DE102006054428B3 - Boundary layer defecting device for e.g. military missile, has body arranged in front edge area of airfoil, where arms of fuselage rest on upper and lower sides of airfoil and apex of device points towards body of missile - Google Patents

Abstract

The device has a specially formed body, which has a basic form of a V-shape. The body is arranged in a front edge area of an airfoil. Arms of a fuselage rest on an upper side (1) and a lower side of the airfoil. Each arm has a trapezoidal cross section provided with two rounded corners, and the base lies on a bearing surface of a missile. An edge surface (5) and a deflecting surface (6) facing the body are provided perpendicular to the base. The surfaces with a missile or wind direction (9) form a preset angle. An apex (3) of the device points towards a body of the missile.

Description

Introduction, State of the art

The Boundary layer, its structure and distribution over the surface of a Missile, has a significant importance in civil and military aircraft, Flight steering body and rocket construction.

At missiles with a hull and several wings (wings or tail) becomes the boundary layer flow the swept wings of the boundary layer flow influenced on the hull. The boundary layer flow on the fuselage reaches to to the wing root usually a highly turbulent character, therefore one speaks of a "contamination" of the flow through the wing the hull.

in the Aircraft and rocket engineering are all manufacturers interested and eager to get one solution for avoidance or eliminating contamination of the airfoil boundary layer by the turbulent fuselage boundary layer to find. Such solutions can be "active" or "passive". The active ones solutions use additional Energy sources, e.g. For the extraction of the contaminated boundary layer or branches of the Existing energy sources of the missile energy for these solutions. Some passive solutions try the boundary layer flow via transition control by means of small vortex generation by artificial roughness for certain pressure gradients to laminarize.

Known also the use of boundary layer fences on the wings (e.g. Fiat G91 or Suchoi SU22).

Of the Invention is based on the object of a passive device Conceive, which is able to the boundary layer on the wings so to shape as if the contaminated boundary layer of the hull does not exist.

The solution This object is achieved with the characterizing features of the claim 1 fulfilled.

The Leading edge of the wing, or the wing is for the generation and for the transport of the boundary layer flow prevail, since the contaminated Boundary layer of the fuselage propagates along this leading edge. The contaminated turbulent boundary layer along the leading edge interrupted, it creates a new laminar boundary layer, which through the propagation along the leading edge the entire boundary layer over the wing controls. The solution according to claim 1 consists in a device at the front edge of the wing.

The solution consists of the contaminated boundary layer in the flow direction over the wing redirect and one spanwise further outside lying starting point for to generate a new, uncontaminated boundary layer. These Redirection has to be done in such a way that upstream and downstream of the Device as small as possible disorder should occur.

• – die verlustarme Teilung und Umlenkung der vom Rumpf kontaminierten Grenzschicht über die Ober- und Unterseite der Tragfläche,
• – die Erzeugung einer neuen, nicht kontaminierten Grenzschicht und die verlustarme Weiterleitung der neuen, nicht kontaminierten Grenzschicht auf die Vorderkante, bzw. Staulinie der Tragfläche
• b) die Funktionsweise ist passiv, sprich sie arbeitet ohne Energiezufuhr
• c) sie ist klein und leicht und erfordert einen minimalen Aufwand für die Montage im Bereich der Vorderkante der Tragfläche
• d) sie ist praktisch für alle Tragflächen (Flügel, Leitwerke) eines Flugkörpers in Überschallströmung, die vom Rumpf kontaminiert sind anwendbar
• e) sie führt zu geringerem spezifischen Kraftstoffverbrauch, geringerer Lärmentwicklung und geringerer Schadstoffemission.

The device consists of a specially shaped body which fulfills two functions simultaneously by means of different surfaces:

• The low-loss division and deflection of the fuselage contaminated boundary layer over the top and bottom of the wing,
• - The generation of a new, uncontaminated boundary layer and the low-loss forwarding of the new, uncontaminated boundary layer on the leading edge, or jam line of the wing
• b) the functionality is passive, that is, it works without energy
• c) it is small and light and requires minimal effort for mounting in the area of the leading edge of the wing
• d) it is practically applicable to all wings (wings, tail units) of a missile in supersonic flow that are contaminated by the hull
• e) it leads to lower specific fuel consumption, less noise and lower pollutant emissions.

in the The invention will be described in more detail below with reference to an exemplary embodiment. Show it

1 Principle of boundary layer redirection - top view

2 Embodiment of the invention - Drawing

3 Cross section through the deflecting device in the plane of symmetry of the wing

4 3D figure of a deflection device for supersonic flow

5 Deflection device for supersonic flow, top view; the height of the device perpendicular to the leading edge is shown in true size

6 Deflection device for supersonic flow, view along the fuselage; the width of the plateau 4 and the transition area 8th are clearly visible

7 Deflection device for supersonic flow, view along the leading edge; the height and the course of the transition are evident in true size

8th Example of friction lines (similar to streamlines) at the leading edge of a wing in supersonic flow from an IBK RANS (Reynolds Averaged Navier-Stokes) simulation; View along the free flow direction. The shape of the friction lines (streamlines) is reminiscent of the shape of the blades on Pelton turbines.

