16), so that wind-tunnel starts.

(3) assessment of control effects adopts schlieren measure system and hot-fluid and drag measurement system to realize.Flash of light source (17) and high speed camera (18) are the building blocks of schlieren system, and the two controls by digital delay signal generator (9), the represented by dotted arrows schlieren light path in figure.Signal input computing machine (20) Storage and Processing that hot-fluid and drag measurement system (19) will collect.

Claims (1)

1. laser reduces IV type Shock wave interaction hot year and a method for wave resistance, comprises following steps:

Step one, estimate IV type Shock wave interaction position and intensity occur

In supersonic speed or Hypersonic Flow Field, utilize the method such as schlieren or shade experiment, numerical simulation to obtain aircraft flow field state, judge whether IV type Shock wave interaction occurs according to oblique shock wave and bow shock interaction situation, interaction position and intensity;

Step 2, be sheet light by laser beam reshaping

Utilize beam Propagation and transformation system, lasing light emitter is shaped as sheet light, be incident to flow field assigned address, this system mainly comprises the assemblies such as high reflective mirror, recessed cylindrical mirror, rectangular slot and convex cylindrical mirror, after laser is exported by laser instrument, after elder generation through high reflective mirror reflection, recessed cylindrical mirror expands, rectangular slot shaping and convex cylindrical mirror are assembled, formation sheet light enters flow field to be measured;

Step 3, sheet light focused on puncture incoming flow, form quasistatic ripple

Utilize post convex lens focus laser sheet optical, form point source explosion wave structure puncturing incoming flow along inlet lip upstream extended line and first precursor oblique shock wave point of intersection, laser output power size is the incoming flow enthalpy H of 0.2 to 0.6 times, H=ρ _∞c _pt _∞v _∞(2R) ², wherein c _pfor specific heat at constant pressure, R is blunt body radius, ρ _∞, T _∞and V _∞be respectively free flow density, temperature and speed, for pulsed laser, select laser frequency according to speed of incoming flow, the point source explosion ripple that single-pulse laser is caused merges formation quasistatic ripple;

Step 4, quasistatic ripple and IV type Shock wave interaction interact, and reduce heat and carry and wave resistance

Bow shock in quasistatic ripple and IV type Shock wave interaction structure interacts, bow shock is caused to be out of shape, lift-off distance increases, IV type Shock wave interaction remitted its fury, form relatively low pressure low-temperature region at blunt body near surface, reduce heat and carry, quasistatic ripple changes blunt body aerodynamic configuration, cone shock instead of bow shock when not applying laser energy, and wave resistance significantly reduces.