Temperature and pressure compensation vortex shedding flowmeter

Abstract

The invention discloses a temperature and pressure compensation vortex shedding flowmeter, and relates to the technical field of flowmeters. The device comprises a generation pipeline, a detection pipeline and an auxiliary measurement pipeline which are coaxially communicated. A vortex generating body composed of a plurality of layers of trapezoid cylinders is arranged in the generating pipeline, composite vortexes are generated, and multi-frequency flow information is provided. A plurality of resonant cavity arrays with different sizes and shapes are arranged on the inner wall of the detection pipeline, self-compensation of flow, temperature and pressure is realized by using a sound wave frequency spectrum, and an additional sensor is not needed. A detection wire and a first MEMS microphone are arranged in the auxiliary measuring pipeline and serve as a supplementary detection means. And the multi-sealing design ensures that the measurement environment is stable. Through composite vortex, multi-cavity cooperation and physical property decoupling, the measurement precision, stability and reliability are improved, meanwhile, the system structure is simplified, and the cost and maintenance difficulty are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flow meters, and particularly to a temperature and pressure compensated vortex flow meter. Background Art

[0002] Vortex flow meters are widely used in fluid flow measurement due to their advantages such as simple structure, no moving parts, and small pressure loss. Its basic principle is to set a vortex generator in the pipeline. When the fluid flows through, a Karman vortex street is generated, and the flow rate is calculated by detecting the vortex frequency. However, the existing technology has the following deficiencies: Limited single-frequency vortex information. The vortex generators of traditional vortex flow meters are mostly of a single shape, only generating vortices of a single frequency, and the flow information is relatively single. Under multiphase flow or complex fluid conditions, it is difficult to accurately reflect the flow state, which limits the measurement accuracy. Temperature and pressure compensation requires additional sensors, and the system is complex. The temperature and pressure of the fluid significantly affect flow measurement. Traditional technologies rely on additional temperature and pressure sensors for compensation. This increases the system complexity, cost, and failure risk, and maintenance is also more cumbersome. Summary of the Invention

[0003] To overcome the defects of the above-mentioned prior art, the present invention provides the following technical solutions: A temperature and pressure compensated vortex flow meter includes a generating pipeline, a detecting pipeline, and an auxiliary measuring pipeline that are coaxially fixedly connected. A partition collar is arranged on the outer side of the detecting pipeline. The partition collar and the outer surfaces of the generating pipeline, the detecting pipeline, and the auxiliary measuring pipeline form a sealed space with negative pressure; a vortex generator is fixedly installed in the radial direction inside the generating pipeline through a vortex generator bracket. The vortex generator is fixedly composed of multiple stacked trapezoidal columns. The multiple layers of trapezoidal columns are used to generate vortices of different sizes and intensities for fluids at different heights, forming a composite vortex for containing more flow information; it also includes a plurality of resonant cavities arranged in a circular equidistant array on the inner wall of the detecting pipeline. Each resonant cavity is a cylindrical or conical cavity, and the diameter, depth, and shape of each resonant cavity are different. Forming a small-diameter shallow cavity: More sensitive to the flow velocity (vortex frequency) because it is more easily excited by high-frequency pressure waves; a large-diameter deep cavity: More sensitive to temperature because temperature changes will significantly affect the propagation of low-frequency sound waves; a medium-sized cavity: More sensitive to pressure because the influence of pressure on fluid density and compressibility is more obvious in the medium-frequency range.

[0004] Preferably, a plurality of detecting wires are arranged along the radial direction of the auxiliary measuring pipeline. The length direction of the detecting wires is parallel to the stacking direction of the vortex generator. One end of the detecting wire is fixedly fitted inside the auxiliary measuring pipeline, and the other end of the detecting wire extends to the outside of the auxiliary measuring pipeline and is fixed on a detecting wire tensioning frame, and the detecting wire tensioning frame is fixed on the outer surface of the auxiliary measuring pipeline.

[0005] Preferably, a rectangular through-hole is provided at the junction of the detection wire and the auxiliary measurement pipeline. A sealing block is fixedly sealed in the rectangular through-hole. A cylindrical through-hole is provided at the junction of the sealing block and the detection wire. A detection wire sealing rubber sleeve is fixedly sealed in the cylindrical through-hole. The detection wire sealing rubber sleeve is sleeved on the detection wire, so as to form an elastic seal between the detection wire and the sealing block.

