CN103953448B - A kind of hypersonic inlet - Google Patents

Abstract

The invention discloses a hypersonic air inlet, which comprises an inlet main body, an inlet lip cover, and a return channel, and the return channel includes an inlet of the return channel, an outlet of the return channel, and a connection between the inlet of the return channel and the outlet of the return channel, etc. Sectional drainage tubing. The working principle of the hypersonic inlet of the present invention is: using the static pressure difference before and after the shock wave induced by the large separation bubble before the inlet when the inlet does not start, the low energy in the separation bubble at the inlet of the inlet is passed through the inlet of the return passage. The flow is drawn out, and after passing through the drainage pipeline, it is re-injected into the precursor of the inlet channel at the outlet of the return channel to form a closed circulation flow. The recirculation channel structure can significantly reduce the self-starting Mach number of the inlet, and at the same time has almost no disturbance to the flow field outside the inlet. Moreover, the recirculation channel has almost no influence on the performance of the inlet at a high Mach number, which ensures the performance of the inlet at a high Mach number. The invention has simple structure and is easy to realize.

Description

A hypersonic air intake

technical field

The invention belongs to the technical field of ramjet engines, in particular to a hypersonic air inlet.

Background technique

Hypersonic flight refers to flight with a Mach number greater than 5. Because of its important strategic significance, the research on hypersonic long-range maneuvering aircraft has become a hot research issue that the world's powers are competing to carry out. As the main component of the hypersonic propulsion system, the air intake is one of the key technologies in the development of air-breathing hypersonic propulsion technology, and its performance often has a crucial impact on the performance of the entire propulsion system. However, at the present stage, the self-starting problem of the hypersonic inlet at low Mach number often limits the working range of the aircraft, which directly has a decisive impact on the booster system and flight cost. Therefore, it is of great practical significance to explore how to effectively reduce the self-starting Mach number of the inlet.

Generally, there are two main technical approaches to widen the operating Mach number range of the inlet: the variable geometry adjustment method and the flow field control method under the fixed geometry surface. At present, the variable geometry inlet schemes are mainly divided into the following categories: rotary type, translational type, adjustable inclined plate, etc. The hypersonic missiles researched by institutions such as the French National Aerospace Technology Research Center (ONERA) and the US X-43A aircraft adopt the lip rotation variable geometry scheme. Compared with the lip rotation scheme, the control difficulty of the shrinking lip variable geometry inlet is relatively low. F.Falempin of France and M.Goldfeld of Russia have studied the starting process of the retractable lip variable geometry inlet. . The variable geometry inlet changes the object surface parameters and throat cross-sectional area mechanically, and then adjusts the mouth wave system and contraction ratio, so it can effectively widen the working Mach number range of the inlet and ensure critical conditions even under different working conditions. The intake port works near peak performance. But its shortcomings are also very prominent: increased weight, complex structure, reduced reliability, and more prominent problems of sealing and heat protection.

The flow field control method under a fixed geometrical surface mostly uses overflow at a low Mach number to reduce the self-starting Mach number of the inlet, such as active suction in the inlet, opening a passive overflow tank, etc. This kind of adjustment method actually "enlarges" the throat cross-sectional area, which alleviates the problem that the throat cross-sectional area of the inlet is too small at low Mach numbers, so it can effectively improve the self-starting performance of the inlet at low Mach numbers. However, this kind of flow field control method under a fixed geometric surface will also bring some adverse effects. For example, after the intake port is started, the overflow that continues to occur will cause the flow loss of the intake port, resulting in the loss of engine thrust. The overflow will also interfere with the external flow field, leading to an increase in the resistance of the air inlet and even the entire aircraft.

Contents of the invention

The problem to be solved by the present invention is to provide a hypersonic inlet with a return flow channel. The inlet is based on closed flow field control technology, and the self-starting performance of the inlet is significantly improved through a simple drainage device. The working Mach number range is significantly widened. The drainage device does not greatly increase the weight of the original inlet, and at the same time there is almost no backflow at high Mach numbers, which has little impact on the performance of the inlet at high Mach numbers.

A hypersonic air intake disclosed by the present invention comprises an intake main body, an air intake lip, and an air intake inner channel formed between the air intake main body and the air intake lip. The beginning of the air intake inner channel is The inlet of the inlet, the compression surface of the inlet is close to the inlet of the inlet, and there is a separation area at the inlet of the inlet; the hypersonic inlet also includes a return channel, and the return channel includes the inlet of the return channel, the outlet of the return channel and the connection The drainage pipeline of the inlet of the return channel and the outlet of the return channel; the inlet of the return channel is opened in the inner channel of the intake channel and is located in the second half of the separation area, and the outlet of the return channel is opened in the compression surface of the same stage of the intake channel where the inlet of the return channel is located .

