Exhaust system and method for a high-altitude negative pressure turbine simulation test bench based on multiple levels in series

Abstract

The application discloses a high-altitude negative pressure turbine simulation test bench exhaust system and method based on multistage series connection, which is used for a turbine test section and comprises an exhaust volute, a three-stage centrifugal device, a three-stage heat exchange device and a sound attenuation tower. The exhaust volute outlet is connected with a primary heat exchanger through a pipeline, and an atmospheric air supplement main valve and an atmospheric air supplement auxiliary valve are arranged on the pipeline. The three-stage centrifugal device is communicated with the sound attenuation tower through a pipeline. The three-stage heat exchange device is connected with the three-stage centrifugal device in a graded series connection mode. Through the combination of the three-stage heat exchange device and the industrial three-stage centrifugal device in a multistage series connection mode, the application simulates various extreme working condition technical indexes of the turbine at an altitude of ten thousand meters, realizes the low-cost negative pressure extraction effect of the high-altitude negative pressure turbine simulation test bench, and meets the long-time working requirement.

Description

Technical Field

[0001] This invention relates to the field of turbine test bench technology, specifically to an exhaust system and method for a high-altitude negative pressure turbine simulation test bench based on multi-stage series connection. Background Technology

[0002] As the "heart" of an aircraft, the performance of the aero-engine directly affects the safe operation of the aircraft. During high-altitude, high-speed operation, aero-engines constantly face extreme and harsh environmental conditions such as low pressure, thin air, high speed, and strong noise. The turbine, as one of the components operating in the harshest environment, experiences a drop in Reynolds number to 0.25 × 10⁻⁶ at altitudes of 10,000 meters due to the low atmospheric density. 5 Below this threshold, which is much lower than the self-modeled Reynolds number, the aerodynamic properties such as the operating point pressure ratio and flow rate will change, and the efficiency will drop sharply, restricting the high-altitude, high-speed performance of the aircraft. Therefore, it is urgent to simulate the real working state of the turbine in the harsh environment of high altitude in turbine testing, especially more realistic turbine exhaust negative pressure conditions. This places higher demands on the exhaust system of the high-altitude turbine test bench.

[0003] The exhaust system of a high-altitude turbine test rig simulates the temperature, negative pressure, and flow conditions of an aircraft flying at different altitudes by establishing different extraction conditions. To simulate negative pressure (pressure below one atmosphere), the patent "An Exhaust Back Pressure Adjustment System and Method Applicable to a Turbine Test Rig (CN 113588233 A)" proposes using an ejector to inject gas into the exhaust pipe. Because the injected gas is a high-speed, high-energy flow, the pressure energy is converted into velocity energy through the ejection effect, causing a pressure drop in the exhaust pipe connection area and creating a vacuum, thus simulating negative pressure conditions. This ejector has a wide adjustment range, from positive to negative pressure, but it requires a large gas source, resulting in high investment costs. The patent "Digital Simulation Method for High-Altitude Test Rig Extraction Units Based on Simulink (CN 115585145 A)" simulates high-altitude negative pressure conditions through dynamic simulation of axial-flow extraction units. However, real axial-flow extraction units have a single installed power of tens of thousands of kilowatts or more, resulting in high equipment power, high energy consumption during test operation, and potential safety hazards and test risks. Summary of the Invention

[0004] To address the aforementioned technical problems in the existing technology, this invention provides an exhaust system and method for a high-altitude negative pressure turbine simulation test bench based on multi-stage series connection.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: It includes an exhaust volute, a three-stage centrifuge unit, a three-stage heat exchanger unit, and a silencer tower; the outlet of the exhaust volute is connected to the first-stage heat exchanger via a pipeline, and an atmospheric air supply main valve and an atmospheric air supply auxiliary valve are installed on the pipeline; the three-stage centrifuge unit is connected to the silencer tower via a pipeline; the three-stage heat exchanger unit and the three-stage centrifuge unit are connected in series in stages; the three-stage heat exchanger unit includes a first-stage heat exchanger, a second-stage heat exchanger, and a third-stage heat exchanger; the three-stage centrifuge unit includes a first-stage centrifuge unit and a second-stage centrifuge unit. The system includes a three-stage centrifuge unit; the outlet of the first-stage heat exchanger is equipped with a first suction switch valve, which is connected to the inlet of the first-stage centrifuge unit via a pipeline; the outlet of the first-stage centrifuge unit is equipped with a third suction switch valve, which is connected to the second-stage heat exchanger via a pipeline; the second-stage heat exchanger is connected to the second-stage centrifuge unit via a gas pipeline; the second-stage centrifuge unit is connected to the third-stage heat exchanger via a gas pipeline; and the third-stage heat exchanger is connected to the third-stage centrifuge unit via a gas pipeline; each of the three-stage centrifuge units is equipped with an exhaust silencer and a vent valve.

