CN215566203U - Exhaust nozzle for piston type aircraft engine - Google Patents

Abstract

The utility model discloses an exhaust nozzle for a piston type aircraft engine, which comprises a pipe body, wherein the upper end of the pipe body is connected with an exhaust port on the engine, a throat is arranged in the middle of the pipe body, the sectional area of the inner wall from the upper end of the pipe body to the throat is gradually reduced, and the sectional area of the inner wall from the throat to the lower end of the pipe body is gradually increased. The spray pipe is simple in structure, exhaust is smooth, exhaust efficiency can be improved, an engine is improved, and exhaust gas is smooth.

Description

Exhaust nozzle for piston type aircraft engine

Technical Field

The utility model relates to the field of piston type aircraft engines, in particular to an exhaust nozzle for a piston type aircraft engine.

Background

At present, the piston type aircraft engine is widely used on a small aircraft. Piston type aircraft engines are generally two-stroke, and include multiple sets of pistons that reciprocate to drive a crankshaft to rotate and output power. On small aircraft, two-cylinder piston engines are commonly used.

As shown in chinese patent No. 201720903142.8, an air inlet of an engine is located in the middle of the engine, exhaust ports are provided on both sides of the air inlet, and a distance between the exhaust port and the air inlet is small. When the engine works, the air inlet easily sucks the tail gas exhausted from the exhaust port into the air inlet again, so that the output power of the engine is influenced. Therefore, as shown in this patent, an exhaust pipe is added to the exhaust port, thereby increasing the distance between the intake port and the exhaust port and preventing exhaust gas from being re-sucked into the intake port. However, the exhaust pipe is only in a simple cylindrical shape, is slender as a whole, is simple in design, has consistent cross-sectional areas at all positions, has no compression and expansion effects on airflow, and is not beneficial to improving the output power of the engine and the exhaust emission.

SUMMERY OF THE UTILITY MODEL

Aiming at the defects in the prior art, the utility model aims to provide the exhaust nozzle for the piston type aircraft engine, which has a simple structure, can enable the engine to jet flow, improves the exhaust efficiency and improves the output power of the engine through the compression and expansion actions in the nozzle.

The technical purpose of the utility model is realized by the following technical scheme: the exhaust nozzle for piston type aeroengine includes one pipe body with upper end connected to the exhaust port of the engine, one throat in the middle part, and from the upper end to the throat, one gradually reduced inner wall and one gradually increased inner wall.

Through above-mentioned technical scheme, the body cross-section sets up like this, and the inside sectional area of body reduces earlier then increases, and the sectional area of choke department is minimum. Tail gas enters the upper end of the pipe body, the sectional area from the upper end of the pipe body to the throat is gradually reduced, and jet flow of the engine is in a compressed state, so that the acting energy of gas in a combustion chamber of the engine can be increased; after the tail gas passes through the throat, the tail gas begins to expand and accelerate, and the tail gas of the engine can be smoothly discharged from the lower end of the pipe body, so that the effective power and the exhaust efficiency of the engine are improved.

Preferably, the shape of the upper opening of the tube body is consistent with that of the exhaust port and is opposite to the exhaust port.

Through above-mentioned technical scheme, can not have step change between body inner chamber and aeroengine's the gas vent, can reduce the flow loss of engine gas, it is more smooth and easy to exhaust.

Preferably, the section of the inner wall of the throat part of the pipe body is circular.

Through the technical scheme, the cross section of the inner wall of the throat part is circular, and the throat part can be gradually transited to the circular shape easily no matter what shape the front end of the tube body is, and meanwhile, the circumference of the circular tube body is the minimum when the tube body is in the same sectional area, so that the material use can be reduced, the contact area between the tube wall and air flow is reduced, and the on-way resistance generated during flowing is reduced.

Preferably, the upper end of the pipe body is provided with a flange, and the flange is provided with a fixing hole.

Through the technical scheme, the connection between the pipe body and the engine can be conveniently realized after the flanging is arranged, the fixing holes are formed in the flanging, and the pipe body can be fixed by using screws and the like.

Preferably, the throat to the rear end of the tube body is in a truncated cone shape.

Through above-mentioned technical scheme, the increase of body back end sectional area subassembly, the tail gas discharge body rear end of being convenient for. Meanwhile, the rear end of the tube body is in a truncated cone shape, and the tube body is convenient to process.

