Design method and system of multi-stage labyrinth regulating valve

Abstract

The invention discloses a design method and system for a multi-stage labyrinth regulating valve, and belongs to the technical field of regulating valves. The method comprises the following steps: determining a pressure degradation grade value range and a structure design size value range according to an initial structure size, a working environment, flow velocity limitation and a fluid impurity size of a valve core; determining the allowable maximum flow according to the flow velocity limit; according to the flow channel pressure difference, the maximum flow and the minimum flow, the value interval of the pressure degradation grade number is determined; the overall size of the flow channel under different expansion coefficients is calculated according to the pressure degradation grade number value interval; after the flow channel structure size meeting the valve requirement is selected, the flow speed and the flow are recalculated according to the determined size parameters in combination with a flow model, and it is ensured that the flow speed and the flow meet the initially-set requirements for the minimum flow and the maximum flow speed; and if not, carrying out iterative adjustment on the size of the runner. The regulating valve designed by the invention can realize flow and pressure control in a supercritical carbon dioxide Brayton cycle bypass system.

Description

Technical Field

[0001] This invention relates to the field of control valve technology, specifically to a design method and system for a multi-stage labyrinth control valve. Background Technology

[0002] The bypass system is a key control strategy for achieving flexible operation in supercritical carbon dioxide Brayton cycles (SCBCs). Figure 1 It is known that the output power of the SCBC can be regulated by adjusting the control valve of the bypass system to change the flow rate into the compressor and turbine. However, the reliability of the control valve is challenged, especially when there is a significant pressure difference between the inlet and outlet of the compressor and turbine.

[0003] Compared to ordinary control valves, multistage labyrinth control valves (MSLRVs) have superior pressure reduction performance due to their specially designed throttling internals. Figure 2 (a) illustrates a typical multi-stage labyrinth control valve, whose throttling internals consist of several metal disks with chemically etched flow channels. The internals incorporate a complex geometric layout of precision throttling structures, creating a complex flow field. Figure 2 (b) It can be seen that the fluid gradually loses energy as it flows through the channel, thus achieving gradual decompression, and the flow velocity is limited below the critical velocity. Although the specific structures of multi-stage labyrinth throttling internals may vary in different studies, their decompression mechanism is consistent with the above explanation.

[0004] Multistage labyrinth valves (MSLVs) are designed to reduce cavitation, noise, and vibration. Their flow characteristics are based on empirical inferences, leading to biases in the description of energy dissipation mechanisms. With the development of computational fluid dynamics (CFD), a more comprehensive understanding of the complex flow field within labyrinth valves has been achieved. Related research mainly focuses on throttling component design, energy dissipation mechanisms, and flow prediction models. Flow channel structural parameters are crucial to the pressure-reducing performance of multistage labyrinth valves, and numerous studies have focused on these parameters. Energy loss mainly occurs within the flow channel, and anti-cavitation performance and noise reduction effects also depend on the effectiveness of the flow channel design. The flow capacity of multistage labyrinth valves also depends on the flow channel structural parameters. Therefore, studying the energy loss mechanism of labyrinth flow channels and predicting their flow performance is key to improving valve pressure-reducing performance and flow control accuracy.

[0005] Predicting its flow properties is key to improving the pressure-reducing performance and flow control accuracy of valves.

[0006] Valve flow prediction models have gained widespread attention in recent years due to their ability to effectively reduce the gap between design performance and actual performance. Although various forms of labyrinth channels have been proposed for different application scenarios, their design purpose is to control energy dissipation within a reasonable range through the actual design of the channel structure. When fluid flows through, the flow rate is regulated while maximizing flow capacity. Insufficient pressure drop stages will lead to ineffective flow velocity limitation within the valve, causing cavitation and excessive noise; conversely, excessive pressure drop stages will adversely affect the flow capacity of the labyrinth channel and increase internal resistance. However, analysis of published literature, patents, and on-site investigations of manufacturing plants reveals that current labyrinth control valve channel design still mainly adopts a one-dimensional linear design method. No published literature or patents systematically explore the specific influence mechanism of the three-dimensional structural dimensions of the labyrinth channel on fluid flow rate and velocity. This limitation severely affects the performance of labyrinth control valves in pressure regulation, flow rate control, and flow performance. A reasonable internal flow channel structure design is crucial for multi-stage labyrinth control valves (MSLRVs) to achieve stepped pressure reduction and maintain good flow capacity. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a design method and system for a multi-stage labyrinth control valve. This method can combine the actual operating conditions and flow requirements of the multi-stage labyrinth control valve during the design phase to complete a precise three-dimensional flow channel structure design, with the design error controlled within 15%.

[0008] This invention is achieved through the following technical solution: A design method for a multi-stage labyrinth control valve includes the following steps: Step 1: Based on the expected operating environment parameters and flow rate limiting parameters of the multi-stage labyrinth control valve, determine the pressure drop stage range of its flow channel; The structural parameters of this multi-stage labyrinth control valve are determined to ensure that the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel. Step 2: Determine the range of straight flow path length along the radial direction of the valve core for different expansion coefficients based on the pressure drop level range; Step 3: Compare the valve core size of the regulating valve with the straight length range of the flow channel; When the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core size is greater than or equal to the straight length of the flow channel S The minimum value, and the valve core width ≤ the straight length of the flow channel. S The maximum value is used to determine the valve core width as the straight length of the flow channel. S The maximum value is calculated, and the range of pressure drop stages is recalculated to obtain the structural parameters of the multi-stage labyrinth control valve.