[0006] Preferably, a wave transmission wire is fixedly installed along the radial direction of the part of the detection wire outside the auxiliary measurement pipeline. One end of the wave transmission wire away from the detection wire is fixedly installed on the housing of the first MEMS microphone. The first MEMS microphone is fixedly installed on the first MEMS microphone mounting plate. The first MEMS microphone mounting plate and the detection wire tensioning frame are fixed into one body through a connecting beam rod. It should be noted that both the detection wire and the wave transmission wire are in a straight and taut state.

[0007] Preferably, a sealing chamber is provided on the outer sides of the detection wire tensioning frame and the first MEMS microphone mounting plate. The sealing chamber is fixedly sealed on the outer surface of the auxiliary measurement pipeline.

[0008] Preferably, an indicating arrow is provided on the outer surface of the generating pipeline. The right direction of the indicating arrow is the movement direction of the fluid.

[0009] Preferably, mounting flanges are fixedly installed at the opposite ends of the generating pipeline and the auxiliary measurement pipeline.

[0010] Preferably, a second MEMS microphone mounting plate is fixedly sealed at one end of each resonant cavity outside the detection pipeline. A second MEMS microphone is fixedly installed on the second MEMS microphone mounting plate.

[0011] The present invention has the following beneficial effects compared with the prior art: (1) The vortex generator of the present invention is composed of multiple trapezoidal cylinders stacked layer by layer, which can generate vortices of different sizes and intensities at different heights, forming composite vortices. This design enables the vortex frequency to contain more flow information, similar to multiple tones in an audio spectrum, which is richer than the traditional single-frequency vortex. By detecting the frequencies of these composite vortices, not only can the flow rate be measured more accurately, but also more comprehensive data support is provided for subsequent temperature and pressure compensation. This multi-frequency characteristic enables the system to more realistically reflect the fluid flow state, thereby significantly improving the measurement accuracy and reliability; (2) The inner wall of the detection pipeline of the present invention is provided with multiple resonant cavities of different diameters, depths, and shapes, arranged in a circular equidistant array. The small-diameter shallow cavities are sensitive to the flow rate, the large-diameter deep cavities are sensitive to the temperature, and the medium-sized cavities are sensitive to the pressure. This differential design enables the resonant cavities to naturally separate the influences of flow rate, temperature, and pressure through the acoustic frequency spectrum, realizing the self-compensation function without additional temperature and pressure sensors. This not only reduces the system cost and maintenance difficulty, but also simplifies the structure and improves the overall practicality and economy; (3) Through the design of different sizes and shapes, the resonant cavities of the present invention have different response sensitivities to the flow rate, temperature, and pressure, forming an effect similar to a filter. The multi-cavity collaborative work can extract independent information from the mixed acoustic wave signals, avoiding complex electronic calculations and directly completing the temperature and pressure compensation through hardware. This way of decoupling physical characteristics enables the measurement results to remain stable under complex working conditions; (4) A detection wire is provided in the auxiliary measurement pipeline of the present invention, and the fluctuation signal caused by the vortex is transmitted to the first MEMS microphone through the fluctuation transmission wire. This auxiliary detection system provides an alternative means for flow measurement, especially as an emergency or reference when the main system fails. Although the complex shape of the vortex generator may introduce certain errors, this design enhances the robustness of the system and ensures the continuity and reliability of the measurement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the external structure of the present invention.

[0013] Figure 2 It is a schematic diagram of the structure of the partition collar of the present invention.

[0014] Figure 3 It is a schematic diagram of the structure of the vortex generator of the present invention.

[0015] Figure 4 It is a schematic diagram of the structure at the detection pipeline of the present invention.

[0016] Figure 5 For the present invention Figure 4 Schematic diagram of the structure at location A.

[0017] Figure 6 It is a schematic diagram of the structure of the resonant cavity of the present invention.

[0018] In the figure: 101 - occurrence pipeline; 102 - installation flange; 103 - separation collar; 104 - indication arrow; 105 - auxiliary measurement pipeline; 106 - detection pipeline; 107 - sealing chamber; 108 - sealing block; 109 - detection wire; 110 - detection wire tensioning frame; 111 - first MEMS microphone mounting plate; 112 - connecting beam rod; 113 - first MEMS microphone; 114 - fluctuation transmission wire; 115 - detection wire sealing rubber sleeve; 116 - resonant cavity; 117 - second MEMS microphone mounting plate; 118 - second MEMS microphone; 119 - vortex generator; 120 - vortex generator bracket. Specific embodiments

[0019] The following combines the attached Figures 1-6 drawings, and further illustrates the technical solution of the present invention through specific embodiments.

