A semi-infinite length regular polygon pressure conduit measuring system

Abstract

This invention discloses a semi-infinitely long regular polygonal pressure tapping tube measurement system, belonging to the field of gas turbine pressure measurement. When measuring the pulsating pressure of unstable combustion, the sensor cannot be directly installed on the wall of the cavity to be measured due to the high temperature of the gas. A pressure tapping tube is needed to extract the pressure signal for measurement. Traditional semi-infinitely long circular pressure tapping tubes, due to their physical structure, create a gas chamber cavity with abrupt flow changes at the pressure sensor installation location, resulting in pressure reflection and affecting measurement accuracy. This invention discloses several novel regular polygonal pressure tapping tube structures that do not change the flow area within the pressure tapping tube after the pressure sensor is connected. Simultaneously, a pressure sensor mounting base is provided on the side wall of the pressure tapping tube to control the insertion depth of the pressure sensor, ensuring that the end face of the inserted pressure sensor is flush with the inner flow channel surface of the pressure tapping tube. Structurally, this avoids the formation of a gas chamber, thereby improving the measurement accuracy of the pressure signal.

Description

Technical Field

[0001] This invention belongs to the field of gas turbine combustion pressure measurement and relates to a novel pressure sampling tube, specifically a pressure sampling device that outputs the acoustic pressure signal of the pressure field to be measured and then connects it to a pressure sensor for measurement. Background Technology

[0002] In aero-engine combustors, fluctuations in fuel equivalence ratio can trigger heat release fluctuations in the combustion field, leading to combustion instability. Combustion chamber pressure pulsation is often monitored as a crucial parameter in combustion instability research. However, due to the extremely high operating temperatures of the combustion gases (exit temperatures reaching 2000K), which significantly exceed the temperature limits of pressure sensors, they cannot be directly installed at the measurement location. Therefore, a pressure sampling device (pressure sampling tube) is typically used to sample air from the measurement location and measure the pressure pulsation characteristics of the sample air within the pressure sampling tube to characterize the pressure pulsation of the combustion field.

[0003] Current research on pressure taps in combustion instability is relatively limited, with most studies focusing on semi-infinite circular pressure taps. Pressure sensors are mounted on the sidewall of these taps to measure the pulsating pressure field. However, the measuring face of the pressure sensor is a smooth plane. Due to physical limitations, mounting it on the sidewall of a circular pressure tap creates a gas chamber with abrupt flow changes at the measurement location. The presence of this gas chamber causes irregular reflections of the pressure wave, resulting in significant errors in the obtained pressure pulsation amplitude and frequency. Summary of the Invention

[0004] To address the aforementioned shortcomings, this invention provides a novel pressure-sensing tube device. By altering the shape of the pressure-sensing tube and incorporating a pressure sensor mounting base, the sampled air flows within a uniform and distortion-free elongated cavity, reducing non-uniform reflections during pressure wave propagation and lowering measurement errors.

[0005] This invention is implemented as follows:

[0006] A semi-infinitely long regular polygonal pressure-sensing tube device is disclosed, the main body of which is a slender regular polygonal pressure-sensing tube. A threaded head is provided at the front of the pressure-sensing tube, and the threaded head is threaded to allow it to be installed on the wall of the cavity to be measured. A pressure sensor mounting base is provided on one side wall of the polygonal pressure-sensing tube, and the pressure sensor can be directly inserted into the mounting base to measure the air pulsation pressure in the combustion chamber.

[0007] Furthermore, in order to ensure that the flow area of ​​the pressure tapping tube does not change abruptly, the size and flow area of ​​the internal flow channel of the threaded head must be the same as those of the internal flow channel of the pressure tapping tube.

[0008] Furthermore, since the pressure sensor is a standard component with a smooth end face, to avoid the formation of an air chamber on the side wall of the pressure tap after the pressure sensor is connected, the side wall with the mounting base should be a smooth plane, and the width of this wall should be greater than the diameter of the pressure sensor.

[0009] Furthermore, since the pressure sensor is directly inserted into the mounting base, a limiting platform is set on the mounting base to ensure that the end face of the pressure sensor is flush with the inner wall of the pressure tapping tube. Therefore, traditional pressure sensors also need to be machined with corresponding bosses.

