JPS59151000A - Ejector - Google Patents

Abstract

PURPOSE:To stabilize the operation and prevent the vibration of the device by a method wherein a parallel mixing part is provided between the inlet port of fluid to be driven and a second throat and the adhering point of the free expanding stream of the driven fluid to the inner wall of the ejector is generated in said mixing part to make the sectional area at said adhering point constant. CONSTITUTION:The parallel mixing part 4 is provided between the inlet port 1 of the fluid to be driven and the second throat 6. According to this constitution, even if the estimation of the streamline condition of the free expanding stream is not correct or there is an error or the like in the attachment of a supersonic nozzle 3, there will never affect to the performance of the device. Even if the adhering point 12 of the free expanding stream 11 is deviated to forward or backward directions, the sectional area at the adhering point 12 is constant and, accordingly, a suction pressure may be estimated and designed very correctly. The pressure recovery, effected by a diffuser 7, becomes constant and a regulation of a back pressure with respect to the pressure recovery becomes the same as the estimation and design thereof, therefore, the ejector may be operated in stable manner and vibration or the like may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ejector used in rocket engine high-altitude combustion test equipment or an industrial ejector for use in steel plants.

The rocket engine high-altitude combustion test facility simulates combustion conditions at high altitude (vacuum) by evacuating rocket engine combustion exhaust gas with an ejector, but in this case, the flow force of the driven flow i Stable operation and suction pressure (achieved vacuum) are required not only at a predetermined value but also at zero.

As shown in FIG. 1, a conventional ejector has an inlet section 1;
It is a cylinder consisting of a gradual mixing part 5 that tapers in the direction of the flow inside the cylinder, a second throat 6, a diffuser 7 that widens in the direction of the flow inside the cylinder, and an outlet 8. A supersonic nozzle 3 and a through pipe 2 for supplying the driving flow P to the supersonic nozzle 3 are provided in the middle of the gradual mixing section 5. In this structure, the driving flow P from the supersonic nozzle 3 is blown out from the supersonic nozzle 3, expands at supersonic speed, and mixes with the driven flow S entering from the inlet section 1 in the gradual contraction mixing section to form a uniform supersonic flow. It becomes a sonic mixed flow. This supersonic mixed flow is throttled by the second throat 6 and then generated by a shock wave 15 in the diffuser 7.
The subsonic flow M/is discharged from the outlet 8 with a roar. However, the entrance part 1 and the second throat 6
If the shape of the gradual contraction mixing section 5 between the It is difficult to design, and in severe cases, it may not work as a supersonic ejector, or it may cause vibrations in the suction pressure. Therefore, the conventional ejector has a driven flow S
The system was operated only when the flow rate was close to the design value, and use at zero or low flow rates was avoided.

The object of the present invention is to eliminate the above-mentioned drawbacks and provide an ejector that operates stably.

The present invention will be described below with reference to the embodiments shown in FIGS. 2 to 5.

In FIG. 2, the ejector body is a cylinder consisting of an inlet part 1, a parallel mixing part 4, a gradual mixing part 5, a second throat 6, a diffuser 7 and its outlet 8, and a supersonic nozzle 3 and a supersonic nozzle 3 inside. A through pipe 2 for supplying a driving flow P to this is provided. This case differs from the conventional one in that it has a parallel mixing section 4 near the exit of the supersonic nozzle 3.

The driving flow (hereinafter referred to as "feeding flow") P passes through the through pipe 2 and is ejected from the outlet of the supersonic nozzle 3 into the parallel mixing section 4 to become a supersonic expansion flow 11'. The driven flow (hereinafter referred to as secondary flow) S entering from the inlet part 1 is accelerated by the expansion flow 11' of the primary flow in the parallel mixing part 4; it reaches the sonic speed at the critical point 14, and then the parallel The primary flow P and the secondary flow S are mixed in the latter half of the mixing section 4 and within the gradual contraction mixing section 5 to form a uniform supersonic mixed flow M. The mixture 3, the flow M, is throttled by the second throat 6 and the Matsuha number becomes small (but less than 1), and then the pressure is recovered by the shock wave 15 in the diffuser 7, and it becomes a subsonic flow M' and is discharged from the outlet 8.

During zero flow flow (the flow rate of the secondary flow S is zero), the supersonic nozzle 3
The secondary flow S jetted out becomes a free expansion flow 11 and adheres to an attachment point 12 of the free expansion flow on the inner wall of the parallel mixing section 4, generating an oblique shock wave 13. Thereafter, the supersonic primary flow M is throttled by the second throat 6 and the pressure is restored in the diffuser 7 by the shock wave 15.

