JPS5912852B2 - Air intake for ramjet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an external compression type ramjet engine,
Particularly regarding its air intake.

A ramjet is the simplest air-breathing propulsion device, and is used for special flying objects because it provides high thrust at high flight speeds, but low thrust at low flight speeds. Due to the unique requirements of the flying object, it is easy to
It has a lightweight, inexpensive fixed structure.

In other words, the jet nozzle, air intake lamp, and cowl pump are all fixed, with no moving parts.

Furthermore, as the air compression method, an external compression type air intake is used because it is easy to start and the operation is stable.

A conventional external compressed air intake will now be described with reference to FIG.

In the figure, 1 is a lamp having inclined surfaces 1a and 1b, 2 is a cowl lip, and an air intake port 3 is provided between the cowl lip 2 and the lamp 1.

The positional relationship between the tip 2a of the cowl lip 2 and the lamp 1 is set according to the flight speed at the time of design, and when the design engine is operated at the design point, that is, the design Matsuha number, as shown in Fig. 3A. As shown, slope 1 of ramp 1
Oblique shock waves O80, O generated from each tip of a and 1b
82 passes near the tip '2a of the cowl lip 2, and a vertical shock wave NS is generated at the throat portion 4 of the air intake port 3 where the flow path is the narrowest.

In this way, a vertical shock wave NS is generated at the throat part 4 of the air intake port.
The state in which this is generated and maintained is called critical operation, and the total pressure recovery rate at the air intake port is the highest, resulting in stable and high output operation of the engine.

Further, when the flight Matsuha number is smaller than the design Matsuha number, the angles of the oblique shock waves O81 and O82 with respect to the flow direction become large, as shown in FIG. 3B.

That is, the oblique shock waves O81 and O82 are on the slope 1a. 1b and separates from the tip 2a of the cowl lip 2, the inflow area that can flow into the air intake port 3 changes from Ho in Figure 3A at the design Matsuha number to Ho' in Figure 3B. decreases to

Due to the inherent characteristics of the ramjet engine, when the flight Matsuha number is lower than the design Matsuha number, the ability to exhaust gas backward from the jet nozzle is greatly reduced even if the engine gas temperature is constant, and the air flowing in from the area of Ho' is I can't get rid of everything.

In this way, the vertical shock wave NS is pushed forward, and the excess portion H
Air with an area of H1 overflows from the cowl lip 2, and only air with an area of H1 corresponding to the discharge capacity of the jet nozzle flows in.

The operating state in which the vertical shock wave NS is pushed forward beyond the throat portion 4 of the air intake port is called a subcritical operation.

As the flying Matsuha number decreases, the area ratio of H1/Ho' also decreases, and the way the vertical shock wave NS is pushed out also becomes stronger.

When it exceeds a certain limit, the vertical shock wave NS begins to violently vibrate back and forth, and the engine output also causes strong vibrations, making it unusable.

This unstable phenomenon caused by sub-critical operation of the air intake port is called a buzz, and is considered to be a dangerous phenomenon that must be avoided.

On the other hand, when the flight Matsuha number is larger than the design Matsuha number, the angles of the oblique shock waves O81 and O82 with respect to the flow direction become smaller, as shown in FIG. 3C.

That is, the oblique shock waves O81 and O82 are on the slope 1a.

It lies in the direction 1b and enters the inside of the cowl lip, and the inflow area becomes a constant value Ho at the time of design.

Also, the ability of the engine to discharge gas from the jet nozzle increases as the Matsuha number increases, so the constant value Ho
The internal pressure behind the air intake must drop to match the incoming air from the area of .

In such a state, the vertical shock wave NS is sucked downstream from the throat portion 4 and becomes a strong vertical shock wave NS.

The operating state in which the vertical shock wave NS crosses the throat portion 4 of the air intake port and is sucked downstream is called a super critical operation.

As the flight Matsuha number becomes larger than the design Matsuha number, the vertical shock wave NS is deeply inhaled, and the total pressure recovery rate decreases, regardless of the function of the air intake port, and is dominated only by the discharge capacity of the jet nozzle.

However, since this supercritical operation is stable, the engine can be used in this operating state as long as the thrust required is met.

A case will be described in which a variable mechanism is used in the air intake port and jet nozzle of a ramjet engine, as is applied to supersonic aircraft, although this is not used in conventional ramjet engines.

In the above variable mechanism, as shown in FIG. 4, the expansion ratio AE/AN is determined by the jet nozzle throat area AN and the jet nozzle area AE, the area Ho of the air intake port,
Throat area H11 ramp angle δ1. δ2, lamp position L
ol>L2 can be independently and arbitrarily changed.

Therefore, the jet nozzle throw surface sAN is set to change so that the vertical shock wave NS is always stably maintained at the nozzle throat 4 position of the air intake, and the ramp angle δ1
．． δ2 is selected to be the value that maximizes the total pressure recovery force at that Matsuhha number.