[0010] This invention also discloses several commonly used polygonal pressure-sensing tube structures, which can be categorized by the geometric shape of the flow cross-section, including regular hexagons, squares, and equilateral triangles. When measuring pulsating pressures due to unstable combustion, the high temperature of the combustion gas prevents the sensor from being directly mounted on the wall of the chamber to be measured; a pressure-sensing tube is required to extract the pressure signal for measurement. Traditional semi-infinite circular pressure-sensing tubes, due to their physical structure, create a gas chamber cavity with abrupt flow changes at the pressure sensor's mounting location, causing uneven emission of pressure waves and affecting measurement accuracy. This invention discloses several novel regular polygonal pressure-sensing tube structures. Through innovative design of the internal flow channel of the pressure-sensing tube, the flow area of ​​the internal flow field is not changed after the pressure sensor is connected. Simultaneously, a pressure sensor mounting base is provided on the side wall of the pressure-sensing tube to control the insertion depth of the pressure sensor, ensuring that the end face of the inserted pressure sensor is flush with the internal flow channel surface of the pressure-sensing tube. Structurally, this avoids the formation of a gas chamber, thereby improving the measurement accuracy of the pressure signal.

[0011] The advantages of this invention compared to the prior art are as follows:

[0012] 1) The semi-infinite polygonal pressure-sensing tube of this invention alters the geometry of the tube so that its internal flow channel geometry remains unchanged when connected to a pressure sensor, preventing the formation of an air chamber at the pressure sensor connection point. This avoids experimental errors caused by irregular reflections of pressure waves in pressure field measurement experiments.

[0013] 2) A limiting platform is set on the mounting base of the pressure sensor. This structure can precisely control the depth of the pressure sensor inserted into the polygonal pressure tapping tube, ensuring that the end face of the pressure sensor is flush with the inner flow channel of the pressure tapping tube. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of traditional pressure tap measurement;

[0015] Figure 2 This is a schematic diagram of the structure of the semi-infinitely long regular hexagonal pressure-sensing tube of the present invention;

[0016] Figure 3 This is a conventional structural diagram of the semi-infinitely long regular polygonal pressure tube of the present invention.

[0017] Among them, 1-threaded head, 201-regular hexagonal pressure tap, 3-pressure sensor mounting base, 4-limiting platform, 5-pressure sensor, 6-bore, 202-regular quadrilateral pressure tap, 203-regular triangular pressure tap, 204-cylindrical pressure tap, 001-test cavity, 002-air chamber. Detailed Implementation

[0018] To make the objectives and effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0019] In the process of pressure field measurement, to reduce measurement errors, the reflection of pressure waves inside the pressure tapping tube should be avoided as much as possible. Ideally, an infinitely long pressure tapping tube structure would be used to sample the pressure field, that is, a pressure sensor would be installed at the outlet of the pressure tapping tube and the pressure sensor would be infinitely far from the sampling position. However, in practical applications, due to space and cost limitations, the requirement of "infinite length" cannot be achieved. Therefore, a semi-infinitely long pressure tapping tube is generally used, that is, the outlet of the pressure tapping tube is in an open state, and the pressure wave flows into the atmosphere after passing through the pressure tapping tube, thereby avoiding the reflection of the pressure wave. This invention mainly innovates on the semi-infinitely long pressure tapping tube.

[0020] In practical applications of semi-infinite pressure tapping tubes, pressure sensors can only be installed on the side wall of the tube, such as... Figure 1 As shown. Because the measuring end face of the pressure sensor is a smooth plane (circular surface), inserting it into the circular pressure tapping tube 204 will create a gas chamber 002 with a structural abrupt change at the insertion position. Since the insertion depth of the pressure sensor is difficult to control, the geometry of the gas chamber also varies randomly. This gas chamber has a significant impact on the geometry of the pressure tapping tube flow channel, thereby causing pressure wave reflection and altering the vibration amplitude and frequency of the pressure wave. The innovative challenge of this invention lies in how to avoid the generation of the gas chamber 002.

[0021] like Figure 2 The diagram shows an application scenario of the regular hexagonal pressure-sensing tube of the present invention. The regular hexagonal pressure-sensing tube 201 is installed on the cavity 001 by engaging the thread of the threaded head 1 with the cavity 001 to be tested. The thread dimensions are determined by the wall thickness and characteristic diameter of the regular polygonal pressure-sensing tube. The geometry and dimensions of the inner wall of the threaded head are the same as those of the inner wall of the pressure-sensing tube body.

