Engine surge test device and engine surge test method

Abstract

The application discloses an engine surging test device and an engine surging test method. The engine surging test device comprises a gas supply pipeline and a pressure regulating pipeline. The gas supply pipeline comprises a gas supply mechanism, an electric pressure reducing valve, a first pressure monitoring mechanism, a three-way valve, a first regulating valve and a first electromagnetic valve which are sequentially connected. The electric pressure reducing valve receives the gas pressure information monitored by the first pressure monitoring mechanism and adjusts the valve opening. The pressure regulating pipeline comprises a second regulating valve and a second electromagnetic valve which are sequentially connected. One end of the second regulating valve is connected with the three-way valve. The engine surging test method uses the above engine surging test device to perform a surging test on an engine. The application is used to solve the technical problems that the existing engine surging test device has a single pressure regulating mode and cannot make the engine instantaneously surge.

Description

Technical Field

[0001] This application relates to the field of engine technology, specifically to an engine surge test device and an engine surge test method. Background Technology

[0002] Surge is an unstable operating condition of an engine that poses a serious threat to its operation. This is especially true for aero engines, whose compressors are prone to sudden surge in harsh flight environments. Improper handling can severely impact normal engine operation and even lead to engine shutdown. To ensure stable operation of aero engines across their entire operating envelope and in harsh environments, engines must be designed with a certain surge margin.

[0003] In the development of aero-engines, to achieve the design target for surge margin and verify the reliability of anti-surge and anti-surge devices, multiple full-engine surge tests are required to obtain the surge margin characteristics of the engine compressor. This provides data support for engine development and a basis for engine design finalization. Existing engine surge test equipment generally includes: high-pressure gas cylinder group, pressure reducing valve, electric valve, solenoid valve, ball valve, metal hose, etc. After connecting this device to the engine's bleed port, a surge test is conducted. Although this device can induce surge in the engine, it can only achieve slow surge by manually and continuously adjusting the intake air pressure. The adjustment method is singular and cannot induce instantaneous surge, thus failing to obtain the engine's operating conditions under different states and failing to provide a more comprehensive reference for engine improvement. Summary of the Invention

[0004] This application aims to address the technical problems of existing engine surge testing devices, which suffer from a single pressure regulation method and the inability to induce instantaneous engine surge. Therefore, it provides an engine surge testing device and a method for engine surge testing.

[0005] To solve the above-mentioned technical problems, the technical solution of this application is as follows: an engine surging test device, comprising: an air supply pipeline and a pressure regulating pipeline;

[0006] The gas supply pipeline includes a gas supply mechanism, an electric pressure reducing valve, a first pressure monitoring mechanism, a three-way valve, a first regulating valve, and a first solenoid valve connected in sequence. The electric pressure reducing valve receives the gas pressure information monitored by the first pressure monitoring mechanism and adjusts the valve opening.

[0007] The pressure regulating pipeline includes a second regulating valve and a second solenoid valve connected in sequence, with one end of the second regulating valve connected to the three-way valve.

[0008] Preferably, a flow monitoring mechanism is connected to the rear end of the first regulating valve.

[0009] Preferably, a temperature monitoring mechanism is connected to the rear end of the first solenoid valve.

[0010] Preferably, the temperature monitoring mechanism is connected to a third pressure monitoring mechanism at its rear end.

[0011] Preferably, the front end of the electric pressure reducing valve is connected to a second pressure monitoring mechanism.

[0012] Preferably, the rear end of the electric pressure reducing valve is connected to the rear filter mechanism.

[0013] Preferably, the first pressure monitoring mechanism is a pressure transmitter.

[0014] An engine surge test method is also provided, which uses the engine surge test apparatus described in any of the above claims to conduct the test, including the following steps:

[0015] Connect the rear end of the first solenoid valve to the engine bleed air connector; close the electric pressure reducing valve, the first solenoid valve, and the second regulating valve; open the first regulating valve and the second regulating valve to the same opening degree; open the second solenoid valve; open the air supply mechanism; the electric pressure reducing valve receives pressure feedback from the first pressure monitoring mechanism and automatically adjusts the rear air pressure until it reaches the set value; start the engine; after the engine is running stably, open the first solenoid valve and close the second solenoid valve at the same time, and the engine enters a momentary surge state.

