CN113899553A

CN113899553A - Method for generating high-frequency disturbance of nozzle inlet based on multiple low-frequency electromagnetic valves

Info

Publication number: CN113899553A
Application number: CN202111228049.9A
Authority: CN
Inventors: 吴佳蔓; 刘勇; 张祥
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2021-10-21
Filing date: 2021-10-21
Publication date: 2022-01-07
Anticipated expiration: 2041-10-21
Also published as: CN113899553B

Abstract

The invention discloses a method for generating high-frequency disturbance of a nozzle inlet based on a plurality of low-frequency electromagnetic valves, which comprises the following steps of firstly establishing an atomization experiment basic model, enabling compressed air to flow into a liquid collecting tank through a pressure valve, arranging a nozzle at the lower part of the liquid collecting tank, connecting the upper part of the liquid collecting tank into a combined high-frequency electromagnetic valve through threads, wherein the combined high-frequency electromagnetic valve comprises a plurality of low-frequency electromagnetic valves which are combined in parallel, the flow characteristics of the low-frequency electromagnetic valves are consistent, and phase differences exist among different low-frequency electromagnetic valves; high-frequency disturbance is provided for the nozzle by controlling each low-frequency electromagnetic valve to work alternately; the invention solves the problem that the existing low-frequency electromagnetic valve is difficult to provide high-frequency disturbance in an atomization combustion experiment, finally obtains the disturbance with higher frequency with lower cost and time consumption, and applies the disturbance to a nozzle atomization experiment, thereby meeting the actual engineering requirement and having strong practicability.

Description

Method for generating high-frequency disturbance of nozzle inlet based on multiple low-frequency electromagnetic valves

Technical Field

The invention relates to the technical field of atomization combustion experiments, in particular to a method for generating high-frequency disturbance of a nozzle inlet based on a plurality of low-frequency electromagnetic valves.

Background

The atomization and combustion experiments have important guiding significance for researching the working characteristics of the liquid rocket engine. Centrifugal nozzles are one of the important working parts in engines, and the research on the great influence of the operating characteristics of the nozzles on the combustion efficiency and the combustion stability has been carried out. The liquid rocket engine can generate high-frequency oscillation in the actual working process, the highest frequency oscillation can reach more than 1000Hz, and the destructiveness is great for the high-thrust liquid rocket engine. In order to more accurately analyze data of atomization and combustion instability, certain disturbance is usually added at the inlet of a centrifugal nozzle in the atomization experiment process, but the frequency of an electromagnetic valve which is easily purchased in the market is usually about three hundred hertz at most, and compared with the disturbance frequency in the actual situation, the disturbance frequency is too low, so that the experiment is difficult to develop.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the problems existing in the prior art, the invention provides a method for generating high-frequency disturbance of a nozzle inlet based on a plurality of low-frequency electromagnetic valves.

The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:

a method for generating high-frequency disturbance of a nozzle inlet based on a plurality of low-frequency electromagnetic valves comprises the following steps of firstly establishing a basic model of an atomization experiment as follows:

compressed air flows into a liquid collecting tank through a pressure valve, a nozzle is arranged at the lower part of the liquid collecting tank, the upper part of the liquid collecting tank is connected into a combined high-frequency electromagnetic valve through threads, the combined high-frequency electromagnetic valve comprises a plurality of low-frequency electromagnetic valves which are combined in parallel, the flow characteristics of the low-frequency electromagnetic valves are consistent, and phase differences exist among different low-frequency electromagnetic valves; and high-frequency disturbance is provided for the nozzle by controlling the low-frequency electromagnetic valves to work alternately.

Further, liquid is contained in the liquid collection box in an initial state, compressed air enters the liquid collection box through the pressure valve, the internal pressure is increased, and the liquid in the liquid collection box flows to the nozzle after being extruded under the action of the internal and external pressure difference; the pressure value at the inlet of the nozzle can be constant through the regulation of the pressure valve; the combined high-frequency electromagnetic valve comprises 3 low-frequency electromagnetic valves; the internal pressure of the liquid collecting tank is adjusted by adjusting the switching states of different low-frequency electromagnetic valves, so that high-frequency disturbance at the nozzle is realized.

Has the advantages that:

the method for generating the high-frequency disturbance of the nozzle inlet based on the plurality of low-frequency electromagnetic valves can finally obtain the disturbance with higher frequency with lower cost and time consumption, is applied to the nozzle atomization experiment, meets the actual engineering requirements, has strong practicability, can be used under the condition of needing a high-frequency disturbance combustion experiment, and solves the problem that the high-frequency disturbance is difficult to provide by using the existing electromagnetic valves in the engineering.

Drawings

FIG. 1 is a schematic diagram of a basic model of an atomization experiment under a disturbance-free condition;

FIG. 2 is a schematic structural diagram of a combined high-frequency electromagnetic valve provided by the invention;

FIG. 3 is a schematic diagram of a fundamental model of an atomization experiment under the condition of high-frequency disturbance in the embodiment of the invention

FIG. 4 is a low frequency solenoid valve flow characteristic curve provided by the present invention

FIG. 5 is a flow rate characteristic curve of the solenoid valve A in one cycle according to the embodiment of the present invention

FIG. 6 is a flow rate characteristic curve of the solenoid valve B in one cycle in the embodiment of the present invention

FIG. 7 is a flow rate characteristic curve of the solenoid valve C in one cycle in the embodiment of the present invention

Fig. 8 is a flow rate characteristic curve of a high-power solenoid valve obtained by connecting the solenoid valves A, B, C in parallel in one cycle according to the embodiment of the present invention.