[0009] Preferably, the method for determining the structural dimensions of the multi-stage labyrinth control valve is as follows: Determine the structural parameters of the multi-stage labyrinth control valve, and determine whether the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel under these structural parameters. If the minimum diameter of the impurity is smaller than the diameter of the flow channel, adjust the structural parameters until the minimum diameter of the impurity is larger than the diameter of the flow channel.

[0010] Preferably, the operating environment parameters include the valve inlet pressure. and export pressure ; The flow rate limiting parameters include the minimum mass flow rate. and maximum flow rate .

[0011] Preferably, the method for determining the voltage drop range is as follows: Calculate the maximum mass flow rate that the flow channel is allowed to pass through based on the maximum flow velocity; According to the valve inlet pressure and export pressure Determine the pressure differential in the flow channel; Calculate the pressure drop range based on the channel pressure difference and the maximum mass flow rate.

[0012] Preferably, the expression for the voltage drop range is as follows:

[0013]

[0014] In the formula, n For the number of pressure drop stages; k Specific heat capacity; The pressure difference in the flow channel; and These are the valve core inlet and outlet pressures, respectively. and These are the inlet and outlet densities of the valve core, respectively. A out This refers to the cross-sectional area of ​​the flow channel outlet. G m For mass flow rate; This refers to the channel spacing; The amplitude of the swing; The aspect ratio of the flow channel; The coefficient of thermal expansion; and They represent n The maximum and minimum values.

[0015] Preferably, the straight length of the flow channel S The calculation method is as follows: When γ=1,

[0016] When γ>1,

[0017]

[0018] In the formula, D is the width of the flow channel. n For the pressure drop stage, The aspect ratio of the flow channel.

[0019] Preferably, when the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core width is less than or equal to the straight length of the flow channel S If the minimum value is reached, then steps 1 and 2 are executed to adjust the structural parameters of the multi-stage labyrinth control valve so that the straight length of the flow channel is... S Reduce until the valve core width is greater than the straight length of the flow channel. S And the valve core width is less than the straight length of the flow channel. S The maximum value is used to obtain the structural parameters of the multi-stage labyrinth control valve.

[0020] Preferably, the valve core width is used as the straight length of the flow channel. S The maximum value is then calculated, and the range of pressure drop stages is recalculated as follows: make:

[0021] Solve When γ=1,

[0022] When γ>1,

[0023] In the formula, k is the specific heat capacity, λ is the channel spacing, and D is the channel width. The aspect ratio of the flow channel. n For the pressure drop stage, is the coefficient of thermal expansion.

[0024] A design system for a multi-stage labyrinth control valve includes: The pressure drop range module is used to determine the pressure drop range of the flow channel based on the expected operating environment parameters and flow rate limit parameters of the multi-stage labyrinth control valve. The structural parameters of this multi-stage labyrinth control valve are determined to ensure that the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel. The flow path length module is used to determine the range of straight flow path length along the radial direction of the valve core for different expansion coefficients based on the pressure drop level range. The optimization module is used to compare the valve core size of the control valve with the straight length range of the flow channel; When the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core size is greater than or equal to the straight length of the flow channel S The minimum value, and the valve core width ≤ the straight length of the flow channel. S The maximum value is used to determine the valve core width as the straight length of the flow channel. S The maximum value is calculated, and the range of pressure drop stages is recalculated to obtain the structural parameters of the multi-stage labyrinth control valve.

[0025] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the design method for the multi-stage labyrinth control valve.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a design method for a multi-stage labyrinth control valve. Based on the initial structural dimensions of the valve core, the operating environment, flow velocity limitations, and fluid impurity sizes, the method determines the range of pressure drop stages and the range of structural design dimensions. It then determines the maximum allowable flow rate based on the flow velocity limitations; determines the range of pressure drop stages based on the flow channel pressure difference and the maximum and minimum flow rates; calculates the overall dimensions of the flow channel under different expansion coefficients based on the pressure drop stage range; after selecting the flow channel structural dimensions that meet the valve requirements, the flow velocity and flow rate should be recalculated based on the determined dimensional parameters and the flow model to ensure they meet the initially set minimum and maximum flow velocity requirements; if not, the flow channel dimensions need to be iteratively adjusted. This method enables the design of a multi-stage labyrinth control valve with flexible, stable, and efficient flow and pressure control in a supercritical carbon dioxide Brayton cycle bypass system, providing crucial support for the safe operation and power regulation of the circulation system.

[0027] This application also proposes a design system for a multi-stage labyrinth control valve, an electronic device, and a computer storage medium, which possess all the advantages of the aforementioned design method for multi-stage labyrinth control valves. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the SCBC disclosed in this invention; Figure 2 This is a diagram illustrating the structure and adjustment effect of the labyrinth valve disclosed in this invention. Figure 3This is a design flowchart of the number of voltage drop stages and structural dimensions disclosed in one embodiment of the present invention; Figure 4 This is a diagram illustrating the effect of different pressure drop stages on mass flow rate according to an embodiment of the present invention; Figure 5 This is a diagram illustrating the influence of different geometric parameters on mass flow rate according to an embodiment of the present invention; Figure 6 The correlation prediction of G disclosed in one embodiment of the present invention m G in numerical computation m Comparison chart (fitting model diagram); Figure 7 The correlation prediction of G disclosed in one embodiment of the present invention m G in numerical computation m Comparison chart (data extrapolation chart); Figure 8 This is a detailed dimensional diagram of the labyrinth flow channel structure disclosed in one embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0032] Although there is limited research in the published literature on the energy dissipation mechanism and flow behavior of supercritical carbon dioxide in multistage labyrinth valves, existing studies have provided valuable insights into the hydrodynamic characteristics of supercritical carbon dioxide within these valves. Labyrinth channel structures are classified into two types: array-type and discrete-type. Array-type channels dissipate energy by simultaneously causing fluid separation and converging collisions; discrete-type channels divide the fluid into multiple non-interfering dispersed flows, dissipating energy through collisions with the wall. Within the limited valve core space, array-type channels offer a larger flow area, but their pressure drop stages are limited; discrete-type channels can effectively limit flow velocity by continuously increasing the number of bends to increase channel resistance. Previous studies on the flow characteristics of water vapor and hydrogen in right-angled zigzag channels have revealed the influence of geometric parameters on the throttling mechanism of these channels. However, the unique thermophysical properties of supercritical carbon dioxide, especially its low dynamic viscosity and strong coupling with temperature and pressure, result in different flow dynamic characteristics.