As a further improvement of the above technical solution, the wall surfaces of the inlet of the return channel and the outlet of the return channel are both perpendicular to the compression surface of the inlet channel.

As a further improvement of the above technical solution, the distance L1 between the cross _- section centerline of the inlet of the return channel and the starting point of the separation zone satisfies:

0.65L _B ≤ L ₁ ≤0.95L _B ,

Among them, L _B is the width of the separation zone along the flow direction;

The distance L ₂ between the centerline of the cross-section of the outlet of the return passage and the starting point of the compression surface of the intake passage satisfies:

0.5b≤L ₂ ≤1.0L _S ,

Among them, L _S is the distance between the starting point of the compression surface where the backflow channel is located and the starting point of the separation zone;

As a further improvement of the above technical solution, the drainage pipeline is a pipeline of equal cross-section.

As a further improvement of the above technical solution, the connection between the drainage pipeline and the inlet of the return channel and the outlet of the return channel are all transitioned through circular arcs.

As a further improvement of the above technical solution, the cross-sectional width b of the drainage pipeline satisfies:

0.2W≤b≤0.5W,

Wherein, W is the inlet width of the channel in the air inlet;

The radius of the transition arc of the inner wall of the drainage pipeline close to the side of the compression surface is R, the vertical distance between the inner wall and the compression surface is L _D , and the following conditions are satisfied:

1.0b≤R≤2.0b,

1.5R ≤ L _D ≤ 2.0R.

Beneficial effects of the present invention:

Only through the simple structure of the drainage device, the self-starting Mach number of the hypersonic inlet is significantly reduced, the working Mach number range of the inlet is widened, and there is almost no interference to the flow field outside the inlet. Moreover, the structure has almost no influence on the performance of the inlet at high Mach numbers, which ensures the performance of the inlet at high Mach numbers. And the work is stable, reliable and easy to implement.

Description of drawings

Fig. 1 is a structural schematic diagram of a hypersonic air inlet of the present invention;

Fig. 2 is a schematic diagram of the components and relative positions of the hypersonic air inlet of the present invention;

Fig. 3-1 and Fig. 3-2 are working principle diagrams of the hypersonic inlet of the present invention;

Fig. 4 is a schematic diagram of the action mechanism of the hypersonic inlet of the present invention;

Figures 5-1, 5-2 and 5-3 are Mach number equivalent diagrams in a typical state during the self-starting process of the hypersonic inlet of the present invention;

Fig. 6 is the Mach number equivalent diagram in a typical state during the self-starting process of the prototype surface inlet (without return passage);

detailed description

A hypersonic air inlet provided by the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, a hypersonic air intake includes an air intake body 5 and an air intake lip 4, and in the air intake formed between the air intake main body 5 and the air intake lip 4 The channel 6, the beginning of the channel 6 in the intake channel is the inlet 8 of the intake channel, and the compression surface 7 of the intake channel is adjacent to the inlet 8 of the intake channel.

When the inlet does not start at a low Mach number, a large separation zone 9 is often formed at the inlet 8 of the inlet, and the width of the separation zone 9 along the flow direction is L _B . The hypersonic air intake also includes a return channel, which includes a return channel inlet 1 , a return channel outlet 2 , and a drainage pipeline 3 of equal cross-section connecting the return channel inlet 1 and the return channel outlet 2 .

The inlet 1 of the return channel is opened in the inner channel 6 of the air intake channel, and is located on the main body 5 of the air intake channel covered by the rear half of the separation area 9 . The distance L ₁ between the cross-sectional centerline of the inlet 1 of the return channel and the starting point of the separation zone 9 satisfies: 0.65L _B ≤ L ₁ ≤ 0.95L _B . The outlet 2 of the return passage is opened in the compression surface 7 of the intake passage of the same stage where the inlet 1 of the return passage is located, and is located in front of the separation area 9 . The wall surfaces of the inlet 1 of the return channel and the outlet 2 of the return channel are both perpendicular to the compression surface 7 of the inlet channel. The distance L ₂ between the center line of the cross-section of the outlet 2 of the return passage and the starting point of the compression surface 7 of the intake passage satisfies: 0.5b≤L ₂ ≤1.0L _S , where L _S is the distance between the starting point of the compression surface 7 and the starting point of the separation zone 9 distance. The cross-sectional width b of the drainage pipeline 3 satisfies: 0.2W≤b≤0.5W, where W is the inlet width of the channel in the air inlet. The connections between the drainage pipeline 3 and the inlet 1 of the return channel and the outlet 2 of the return channel all pass through arc transitions. The radius of the transition arc of the inner wall surface of the side of the drainage pipeline 3 close to the compression surface 7 is R, and the vertical distance between the inner wall surface and the compression surface 7 is L _D , and it satisfies: 1.0b≤R≤2.0b, 1.5R≤L _D≤2.0R .