[0016] Preferably, if the engine does not enter a momentary surge state, the opening of the first regulating valve is increased or the set value of the electric pressure reducing valve is increased until the engine surges.

[0017] Preferably, after the engine surge is successfully completed, the first solenoid valve is closed and the second solenoid valve is opened; the engine bleed air connector is disconnected, and the electric pressure reducing valve and the air supply mechanism are closed; then the electric pressure reducing valve is opened again, and the high-pressure gas in the pipeline is discharged through the second regulating valve and the second solenoid valve.

[0018] The technical solution of this application has the following advantages:

[0019] 1. In the engine surge test device provided in this application, when automatic pressure regulation and instantaneous engine surge are required, the first pressure monitoring mechanism monitors the air pressure at the downstream end of the electric pressure reducing valve and provides real-time feedback to the electric pressure reducing valve. The electric pressure reducing valve automatically adjusts the valve opening according to the feedback from the first pressure monitoring mechanism until the air pressure at the downstream end reaches the set value, thus realizing automatic regulation and precise control of the air pressure in the air supply pipeline. The pressure regulating pipeline divides the pressure in the air supply pipeline. By closing the second solenoid valve, the air pressure in the air supply pipeline can be instantly increased to an intake air pressure sufficient to cause engine surge, thereby causing the engine to enter instantaneous surge. Alternatively, the air pressure in the air supply pipeline can be manually adjusted using this device to gradually bring the engine into a surge state. When manual pressure regulation and slow engine surge are required, the electric pressure reducing valve is set to "manual adjustment" mode. After the engine stabilizes, the first solenoid valve is opened, and the electric pressure reducing valve is opened slowly at the same time. As the air supply pressure and flow rate increase, the engine slowly enters the surge state. The study separately investigates the instantaneous surge and gradual surge phenomena of the engine, which will provide a more comprehensive reference for engine improvement.

[0020] 2. In the engine surge test device provided in this application, the flow monitoring mechanism accurately measures the air supply flow rate, which can provide a more comprehensive understanding of the air supply status of the engine surge test, improve the success rate of the surge test, and provide data support for engine surge test research; the third pressure monitoring mechanism accurately measures the engine's air supply pressure, which can provide an understanding of the gas pressure changes in the entire air supply pipeline; the flow monitoring mechanism and the third pressure monitoring mechanism can monitor and regulate the air supply status, realize a surge test with fixed air pressure and fixed flow rate, and facilitate precise control of the engine surge test.

[0021] 3. In the engine surge test device provided in this application, the temperature of the backflow gas at the rear end of the first solenoid valve can be monitored by the temperature monitoring mechanism, so as to know the temperature change of the backflow gas under different engine states when no gas is supplied, providing a reference for engine improvement and also providing reference data for the selection of surge test device equipment.

[0022] 4. In the engine surge test device provided in this application, the airflow in the pipeline is filtered by a filtration mechanism to remove foreign matter in the airflow that could damage the engine, thereby improving the safety of the engine surge test.

[0023] 5. In the engine surge test method provided in this application, the engine surge test device provided in this application is used to precisely control the engine surge test. Through specific operating steps, the engine enters instantaneous surge, which facilitates the acquisition of more comprehensive test information. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the engine breathing test device in the embodiments of this application;

[0026] Figure 2 This is a schematic diagram of the workflow of the engine breathing test method in the embodiments of this application.