[0033] To improve the accuracy of flow prediction in the design of SCBC bypass control valves, this invention proposes a design method for multi-stage labyrinth control valves. Please refer to [link / reference]. Figure 3 As shown, it includes: Step 1: Determine the structural dimensions of a set of multi-stage labyrinth control valves, and determine whether the minimum diameter of impurities in the bypass system is greater than the flow channel diameter; if so, proceed to flow calculation; otherwise, adjust the structural dimensions and re-determine until the minimum diameter of impurities is greater than the flow channel diameter. The structural dimensions of this multi-stage labyrinth control valve include the outer diameter L of the valve core and the inner diameter. l The coefficient of expansion γ and the channel spacing λ, the channel width D and the channel height H; Step 2: Determine the flow rate limiting parameters and operating environment parameters of the multi-stage labyrinth control valve; Flow rate limiting parameters include minimum mass flow rate Maximum flow rate ; The flow channel pressure difference is calculated based on the working environment parameters, as follows: Operating environment parameters include valve inlet pressure Export pressure Flow channel pressure difference ; Step 3: Calculate the maximum mass flow rate allowed through the flow channel based on the maximum flow rate parameter in the flow rate limitation parameters, as shown in the following expression:

[0034] In the formula, Where is the valve outlet cross-sectional area. The fluid density at the valve outlet; Step 4: Calculate the pressure drop stage range based on the flow channel pressure difference and maximum mass flow rate:

[0035] ; In the formula, k is the specific heat capacity. This refers to the channel spacing; Step 5: Calculate the straight length of the flow channel along the radial direction of the valve core under different expansion coefficients based on the pressure drop level range. S ; When γ=1,

[0036] When γ>1,

[0037]

[0038] Step 6: Based on the outer diameter L and inner diameter of the valve core l Determine the width of the valve core. Determine if the valve core width is less than or equal to the straight length of the flow channel. S The minimum value; if so, it is determined to be the straight length of the flow channel. S The flow channel size is too large. Return to step 1 to adjust the flow channel size, and repeat steps 2-5 until the valve core width is greater than the straight length of the flow channel. S Then proceed to step 7.

[0039] Step 7: Determine if the valve core width is less than or equal to the straight length of the flow channel. S The maximum value; When the valve core width is less than or equal to the straight length of the flow channel S If the maximum value is reached, proceed to step 8 to redetermine the pressure level range; When the valve core width is greater than the straight length of the flow channel S The maximum value is used to output the structural parameters of the multi-stage labyrinth control valve. Output the structural parameters of the multi-stage labyrinth control valve, including the number of pressure drop stages and the straight length of the flow path. S maximum value and minimum value The flow channel aspect ratio, flow channel spacing λ, expansion coefficient γ, and flow channel height H.

[0040] Step 8: When the valve core width is less than or equal to the straight length of the flow channel S The maximum value indicates that the valve core width restricts the flow channel arrangement, and the valve core width is used as the straight length of the flow channel. S The maximum value is determined, and the range of pressure drop stages is recalculated.

[0041] make:

[0042] Solve When γ=1,

[0043] When γ>1,

[0044] Step 9: Output the structural parameters of the multi-stage labyrinth control valve, and the design process ends.

[0045] Arbitrary series between n min and n max At this point, the data flow can meet the preset requirements. At this time, you need to make a selection based on the actual situation.

[0046] The design method of this invention first establishes a numerical model considering the key geometric parameters of a multi-stage labyrinth flow channel. These parameters include: pressure drop stage number (n), expansion coefficient (γ), and oscillation amplitude (γ). ), channel spacing ( The numerical model is then used to study the influence of geometric parameters on the Mach number and pressure distribution of supercritical carbon dioxide in a labyrinthine flow channel. Finally, the impact of key geometric parameters on flow rate is systematically evaluated, and a novel predictive model is developed. The results of this invention contribute to a deeper understanding of the flow characteristics of supercritical carbon dioxide in a labyrinthine flow channel, and the established flow channel design method provides a theoretical basis for the design of valve cores in efficient SCBC bypass systems, thereby achieving flexible and precise flow control.

[0047] The calculation model for the pressure drop level interval used in step 4 of this invention will be explained below.

[0048] The right-angle zigzag flow channel (SZC) is widely used for pressure regulation of gases such as hydrogen and high-temperature steam due to its excellent pressure reduction performance. Dynamic viscosity is the main physical property affecting viscous dissipation. Table 1 compares the physical properties of different substances under typical scenarios. The dynamic viscosity of supercritical carbon dioxide is comparable to that of hydrogen and high-temperature steam. Therefore, this invention selects a labyrinth flow channel structure similar to that in previous studies, as detailed in [see details]. Figure 8 As shown.