As shown in Fig. 1, Fig. 3-1, and Fig. 3-2, for a hypersonic inlet, at low Mach number, when the captured flow of the inlet cannot pass through the throat completely, it is often at the inlet 8 A large separation bubble is formed at the place where the induced shock wave 10 is generated. After the airflow passes through the induced shock wave 10, the static pressure value increases significantly. At this time, the static pressure difference between the front and rear of the induced shock wave 10 is used as the power source to "drive" the low energy in the separation area. The flow is drawn out at the inlet 1 of the return channel, and is led back to the precursor of the intake channel by the drainage pipeline 3, and the secondary flow 11 is formed. The return flow re-injects into the intake channel at the outlet 2 of the return channel, and forms a "bulge-shaped" aerodynamic wall surface 12 there. The high-speed outflow flows through the convex aerodynamic wall surface 12, which induces a series of weak compression and expansion wave systems to "modify" the wedge surface compression wave 13, so that the wedge surface compression wave 13 is obviously bent and shifted outward, resulting in overflow window 14 becomes larger, the supersonic overflow of the intake port precursor increases, and the capture flow rate of the intake port decreases, which is obviously beneficial to the start at the low Mach number of the intake port. At the same time, as shown in Figure 4, at a low Mach number, with the start of drainage, the low-energy flow in the separation zone is drawn out from the inlet of the return channel, the separation bubble gradually decreases, and the intensity of the induced shock wave weakens accordingly, resulting in the return channel entering and exiting. The static pressure difference between the outlets decreases, the reduction of the driving pressure difference reduces the return flow, and the influence of the compression wave system on the precursor of the inlet port is weakened, thus forming a "negative feedback response" until the separation bubble and the induced shock wave disappear, and the inlet port Immediately start.

Application example 1:

(1) Technical indicators:

Working Mach number range: 5.0~7.0, the design working state is Mach 6.0

(2) Program introduction:

A binary hypersonic inlet with three-stage compression surfaces is designed, the angles of the three compression wedges are 5°, 5.4° and 5.9° respectively, the throat height A _t = 18.7mm, and the length of the inlet isolation section is The width of the throat is 7 times, and the shrinkage ratio in the throat is CR=1.6. For the consideration of thermal protection, the front edge of the compression face and the front edge of the lip cover are passivated. A return channel is set up in the inlet port of the prototype surface, and the design parameters of the return channel are: L ₁ ≈0.70L _B , b=0.2W, L ₂ =0.5b, R=1.0b, L _D =1.5R. The two-dimensional simulation of the flow field of the inlet with return passage is carried out through numerical simulation. From the simulation results shown in Figure 5-1, it can be seen that the inlet realizes self-starting at Mach 4.2.

Application example 2:

Set up a return channel in the inlet port of the prototype surface described in Application Example 1, and change the parameters of the return channel in Example 1. The design parameters of the return channel in this embodiment are: L ₁ ≈0.90L _B , b=0.4W, L ₂ = 1.0L _S , R = 1.5b, L _D = 2.0R. The two-dimensional simulation of the flow field of the inlet with return channel is carried out through numerical simulation. From the simulation results shown in Figure 5-2, it can be seen that the inlet realizes self-starting at Mach 4.2.

Application example 3:

Set up a return channel in the inlet port of the prototype surface described in Application Example 1, and change the parameters of the return channel in Example 1. The design parameters of the return channel in this embodiment are: L ₁ ≈0.84L _B , b=0.27W, L ₂ = 0.33L _S , R = 1.25b, L _D = 1.5R. The two-dimensional simulation of the flow field of the inlet port on the prototype surface and the inlet port with return channel is carried out through numerical simulation, and the simulation results are analyzed and compared.