[0020] The present invention provides a temperature and pressure compensated vortex flowmeter, which includes a generating pipe 101, a detecting pipe 106 and an auxiliary measuring pipe 105 that are coaxially and fixedly connected. A separating collar 103 is arranged on the outer side of the detecting pipe 106. The separating collar 103 and the outer surfaces of the generating pipe 101, the detecting pipe 106 and the auxiliary measuring pipe 105 form a sealed space with negative pressure. In the radial direction inside the generating pipe 101, a vortex generator 119 is fixedly installed overhead through a vortex generator bracket 120. The vortex generator 119 is fixedly composed of a plurality of trapezoidal cylinders stacked layer by layer. The multi-layer trapezoidal cylinders are used to generate vortices of different sizes and intensities for fluids at different heights, forming a composite vortex, which is used to contain more flow information. It also includes a plurality of resonant cavities 116 arranged in a circular equidistant array on the inner wall of the detecting pipe 106. Each resonant cavity 116 is a cylindrical or conical cavity, and the diameter, depth and shape of each resonant cavity 116 are different. Small-diameter shallow cavities are more sensitive to flow velocity (vortex frequency) because they are more easily excited by high-frequency pressure waves; large-diameter deep cavities are more sensitive to temperature because temperature changes will significantly affect the propagation of low-frequency sound waves; medium-sized cavities are more sensitive to pressure because the influence of pressure on fluid density and compressibility is more obvious in the medium-frequency range. A plurality of detecting wires 109 are arranged radially inside the auxiliary measuring pipe 105. The length direction of the detecting wires 109 is arranged parallel to the stacking direction of the vortex generator 119. One end of the detecting wire 109 is fixedly matched with the inside of the auxiliary measuring pipe 105, and the other end of the detecting wire 109 extends to the outside of the auxiliary measuring pipe 105, and the other end of the detecting wire 109 is fixed on a detecting wire tensioning frame 110, and the detecting wire tensioning frame 110 is fixed on the outer surface of the auxiliary measuring pipe 105. A rectangular through hole is opened at the junction of the detecting wire 109 and the auxiliary measuring pipe 105. A sealing block 108 is fixedly sealed in the rectangular through hole. A cylindrical through hole is opened at the junction of the sealing block 108 and the detecting wire 109. A detecting wire sealing rubber sleeve 115 is fixedly sealed in the cylindrical through hole. The detecting wire sealing rubber sleeve 115 is sleeved on the detecting wire 109, so that an elastic seal is formed between the detecting wire 109 and the sealing block 108. A wave transmission wire 114 is fixedly installed radially on the part of the detecting wire 109 located outside the auxiliary measuring pipe 105. One end of the wave transmission wire 114 away from the detecting wire 109 is fixedly installed on the housing of the first MEMS microphone 113. The first MEMS microphone 113 is fixedly installed on a first MEMS microphone mounting plate 111. The first MEMS microphone mounting plate 111 and the detecting wire tensioning frame 110 are fixed into one body through a connecting beam rod 112. It should be noted that both the detecting wire 109 and the wave transmission wire 114 are in a straight and taut state. A sealing chamber 107 is arranged outside the detecting wire tensioning frame 110 and the first MEMS microphone mounting plate 111. The sealing chamber 107 is fixedly sealed on the outer surface of the auxiliary measuring pipe 105.The outer surface of the occurrence pipe 101 is provided with an indicating arrow 104, and the right direction of the indicating arrow 104 is the movement direction of the fluid. Mounting flanges 102 are fixedly installed at the opposite ends of the occurrence pipe 101 and the auxiliary measurement pipe 105. At one end of each resonator cavity 116 located outside the detection pipe 106, a second MEMS microphone mounting plate 117 is fixedly sealed, and a second MEMS microphone 118 is fixedly installed on the second MEMS microphone mounting plate 117.