[0049] Table 1. Thermophysical properties of fluids within a multistage labyrinth valve

[0050] The labyrinth flow channel transforms the disordered decompression process of fluid under high pressure differential into multiple continuous and controllable mild decompression stages. The fluid gradually dissipates energy through continuous collisions with the wall, reducing flow velocity and impact force. Experiments have indirectly confirmed that the channel's geometric parameters have a significant impact on decompression and velocity-limiting performance. Therefore, to quantitatively study the influence of geometric parameters on fluid behavior within the labyrinth flow channel, the geometric characteristics of the labyrinth flow channel are divided into five key parameters, and the inlet area of ​​all channels is fixed at 18 mm². The definitions of each parameter are as follows: 1) The pressure drop number (n) is defined as the number of times the flow direction changes from the inlet to the outlet. The pressure drop number (n) of a labyrinth flow channel can be 16.

[0051] 2) The expansion coefficient, also called the expansion factor (γ), is defined as the ratio of the widths of two adjacent flow channels, as shown in equation (1): (1) 3) Swing amplitude ( The dimensionless oscillation amplitude of the flow channel along the Z direction is defined as shown in equation (2): (2) in, Defined as the equivalent diameter of the inlet section of the labyrinth flow channel, as shown in equation (3): (3) 4) Channel spacing ( The dimensionless spacing distance of the flow channel along the X direction is defined as shown in equation (4): (4) 5) The width-to-height ratio (σ) of the flow channel is defined as the ratio of the width to the height of the flow channel, as shown in equation (5): (5) Table 2 lists the value ranges of the above key parameters.

[0052] Table 2 Geometric parameters of the labyrinth flow channel

[0053] The numerical method of the present invention will be described below.

[0054] The thermophysical properties of supercritical carbon dioxide change significantly near the critical region, while remaining relatively stable far from the critical point. Therefore, this invention focuses on the flow behavior within the compressor bypass valve.

[0055] Table 4 lists the settings for the steady-state CFD numerical method. Based on NIST REFPROP, real gas property files (RGPs) with (P, T) average intervals of 0.2 MPa and 0.2 K were used to determine the thermophysical properties of carbon dioxide, achieving satisfactory accuracy as shown in previous studies. Automatic near-wall treatment was employed to address the γ+ instability caused by direct fluid impact on the wall.

[0056] To simulate the actual state of the compressor bypass valve, the inlet pressure and temperature were set to 12.6 MPa and 363.15 K, respectively. Since the downstream pressure changes during valve operation, it is necessary to study the flow characteristics and energy losses within the flow channel under different pressure differentials. Therefore, the outlet static pressure was set to five different levels: 7.6 MPa, 8.6 MPa, 9.6 MPa, 10.6 MPa, and 11.6 MPa.

[0057] Table 4 Steady-state CFD method settings

[0058] This invention quantitatively studies the geometric parameters of a labyrinth flow channel (including pressure drop number (n), expansion coefficient (γ), and oscillation amplitude) to investigate the flow characteristics within the labyrinth flow channel. ), channel spacing ( The influence of flow characteristics on the width-to-height ratio (σ) of the flow channel.

[0059] The basic flow channel structure parameter is defined as γ=1.0. =0, =0.5, σ=2. Pressure distribution at n=8, 12, and 16; pressure recovers after fluid impacts the wall. Isobars converge at the corner where the fluid changes direction, indicating that decompression occurs after the change in flow direction. After the last stage of the throttling structure, there is always a region where the pressure is lower than the outlet pressure. This region shrinks significantly with increasing pressure drop stages. Pressure decreases linearly for different n values. When ΔP=5 MPa and n=8, the average interstage pressure drop is 1.2 MPa with a standard deviation SD=0.30 MPa; when n=16, the average interstage pressure drop is 0.6 MPa with a standard deviation SD=0.15 MPa. Increasing the number of stages effectively slows down the pressure drop rate, thereby improving the stability of the pressure field.

[0060] Mach number variation under different n values: The flow field within the labyrinthine channel can be divided into two regions: a high Mach number mainstream region that continuously changes with the channel structure direction, and a low-velocity vortex region formed after boundary layer separation due to the throttling structure. When the pressure drop stage number decreases, the mainstream region suddenly accelerates after carbon dioxide leaves the last stage throttling structure. That is, when ΔP=5MPA, the maximum Mach number at the final stage outlet is 0.53 when n=16, and 0.72 when n=8, an increase of 35.8%. When ΔP=5 MPA, the average Mach number of the channel is 0.252 when n=8, and 0.191 when n=16, a decrease of 24.2%. This indicates that increasing the number of stages can significantly reduce the fluid velocity and improve the stability of the flow field, but this also affects the valve's flow efficiency. Furthermore, as the pressure difference between the inlet and outlet of the channel increases, the fluid velocity tends to increase. When ΔP=1MPA, the average Mach number of the fluid in the n=16 channel is 7.85×10-2, and the standard deviation of the velocity S=1.47×10-2. When ΔP=5MPA, the average Mach number of the fluid in the channel is 1.91×10-1, and the standard deviation of the velocity S=4.68×10-2. This indicates that the increase in pressure difference is the key reason for the instability of the flow in the labyrinth channel.

[0061] The flow channel geometric parameters of the present invention are described below.