In addition, the lamp positions Lo1 and L2 are the oblique shock waves O81.
, O82 is selected according to the conditions in which it will fly past near the tip of the cowl lip, and the area Ho of the air intake port is:
It is selected to match the thrust requirements of the aircraft.

In this way, it is possible to operate the same engine stably and efficiently over a very wide range, that is, from high subsonic speeds to flight speeds of around 5 matsuha.

However, since the above-mentioned variable mechanism has a complicated structure, if it is applied to a ramjet as it is, there is a problem that the features of the ramjet, such as simplicity, light weight, and low cost, will be halved.

Furthermore, as mentioned above, conventional ramjet has a fixed structure.

Therefore, to avoid air intake buzz during low speed operation,
Since the set point is set at the lowest Matsuha number within the operational Matsuha number range, the main operating range becomes super critical operation, and the problem is that a method that is stable but operates with a low total pressure recovery rate must be selected. There is.

Furthermore, according to this method, the operational Matsuha number range that can be covered by the same engine is an extremely narrow range E1 of about 1 to 2 Matsuha, as shown in the thrust coefficient-Matsuha number characteristic diagram in Figure 5.
The problem is that it is limited to.

Lines P1' to P3' in FIG. 5 are the thrust coefficients for the Matsusha number according to the conventional method, and D is the drag coefficient.

The difference between P1', P2', and P3' is the difference when the mixture ratio of fuel to air is changed, and is P1'→P2'→P3'
The mixture ratio of fuel to air decreases in this order.

Furthermore, the point A is the design Matsuh number, and the reason why this design Matsuh number is set to a low value is to prevent buzz in sub-critical operations as described above.

The present invention has been made in view of the above points, and the present invention, like the conventional fixed structure ramjet engine, has a fixed jet nozzle and a fixed air intake cowl lip. and a ramp that has an integral structure with each angle of the slope fixed, and the difference from conventional air intakes is that the ramp can move linearly back and forth with respect to the cowl lip. The present invention is characterized in that it includes a drive device and a control device that controls the amount of movement.

Therefore, it is an object of the present invention to provide an air intake port for a ramjet that has a simple structure, can be used over a wide range of numbers (and does not cause any buzz).

Next, an embodiment of the air intake for a ramjet according to the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway side view showing a ramjet flying object having an air intake according to the present invention, and FIG. 2 is a sectional view showing a main part of the air intake.

In the figure, reference numeral 10 denotes a ramjet flying body, and a ramjet engine 14 is mounted at the rear of the body 10, and a plurality of air intake ports 13 of this engine 14 are provided on the side of the body 10.

Each of the air intake ports 13 communicates with a fuel injection section 15 and a combustion chamber 16, and a nozzle throat 17 and a jet nozzle 1 are fixed at the rear of the combustion chamber 16.
8 is formed.

The air intake port 13 includes a cowl lip 12 having a fixed structure;
A ramp 11 that is movable linearly along the fuselage 10
The ramp 11 has a slope 11a.
, 11b, a plurality of pressure detectors 19 are formed on the slope 11b, and guide rollers 20, 20 are formed on the side of the ramp 11 that contacts the body 10.

On the other hand, the fuselage 10 side (on the other hand, the guide rail 21 on which the guide rollers 20, 20 are movably held, and the ramp 11
A drive device 22 for moving and operating the sleeve 2 and a control device 23 for controlling the drive are provided.
An electric operating device is used, which includes a screw rod 25 that is engaged with the screw rod 4, a motor 26 that rotates the screw rod 25, and a motor 26 that rotates the screw rod 25.

That is, the guide rollers 20.20 are guides for moving the lamp 11 back and forth correctly and with little resistance along the guide rails 21 of the fuselage 10, and the drive device 2
2, the screw sleeve 24 is fixed to a part of the lamp 11, and the lamp 11 is moved back and forth according to the rotation of the motor 26.

The control device 23 also includes two or more pressure detectors 1.
9, the motor 26 is configured to send a current to rotate the motor 26 forward or reverse so that the vertical shock wave NS is located at the throat portion of the air intake port 13.

The pressure detectors 19 are provided in small numbers (one each at each end of the proper position range of the vertical shock wave NS). In this embodiment, there are three pressure detectors including a pressure detector serving as a pressure reference. 19 is used.

Next, the operation of the air intake port with the above configuration will be explained.

First, if the design Matsuha number and the flight Matsuha number match, the lamp position will be the same as in FIG. 3A, and the oblique shock waves O81 and O82 will pass near the tip of the cowl lip 12,
The vertical shock wave NS settles near the throat portion 40, and the air flowing in from the inflow area Ho matches the amount of gas discharged from the jet nozzle 18, so that the air intake port 13 obtains a high total pressure recovery rate and operates stably. do.

On the other hand, if the flight Matsuha number is smaller than the design Matsuha number, the vertical shock wave NS is pushed forward as shown in Figure 3B, and in this case, the vertical shock wave NS shown in Figure 3B is Throat area H is added to the inflow area H1' just before.
As shown in FIG. 2, the lamps 11 are arranged so that i is equal.
Move forward by ΔL.