According to the list of reference numerals at the end of this description, with various numbers, the most important areas of the device in the 1 and 3 to 7 shown.

• A) Sie ist am Anfang nahezu tangent zur Vorderkante 10, um möglichst stoßfrei die Strömung entlang der Vorderkante abzufangen
• B) Sie ist am Ende nahezu tangent zur Freiströmrichtung, um die umgeleitete Grenzschichtströmung in diese Richtung möglichst stoßfrei freizugeben 7. Unter Umständen kann man eine leicht stärkere Umlenkung vorsehen, da infolge ihrer Trägheit, die Grenzschichtströmung etwas weniger umgelenkt wird

The outline sketch in 1 shows in plan view the fuselage with the swept wing. The free-flow direction or wind direction 9 is identical except for the direction of the arrow with the direction of flight of the missile. Therefore, in the sketch, the arrows of the free-flow direction are parallel with the trunk 14 shown. The presence of the wing of finite thickness causes the flow to be a component 12 towards the leading edge or jam line 10 having. This component transports the contaminated boundary layer flow along the leading edge or jam line to the deflection device. The deflector is represented by thick black lines and has two important characteristics for trouble-free deflection:

• A) It is almost tangent to the leading edge at the beginning 10 to intercept the flow along the leading edge as smoothly as possible
• B) At the end it is almost tangent to the free flow direction in order to release the diverted boundary layer flow in this direction as smoothly as possible 7 , Under certain circumstances, it is possible to provide a slightly stronger deflection, because due to its inertia, the boundary layer flow is deflected a little less

• – Ein Ausführungsbeispiel der Lösung ist als Zeichnung in 2 und dreidimensional in 4 vorgestellt. Maßgebend ist die Geometrie der Vorrichtung, die durch die Gestaltung der Flanken stromauf dafür sorgt, dass die kontaminierte Grenzschicht sanft (ohne Stöße) umgeleitet wird. Als Analogie kann man die Umleitung eines Wasserstrahls im Wasserkraftbau durch die Schaufel einer Pelton Turbine erwähnen, die nahezu stoßfrei arbeitet.

These features are reminiscent of a blade in turbomachinery, which must meet similar requirements. Due to the thickness of the wing, the geometry of the device is not as simple as shown in the schematic diagram only on the top. The optimal shape of the deflecting edges of an efficient device is given by the course of the flow lines in the region of the leading edge (s. 8th ).

• - An embodiment of the solution is as drawing in 2 and three-dimensional in 4 presented. Decisive is the geometry of the device, which ensures by the design of the flanks upstream that the contaminated boundary layer is gently diverted (without shocks). As an analogy, one can mention the diversion of a water jet in hydropower by the blade of a Pelton turbine, which works almost bumpless.

If one cuts the wing and the device through a plane perpendicular to the wing, which involves the leading edge or jam line, one receives the sketch in 3 where the most important parameters of the cross section are drawn. In the following, all parameters will be discussed and their properties will be analyzed.

The cutting or storage edges with 5 in 4 to 7 marked - are the surfaces that come into contact with the contaminated boundary layer first and, as the name says, cut or split in half. To accomplish this task as optimally as possible, these cutting flanks must be perpendicular to the wing surface and symmetrical to the leading edge. Theoretically, these flanks could form a sharp edge on the foremost side. Practically, it is better a small radius of curvature (about 1-2 mm s. 2 and 4 ) at this edge, since the angle of incidence of the missiles varies during flight in a small area, and thus the position of the jam line (leading edge) along the wing changes slightly. In addition, a rounded edge - as well as the wing itself - even in the supersonic flow is preferable to a sharp, as strength and erosion aspects also play an important role. This leads to a congestion effect on these surfaces, hence the name Stauflanken.

The height of the device or the cross section 5 (S. 3 ), measured in the direction of the normal to the base or wing surface, is decisive and must be sufficiently large to exceed the congestion effect of the boundary layer on the device, which is unavoidable. But it must not be much larger, otherwise the device generates additional losses. The height of the device is chosen so that it is sufficient for the most unfavorable flight conditions. In the present proposal, it is about 5 undisturbed boundary layer thicknesses large.

