Flow Characteristics Of Valve Research Articles

Transient Flow Characteristics of a Pressure Differential Valve with Different Valve Spool Damping Orifice Structures

Lubrication system failure is a significant cause of in-flight shutdown incidents in aviation engines. The pressure differential valve, an essential component of a certain type of aviation engine lubrication system, is responsible for controlling the flow rate and pressure of the lubricating oil. Comprehending the transient flow characteristics of the pressure differential valve is of paramount importance for the secure operation of lubrication systems. This paper establishes a transient flow model of a pressure differential valve based on a transient computational fluid dynamics (CFD) method, and the experimental validation demonstrates the effectiveness of the computational model. The internal flow characteristics of the differential pressure valve at different stages during the opening process were studied. Additionally, four transient lubricating oil flow models with different valve spool damping orifice were established to analyse the impact of damping orifice structure on valve spool movement characteristics, pressure control characteristics, and flow field distribution. The results indicate that when the diameter of the valve spool damping orifice increases from 0.3 mm to 1.0 mm, the valve spool displacement and fluid force increase by 88 % and 20 %, respectively. Meanwhile, the peak valve spool velocity, peak oil supply pressure, and steady-state value decreased by 15 %, 29 %, and 34 %, respectively. As the length of the valve spool damping orifice increases from 0.894 mm to 4.0 mm, the growth rate of valve spool displacement and fluid force gradually decreases, with the peak valve spool velocity decreasing by 7 %. This study has potential significance for the structural optimization and application of pressure differential valve in lubrication systems.

Numerical Study of Cavitation Characteristics through Butterfly Valve under Different Regulation Conditions

Butterfly valves are widely used in the pipeline transportation industry due to their safety and reliability, as well as their low manufacturing and operation costs. Cavitation is a common phenomenon in the butterfly valve that can lead to serious damage to a valve’s components. Therefore, it is important to investigate the generation and evolution of cavitation in butterfly valves. In this study, LES and the Zwart model were used as the turbulence and cavitation models, respectively, to simulate cavitation through a butterfly valve. The influence of the valve opening degree and inlet flow velocity on dynamic cavitation through the butterfly valve were studied. Furthermore, the cavitated flow field was examined, along with the performance coefficients of the butterfly valve. With the increase in the incoming flow velocity, the high-speed jet zone over a large-range and low-pressure zone appeared inside the downstream of butterfly valve, which affected its stability and the cavitation generation through the valve. Furthermore, the flow coefficient decreased with the increase in vapor volume. In addition, the results indicated that cavitation was more easily induced for smaller valve opening degrees, and the interaction between cavitation and solid walls was stronger. Due to the existence of cavitation, the flow characteristics of butterfly valves are seriously affected.

Research on high precision flow control technology of low speed wind tunnel air supply system

Aiming at the shortcomings of traditional analog control valves and digital valves, a high-pressure air supply system with accurate flow control is designed. Firstly, the ER5000 controller and pilot proportional valve drive several diaphragm reducing valves to achieve the preliminary adjustment of air pressure. Secondly, a needle valve based on the PCM digital valve and equal percentage flow characteristics is used to achieve accurate control of gas flow. Then, the Venturi flow meter with a honeycomb and damping network is used to accurately measure the airflow. Finally, a PID flow control algorithm based on nonlinear self-tuning is proposed. The results show that the flow regulation range of the system reaches 0.1∼8 kg/s, the absolute control accuracy is better than ±3 g/s, and the relative control accuracy is better than ±0.04%. Moreover, the system has the characteristics of short regulation time, small overshoot, and good dynamic performance, which can achieve strong support for wind tunnel air supply tests.

High-altitude long-duration latex balloon venting valves

With the demand of near-space exploration, it is required to continually improve the flat drifting capability of high-altitude latex balloons. To extend the flat drift time of latex balloons at a high altitude, it is necessary to design a gas release device to control the volume of gas discharged from the balloon. However, there are few such studies, especially on the type of high-altitude latex balloon exhaust valve and the control of release gas flow rate by balloon height. In this study, based on the high-altitude atmospheric data in Hunan Province, China, the release process of gas in high-altitude balloons in the fluid turbulence mode was determined using Reynolds method. The dynamic characteristics of two types of release valves, ball valve and butterfly valve, during the opening and closing and the steady-state flow characteristics of butterfly valve under a certain valve opening were simulated using gas motion equations and slip grid technology. By comparing the flow rate of these two types of valves at the same time, the adjustable time range under the same flow rate, as well as the ascending and drifting trajectory of the latex balloon, it was determined that the performance of butterfly valve is more suitable for the high-altitude latex balloon gas release system. Finally, the butterfly valve was applied to the high-altitude balloon gas release system, and a solution was designed for day and night flat drift balloons, which provide a reference for the design of high-altitude long-duration latex balloons.