[0027] Explanation of reference numerals in the attached diagram: 1. Air supply mechanism; 2. Air guide pipe; 3. Air collection pipe; 4. Second pressure monitoring mechanism; 5. Electric pressure reducing valve; 6. Filtering mechanism; 7. First pressure monitoring mechanism; 8. Three-way valve; 9. First regulating valve; 10. Flow monitoring mechanism; 11. First solenoid valve; 12. Temperature monitoring mechanism; 13. Third pressure monitoring mechanism; 14. Engine air supply pipe; 15. Engine bleed air connector; 16. Second regulating valve; 17. Second solenoid valve. Detailed Implementation

[0028] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] Example 1

[0031] This embodiment provides an engine surge testing device and an engine surge testing method. The engine surge testing device includes: an air supply line and a pressure regulating line, such as... Figure 1As shown, the air supply pipeline includes an air supply mechanism 1, an electric pressure reducing valve 5, a first pressure monitoring mechanism 7, a three-way valve 8, a first regulating valve 9, and a first solenoid valve 11 connected in sequence. The electric pressure reducing valve 5 receives the air pressure information monitored by the first pressure monitoring mechanism 7 and adjusts the valve opening. The pressure regulating pipeline includes a second regulating valve 16 and a second solenoid valve 17 connected in sequence. One end of the second regulating valve 16 is connected to the three-way valve 8. Specifically, the air supply mechanism 1 can be a high-pressure gas tank group. Several high-pressure gas tanks are connected to a gas collecting pipe 3 through a gas guide pipe 2. One end of the gas collecting pipe 3 is then connected to the electric pressure reducing valve 5. The rear end of the first solenoid valve 11 is connected to the engine bleed air connector 15 through the engine air supply pipe 14.

[0032] The working process of the engine surging test device provided in this embodiment is as follows: Compressed air is supplied by a high-pressure gas tank group, introduced into the gas collecting pipe 3 through the gas guide pipe 2, and then collected through the gas collecting pipe 3. It flows through the electric pressure reducing valve 5 and the first pressure monitoring mechanism 7. The first pressure monitoring mechanism 7 monitors the gas pressure information at the downstream end of the electric pressure reducing valve 5 in real time and feeds it back to the electric pressure reducing valve 5, providing a control signal for the electric pressure reducing valve 5. The compressed air is then divided into two paths by the three-way valve 8. One path enters the air supply pipeline, flows through the first regulating valve 9 and the first solenoid valve 11, the engine air supply pipe 14, and the engine bleed air connector 15, and finally enters the engine flow channel. The other path enters the pressure regulating pipeline, which is used for pressure regulation and exhaust. The compressed air in this path flows through the second regulating valve 16 and the second solenoid valve 17 before being discharged into the atmosphere. Among them, the electric pressure reducing valve 5 is used to regulate the air supply pressure, the first regulating valve 9 is used to regulate the air supply flow, the first solenoid valve 11 is used to control the on / off of the air supply, the second regulating valve 16 is used to assist in regulating the air supply pressure, and the second solenoid valve 17 is used to control the on / off of the pressure regulating pipeline.

[0033] To ensure the smooth conduct of the test, equipment checks and foreign object removal can be performed before connecting the engine surge test device to the engine. The specific operating steps are as follows: After completing the equipment installation, check and debug whether each valve and other equipment is working properly; after confirming that each valve and other equipment is working properly, fully open the first regulating valve 9, the second regulating valve 16, the first solenoid valve 11, and the second solenoid valve 17, open 1-2 high-pressure gas tanks, set the electric pressure reducing valve 5 to manual adjustment, fix the engine air supply pipe 14 to the outlet of the exhaust pipe, and slowly open the electric pressure reducing valve 5 until the maximum opening degree, repeating several times to remove foreign objects (easily detachable welding slag, sand, etc.) from the test device pipeline.

[0034] The engine surging test method of this embodiment utilizes the engine surging test device of this embodiment, and can perform two engine surging test methods.