Detailed Description

The present invention will be further described with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a schematic diagram of a basic model of an atomization experiment under a disturbance-free condition, and the basic model consists of three main parts: compressed air, a header tank, and a nozzle. The liquid collecting tank is filled with liquid with a certain volume in an initial state, when compressed air is opened and pressure is adjusted by using the pressure valve, the pressure in the liquid collecting tank rises, the liquid in the liquid collecting tank is extruded under the action of internal and external pressure difference and then flows to the nozzle, and the pressure at the inlet of the nozzle is a constant value P at the moment.

In order to change the pressure value at the inlet of the nozzle from a constant value P to a pressure value with certain high frequency conversion, a plurality of low-frequency electromagnetic valves are selected and combined in parallel to form an electromagnetic valve with high frequency conversion. Specifically, taking the parallel operation of three low-frequency solenoid valves as an example, as shown in fig. 2, a low-frequency solenoid valve is added at an outlet of each of the first inlet and third outlet pipes, and the low-frequency solenoid valves are respectively called as a solenoid valve a, a solenoid valve B, and a solenoid valve C from left to right in the drawing.

When the combined type high-frequency electromagnetic valve is used, the upper part of the liquid collecting tank is connected into the combined type high-frequency electromagnetic valve through threads, as shown in figure 3. The combined high-frequency electromagnetic valve comprises a plurality of low-frequency electromagnetic valves which are combined in parallel, the flow characteristics of the low-frequency electromagnetic valves are consistent, and the difference is that phase differences exist among different low-frequency electromagnetic valves.

When a certain low-frequency electromagnetic valve is in an open state, at the moment, the gas in the liquid collecting box can be partially discharged, and the pressure in the liquid collecting box is reduced, so that the liquid pressure at the inlet of the nozzle is finally reduced. Taking the single working condition of one electromagnetic valve as an example, the ordinate in fig. 5-7 represents the opening degree: the solenoid valve is in a closed state by 0, the solenoid valve is in an open state by 1, the battery valve is in an opening process by 0-1, and the solenoid valve is in a closing process by 1-0.

Liquid is contained in the liquid collection box in an initial state, compressed air enters the liquid collection box through the pressure valve, the internal pressure is increased, and the liquid in the liquid collection box flows to the nozzle after being extruded under the action of internal and external pressure difference. At the moment, the combined high-frequency electromagnetic valve is completely closed, and the pressure value at the inlet of the nozzle can be constant to be P through the adjustment of the pressure valve.

When the working condition is stable, the working state of the electromagnetic valve can be adjusted. The flow characteristic of each low frequency solenoid valve exhibits a linear characteristic, as shown in fig. 4. And each low-frequency electromagnetic valve is controlled by a PLC. When the working frequency of an electromagnetic valve is determined, the working state of the electromagnetic valve is as follows because the working switching process of the electromagnetic valve needs to occupy a certain time in a period: (1) in one period, only the working state of alternating on and off exists, and the long on or long off state does not exist; (2) the solenoid valve is opened for a period of time during one cycle and then closed. The working state of a single electromagnetic valve used in the invention is (2), the electromagnetic valve A, B, C works alternately by taking the closing state of the electromagnetic valve A as the timing starting time, and the working state of each valve in a specific period is as follows: the flow working state of the solenoid valve a in one period is shown in fig. 5, the flow working state of the solenoid valve B in one period is shown in fig. 6, and the flow working state of the solenoid valve C in one period is shown in fig. 7, that is, when a certain solenoid valve is in an opening process or a closing process, the remaining solenoid valves are still in a normally open state, and finally, the overall frequency of the solenoid valves after being connected in parallel is improved in the whole working time, wherein the specific working state of each solenoid valve is controlled by a PLC. The flow rate working state of the high-frequency solenoid valve obtained after the solenoid valves A, B, C are finally combined in parallel and alternately operated is shown in fig. 8, and it can be seen that the time of one period is shortened by three times, that is, the frequency is increased by three times compared with the previous single solenoid valve operation. When the ordinate is equal to 2, the three electromagnetic valves are opened, when the ordinate is equal to 3, the three electromagnetic valves are opened, and the abscissa number does not represent specific time.

In the practical use process, when the electromagnetic valves work in parallel through the steps, the frequency is increased by three times compared with the working of a single electromagnetic valve, and the frequency of high-pressure air filled in the liquid collecting box through the air bottle and discharged by the electromagnetic valve is increased by three times, namely the pressure change in the water tank is increased by three times, so that the frequency of liquid flowing out of the liquid collecting box, namely the frequency of the nozzle inlet is increased by three times, and high-frequency disturbance of the nozzle inlet based on a plurality of low-frequency electromagnetic valves is realized.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims

1. A method for generating high-frequency disturbance of a nozzle inlet based on a plurality of low-frequency electromagnetic valves is characterized in that a basic model of an atomization experiment is established as follows:

2. The method for generating high-frequency disturbance of the nozzle inlet based on the plurality of low-frequency electromagnetic valves as claimed in claim 1, wherein the liquid is contained in the liquid collecting tank in an initial state, compressed air enters the liquid collecting tank through a pressure valve, the internal pressure is increased, and the liquid in the liquid collecting tank flows to the nozzle after being extruded under the action of the difference of the internal pressure and the external pressure; the pressure value at the inlet of the nozzle can be constant through the regulation of the pressure valve; the combined high-frequency electromagnetic valve comprises 3 low-frequency electromagnetic valves; the internal pressure of the liquid collecting tank is adjusted by adjusting the switching states of different low-frequency electromagnetic valves, so that high-frequency disturbance at the nozzle is realized.