Dynamic Modeling and Combination Analysis of Plunger Valve Considering Both Flow and Actuator

The plunger valve has an important role in a large compressor system as its operating characteristics directly affect the aerodynamic boundary condition of the compressor equipment. In this study, dynamic modeling and analysis method of the plunger valve are proposed for an accurate control of the system. By considering the interaction between the dynamic flow in the valve and actuator action, a lumped parameter model for the fluid–structure interaction force and multibody dynamic model of the actuator are developed based on intrinsic correlation parameters. A combination analysis to simultaneously predict valve flow and actuator dynamic characteristics is proposed. The predicted results are in a good agreement with experimental data, which validates the proposed model and analysis method. The analysis results show that the coupling effect between the valve flow and actuator is significant and has an important role in valve control, particularly when the valve opening is smaller. Compared to the experimental data and computational fluid dynamics results, the presented methods are accurate for valve control and effective for prediction of flow rate.

Numerical analysis of fluid force on orifice structure of valve disc for nuclear globe valve

The globe valve fails to open completely sometimes due to insufficient lifting of the valve disc during the operation of the nuclear power plant. The main reason is the inadequate understanding of changes in fluid force. Therefore, conducting research on the fluid force of the globe valve is crucial. In this study, we establish a high-fidelity computational fluid dynamics (CFD) numerical model to investigate the flow characteristics of a novel balanced globe valve. Based on the analysis results, we concluded that the size of the throttle orifice is an essential factor affecting fluid force. Therefore, the impact of the throttle orifice sizes on the fluid force is studied. Meanwhile, the coupling influence of different valve disc displacements and inlet pressures on fluid force is quantitatively analyzed. This study provides a basis for the design of globe valves and has potential value for the dynamic control and energy utilization.

Thermal-mixing flow characteristics of mixing valve

Mixing valves play an important role in fluid transmission pipeline systems and fluid heat mixing in the chemical-energy industry. To limit thermal fatigue cracking failure of cross-combination pipelines and thermal-mixing equipment, this study investigated the effect of plunger strokes on the internal flow and temperature fluctuation of a mixing valve. A large eddy simulation method was used to study the temperature distribution and fluctuation mechanism of a fluid during hot mixing using a mixing valve with different plunger strokes. For mixing valves, the centroid of the effective jet section of the branch pipe moves to the negative Y-axis during plunger stroke operations, resulting in a jet angle change in the branch pipe. As the effective jet area of the branch pipe decreases, the vortex structure of the branch pipe also changes. When the plunger stroke is small, there is a higher and stronger temperature fluctuation in the 90° circumferential area of the wingspan section, whereas when the plunger stroke is large, there is a higher and stronger temperature fluctuation in the 270° circumferential area of the wingspan section. The results showed that valve operation should be avoided at these plunger strokes and monitoring at these positions is required during operation. The study results provide an industry reference for the internal hot-mixing flow characteristics of mixing equipment with adjustable flow channels.

Energy-Saving Testing System for a Coal Mine Emulsion Pump Using the Pressure Differential Flow Characteristics of Digital Relief Valves

Most energy-saving testing methods for plunger pumps use hydraulic motors. The loading test of coal mine emulsion pumps generally uses an overflow valve as the loading unit, which is characterized by high energy consumption. The coal mine emulsion pump uses emulsion as the transmission medium, and the viscosity and lubricity of the emulsion are much lower than those of hydraulic oil, which creates great difficulties in the development of high water-based hydraulic products. The nominal flow rate of the emulsion motor is much smaller than that of the emulsion pump, and there is no mature and reliable water-based flow control valve. Based on the above reasons, traditional energy-saving testing methods cannot be utilized for the testing process of emulsion pumps. The loading test of emulsion pumps generally uses an overflow valve as the loading unit, and during the testing process, all electrical energy is converted into internal energy, resulting in very high energy consumption. This article proposes an energy-saving testing system for emulsion pumps based on multiple emulsion motors in parallel. In order to solve the flow regulation problem of each parallel branch, a flow-intelligent control algorithm is proposed that utilizes the pressure difference flow characteristics of digital relief valves combined with artificial neural network predictive control. Firstly, the feasibility of the proposed system and method is theoretically verified through the analysis of the mathematical model of the digital relief valve. Secondly, further verification is carried out by establishing simulation and testing platforms. The simulation results show that the energy recovery efficiency of the system exceeds 53%. The experimental results show that the proposed testing system has a pressure control error of less than 1%, a flow control error of about 5%, and a maximum overshoot of about 9 L/min relative to the steady-state flow rate. The control accuracy and system stability are high.