[0035] When it is necessary for the electric pressure reducing valve 5 to automatically adjust pressure and for the engine to enter a momentary suffocation state: connect the rear end of the first solenoid valve 11 to the engine bleed air connector 15; close the electric pressure reducing valve 5, the first solenoid valve 11, and the second regulating valve 16; open the first regulating valve 9 and the second regulating valve 16 to the same opening degree (the opening degree of the first regulating valve 9 and the second regulating valve 16 is determined according to the test air supply quality requirements and repeated debugging); open the second solenoid valve 17; set the electric pressure reducing valve 5 to "automatic adjustment" mode; open the air supply mechanism 1; the electric pressure reducing valve 5 receives pressure feedback from the first pressure monitoring mechanism 7. The system automatically adjusts the downstream air pressure until it reaches the set value. The pressure value at the downstream end of the electric pressure reducing valve 5 is set to P. The first pressure monitoring mechanism 7 feeds back the pressure information at the downstream end of the electric pressure reducing valve 5 to the electric pressure reducing valve 5. The electric pressure reducing valve 5 automatically adjusts its valve opening according to the feedback value from the first pressure monitoring mechanism 7 until the pressure value at the downstream end of the electric pressure reducing valve 5 stabilizes at the value P (this step can also be adjusted after the engine is started and before it enters the forced surge air supply state). The engine is started, and after the engine is running stably, the first solenoid valve 11 is opened, and the second solenoid valve 17 is closed at the same time, and the engine enters the momentary surge state. At this time, if the engine successfully enters the momentary surge state, the test is completed. If the engine does not enter the momentary surge state, the opening of the first regulating valve 9 is increased (increasing the air supply volume) or the set value of the electric pressure reducing valve 5 is increased (increasing the air supply pressure and flow rate) until the engine surges. After the engine surge test is successful, the test phase ends. The equipment should be restored to its original state. The equipment can be restored by following these steps: close the first solenoid valve 11 and open the second solenoid valve 17; disconnect the engine bleed air connector 15 and close the electric pressure reducing valve 5 and the air supply mechanism 1; then open the electric pressure reducing valve 5 again and discharge the high-pressure air in the pipeline through the second regulating valve 16 and the second solenoid valve 17.

[0036] When it is necessary to manually adjust the pressure of the electric pressure reducing valve 5 and slowly bring the engine into a surging state: connect the rear end of the first solenoid valve 11 to the engine bleed air connector 15; close the electric pressure reducing valve 5, open the first regulating valve 9 to a certain degree (the opening degree is determined according to the test air supply quality requirements and repeated adjustments), close the first solenoid valve 11, open the second regulating valve 16 to a certain degree (the opening degree is the same as the opening degree of the first regulating valve 9), and close the second solenoid valve 17; set the electric pressure reducing valve 5 to "manual adjustment" mode; open the air supply mechanism 1; start the engine, and when the engine is running stably, open the first solenoid valve 11, and at the same time slowly open the electric pressure reducing valve 5. As the air supply pressure and flow rate increase, the engine gradually enters the surging state. If the engine does not enter the surging state, the air supply is insufficient, and the test can be stopped. Increase the air supply pressure of the air supply mechanism 1 and then conduct the test again until the engine gradually enters the surging state. After the engine surge test is successful, the test phase ends. The equipment should be restored to its original state. The equipment can be restored by following these steps: close the first solenoid valve 11 and open the second solenoid valve 17; disconnect the engine bleed air connector 15 and close the electric pressure reducing valve 5 and the air supply mechanism 1; then open the electric pressure reducing valve 5 again and discharge the high-pressure air in the pipeline through the second regulating valve 16 and the second solenoid valve 17.

[0037] The aforementioned engine surge test device and method, through the cooperation of the first pressure monitoring mechanism 7 and the electric pressure reducing valve 5, can automatically regulate and precisely control the air pressure in the air collection pipe 3. The pressure regulating pipeline can distribute pressure in the air supply pipeline, and the opening and closing of the second solenoid valve 17 can induce an instantaneous surge state in the engine. Alternatively, the electric pressure reducing valve 5 can be manually adjusted to gradually induce a surge state in the engine. This embodiment can realize both instantaneous and gradual surge in the engine, providing different conditions for engine surge testing, including the surge conditions and reaction phenomena, thus providing a more comprehensive reference for engine improvement.

[0038] Example 2

[0039] This embodiment, as a further improvement to Embodiment 1, includes a flow monitoring mechanism 10, a first solenoid valve 11, a temperature monitoring mechanism 12, and a third pressure monitoring mechanism 13 sequentially connected to the rear end of the first regulating valve 9 in the engine surging test device. A second pressure monitoring mechanism 4 is connected to the front end of the electric pressure reducing valve 5, and a post-filter mechanism 6 is connected to the rear end of the electric pressure reducing valve 5. The first pressure monitoring mechanism 7 is specifically a pressure transmitter.