This is because all the signals from the pressure detector 19 indicate a high pressure after the vertical shock wave NS, so the motor 26 is rotated by the operation of the control device 23, and the screw sleeve 24 is advanced to advance the lamp 11.

In this way, the lamp 11 moves forward by an amount Δ, causing a vertical shock wave NS.
When reaches the throat 40, the controller 23 stops the motor 26 and removes its critical operating condition, since the signal of the detector 19 indicates a low pressure before the vertical shock wave NS and a high pressure after the vertical shock wave NS. Hold.

On the other hand, when the number of flying pins increases slightly and the vertical shock wave NS recedes from the throat portion 40 as shown in FIG. 3C, the detector 19 detects only the low pressure in front of the vertical shock wave NS.

As a result, the control device 23 moves the lamp 11 backward, causes the vertical shock wave NS to be held in the throat portion 40, and maintains the critical operation.

In this way, even if the flight Matsuha number is lower than the design Matsuha number, the lamp 11 is always controlled to an appropriate position, and the amount of air flowing into the air intake port 13 is matched to the amount of gas exhausted from the fixed jet nozzle 18. Therefore, it is always maintained in a critical operating state and can always operate stably without the dangerous buzz that occurs during sub-critical operating as seen with conventional fixed air intakes.

Moreover, unlike during super-critical operation, a relatively high pressure recovery rate can be obtained and the engine can be operated effectively.

Further, when designing the engine having the air intake according to the present invention described above, it is desirable to set the design point at the center of the operational flight number range in a rather high Matsuba number range.

Then, as shown in the curves 21 to 23 in Figure 5, even in the matsuba number range below the design point, there will be no restriction on the generation of buzz, and the range E2 will be wide enough to the point where the thrust coefficient matches the drag coefficient. The range of use has been expanded over the years, and the range of pine trees, which are higher than the design point, has also been expanded accordingly.

In this Fig. 5, point B is the design Matsuba number of the embodiment of the present invention, and the difference between Pl, P2° and P3 is the difference when the mixing ratio of fuel to air is changed. The mixing ratio of fuel to

In addition, the main operation range where conventionally a low thrust coefficient had to be used due to a low pressure recovery rate in a super critical state can now be achieved by high performance engine operation in a relatively large thrust coefficient range due to a critical operation or a light super critical operation. , which enables more effective flying object operations.

The present invention is not limited to the embodiments described above, and various modifications can be made without changing the gist.

For example, the driving device may be electric, hydraulic, gas pressure, or any other type as long as it is a simple device that can reliably move and hold the lamp by the required amount (it is most suitable in conjunction with other equipment on the flying object). All you have to do is choose the one you did.

Further, the lamp 11 in the above embodiment has two slopes 1
1 a and 1 l b, but this can be composed of one slope, or it can be a slope bent in multiple stages, or it can be a curved surface.

If the slope is multi-staged or curved in this way, the total pressure recovery rate will be further improved.

As explained above, according to the present invention, a ramp having a fixed slope is moved linearly along the machine axis direction,
Since the vertical shock wave is always generated at the throat of the air intake, the structure is simple, but it has the effect of expanding the range of operational numbers.

In other words, according to the present invention, there is no risk of buzz occurring even in the Matsuba number range below the design point (there is an effect that the range of use is expanded over a sufficiently wide range to the point where the thrust coefficient matches the drag coefficient, and This has the effect of expanding the Matsuba number range higher than the design point by that amount.

In addition, even in the case of super critical operation, this can be reduced, which has the effect of increasing (improving) efficiency.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing a ramjet flying object in which an air intake according to the present invention is used, and FIG. 2 is a sectional view showing an embodiment of the air intake according to the present invention. Figure 3A
, B, and C are cross-sectional explanatory views showing a conventional air intake port and its function. Figures 4A and B are explanatory views showing an outline of the intake port and jet nozzle assuming a variable mechanism. FIG. 3 is a graph diagram showing thrust coefficient-Matsuba number characteristics due to the air intake port of the invention. 10... Aircraft, 11... Lamp, 11
a. 11b... Slope, 12... Cowl lip, 19... Pressure detector, 22... Drive device, 23... Control device, 40...
Throat section, NS... Vertical shock wave.

Claims (1)

[Claims] 1. A fixed cowl lip, a ramp with a fixed slope angle, a drive device that moves the ramp linearly back and forth along the axis of the aircraft, and detection of the position of the vertical shock wave. a pressure detector, and in response to a signal from the pressure detector, the lamp is moved relatively forward when the flight Matsuha number is smaller than the design Matsuha number to reduce the air intake amount, and when the same Matsuha number is larger than the design Matsuha number, the lamp is moved relatively forward. It is equipped with a control device that controls the amount of movement so as to expand the amount of air intake by moving it relatively backward, and is configured to constantly generate vertical shock waves at the throat of the air intake. Characteristic air intake for ramjet.