(1) Comparison of self-starting characteristics:

It is defined as the start-up state of the inlet when the separation zone completely disappears. For the prototype surface inlet, as shown in Figure 6, a large separation bubble is formed at the inlet of the inlet at a low Mach number. With the increase of the incoming Mach number, the separation bubble exists until Mach 5.4 and disappears. The inlet realizes self-starting, and the self-starting Mach number has greatly exceeded the lower limit of the normal working range, which reduces the range of the normal working Mach number of the inlet. However, a return channel is set up in the air inlet, and through a simple drainage device, it can be seen from Figure 5-3 that the separation bubble at the inlet of the air inlet rapidly decreases to disappear, and the air inlet realizes self-starting at Mach 3.7. It can be seen that the recirculation channel reduces the self-starting Mach number of the inlet from Mach 5.4 to Mach 3.7, the self-starting performance of the inlet is significantly improved, and the working Mach number range of the inlet is significantly widened.

(2) Inlet performance comparison in the full Mach number range:

Table 1 compares the outlet performance of the prototype surface inlet and the inlet of the present invention, that is, the isolation section of the inlet with the return passage, in a typical state, where σ is the recovery coefficient of the total pressure of the inlet, is the inlet flow coefficient. It can be seen from the table that at Mach 3.5, both are not started, and the flow coefficient of the intake port with the recirculation channel is lower than that of the prototype surface intake port. As the Mach number of the incoming flow increases to Mach 3.7, the inlet of the prototype surface does not start, but the inlet with the return flow channel starts. At this time, the total pressure recovery coefficient and flow coefficient of the inlet are greatly increased. After the prototype surface inlet is also started at a high Mach number, it can be seen from Figure 5-3 that at this time, since the oblique shock wave incident point at the inlet of the inlet is located behind the inlet of the return channel, the static pressure difference between the inlet and outlet of the channel Very small, very little back flow. For example, at Mach 5.5, the return flow rate is about 0.004kg/s, accounting for about 0.1% of the inlet flow rate, the inlet flow coefficient remains almost unchanged, and the total pressure recovery coefficient increases slightly. It can be seen that the structure of the recirculation channel has almost no influence on the performance of the inlet at high Mach numbers, which ensures the performance of the inlet at high Mach numbers.

Table 1 Comparison of outlet performance of the inlet isolation section in the full Mach number range

There are many specific application approaches of the present invention, and the above description is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can also be made without departing from the principles of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims (6)

1. a hypersonic inlet, comprises air intake duct main body (5), air intake duct lip cover (4),The air intake duct internal channel (6) forming between air intake duct main body (5), air intake duct lip cover (4), entersAir flue internal channel (6) top is Fighter Inlet (8), air intake duct compressing surface (7) next-door neighbour air intake ductImport (8), Fighter Inlet (8) has been located Disengagement zone (9); It is characterized in that: this is hypersonicAir intake duct also comprises return flow line, and described return flow line comprises return flow line import (1), return flow lineThe drainage pipeline (3) of outlet (2) and connection return flow line import (1) and return flow line outlet (2);Return flow line import (1) is opened in air intake duct internal channel (6), and it is later half to be positioned at Disengagement zone (9)Portion, return flow line outlet (2) is opened in the residing same grading airway pressure of return flow line import (1)In contracting face (7).

2. hypersonic inlet according to claim 1, is characterized in that: described backflow is logicalRoad import (1) and return flow line outlet (2) wall are all perpendicular to air intake duct compressing surface (7).

3. hypersonic inlet according to claim 2, is characterized in that: described backflow is logicalThe distance L of the kernel of section line of road import (1) and Disengagement zone (9) originating point₁Meet:

0.65L_B≤L₁≤0.95L_B，

Wherein, L_BFor Disengagement zone (9) are along the width flowing to;

The return flow line outlet kernel of section line of (2) and the distance L of air intake duct compressing surface (7) initial point₂FullFoot:

0.5b≤L₂≤1.0L_S，

Wherein, L_SFor the distance between initial point and Disengagement zone (9) originating point of compressing surface (7), b is for drawingThe cross-sectional width of stream pipeline (3).

4. hypersonic inlet according to claim 3, is characterized in that: described drainage tubeRoad (3) is constant section duct.

5. hypersonic inlet according to claim 4, is characterized in that: drainage pipeline (3)And arc transition is all passed through in connecting between return flow line import (1), return flow line outlet (2).

6. hypersonic inlet according to claim 5, is characterized in that: drainage pipeline (3)Cross-sectional width b meet:

0.2W≤b≤0.5W，

Wherein, W is the entrance width of air intake duct internal channel;

Drainage pipeline (3) is R, is somebody's turn to do near the transition arc radius of the internal face of compressing surface (7) one sidesInternal face is L apart from the vertical range of compressing surface (7)_D, and meet:

1.0b≤R≤2.0b，

1.5R≤L_D≤2.0R。