[0040] Compressed air is collected through the air collection pipe 3 and flows sequentially through the second pressure monitoring mechanism 4, the electric pressure reducing valve 5, the filter mechanism 6, the pressure transmitter, and the three-way valve 8. At the three-way valve 8, the compressed air splits into two pipelines. On one pipeline, the compressed air flows sequentially through the first regulating valve 9, the flow monitoring mechanism 10, the first solenoid valve 11, the temperature monitoring mechanism 12, and the third pressure monitoring mechanism 13 before connecting to the engine. The compressed air also flows through the second regulating valve 16 and the second solenoid valve 17 on the other pipeline. The second pressure monitoring mechanism 4 measures the air pressure at the front end of the electric regulating valve (equivalent to the total pressure in the entire test pipeline), effectively controlling the air supply pressure of the air supply mechanism 1. The flow monitoring mechanism 10 accurately measures the air supply flow rate, providing a more comprehensive understanding of the air supply status during the engine surge test, improving the success rate of the surge test, and providing data support for engine surge test research. The third pressure monitoring mechanism 13 accurately measures the engine's air supply pressure, understanding the gas pressure changes in the entire air supply pipeline. The air supply can be monitored and regulated by the flow monitoring mechanism 10 and the third pressure monitoring mechanism 13 to achieve a forced-surge test with fixed air pressure and flow rate, facilitating precise control of the engine forced-surge test. The temperature monitoring mechanism 12 can monitor the temperature of the backflow gas downstream of the first solenoid valve 11, revealing the temperature changes of the backflow gas under different engine conditions when no air supply is available. This provides a reference for engine improvement and also provides reference data for the selection of forced-surge test equipment. The filtration mechanism 6 filters the airflow in the pipeline, removing foreign substances that could damage the engine and improving the safety of the engine forced-surge test.

[0041] To improve the success rate and safety of experiments, the following points should be considered when selecting equipment:

[0042] 1. The number of high-pressure gas tank sets must be sufficient;

[0043] 2. The pipe joints at both ends of the gas guide pipe 2 must be compatible with the joints of the high-pressure gas tank group and the gas collection pipe 3, and must withstand a pressure ≥ 1.5 times the maximum pressure of the high-pressure gas tank group (recommended value);

[0044] 3. The gas collection pipe 3 is equipped with a plug. After welding and processing, a pressure test should be performed separately. The pressure test pressure should be ≥ 1.5 times the maximum pressure of the high-pressure gas tank group (recommended value).

[0045] 4. The maximum measuring pressure of the second pressure monitoring unit 4 and the third pressure monitoring unit 13 is ≥ 1.2 times the maximum pressure of the high-pressure gas tank group (recommended value). The measuring tube is made of stainless steel (suitable for high-pressure measurement and can prevent gas leakage).

[0046] 5. The electric pressure reducing valve 5 can be selected at room temperature. The pressure before the valve is ≥1.2 times the maximum pressure of the high-pressure gas tank group (recommended value), and the pressure after the valve is ≤ the engine bleed air port pressure.

[0047] 6. Filter mechanism 6 can be equipped with a 5μm filter;

[0048] 7. Pressure transmitter paired with electric pressure reducing valve 5;

[0049] 8. Three-way valve 8 can be selected as a standard stainless steel three-way valve;

[0050] 9. First regulating valve 9, maximum working pressure ≥ 1.2 times the maximum pressure of the high-pressure gas tank group, maximum working temperature ≥ the temperature measured by temperature monitoring mechanism 12, equipped with 4-20mA valve position feedback signal, and equipped with 4-20mA valve position control signal;

[0051] 10. Flow monitoring mechanism 10, measuring range 0-2 times the required gas supply flow rate for the test, pressure: 0-maximum pressure of the high-pressure gas tank group (recommended value), maximum operating temperature ≥ temperature measured by temperature monitoring mechanism 12;

[0052] 11. The first solenoid valve 11 has a maximum working pressure ≥ 1.2 times the maximum pressure of the high-pressure gas tank group and a maximum working temperature ≥ the bleed air temperature of the engine bleed air port.