[0062] Using n=16, w*=0.5, λ*=0.5, σ=2, and γ=1.0 as the basic flow channel structure, the pressure distribution was analyzed by fixing the number of flow channel pressure drop stages and changing the oscillation amplitude (w*), flow channel spacing (λ*), flow channel aspect ratio (σ), and expansion coefficient (γ). This invention found that fixing the number of flow channel stages does not significantly affect the pressure drop along the flow path; the pressure still exhibits a linear decreasing trend along the inlet and outlet.

[0063] The Mach number distribution in the flow channel under different w* values ​​shows that the change in fluid flow direction increases with the increase of the oscillation amplitude, meaning that the collision deceleration effect of the upper and lower walls on the fluid will be more pronounced. The oscillation amplitude limits further increases in flow velocity. When w*=0, the average Mach number of CO2 in the flow channel is 0.191, and when w*=1, the average Mach number of CO2 in the flow channel is 0.184. Although it decreased by 3.6%, the area required for the flow channel setup increased by 14.5%.

[0064] The distribution of Mach number within the flow channel under different λ* values. As the spacing distance increases, the change in fluid flow direction gradually decreases; however, this phenomenon does not lead to an increase in flow velocity within the channel, but rather a certain degree of decrease. This is because although the reduction in oscillation amplitude weakens the influence of the upper and lower walls on the flow, it simultaneously enhances the effect of the wall perpendicular to the x-direction on the flow, thus further exacerbating local energy loss. Although λ* can effectively reduce the average Mach number, the loss of wall influence after the final stage pressure reduction leads to a further increase in flow velocity. Furthermore, with the increase of λ*, the range of the mainstream region within the flow channel will also expand accordingly.

[0065] As σ increases, the influence of the channel wall effect on the flow becomes more significant. The low-speed vortex region gradually expands and occupies the upper and lower wall regions, thus hindering the possibility of high-speed fluid dissipating energy through direct collision. Compared with σ=2, when σ=4, the average Mach number in the channel decreases to 0.183, a decrease of 4.2%. In addition, the effective flow area of ​​carbon dioxide also decreases significantly with increasing σ, which will affect the flow capacity of the labyrinth channel.

[0066] An increase in γ can also lead to an excessively large aspect ratio in the flow channel structure. Carbon dioxide can still dissipate energy through collisions with the upper and lower walls, and the effective flow area does not decrease. The carbon dioxide velocity in the inlet region of the flow channel gradually increases with the increase in γ value, tends to stabilize in the middle region, and decreases in Mach number near the outlet region due to the increase in flow area.

[0067] The above research shows that the geometry of the flow channel has a significant impact on the details of the internal flow field. To reduce the difference between design performance and actual performance, the relationship between flow channel structure and flow capacity is investigated below, exploring the influence of flow channel geometric parameters on flow rate.

[0068] First, the flow of compressible fluid in a multi-stage labyrinth channel is simplified to a one-dimensional linear flow for analysis. Clearly, the incompressible Bernoulli equation is no longer applicable to situations where fluid density changes significantly. Therefore, this invention introduces the Bernoulli equation for steady flow of compressible fluids, namely: (10) For adiabatic flow, the process equations can be used to derive: During the flow, the gravitational potential energy remains constant, and the above equation can be simplified to: (11) In equation (11), the dissipation caused by the flow channel structure and viscous friction is ignored. Therefore, hw is used to describe the energy loss generated by the flow, and , This is the local drag coefficient, and its value depends on the throttling structure. Enter the maze-like flow path The outlet is the control volume, and assuming the pressure drop stage of the labyrinth flow channel is n, equation (11) can be simplified to: (12) Based on the previous study of the flow characteristics in the labyrinth channel, it was found that the pressure drop series has the greatest impact on the pressure loss and the variation of Mach number along the flow path, and the flow instability in the channel intensifies with the increase of the inlet and outlet pressure difference. Therefore, this invention makes the following assumptions: 1) When the fluid passes through the labyrinthine flow channel, the velocity is well controlled, and the outlet velocity is consistent with the inlet velocity, that is: ; 2) The energy loss to the flow is the same at each stage of the throttling structure: .

[0069] However, as the pressure difference between the inlet and outlet increases, the velocity difference of the fluid passing through each stage of the throttling structure increases. Flow instability ( To correct the errors arising from the above assumptions, i.e. Equation (12) can be simplified to: (13) According to the law of conservation of mass, during the flow process: ,and Therefore, we can deduce that: (14) By combining equations (13) and (14), we can deduce: (15) In equation (15), only ξ and n are related to the flow channel structure. Therefore, let Cd is the flow coefficient, and equation (15) can be further simplified to: (16) It is worth noting that the temperature of different ideal gases does not change during adiabatic throttling, while the temperature of carbon dioxide decreases significantly during throttling. Therefore, applying equation (16) to the flow of carbon dioxide requires using the inlet and outlet arithmetic average of the adiabatic index to improve accuracy. The Cd in equation (16) and... It cannot be directly derived through theoretical derivation, and will be further studied below.