Cavitation Characteristics and Structure Optimization of Two-Dimensional Valve Based on Entropy Production Theory

In addition to noise and vibration, cavitation also lowers the efficiency, performance, and working lives of two-dimensional valves. To study the effect of cavitation on the flow characteristics of two-dimensional valves, standard turbulence model and an energy equation model were selected, and the local entropy production rate was defined using the custom field function. The entropy production theory was introduced to numerically simulate the cavitation flow in a two-dimensional valve, and based on this, the structure of the pilot stage of the valve was optimized. The results showed that there was a distinct correlation between the entropy production and the flow characteristics of the valve. When the mass flow rate changed, the entropy production also changed. The turbulent dissipation entropy production always accounted for more than 50% of the total entropy production in the flow field. In the valve sleeve chute area downstream of the valve throttling port, turbulence dissipation entropy production was concentrated; and the energy loss was large. According to the optimization of the structure of this area, the total entropy production of the side-V-slot valve sleeve structure was 7.46% lower than that of the unslotted valve sleeve structure for different valve openings, while the total entropy production of the rear-V-slot valve sleeve structure was 14.31% higher. The energy loss caused by cavitation could be better reduced using a V-shaped groove on the side of the valve sleeve.

Numerical and experimental analysis of cavitation characteristics in safety valves of the nuclear power second circuit using a modified cavitation model

Cavitation frequently arises in the safety valve of nuclear power plants’ secondary circuits operating under high pressure conditions. This study integrates valve flow characteristics and velocity strain rate corrections into the Zwart-Gerber-Belamri model to accurately simulate cavitation inside the valve, reducing the impact of physical empirical coefficient variations on cavitation length prediction. Subsequently, a visualisation test rig is developed to validate the accuracy of the numerical model, and experimental cavitation results are obtained using the grayscale detection method. The evaporation/condensation coefficients are optimised using the AES-MSI model and GA based on the experimental results. The accuracy of the constructed model is validated by comparing it with experimental results obtained under various operating conditions. Finally, the high-fidelity numerical model is employed to investigate the effects of pressure drop and valve openings on cavitation, elucidating the underlying mechanisms governing cavitation variations resulting from pressure drops. Furthermore, a comprehensive equation is derived to determine the effective flow area, aiding in the identification of cavitation locations and offering insights into the relationship between cavitation behaviour and valve openings. The modified cavitation model proposed in this study can be readily extended to investigate cavitation prediction in other valves or throttle elements.

Numerical simulation of liquid–solid two-phase flow and erosion of Y-type slurry valve with different openings

Most conveyed industrial slurries contain hard particles, and the Y-type slurry valve is eroded after the long-term operation, causing economic losses. In this study, the liquid–solid two-phase flow and erosion characteristics of the Y-type slurry valve were studied. The distribution positions of particles with different sizes were determined, and large particles showed a deposition phenomenon. The particle distributions were more dispersed. At smaller valve opening degrees and the average velocity of solid particles decreased with the increase in valve opening degree. The main erosion area of the valve was concentrated on the ring area around the valve body connecting the downstream pipeline, and the valve disc. The relationship between the particle size and the erosion rate was analyzed, and the distribution of the main erosion area was obtained.

Research on the flow characteristics identification of steam turbine valve based on FCM-LSSVM

Due to aging and deformation of the through-flow path and system modifications, the flow characteristics of the turbine inlet valve often deviate from the design value, which affects the unit load control accuracy and operational stability. In order to obtain the actual valve flow characteristics of the turbine and thus improve the FM performance, an FCMLSSVM model is proposed in this paper to identify the valve flow characteristics. First, FCM clustering is proposed to classify the historical operating data of the plant and obtain a wide range of variable operating conditions. Then, using least squares support vector machine (LSSVM), the relationship between turbine input and output variables was modeled in each condition cluster, with integrated valve position command, speed, and real power generated as input variables and actual steam inlet flow as output variables. Using a 330 MW turbine unit as an application example, the established FCM-LSSVM model was validated for the valve flow characteristics of the turbine. The results show that the model can obtain accurate valve flow characteristics without conducting tests on the turbine. The method can save a lot of labor and material resources in doing the characteristic test, and after comparison, the proposed method can identify the flow characteristics more accurately among the existing neural network identification methods, which can provide technical support to improve the unit frequency regulation characteristics and improve the accuracy of valve operation.