Preferably, the section of the upper end of the pipe body is rectangular, and the section from the upper end of the pipe body to the throat gradually changes from rectangular to circular.

The exhaust port of a common piston type aircraft engine is rectangular, and the section of the upper end of the pipe body is rectangular and is consistent with that of the exhaust port of the engine. The section of the upper part of the pipe body is gradually changed, so that the turbulence generated when tail gas flows in the upper part of the pipe body can be reduced, and the tail gas flows more smoothly.

Preferably, the longitudinal section of the inner wall of the pipe body is streamline.

Through above-mentioned technical characteristic, tail gas is more smooth and easy when the body inner wall flows, and exhaust resistance is littleer.

Compared with the prior art, the utility model has the beneficial effects that: through the improvement to the body structure, can increase the efficiency of doing work of engine gas for the exhaust velocity of tail gas to the effective output of strip engine.

Drawings

FIG. 1 is a state diagram of the use of the embodiment;

FIG. 2 is an exploded view of the embodiment in use;

FIG. 3 is a perspective view of the embodiment;

FIG. 4 is a first longitudinal cross-sectional view of the embodiment;

FIG. 5 is a schematic longitudinal sectional view of the second embodiment.

Reference numerals: 1. a pipe body; 2. an exhaust port; 3. an engine; 4. a throat; 5. flanging; 6. and (7) fixing holes.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

As shown in figures 1-5, the exhaust nozzle for the piston type aircraft engine 3 comprises a pipe body 1, wherein a cavity is formed inside the pipe body 1, and the tail gas is circulated, so that the position of the tail gas can be far away from an air inlet. The upper end of the pipe body 1 is provided with a turned edge 5 which is turned outwards, and the turned edge 5 is fixed at the upper end of the pipe body 1. The fixing holes 6 are formed in the turned-over edges 5, and the fixing holes 6 are formed in the turned-over edges 5 on the left side and the right side of the pipe body 1. During installation, the opening at the upper end of the pipe body 1 is opposite to the exhaust port 2 of the engine 3, and the screw penetrates through the fixing hole 6 on the flanging 5 and is screwed on the engine 3, so that the exhaust nozzle is fixed.

The shape of the opening at the upper end of the pipe body 1 is the same as the cross section shape of the exhaust port 2 of the engine 3, so that tail gas can be smoothly discharged from the exhaust port 2 to enter the upper end of the pipe body 1, step change cannot occur, the effective flow area at the position is affected, and exhaust at the position is smoother.

The middle part of the tube body 1 is provided with a throat 4, and the sectional area of the inner wall of the throat 4 is the minimum part of the sectional area of the inner wall of the tube body 1. The section of the inner wall of the tube body 1 at the throat 4 is circular. The area of the section of the inner wall from the upper end of the tube body 1 to the section of the inner wall at the throat 4 is gradually reduced, and the area of the section of the inner wall from the throat 4 to the lower end of the tube body 1 is gradually increased. Because the section of the exhaust port 2 on the engine 3 is rectangular, the section of the upper end of the pipe body 1 is also rectangular. The section of the inner wall of the tube body 1 from the upper end of the tube body 1 to the throat 4 is gradually changed into a circle from a rectangle.

The inner wall section of the rear end of the tube body 1 is circular. The whole body 1 at the rear end of the throat 4 is approximately in a cone frustum shape, the section of the inner wall of the part close to the throat is small, and the section of the inner wall of the part far away from the throat is large. The longitudinal section of the inner wall of the pipe body 1 is streamline, so that when tail gas flows in the pipe body 1, the tail gas flows more smoothly, vortex flow and the like are not easy to generate, and exhaust resistance is reduced.

In actual use, the exhaust nozzle is vertically mounted on the exhaust port 2 of the engine 3 such that the lower end of the exhaust nozzle is away from the intake port of the engine 3. The tail gas is discharged from the exhaust port 2, enters the upper end of the pipe body 1 and flows towards the lower end of the pipe body 1. Because the cross-sectional area from the upper end of the tube body 1 to the throat 4 is gradually reduced, the engine Penliu is in a compression state, the acting energy of gas in an engine combustion chamber can be increased, and the effective power of the engine is improved. After the tail gas passes through the throat, the tail gas begins to expand and accelerate, so that the tail gas of the engine can be smoothly discharged from the lower end of the pipe body, and the effective power and the exhaust efficiency of the engine are improved.