[0021] The working principle of a temperature and pressure compensated vortex flowmeter disclosed by the present invention is as follows: It is integrally and serially arranged in a pipeline, such that the right-hand direction indicated by the indicating arrow 104 is the direction of fluid movement. During installation, the axis of the pipeline 101 should be arranged horizontally as much as possible, and the direction locked by the indicating arrow 104 is vertically upward. When the fluid passes through the vortex generator 119, compound vortices will be formed behind the vortex generator 119 (in the direction of fluid flow through the vortex generator 119). These vortices have specific frequencies and contain more information than traditional single frequencies (similar to an audio spectrum with multiple tones). When the fluid flows through this vortex generator 119, the wide trapezoid at the bottom generates large vortices, and the narrow trapezoid at the top generates small vortices. These vortices propagate downstream like waves, providing a basis for subsequent measurements. The flow rate is detected by detecting the frequency of the vortices. The pressure wave generated by the vortices enters the resonant cavity 116, and the resonant cavity 116 emits sound waves. The frequencies of these sound waves are not only related to the flow rate but also naturally contain information about temperature and pressure. Without the need for additional temperature and pressure sensors, the resonant cavity 116 itself completes the compensation. The sound wave frequency emitted by the resonant cavity 116 is triggered by the pressure wave when the fluid passes through, and this frequency is affected by the following three physical quantities: Flow rate (flow velocity): The flow velocity determines the generation frequency of the vortices (Kármán vortex street principle). The vortex frequency directly affects the frequency of the pressure wave, which in turn drives the resonance of the resonant cavity 116; Temperature: Temperature changes the density and sound velocity of the fluid, affecting the propagation characteristics of sound waves in the resonant cavity 116; Pressure: Pressure changes the density and compressibility of the fluid, and also affects the frequency of sound waves in the resonant cavity 116. On the surface, the sound wave frequency output by the resonant cavity 116 is a mixed signal, containing the superposition effect of the three. However, the ingenuity of this design lies in that through the collaborative work of multiple cavities and the decoupling of physical characteristics, independent information can be extracted from this signal without the need for additional temperature and pressure sensors. Specifically, the sensitivity partitioning of different resonant cavities 116: The array of resonant cavities 116 is not completely the same but is deliberately designed with different sizes and shapes (such as different diameters and depths). Each resonant cavity 116 has different response sensitivities to flow rate, temperature, and pressure. For example: Small-diameter shallow cavity: More sensitive to the flow velocity (vortex frequency) because it is more easily excited by high-frequency pressure waves. Large-diameter deep cavity: More sensitive to temperature because temperature changes significantly affect the propagation of low-frequency sound waves. Medium-sized cavity: More sensitive to pressure because the influence of pressure on the density and compressibility of the fluid is more obvious in the medium-frequency range. This differential design is like a filter, making the sound wave frequency of each resonant cavity 116 tend to reflect a certain dominant factor (where the multiple stacked trapezoidal columns of the vortex generator 119, corresponding to the far away being the same, all generate corresponding sound waves in a specific resonant cavity 116, and the judgment is made through the frequency of the sound waves). Suppose there are 10 resonant cavities 116, and each resonant cavity 116 emits a unique sound wave frequency (passively).Instead of obtaining a single frequency, a frequency spectrum (similar to a spectrum) containing multiple frequency components is obtained. By analyzing this frequency spectrum, the effects of flow rate, temperature, and pressure can be separated and then compensated for.

[0022] The flow velocity is linearly related to the vortex frequency (i.e., the pressure wave frequency), f = St·v / d (where (f) is the vortex frequency, (St) is the Strouhal number, (v) is the flow velocity, and (d) is the diameter of the bluff body); the acoustic wave frequency of the resonant cavity 116 will follow the vortex frequency, so the high-frequency part in the frequency spectrum mainly reflects the flow rate.

[0023] Temperature changes the speed of sound (c) of the fluid. The formula for the speed of sound is: c = √γRT / M (where γ is the specific heat ratio, (R) is the gas constant, (T) is the temperature, and (M) is the molar mass). When the speed of sound increases, the acoustic wave frequency in the resonant cavity 116 will shift upward as a whole, especially more significantly in the low-frequency cavity. This "frequency drift" can be used to calculate the temperature.

[0024] Pressure changes the fluid density ρ. The relationship between density and pressure is: ρ = PM / RT (where (P) is the pressure). The density change will affect the wavelength and intensity of the acoustic wave, especially significantly affecting the resonant cavity 116 with medium frequencies. The pressure can be calculated through the amplitude change of certain specific peaks in the frequency spectrum.

[0025] Assumption: The fluid is air, and there are 3 resonant cavities 116 in the pipeline: Cavity 1 (small shallow cavity): frequency 1000 Hz, mainly reflecting a flow velocity of 10 m / s; Cavity 2 (medium cavity): frequency 500 Hz, with enhanced intensity, reflecting a pressure of 2 bar; Cavity 3 (large deep cavity): frequency 200 Hz, shifted up to 220 Hz, reflecting the temperature rising from 20°C to 30°C. The information of the resonant cavity 116 is not single, but is reflected through the frequency spectra of multiple resonant cavities 116. Different resonant cavities 116 have different sensitivities to flow rate, temperature, and pressure, enabling these three variables to be decoupled from the frequency spectrum. This completely relies on physical characteristics, avoiding electronic calculations and directly completing temperature and pressure compensation with a hardware structure.