[0006] Furthermore, the outlet of the turbine test section is connected to the exhaust volute, which is designed with constant flow velocity in aerodynamics. The exhaust velocity inside the exhaust volute is ≤50m / s, and the cross-section of the exhaust volute flow channel is circular.

[0007] Furthermore, a second suction switch valve is installed on the gas pipeline branch at the outlet of the first-stage heat exchanger, and the second suction switch valve is connected to the inlet of the second-stage heat exchanger.

[0008] An exhaust method for an exhaust system based on a multi-stage series high-altitude negative pressure turbine simulation test bench includes the following steps:

[0009] S1, Centrifuge Unit Flow Matching: Quality of Inlet Flow Rate of the Unit In the formula, For the density of the imported gas, For intake speed, Given the cross-sectional area of ​​the inlet pipe, calculate the inlet flow volume. Based on the flow-pressure ratio performance curve of the primary centrifuge unit, the pressure ratio is selected. In the formula This refers to the total inlet pressure of the centrifuge unit. The total outlet pressure of the centrifuge unit is [value]; the outlet flow rate is [value]. According to the gas continuity equation and the gas law The gas density after passing through the extraction unit was derived. The corresponding flow volume is Export speed is Heat exchangers were added between the various heat exchange stages to cool the compressed gas. Then the mass of the intake air flow of the next stage centrifuge unit is The pressure loss during the cooling process is Meanwhile, the pressure loss of gas flow in the pipeline is Then the next stage intake pressure ratio is Based on the flow-pressure ratio performance curve of the two-stage centrifuge unit, the pressure ratio is selected. Similarly, flow matching is performed on the latter two stages to ensure that the outlet flow of the three-stage centrifuge unit satisfies the mass flow conservation rule, while the total pressure ratio of the three-stage centrifuge unit is also optimized. ,ensure , Standard atmospheric pressure;

[0010] S2, Obtain centrifuge unit speed: based on the flow rate provided by the predetermined test conditions. and negative pressure Based on the flow-pressure ratio performance curves of the centrifuge units, and the calculated pressure ratios of the first-stage, second-stage, and third-stage centrifuge units, respectively... 、 、 The corresponding rotational speed is obtained as follows: , , ;

[0011] S3, Negative Pressure Exhaust: Close the main and auxiliary valves of the turbine regulator's atmospheric air supply to ensure that the intake air of the centrifugal unit enters the exhaust tower through its own vent valve; start the turbine vacuum machines inside the first-stage, second-stage, and third-stage centrifugal units in sequence, open the built-in vent valves, and perform thorough evacuation by centrifugal pumping, adjusting to the predetermined speed. , , Open the main valve for regulating atmospheric air supply to the turbine intake, and gradually close the vent valve of the centrifugal device. By adjusting the auxiliary valve for atmospheric air supply and the frequency converter control of the centrifugal device, the negative pressure state is controlled, and a predetermined negative pressure is generated at the exhaust volute outlet. The high-temperature gas is drawn in by the negative pressure generated by the extraction unit, and then cooled step by step through the heat exchange device. Finally, it flows into the silencer tower for noise reduction and cooling before being discharged into the atmosphere.

[0012] Furthermore, the second suction switch valve directs the gas discharged from the exhaust volute through the gas pipeline of the branch line to the secondary centrifuge unit, and closes the first suction switch valve and the third suction switch valve.

[0013] The technical effects of this invention are:

[0014] 1. This invention uses a centrifugal vacuum pump for vacuuming operations. Compared with traditional methods, it significantly reduces the construction cost of the test bench in terms of investment scale, economic efficiency, and technical difficulty of construction and operation. At the same time, it has a compact structure and saves a lot of space.

[0015] 2. The exhaust negative pressure system of the present invention adopts a combination of three-stage heat exchange and three-stage centrifugal device to generate the required negative pressure at the turbine test section outlet. The staged heat exchange reduces the impact of high temperature on centrifugal exhaust and improves the overall system's working margin, thereby simulating the turbine's operating state in a high-altitude, low Reynolds number environment and solving the problem of simulating the negative pressure limit of a high-altitude turbine test bench in the existing technology.