[0070] Secondly, numerical simulation studies were conducted to investigate the influence of channel geometry parameters on flow capacity. For example... Figure 4As shown, using a flow channel structure with w* = 0.5, λ* = 0.5, σ = 2, and γ = 1.0 as the base, the effects of different pressure differences and the number of pressure drop stages on flow capacity were studied. When ΔP = 5 MPa and n = 8, the flow channel mass flow rate was 0.213 kg / s. When n = 16, the flow channel mass flow rate was 0.148 kg / s, a decrease of 43.9%. When ΔP = 1 MPa and n = 8, the flow channel mass flow rate was 0.104 kg / s. When n = 16, the flow channel mass flow rate was 0.071 kg / s, a decrease of 31.7%. This indicates that the effect of the pressure drop stage on the flow channel capacity becomes more significant with increasing inlet and outlet pressure difference. When ΔP = 5 MPa, the flow rate decreased by 11.7% for n = 8 and n = 10, while it decreased by 6.9% for n = 14 and n = 16. The mass flow rate decreased significantly with increasing pressure drop stage, but the decreasing trend was not linear. The higher the pressure drop level, the weaker its impact on mass flow rate.

[0071] Figure 5 The influence of other geometric parameters on mass flow rate is explained. It can be seen that the oscillation amplitude, aspect ratio, and mass flow rate are negatively correlated, while the channel spacing and expansion coefficient are positively correlated with mass flow rate. Figure 5 (a) The oscillation amplitude has a slight effect on the mass flow rate; when ΔP = 1 MPa, Gm only changes with... The increase in amplitude reduced the flow rate by 5.6%, while at ΔP=5MPa, this value was 4.1%. This indicates that although the oscillation amplitude enhanced the impact of the fluid on the channel wall, this change did not significantly affect the flow capacity of the channel. Figure 5 (b) When the channel aspect ratio is between 3 and 5, a sudden decrease in mass flow rate occurs. This is because the influence of the upper and lower walls of the channel on the mainstream flow capacity reaches its maximum in this range as the aspect ratio increases. The wall effect weakens as the aspect ratio further increases. Figure 5 (c) The mass flow rate increases with increasing spacing and expansion coefficient, with a non-linear relationship between spacing and mass flow rate. Specifically, as the spacing increases, its impact on the increase in mass flow rate gradually weakens. The expansion coefficient, however, exhibits a linear relationship with mass flow rate. Both increases affect the channel structure; the spacing increases the channel length, while the expansion coefficient significantly increases the space required for channel layout.

[0072] Based on the relationship between mass flow rate and structural parameters at pressures of 1 MPa, 3 MPa, and 5 MPa, the relationship between Cd and... Fitting was performed. The fitting method adopted was a multivariate nonlinear fitting method based on the least squares method. Combining the theoretical equation (16) and the influence law of the above structural parameters on the mass flow rate, the mass flow rate prediction model was constructed as shown in equation (17). The fitting results are as follows: Figure 6 As shown, the correlation equation of the present invention has good consistency with the numerical results of Gm, and the relative error is kept within 10%.

[0073] (17) In equation (17), the expansion coefficient and the flow rate show a negative correlation, which is consistent with... Figure 5 The result in (d) is inconsistent. The main reason is that although the increase in the expansion coefficient can increase the mass flow rate, in equation (17), the mass flow rate is characterized by the outlet cross-sectional area. Since the increase in the expansion coefficient causes the increase in mass flow rate to be less than the increase in the outlet cross-sectional area, the mass flow rate at the outlet decreases.

[0074] To further demonstrate the reliability of the prediction model, a new structural sample was used to verify the accuracy of the equations. The new structure is based on σ=3 and σ=1, with changes made to the remaining structural parameters. Similarly, to verify the accuracy of the model for pressure instability... The prediction accuracy was improved, and the operating condition of ΔP=2.6 MPa was also supplemented. Through this invention, it was found that the pressure drop stage has the greatest impact on flow rate and flow field. To ensure the prediction accuracy for the pressure drop stage n, the structure was extended to the case of n=28. Verification results are shown in [link to verification results]. Figure 7 As shown, its relative error of less than 15% proves the reliability of the prediction model proposed in this invention.

[0075] Labyrinth control valves possess the advantages of achieving stepped pressure drops and limiting flow velocity under high pressure. Their flow channel structure determines the valve's pressure-reducing performance and flow capacity. However, the physical properties of supercritical carbon dioxide pose challenges to the application of labyrinth control valves in SCBC bypass systems. In this invention, the hydrodynamic properties of carbon dioxide in a labyrinth flow channel were numerically investigated. A numerical model was constructed, incorporating pressure drop stages (n), expansion coefficient (γ), oscillation amplitude (w*), channel spacing (λ*), and channel aspect ratio (σ). The influence of different labyrinth flow channel geometric parameters on pressure drop and Mach number was analyzed. Finally, the intrinsic relationship between flow channel structure and labyrinth flow channel flow capacity was revealed, and a flow prediction model was proposed based on this. The main conclusions are as follows: Changing the flow channel geometry does not significantly affect the pressure drop pattern along the flow path; the pressure still exhibits a linear decreasing trend. Compared to other flow channel geometry parameters, the number of pressure drop stages (n) has the most significant impact on the average Mach number within the flow channel. When n increases from 8 to 16, the average Mach number inside the flow channel decreases by 24.2%. Furthermore, when the flow channel stage design is inappropriate, the fluid velocity will suddenly increase after passing through the last throttling structure. The flow channel spacing (λ*) and the expansion coefficient (γ) increase the effective flow area of ​​the flow channel but do not increase the flow velocity. However, the flow channel aspect ratio (σ) increases the wall effect, leading to a significant reduction in the effective flow area.