[0026] In addition, to ensure stability, when a vortex passes through the detection wire 109, the detection wire 109 will also generate corresponding fluctuations. These fluctuations will be transmitted to the fluctuation transmission wire 114 and then through the fluctuation transmission wire 114 to the first MEMS microphone 113. Therefore, the first MEMS microphone 113 can detect the fluctuation frequency of the detection wire 109, thereby judging the frequency generated by the vortex and then knowing the flow velocity (due to the shape of the vortex generator 119, there will be errors in this method, but it is used as a supplementary detection device for emergencies or reference).

Claims

1. A temperature and pressure compensated vortex flowmeter, characterized in that: It includes an occurrence pipeline (101), a detection pipeline (106) and an auxiliary measurement pipeline (105) which are coaxially fixedly connected. A separation collar (103) is arranged on the outer side of the detection pipeline (106). The separation collar (103) and the outer surfaces of the occurrence pipeline (101), the detection pipeline (106) and the auxiliary measurement pipeline (105) form a negative pressure sealed space. In the radial direction inside the occurrence pipeline (101), a vortex generator (119) is fixedly installed overhead through a vortex generator bracket (120). The vortex generator (119) is fixedly composed of multiple trapezoidal cylinders stacked layer by layer. The multiple trapezoidal cylinders are used to generate vortices of different sizes and intensities for fluids at different heights, forming a composite vortex, which is used to contain more flow information. It also includes a plurality of resonant cavities (116) arranged in a circular equidistant array on the inner wall of the detection pipeline (106). Each resonant cavity (116) is a cylindrical or conical cavity, and the diameter, depth and shape of each resonant cavity (116) are different.

2. The temperature and pressure compensated vortex flowmeter according to claim 1, characterized in that: A plurality of detection wires (109) are arranged along the radial direction of the auxiliary measurement pipeline (105). The length direction of the detection wires (109) is parallel to the stacking direction of the vortex generator (119). One end of the detection wires (109) is fixedly fitted with the inside of the auxiliary measurement pipeline (105). The other end of the detection wires (109) extends to the outside of the auxiliary measurement pipeline (105), and the other end of the detection wires (109) is fixed on a detection wire tensioning frame (110). The detection wire tensioning frame (110) is fixed on the outer surface of the auxiliary measurement pipeline (105).

3. The vortex flowmeter with temperature and pressure compensation according to claim 2, characterized in that: A rectangular through hole is opened at the junction of the detection wire (109) and the auxiliary measurement pipeline (105). A sealing block (108) is fixedly sealed in the rectangular through hole. A cylindrical through hole is opened at the junction of the sealing block (108) and the detection wire (109). A detection wire sealing rubber sleeve (115) is fixedly sealed in the cylindrical through hole. The detection wire sealing rubber sleeve (115) is sleeved on the detection wire (109), so that an elastic seal is formed between the detection wire (109) and the sealing block (108).

4. The warm and pressure compensated vortex flowmeter according to claim 3, characterized in that: A wave transmission wire (114) is fixedly installed along the radial direction of the part of the detection wire (109) located outside the auxiliary measurement pipeline (105). One end of the wave transmission wire (114) far from the detection wire (109) is fixedly installed on the housing of the first MEMS microphone (113). The first MEMS microphone (113) is fixedly installed on a first MEMS microphone mounting plate (111). The first MEMS microphone mounting plate (111) and the detection wire tensioning frame (110) are fixed into one body through a connecting beam rod (112).

5. The vortex flowmeter with temperature and pressure compensation according to claim 4, characterized in that: A sealing chamber (107) is arranged outside the detection wire tensioning frame (110) and the first MEMS microphone mounting plate (111). The sealing chamber (107) is fixedly sealed on the outer surface of the auxiliary measurement pipeline (105).

6. The warm pressure compensated vortex flowmeter according to claim 5, characterized in that: An indicating arrow (104) is arranged on the outer surface of the occurrence pipeline (101). The right direction of the indicating arrow (104) is the movement direction of the fluid.

7. The temperature and pressure compensated vortex flowmeter according to claim 6, wherein: Mounting flanges (102) are fixedly installed at both opposite ends of the main pipe (101) and the auxiliary measurement pipe (105).

8. The temperature and pressure compensated vortex flowmeter according to claim 7, wherein: At one end of each resonator (116) located outside the detection pipe (106), a second MEMS microphone mounting plate (117) is fixedly sealed, and a second MEMS microphone (118) is fixedly installed on the second MEMS microphone mounting plate (117).

Images