[0016] 3. This invention includes three sets of industrial-grade centrifugal pumping units, among which the main features of the single-unit turbine vacuum machine are high efficiency, low energy consumption, and low efficiency, in order to meet the technical requirements of long-term continuous operation; it is equipped with a complete automatic control system, providing a technical basis for studying the operating status of the turbine under different working conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 This is a simplified flowchart of the structure of the present invention;

[0019] Figure 3 This is a flow-pressure ratio performance curve of a primary centrifuge unit;

[0020] Figure 4 This is a flow-pressure ratio performance curve of a two-stage centrifuge unit;

[0021] Figure 5 This is a flow-pressure ratio performance curve of a three-stage centrifugal chiller unit.

[0022] 1. Turbine test section; 2. Exhaust volute; 3. First-stage heat exchanger; 4. First-stage centrifuge unit; 5. Second-stage heat exchanger; 6. Silencer tower; 7. Second-stage centrifuge unit; 8. Third-stage heat exchanger; 9. Third-stage centrifuge unit; 10. First suction switch valve; 11. Second suction switch valve; 12. Third suction switch valve; 13. Atmospheric air supply main valve; 14. Atmospheric air supply auxiliary valve. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0024] like Figure 1As shown, the present invention provides an exhaust system for a high-altitude negative pressure turbine simulation test bench based on multi-stage series connection, including a turbine test section 1, an exhaust volute 2, a three-stage centrifuge device, a three-stage heat exchange device, and a silencer tower; the outlet of the exhaust volute 2 is connected to the first-stage heat exchanger 3 through a pipeline, and an atmospheric air supply main valve 13 and an atmospheric air supply auxiliary valve 14 are installed on the pipeline; the three-stage centrifuge device is connected to the silencer tower through a pipeline; the three-stage heat exchange device and the three-stage centrifuge device are connected in series in stages.

[0025] The three-stage heat exchange device includes a primary heat exchanger 3, a secondary heat exchanger 5, and a tertiary heat exchanger 8; the primary heat exchanger 3 is connected to the inlet of the primary centrifuge unit 4 via a pipeline.

[0026] The three-stage centrifuge unit includes a primary centrifuge unit 4, a secondary centrifuge unit 7, and a tertiary centrifuge unit 9. A first suction switch valve 10 is installed at the outlet of the primary heat exchanger 3. The first suction switch valve 10 is connected to the primary centrifuge unit 4 via a pipeline. A third suction switch valve 12 is installed at the outlet of the primary centrifuge unit 4. The third suction switch valve 12 is connected to the secondary heat exchanger 5 via a pipeline. The secondary heat exchanger 5 is connected to the secondary centrifuge unit 7 via a pipeline. The secondary centrifuge unit 7 is connected to the tertiary heat exchanger 8 via a pipeline. The tertiary heat exchanger 8 is connected to the tertiary centrifuge unit 9 via a pipeline. Each of the three-stage centrifuge units is equipped with an exhaust silencer and a vent valve.

[0027] The exhaust volute 2 adopts a constant flow velocity design in aerodynamic design; the exhaust velocity inside the exhaust volute 2 is ≤50m / s; the cross-section of the flow channel of the exhaust volute 2 adopts a circular shape with strong pressure resistance.

[0028] The gas pipeline branch at the outlet of the exhaust volute 2 is equipped with a first suction switch valve and a second suction switch valve. The first suction switch valve controls the gas to flow to the inlet of the first-stage heat exchanger 3, and the second suction switch valve controls the gas to flow to the inlet of the second-stage heat exchanger 5.

[0029] In one embodiment of the present invention, such as Figure 2 This paper introduces a method for negative pressure extraction of exhaust gas on a high-altitude turbine test bench, including the following steps:

[0030] S1, Centrifuge Unit Flow Matching: Quality of Inlet Flow Rate of the Unit In the formula, For the density of the imported gas, For intake speed, Given the cross-sectional area of ​​the inlet pipe, calculate the inlet flow volume. Based on the flow-pressure ratio performance curve of centrifuge unit 1, the pressure ratio is selected. In the formula This refers to the total inlet pressure of the centrifuge unit. The total outlet pressure of the centrifuge unit is [value]; the outlet flow rate is [value]. According to the gas continuity equation and the gas law The gas density after passing through the extraction unit was derived. The corresponding flow volume is Export speed is To prevent overheating during multiple gas compression processes, heat exchangers are added between each heat exchange stage to cool the compressed gas. Then the mass of the intake air flow of the next stage centrifuge unit is There will be pressure loss during the cooling process. Meanwhile, the pressure loss of gas flow in the pipeline is Then the next stage intake pressure ratio is Based on the flow-pressure ratio performance curve of the next-stage centrifuge unit 2, the pressure ratio is selected. Similarly, flow matching is performed on the latter two stages to ensure that the outlet flow of the three-stage centrifuge unit satisfies the mass flow conservation rule, while the total pressure ratio of the three-stage centrifuge unit is also optimized. ,ensure , The pressure is standard atmospheric pressure. The three-stage centrifugal unit used in this system can reasonably allocate the pressure ratio to maximize the utilization efficiency of each stage of the centrifuge unit, ensure the coordination and matching between flow rate and total pressure ratio, and prevent the unit from entering the surge region during operation.

[0031] S2, Obtain centrifuge unit speed: based on the flow rate provided by the predetermined test conditions. and negative pressure Based on the flow-pressure ratio performance curves of the centrifuge units, and the calculated pressure ratios of the first-stage, second-stage, and third-stage centrifuge units, respectively... 、 、 The corresponding rotational speed is obtained as follows: , , .

[0032] S3, Negative Pressure Exhaust: Close the main and auxiliary valves of the turbine regulator's atmospheric air supply to ensure that the intake air of the centrifugal unit enters the exhaust tower through its own vent valve; sequentially start the turbine vacuum machines inside the first-stage centrifugal unit 4, the second-stage centrifugal unit 7, and the third-stage centrifugal unit 8, open the built-in vent valves, and fully evacuate the air using centrifugal evacuation, adjusting to the predetermined speed. , , Open the main air supply valve 11 for regulating the turbine intake, and gradually close the vent valve of the centrifugal device. By adjusting the auxiliary air supply valve 12 and the frequency converter of the centrifugal device, the negative pressure state is controlled, and a predetermined negative pressure is generated at the outlet of the exhaust volute 2. The high-temperature gas is drawn in by the negative pressure generated by the extraction unit, and is cooled down step by step by the heat exchange device. Finally, it flows into the silencer tower 6 for noise reduction and cooling before being discharged into the atmosphere.

[0033] In this invention, the three-stage heat exchange device cools the gas entering the centrifuge unit and exchanges heat with cold water. All three heat exchangers can achieve the effect of cooling the gas to below 50°C, making the negative pressure effect generated by the centrifuge unit more significant.

[0034] Figure 3 , Figure 4 and Figure 5 These are the characteristic curves of gas flow rate versus corresponding pressure ratio at different speeds for the first-stage, second-stage, and third-stage centrifuge units of this invention. Based on the operating conditions of different turbine states, including inlet pressure and inlet flow rate, the pressure ratio of each centrifuge unit is calculated using the characteristic curves of the three-stage centrifuge unit, thus achieving the overall negative pressure function of the turbine test section. This design can set a predetermined negative pressure effect within a wide range of design operating conditions, making the high-altitude simulation of the high-altitude turbine test bench more closely match the requirements.

[0035] In one embodiment of the present invention, based on the flow-pressure ratio characteristic curve of the three-stage centrifugal device, the combination of three-stage heat exchange and three-stage centrifugal can achieve a minimum negative pressure of 0.12 bar; the pressure ratios of the first-stage centrifugal unit, the second-stage centrifugal unit, and the third-stage centrifugal unit are 2.17, 2.26, and 2.29, respectively, using the formula... Calculation Before entering the centrifuge unit, the high-temperature gas is cooled to 50°C by a heat exchanger; the pressure loss of gas flow in the pipeline includes the pressure loss of the heat exchanger and the overall pressure loss of the pipeline bends, which is... =0.09 bar; when discharged into the atmosphere, The pressure difference with the outside atmosphere is 0.1 bar, which is sufficient to compensate for the overall pipeline pressure difference. Considering a 10% margin, the total pressure increase ratio of the centrifugal chiller unit is 9.2, which is less than the current maximum total pressure ratio of 12.26, and has sufficient capability to achieve a minimum negative pressure of 0.12 bar.