[0076] Regarding the flow capacity of the flow channels, a positive correlation was found between the expansion coefficient (γ) and the channel spacing (λ*). A negative correlation was found between the pressure drop stage number (n), the channel aspect ratio (σ), and the oscillation amplitude (w*). While the expansion coefficient (γ) increases the outlet mass flow rate, it significantly increases the outlet channel area, leading to a decrease in the mass flow rate. Increasing the channel spacing (λ*) results in a longer channel length, affecting the compactness of the core. Finally, based on numerical simulation results with different channel geometric parameters, a flow prediction model was proposed. The model's flow prediction error is within ±15%.

[0077] The integrated flow prediction model can be directly applied to step 4 of the labyrinth flow channel structure design procedure proposed in this invention. The research results of this invention enhance the understanding of the flow characteristics of supercritical carbon dioxide in labyrinth flow channels. The established prediction model provides a theoretical basis for designing efficient SCBC bypass system valve cores, thereby enabling precise design of valve flow channel structures. Furthermore, the prediction model proposed in this invention can also be combined with system simulation programs to achieve the evaluation of SCBC performance.

[0078] The design method of the present invention has at least the following advantages: 1. The design method of this multi-stage labyrinth regulating valve transforms the disordered pressure reduction under high pressure difference into a continuous and controllable mild pressure reduction process through a multi-stage throttling structure (the pressure drop stage n is adjustable). The pressure decreases linearly along the flow path, avoiding flow field instability caused by local pressure changes. 2. The design method of this multi-stage labyrinth control valve allows the flow channel design to control the flow velocity below the critical velocity. Especially when the number of pressure drop stages is reasonable (e.g., when the pressure difference is 5MPa, n=16), it can significantly reduce the outlet velocity of the final stage (compared to n=8, the maximum Mach number is reduced by 35.8%), reducing noise and vibration risks. 3. The design method of this multi-stage labyrinth control valve is based on viscous dissipation as the main energy loss in the flow channel (Be number < 0.05). Energy is efficiently dissipated through mechanisms such as boundary layer separation between the mainstream and the eddies, direct impact of the fluid on the wall, and high-speed converging eddies, achieving pressure reduction without additional energy consumption. By optimizing geometric parameters (such as increasing the number of pressure drop stages or the expansion coefficient), the energy dissipation effect can be enhanced (the end dissipation ratio is increased by 82.7% when n=16 compared to n=8), adapting to the energy control requirements of different pressure difference scenarios. 4. The design method of this multi-stage labyrinth regulating valve can flexibly adjust the flow capacity by adjusting the flow channel geometry parameters (such as expansion coefficient, flow channel spacing, etc.) to meet the diverse power regulation needs of the SCBC system; while ensuring flow velocity stability (such as reducing the standard deviation of Mach number), the impact on flow efficiency can be reduced through parameter optimization, avoiding energy waste caused by excessive pressure reduction. 5. The design method of this multi-stage labyrinth regulating valve takes into account the low dynamic viscosity of S-CO2 and its strong coupling with temperature and pressure. The flow channel structure (such as a right-angle zigzag flow channel) can effectively utilize its viscous dissipation characteristics and avoid pressure reduction failure or flow field disturbance caused by special physical properties. By rationally designing the number and size of the flow channel, the temperature drop problem during the throttling process of S-CO2 is alleviated, and material damage or performance fluctuation caused by sudden temperature changes is reduced. 6. The design method of this multi-stage labyrinth control valve, based on the flow prediction model (within ±15% error) developed by the flow channel geometric parameters, can quickly estimate the mass flow rate under different structures and operating conditions, reduce the design iteration cost, and provide a theoretical basis for the design of high-efficiency valve cores. By optimizing parameters such as the flow channel spacing λ* and the expansion coefficient γ, the flow channel space occupation can be controlled while ensuring performance (such as avoiding excessive increase in flow channel length or area), adapting to the compact layout requirements of SCBC systems.

[0079] Correspondingly, this application also provides a design system for a multi-stage labyrinth control valve, including: The pressure drop range module is used to determine the pressure drop range of the flow channel based on the expected operating environment parameters and flow rate limit parameters of the multi-stage labyrinth control valve. The structural parameters of this multi-stage labyrinth control valve are determined to ensure that the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel. The flow path length module is used to determine the range of straight flow path length along the radial direction of the valve core for different expansion coefficients based on the pressure drop level range. The optimization module is used to compare the valve core size of the control valve with the straight length range of the flow channel; When the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core size is greater than or equal to the straight length of the flow channel S The minimum value, and the valve core width ≤ the straight length of the flow channel.S The maximum value is used to determine the valve core width as the straight length of the flow channel. S The maximum value is calculated, and the range of pressure drop stages is recalculated to obtain the structural parameters of the multi-stage labyrinth control valve.

[0080] It should be noted that, in the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another device, or some features may be ignored or not executed. The modules described as separate components may or may not be physically separated. The components shown as modules may be one or more physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the modules can be selected to achieve the purpose of the solution in this embodiment according to actual needs.

[0081] Furthermore, in the various embodiments of the present invention, the modules can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The integrated unit described above can be implemented in hardware or as a software functional unit.

[0082] An electronic device provided in this application includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the design method for a multi-stage labyrinth control valve as described in any of the above embodiments.

[0083] Another electronic device provided in this application embodiment may further include: an input port connected to a processor for transmitting multimodal data collected by an external acquisition device to the processor; a display unit connected to the processor for displaying the processor's processing results to the outside world; and a communication module connected to the processor for enabling communication between the electronic device and the outside world. The display unit may be a display panel, a laser scanning display, etc.; the communication method adopted by the communication module includes, but is not limited to, Mobile High Definition Link (HML), Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), and wireless connection (including Wi-Fi, Bluetooth, Bluetooth Low Energy, and IEEE 802.11s-based communication technology).