The deflection or bypass edges 6 (s 4 to 7 ) have the important role of diverting the contaminated and already divided boundary layer flow as gently as possible (bumpless) to the top or bottom of the wing. They are - like the cutting flanks - oriented perpendicular to the surface of the wing and ideally follow the streamlines of the boundary layer flow. These can be visualized either during a wind tunnel test or by means of a flow simulation in order to achieve the best shape of these flanks (s. 8th ). In the same way, the position of the jam line at the front edge can be determined for different angles of attack. As already mentioned, these flanks can have a slightly larger deflection angle (by 1-2 °) in order to compensate for the inertia of the flow.

The tip of the device 3 (in 2 and 4 ) and the first part of the plateau 4 The task is to provide the required space for the new starting point (stagnation point) for the uncontaminated boundary layer. For the tip receives a small radius of curvature (about 0.5 mm). A larger radius of curvature leads to a greater height of the device. The width of the plateau should be at least as large as the height of the device in order to avoid a possible suction effect of the new flow on the old contaminated boundary layer in front of the device (see also 2 , 3 , 4 ). An upper limit of the width can be determined by the attachment at the leading edge, probably not more than twice the height.

The trailing edge of the device 7 (in 4 to 7 ), which should be connected with a radius of curvature with the plateau upstream and with the wing downstream, in order to produce as few or very small shocks, has the task of a "guide surface" (chute) .The new, uncontaminated boundary layer downstream The main parameter is the inclination of this surface, which in 3 through the trailing edge 7 is visible in cross section. The inclination must be chosen so that the free flow direction with this trailing edge has a small angle γ = α - β (about 2 ° -3 ° in 2 and 3 ).

The transition region of the device 8th (in 4 to 7 ) has the role of making the smoothest possible transition from the height of the device (plateau) to the smooth surface (top and bottom) of the wing. In this embodiment, the transition from the initial height of 5 mm to zero has been made linearly and at a small angle (over a correspondingly greater length), but other transitional shapes may also be envisioned.

The wings have basically at the leading edge a radius of curvature, which plays an essential role for the boundary layer flow and thus also for the design of the device. On the one hand, by its presence in the formula for the Reynolds number, it determines the type of boundary layer flow, on the other hand, the device must be extended beyond the radius of curvature of the leading edge on the top and bottom of the wing to a smooth (bumpless) deflection to ensure the boundary layer on the wing (s. 2 . 4 and 7 ). Theoretically, the device can be pulled in the depth direction of the wing to the trailing edge to draw a material boundary between contaminated and new, uncontaminated boundary layer and thereby prevent interaction between these regions on the wing (boundary layer fence). However, this is not necessary because the two arms of the device are in the direction of free, undisturbed flow and thus no pressure gradients across the arms in the spanwise direction are to be expected, apart from the back pressure at the top.

materials:

The Deflection device can be made of similar materials like the wing, Aluminum, steel or titanium alloys are manufactured. At lesser Mach number can also be considered plastic.

The Manufacturing process can Casting, forging, Fresen or similar be. The only requirements for the material are dimensional stability under the flight conditions and a minimum strength required for reliable fastening and Operation of the deflection is needed.

Assembly:

The Deflection device should as possible close to the hull, but outside whose boundary layer, fixedly mounted on the leading edge, or jam line of the wing be in order to achieve the maximum benefits.

The most important areas of the device are with different numbers in the 1 and 3 to 7 shown:

1

top the wing

2

bottom the wing

3

top the device

4

plateau the device

5

Jam or cutting flanks, also as height in 3 appropriate

6

Umlenkflanken

7

Behind- or leading edges

8th

Transition area to the wing

9

Flight- or wind direction

10

leading edge or stagnant line

11

Base of the trapezoidal section

12

flow component along the leading edge or jam line

13

Trapezoidal cross-section the device

14

hull or hull-like body

Claims (3)

Deflection device on the swept wings of a missile in supersonic flow with egg nem hull or hull-like body characterized in 1 that it consists of a single, specially shaped body 2 which has the basic shape of the letter V, 3 is arranged in the leading edge region of the wing 4, with the tip in the direction of the fuselage, 5. whose two arms are on the upper ( 1 ) - and underside ( 2 6) each arm has a trapezoidal cross-section with two rounded corners at the shorter baseline, where the base (the longer baseline) rests on the wing 7 and the hull or the wing Hull-like body-facing side surface ( 5 . 6 ) is perpendicular to the base, 8. while the side facing away from the trunk or body-like body ( 7 ) with the direction of flight ( 9 ) in cross-section ( 13 ) has a small angle γ = α - β 9 and has a soft transition to the support surface to be realized by means of a radius. Device according to claim 1, characterized in that that they are particularly useful in supersonic aircraft, Missiles, flight steering bodies, Drones and space ferries Use finds. Device according to one of the preceding claims, characterized characterized in that the fuselage or body similar body facing a Angle from 80 ° to 100 ° with the basis forms.