Claims

1. A multi-stage series-based high-altitude negative pressure turbine simulation test bench exhaust system for a turbine test section, characterized by: The exhaust volute, the three-stage centrifuge device, the three-stage heat exchange device and the sound elimination tower are included; the exhaust volute outlet is connected with the primary heat exchanger through a pipeline, and the pipeline is provided with an atmospheric air supplement main valve and an atmospheric air supplement auxiliary valve; the three-stage centrifuge device is communicated with the sound elimination tower through a pipeline; the three-stage heat exchange device is connected with the three-stage centrifuge device in series; the three-stage heat exchange device includes a primary heat exchanger, a secondary heat exchanger and a tertiary heat exchanger; the three-stage centrifuge device includes a primary centrifuge group, a secondary centrifuge group and a tertiary centrifuge group; the primary heat exchanger outlet is provided with a first suction switch valve connected with the primary centrifuge group inlet through a pipeline; the primary centrifuge group outlet is provided with a third suction switch valve connected with the secondary heat exchanger through a pipeline; the secondary heat exchanger is communicated with the secondary centrifuge group through a gas pipeline; the secondary centrifuge group is connected with the tertiary heat exchanger through a gas pipeline; the tertiary heat exchanger is connected with the tertiary centrifuge group through a gas pipeline; the three-stage centrifuge device is provided with an exhaust silencer and a vent valve.

2. The multi-stage series high-altitude negative pressure turbine simulation test bench exhaust system according to claim 1, characterized in that: The turbine test section outlet is connected with the exhaust volute, the exhaust volute adopts the equal flow velocity design in the aerodynamic design, the exhaust volute internal exhaust velocity is less than or equal to 50 m / s, and the exhaust volute flow passage section is circular.

3. The multi-stage series high-altitude negative pressure turbine simulation test bench exhaust system according to claim 1, characterized in that: The primary heat exchanger outlet gas pipeline branch is provided with a second suction switch valve connected with the secondary heat exchanger inlet.

4. The exhaust method of the high-altitude negative pressure turbine simulation test bench exhaust system based on the multi-stage series connection according to claim 3, comprising the following steps: S1, centrifugal unit flow matching: unit inlet flow mass , where is the inlet gas density, is the inlet gas velocity, is the inlet duct cross-sectional area; the inlet flow volume is then calculated as , based on the flow pressure ratio performance curve of the primary centrifugal unit, the pressure ratio is selected as , where is the total pressure at the inlet of the centrifugal unit, is the total pressure at the outlet of the centrifugal unit; The outlet flow rate is ; according to the gas continuity equation and the gas state equation , the gas density after the air extraction unit is derived as , the corresponding flow volume is , and the outlet velocity is ; heat exchangers are added between each stage of heat exchange to cool the compressed gas to , so that the inlet flow rate mass of the next centrifugal unit is ; the pressure loss during the cooling process is , and the pressure loss of the gas flow in the pipeline is , so that the next stage inlet pressure ratio is , based on the flow pressure ratio performance curve of the two-stage centrifugal unit, the pressure ratio is selected, and the flow rate of the next two stages is matched in the same way so that the outlet flow rate of the three-stage centrifugal unit satisfies the mass flow conservation, and the total pressure ratio of the three-stage centrifugal device is , ensuring that , is the standard atmospheric pressure; S2, obtaining the rotating speed of the centrifugal unit: according to the flow provided by the predetermined test working condition and negative pressure , combining the flow-pressure ratio performance curve of the centrifugal unit, and the obtained pressure ratio of the first centrifugal unit, the second centrifugal unit and the third centrifugal unit respectively 、 、 , the corresponding rotating speed is 、 、 ; S3, negative pressure exhaust: close the turbine adjustment atmospheric air supply main valve and auxiliary valve, ensure the suction of centrifugal device through its vent valve into the exhaust tower; start the turbine vacuum machine in the first, second and third centrifugal machine groups in sequence, open the built-in vent valve, fully exhaust by centrifugal exhaust method, and adjust to the predetermined speed , , ; The turbine intake adjusting atmospheric air supplement main valve is opened, the centrifuge device vent valve is gradually closed, the negative pressure state is controlled through the atmospheric air supplement auxiliary valve and the centrifuge device frequency conversion control, the predetermined negative pressure is generated at the exhaust volute outlet, the high-temperature gas is sucked through the negative pressure generated by the air suction group, and is gradually cooled through the heat exchange device, and finally flows into the sound elimination tower for sound elimination and cooling treatment and then is discharged into the atmosphere.

5. The exhaust method of the high-altitude negative pressure turbine simulation test bench exhaust system based on multi-stage series connection according to claim 4, characterized in that: The second suction switch valve connects the exhaust volute exhaust gas with the secondary centrifuge group through the branch gas pipeline, and the first suction switch valve and the third suction switch valve are closed.

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