The suction pressure of the ejector during atmosphere flow is the primary flow free expansion flow 11
The expansion ratio A of the cross-sectional area at the attachment point 12 of the supersonic nozzle 3 (referred to as A) and the cross-sectional area of the throat 3* of the supersonic nozzle 3 (referred to as A*)
/A*. However, it is difficult to calculate and predict the streamline situation of the free expansion flow 11, and even if it were possible to predict it, due to installation errors of the supersonic nozzle 3, manufacturing errors of the gradual contraction mixing section 5, etc., it is difficult to predict the flow line state of the free expansion flow 11. Now, the free expansion flow 11
The position of the attachment point 12 was unclear. In this case, for example, if the attachment point 12 shifts downstream than predicted, the expansion ratio A/A*
becomes smaller and the suction pressure becomes higher (the ultimate degree of vacuum becomes worse).

Conversely, if it deviates upstream from the prediction, the expansion ratio A, /A* becomes thicker (
Although the suction pressure becomes low, the recovery pressure at the outlet 8 of the diffuser 7 becomes low (in severe cases, it becomes impossible to match with the back pressure, and the free expansion flow 11 eventually flows into the gradual contraction mixing section 5).
If it does not adhere to the inner wall of the diffuser 7, it will cause separation. If this happens, the supersonic ejector will not work, or the gas in the diffuser 7 will flow back into the inlet 1 and vibrate, causing dangerous equipment. It can also be a state.

In contrast, in the ejector of the present invention (see FIG. 2), since there is a parallel mixing section 4, even if the prediction of the streamline situation of the free expansion flow 11 is not accurate, the handling error of the ultrasonic nozzle 3 etc. Even if there are, it is not affected by them. That is, the free expanding flow 1
Even if the attachment point 12 of 1 shifts back and forth, the cross-sectional area at the attachment point 12 is A! The suction pressure (achieved vacuum) determined by A/A* can be predicted and designed extremely accurately. Moreover, as a result, the pressure recovery by the diffuser 7 is also constant, and the matching with the back pressure is as predicted and designed, resulting in stable operation and freedom from problems such as vibration.

The above effect is exerted not only when the secondary flow S
Since the critical point 14 of is located in the parallel mixing section 4, the critical point 14
Even if the position of is changed, the sum of the cross-sectional area of the secondary flow S at the critical point 14 (referred to as i) and the cross-sectional area of the − sending flow P (referred to as A') = A is constant. Therefore, the suction pressure for a certain secondary flow rate S becomes constant, and the recovery pressure of the mixed flow M also becomes constant.

Here, the effect of the second throat 6 will be explained for reference. The name "second throat" comes from the meaning of the second throat when the throat 3* of the supersonic nozzle 3 is regarded as the first throat. By narrowing the mixed flow M (only - flow when sending zero two flows) by the second throat 6, the Matsuha number just before the shock wave 15 is reduced, and therefore the loss of total pressure due to the shock wave 15 can be suppressed. This makes it possible to increase the recovery pressure at the outlet 8 of 7.

In Fig. 2, in order to suppress the pressure loss of the secondary flow S at the inlet part 1, the diameter of the inlet part 10 is made larger than the diameter of the parallel mixing part 40, but if the pressure loss between the
As shown in the figure, the diameters of the inlet section 1 and the parallel mixing section 40 may be the same. This should not be confused with the conventional one shown in FIG.

Moreover, the supersonic nozzle 3 for the -flow P does not have to be provided at the center of the ejector body, but may be provided at the edge of the ejector body as shown in FIG. The system is called an annular nozzle.

The secondary flow inlet section 1 may be bent as shown in FIG.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional ejector, and Figures 2 to 5.
The figures are sectional views of different embodiments of ejectors according to the invention. 1. Inlet part, 2. Penetration pipe, 13. Supersonic nozzle,
3*Fist/supersonic nozzle throat, 4/φ parallel mixing part,
5. Gradual contraction mixing section, 6. Second throat, 7. Medium tiff user, 8φ outlet, 11. Free expansion flow, 11!
・Supersonic expansion flow, 12φ・Attachment point of free expansion flow, 13
...Diagonally, Kasu! Wave, 14...critical point, 15...shock wave. Fig. 1 yf, Z Fig. 3 Fig. 4, Fig. 5

Claims (1)

[Claims] A parallel mixing section is provided between the inlet of the driven fluid and the second throat, and an inner wall attachment point of the free expansion flow of the driving flow or a critical point of the driven flow is generated in this parallel mixing section. ejector.