[0084] This application provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the steps of the design method for a multi-stage labyrinth control valve as described in any of the above embodiments.

[0085] For descriptions of relevant parts in the design system, electronic device, and computer-readable storage medium of the multi-stage labyrinth control valve provided in this application, please refer to the detailed description of the corresponding parts in the design method of the multi-stage labyrinth control valve provided in this application, which will not be repeated here. Furthermore, parts of the technical solutions provided in this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0086] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A design method for a multi-stage labyrinth control valve, characterized in that, Includes the following steps: Step 1: Based on the expected operating environment parameters and flow rate limiting parameters of the multi-stage labyrinth control valve, determine the pressure drop stage range of its flow channel; The structural parameters of this multi-stage labyrinth control valve are determined to ensure that the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel. Step 2: Determine the range of straight flow path length along the radial direction of the valve core for different expansion coefficients based on the pressure drop level range; Step 3: Compare the valve core size of the regulating valve with the straight length range of the flow channel; When the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core size is greater than or equal to the straight length of the flow channel S The minimum value, and the valve core width ≤ the straight length of the flow channel. S The maximum value is used to determine the valve core width as the straight length of the flow channel. S The maximum value is calculated, and the range of pressure drop stages is recalculated to obtain the structural parameters of the multi-stage labyrinth control valve.

2. The design method of a multi-stage labyrinth regulating valve according to claim 1, characterized in that, The method for determining the structural dimensions of the multi-stage labyrinth control valve is as follows: Determine the structural parameters of the multi-stage labyrinth control valve, and determine whether the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel under these structural parameters. If the minimum diameter of the impurity is smaller than the diameter of the flow channel, adjust the structural parameters until the minimum diameter of the impurity is larger than the diameter of the flow channel.

3. The design method of a multi-stage labyrinth regulating valve according to claim 1, characterized in that, The operating environment parameters include the valve inlet pressure. and export pressure ; The flow rate limiting parameters include the minimum mass flow rate. and maximum flow rate .

4. The design method of a multi-stage labyrinth regulating valve according to claim 3, characterized in that, The method for determining the pressure drop level range is as follows: Calculate the maximum mass flow rate that the flow channel is allowed to pass through based on the maximum flow velocity; According to the valve inlet pressure and export pressure Determine the pressure differential in the flow channel; Calculate the pressure drop range based on the channel pressure difference and the maximum mass flow rate.

5. The design method of a multi-stage labyrinth regulating valve according to claim 1, characterized in that, The expression for the pressure drop level interval is as follows: In the formula, n For the number of pressure drop stages; k Specific heat capacity; The pressure difference in the flow channel; and These are the valve core inlet and outlet pressures, respectively. and These are the inlet and outlet densities of the valve core, respectively. A out This refers to the cross-sectional area of ​​the flow channel outlet. G m For mass flow rate; The channel spacing; The amplitude of the swing; The aspect ratio of the flow channel; The coefficient of thermal expansion; and They represent n The maximum and minimum values.

6. The design method of a multi-stage labyrinth regulating valve according to claim 1, characterized in that, The straight length of the flow channel S The calculation method is as follows: When γ=1, When γ>1, In the formula, D is the width of the flow channel. n For the pressure drop stage, The aspect ratio of the flow channel.

7. The design method of a multi-stage labyrinth regulating valve according to claim 1, characterized in that, When the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core width is less than or equal to the straight length of the flow channel S If the minimum value is reached, then steps 1 and 2 are executed to adjust the structural parameters of the multi-stage labyrinth control valve so that the straight length of the flow channel is... S Reduce until the valve core width is greater than the straight length of the flow channel. S And the valve core width is less than the straight length of the flow channel. S The maximum value is used to obtain the structural parameters of the multi-stage labyrinth control valve.

8. The design method of a multi-stage labyrinth regulating valve according to claim 1, characterized in that, The valve core width is used as the straight length of the flow channel. S The maximum value is then calculated, and the range of pressure drop stages is recalculated as follows: make: Solve When γ=1, When γ>1, In the formula, k is the specific heat capacity, λ is the channel spacing, and D is the channel width. The aspect ratio of the flow channel. n For the pressure drop stage, is the coefficient of thermal expansion.

9. A design system for a multi-stage labyrinth control valve, characterized in that, include: The pressure drop range module is used to determine the pressure drop range of the flow channel based on the expected operating environment parameters and flow rate limit parameters of the multi-stage labyrinth control valve. The structural parameters of this multi-stage labyrinth control valve are determined to ensure that the minimum diameter of impurities in the bypass system is greater than the diameter of the flow channel. The flow path length module is used to determine the range of straight flow path length along the radial direction of the valve core for different expansion coefficients based on the pressure drop level range. The optimization module is used to compare the valve core size of the control valve with the straight length range of the flow channel; When the straight length range of the flow channel is within the constraint range of the valve core size, the structural parameters of the multi-stage labyrinth control valve are obtained; When the valve core size is greater than or equal to the straight length of the flow channel S The minimum value, and the valve core width ≤ the straight length of the flow channel. S The maximum value is used to determine the valve core width as the straight length of the flow channel. S The maximum value is calculated, and the range of pressure drop stages is recalculated to obtain the structural parameters of the multi-stage labyrinth control valve.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the design method for the multi-stage labyrinth control valve as described in any one of claims 1-8.

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