[0053] 12. Temperature monitoring mechanism 12, the sensor and test line can be the same model as those used for measuring the temperature of the engine bleed air section;

[0054] 13. Engine air supply pipe 14, optional metal hose, working pressure ≥ 3 times the engine bleed air pressure, working temperature ≥ 1.5 times the engine bleed air temperature;

[0055] 14. Engine bleed air connector 15, made of high-temperature resistant material, with a temperature ≥ 1.5 times the bleed air temperature of the engine bleed air inlet;

[0056] 15. Second regulating valve 16, maximum working pressure ≥ 1.2 times the maximum pressure of the high-pressure gas tank group, working temperature: normal temperature, equipped with a 4-20mA valve position feedback signal, equipped with a 4-20mA valve position control signal, and the same diameter as the first regulating valve 9;

[0057] 16. Second solenoid valve 17, maximum working pressure ≥1.2 pressure of high-pressure gas tank group, working temperature room temperature.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for engine power surge testing, characterized in that, The engine surging test device is used to conduct the test, which includes an air supply line and a pressure regulating line. The gas supply pipeline includes a gas supply mechanism (1), an electric pressure reducing valve (5), a first pressure monitoring mechanism (7), a three-way valve (8), a first regulating valve (9), and a first solenoid valve (11) connected in sequence. The electric pressure reducing valve (5) receives the gas pressure information monitored by the first pressure monitoring mechanism (7) and adjusts the valve opening. The pressure regulating pipeline includes a second regulating valve (16) and a second solenoid valve (17) connected in sequence, and one end of the second regulating valve (16) is connected to the three-way valve (8); The experimental method includes the following steps: Connect the rear end of the first solenoid valve (11) to the engine bleed air connector (15); close the electric pressure reducing valve (5), the first solenoid valve (11) and the second regulating valve (16), open the first regulating valve (9) and the second regulating valve (16) to the same opening degree, and open the second solenoid valve (17); open the air supply mechanism (1); the electric pressure reducing valve (5) receives pressure feedback from the first pressure monitoring mechanism (7) and automatically adjusts the rear air pressure until it reaches the set value; start the engine, and when the engine is working stably, open the first solenoid valve (11) and close the second solenoid valve (17) at the same time, and the engine enters the instantaneous surge state.

2. The engine surge test method according to claim 1, characterized in that, The first regulating valve (9) is connected to a flow monitoring mechanism (10) at its rear end.

3. The engine surge test method according to claim 1, characterized in that, The rear end of the first solenoid valve (11) is connected to a temperature monitoring mechanism (12).

4. The engine surge test method according to claim 3, characterized in that, The temperature monitoring mechanism (12) is connected to a third pressure monitoring mechanism (13) at its rear end.

5. The engine surge test method according to claim 1, characterized in that, The electric pressure reducing valve (5) is connected to a second pressure monitoring mechanism (4) at its front end.

6. The engine surge test method according to claim 1, characterized in that, The rear end of the electric pressure reducing valve (5) is connected to the rear filter mechanism (6).

7. The engine surge test method according to any one of claims 1-6, characterized in that, The first pressure monitoring device (7) is a pressure transmitter.

8. The engine surge test method according to claim 1, characterized in that, If the engine does not enter a momentary surge state, increase the opening of the first regulating valve (9) or increase the setting value of the electric pressure reducing valve (5) until the engine surges.

9. The engine surge test method according to claim 1 or 8, characterized in that, After the engine surge is successfully completed, close the first solenoid valve (11) and open the second solenoid valve (17); disconnect the engine bleed air connector (15), close the electric pressure reducing valve (5) and the air supply mechanism (1); then open the electric pressure reducing valve (5) again, and discharge the high-pressure gas in the pipeline through the second regulating valve (16) and the second solenoid valve (17).

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