When the compression process of the two-stroke engine 3 is finished, the spark plug generates electric sparks to ignite combustible mixed gas in the cylinder, and the combustion gas expands to do work. At the moment, the exhaust hole and the scavenging hole are both closed by the piston, and only the air inlet hole is still opened. Air and gasoline continue to flow into the crankcase through the intake ports until the piston skirt closes the intake ports. As the piston continues to move towards bottom dead center, the crankcase volume continues to shrink and the mixture therein is compressed. After that, the exhaust hole is opened at the head of the piston, the expanded high-temperature and high-pressure combustion gas is exhausted through the exhaust hole, and the piston is opened for early exhaust. Then the piston opens the scavenging hole again, and the combustible mixture passing through the piston and compressed enters the cylinder from the crankcase through the scavenging hole to scavenge the waste gas therein, and the scavenging process is started. When the combustible gas is ignited in the cylinder, combustion is not completed instantly, but is a continuous process, and combustion does not only occur in the cylinder, and sometimes even continues into the exhaust nozzle, so that the combustion phenomenon can be observed from the tail end of the exhaust nozzle. The mass of the gas discharged in the early exhaust process is much larger than that in the scavenging process.

The sectional area inside the upper end of the spray pipe connected with the exhaust hole is gradually reduced, and when the gas flows through the upper end of the spray pipe in the early exhaust process, the gas is compressed, so that the pressure in the cylinder body can be improved, and the flow speed of the tail gas is improved. The pressure in the cylinder increases, the thrust acting on the piston increases, the output power of the engine 3 is improved, the utilization rate of energy is improved, and the energy generated by combustion is fully utilized. The flow velocity of the tail gas is improved, the flow velocity of partial tail gas can be increased to the sonic velocity, the flow velocity of the gas flow accelerated to the sonic velocity enters the lower section of the spray pipe with the gradually increased sectional area, the flow velocity of the gas flow is continuously increased, the partial gas flow flows out of the lower section of the spray pipe at the supersonic speed, the whole spray pipe has the effect similar to a Laval spray pipe, and the exhaust is smoother. Meanwhile, because the mass of the air discharged in the scavenging process is far smaller than that of the air discharged in the exhaust process, the arrangement of the spray pipe does not cause great obstruction to the air flow discharged in the scavenging process. The arrangement of the nozzle pipes can thus improve the effective power and exhaust efficiency of the engine 3.

The above description is intended to be illustrative of the present invention and not to limit the scope of the utility model, which is defined by the claims appended hereto.

Claims (7)

1. The utility model provides an exhaust nozzle for piston aeroengine, includes body (1), and body (1) upper end is connected characterized by with gas vent (2) on engine (3): the middle part of the tube body (1) is provided with a throat (4), the sectional area from the upper end of the tube body (1) to the throat (4) is gradually reduced, and the sectional area from the throat (4) to the lower end of the tube body (1) is gradually increased.

2. An exhaust nozzle for a piston-type aircraft engine according to claim 1, characterised in that: the shape of the upper end opening of the tube body (1) is consistent with that of the exhaust port (2) and is opposite to the exhaust port (2).

3. An exhaust nozzle for a piston-type aircraft engine according to claim 1, characterised in that: the section of the inner wall of the throat part of the tube body (1) is circular.

4. An exhaust nozzle for a piston-type aircraft engine according to claim 1, characterised in that: the upper end of the pipe body (1) is provided with a flanging (5), and the flanging (5) is provided with a fixing hole (6).

5. An exhaust nozzle for a piston-type aircraft engine according to claim 3, characterised in that: the throat (4) and the rear end of the tube body (1) are in a cone frustum shape.

6. An exhaust nozzle for a piston-type aircraft engine according to claim 3, characterised in that: the section of the upper end of the tube body (1) is rectangular, and the section from the upper end of the tube body (1) to the throat (4) gradually changes from rectangular to circular.

7. An exhaust nozzle for a piston-type aircraft engine according to claim 1, characterised in that: the longitudinal section of the inner wall of the pipe body (1) is streamline.

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