[0022] This invention provides a pressure sensor mounting base 3 on the side wall of the pressure tapping tube. The mounting base consists of two concentric cylindrical holes. The smaller cylindrical hole is used to install the pressure sensor, and the larger cylindrical hole and the smaller cylindrical hole form a step due to the diameter difference, which is called a limiting platform 4. When a matching boss 6 is designed on the pressure sensor 5, the insertion depth of the pressure sensor can be limited.

[0023] To avoid the formation of air chamber 002 in the pressure tapping tube flow channel, the inner flow channel of the polygonal pressure tapping tube has dimensional requirements. Specifically, the width of the inner wall of the side where the pressure sensor is installed should be greater than the diameter of the pressure sensor.

[0024] To meet the installation requirements of pressure sensors, this paper discloses several structures of regular polygonal pressure taps, such as... Figure 3 As shown, the pressure-sensing tubes are a regular hexagonal, a regular quadrilateral, and a regular triangular shape, respectively. Our team's acoustic numerical calculations demonstrate that, with the same characteristic diameter, the sound pressure level difference between any point inside the cylindrical pressure-sensing tube and the monitoring point (the access point of the cavity under test 001) is the same for both the regular polygonal and cylindrical tubes. This indicates that the semi-infinitely long regular polygonal pressure-sensing tube can accurately characterize the pulsation characteristics of the pressure wave at the monitoring location. Compared to the traditional cylindrical pressure-sensing tube, it avoids the reflection of sound waves by the air chamber generated by the pressure sensor connection, thus improving the accuracy of the measurement results.

[0025] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A semi-infinite length regular polygon pressure tap measurement system, characterized by, The system includes: The pressure tube is a regular polygonal pressure tube, a threaded head (1) located at the front end of the regular polygonal pressure tube, and a pressure sensor mounting base (3) located on the side wall of the regular polygonal pressure tube. The inner flow channel of the threaded head (1) has the same size and shape as the inner flow channel of the regular polygonal pressure tube.

2. A semi-infinite length regular polygon pressure tap measurement system according to claim 1, wherein, The main body of the regular polygon pressure tube is a slender, semi-infinite regular polygon pressure tube; the regular polygon pressure tube includes: a regular hexagonal pressure tube (201), a regular quadrilateral pressure tube (202), an equilateral triangular pressure tube (203), and a cylindrical pressure tube (204).

3. A semi-infinite regular polygonal draft tube measurement system according to claim 2, wherein, Under the same characteristic diameter, the sound pressure level difference between any point inside the tube and the monitoring point obtained by the regular hexagonal pressure tube (201), the regular quadrilateral pressure tube (202), the regular triangular pressure tube (203), and the cylindrical pressure tube (204) is the same; the regular polygonal pressure tube can accurately characterize the pulsation characteristics of the pressure wave at the monitoring position, and can avoid the reflection of sound waves by the air chamber generated by the pressure sensor connection, thereby improving the accuracy of the measurement results.

4. A semi-infinite length regular polygon pressure tap measurement system according to claim 1, wherein, The pressure sensor mounting base (3) is provided on the side wall of the regular polygonal pressure tapping tube. The pressure sensor mounting base (3) consists of two concentric cylindrical holes of different sizes. The smaller cylindrical hole is used to install the pressure sensor (5). The step between the larger cylindrical hole and the smaller cylindrical hole is a limiting platform (4). The limiting platform (4) is used to limit the insertion depth of the pressure sensor (5) to ensure that the end face of the pressure sensor (5) is flush with the inner flow channel surface of the regular polygonal pressure tapping tube.

5. A semi-infinite length regular polygonal draft tube measurement system according to claim 4, wherein, The pressure sensor (5) is provided with a matching boss (6), which limits the insertion depth of the pressure sensor (5).

6. A semi-infinite regular polygonic pressure tap measuring system according to claim 1, characterized in that, Since the pressure sensor mounting base (3) is provided on the side wall of the regular polygonal pressure tapping tube, the width of the side wall of the regular polygonal pressure tapping tube is greater than the diameter of the pressure sensor (5), thereby avoiding the generation of air chamber (002) in the flow channel of the regular polygonal pressure tapping tube.

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