Influence of the flow area around the ball valve on the flow characteristics of the injector control valve

The increase in common rail pressure can lead to increased cavitation inside the injector, resulting in degradation of injector performance and reduced life. The paper investigates the effect of the pressure block structure parameters (initial flow area around the ball valve) on the velocity field, pressure field, fuel gas phase volume fraction and drain rate of the control valve. The relationship between the initial flow area around the ball valve on the cavitation strength and unloading rate inside the valve was revealed. The results show that both the reduction of the flow area around the ball valve and the increase of the cavitation intensity inhibit the rate of oil discharge from the control valve. The reduction of the fuel flow area inhibits the expansion of the low-pressure region (0–1 MPa) within the flow layer, thus limiting the development of cavitation. The reduction of the cavitation area increases the fuel flow rate, however, the increase in flow rate increases the cavitation phenomenon, and these changes form a cycle (Reviewer 5. comment 2). The increase in cavitation inhibits the control valve pressure relief rate more significantly than the decrease in the initial flow area around the ball valve. Based on this, a stepped-pressure block model is proposed. The stepped pressure block model can effectively reduce the cavitation strength near the seal and enhance the oil discharge rate of the control valve. The study can provide a reference for the engineering optimization design of high-pressure common rail injector control valves.

Optimization of Valve Flow Characteristics Based on Improved Particle Swarm Algorithm

After long-term operation, the flow characteristics of the high-pressure regulating valve of a thermal power unit may be shifted to a certain extent, resulting in inconsistent changes in the total valve position and opening degree, which in turn affects the PFR function of the unit. Based on the historical operation data of a thermal power unit, the flow characteristics of the unit's high-pressure regulating valve are optimized using an improved particle swarm algorithm. By experimentally verifying the primary FM in different total valve position intervals, the influence of valve flow characteristics on the primary FM function is discussed. The results of the primary FM example show that, with the optimized valve flow characteristics, the output response index of the unit in 15 and 30 seconds is increased to 85.44% and 94.11%, respectively, which meets the assessment requirements of the grid-connected operation and management of the power plant for the primary FM, and optimizes the primary FM performance of the unit.

Design of Noise-Reducing Two-Stage Cage Control Valve and Its Fluid Characteristics and Cavitation Study

For all kinds of media noise, noise reduction valve cage cannot meet the equal percentage flow characteristics, and for manufacturing and processing and other technical problems, research and design of new noise reduction two-stage cage control valve are necessary. The valve adopts noise reduction valve cage and curve valve cage with noise reduction, forming a two-stage noise reduction, with uniform flow, diffusion, and noise reduction effect, to meet the regulating valve equal percentage flow characteristics. The spool is evenly stressed and not easy to loosen and fall off, and the small opening is not easy to vibrate and shake. The flow characteristics of the noise-reducing two-stage cage control valve are studied, and the fluid flow coefficients, flow characteristic curves, the relationship of flow coefficients with nominal diameter at the same stroke, and the relationship of flow coefficients with different nominal diameters at different strokes are analyzed. The relationship between nominal diameter constant opening and cavitation coefficient with inlet velocity, the relationship between inlet velocity and cavitation coefficient with nominal diameter at half opening, and the relationship between inlet velocity and cavitation coefficient with nominal diameter at full opening were studied, and the cavitation generation and its effect on noise were analyzed. The noise and cavitation test showed that noise is very small and cavitation is difficult to produce, all meeting the noise reduction requirements.

Study on Transient Flow and Dynamic Characteristics of Dual Disc Check Valve Mounted in Pipeline System during Opening and Closing

Check valves are used extensively in industrial piping systems. Based on dynamic mesh technology, this study uses the RNG k-ε turbulence model to numerically calculate the dual disc check valve’s three-dimensional transient flow. The dynamic characteristics of the check valve in the pipeline system are also experimentally studied. To this end, the two discs are opened synchronously during the valve-opening process, including four stages: opening discs at a constant angular velocity, opening slowing down discs, slowly returning discs to the balance point, and discs maintaining oscillation. However, the movements of the two discs are asynchronous in the valve-closing process. As the downstream pressure increases, the valve disc begins to close, and the flow gradually stops; reverse flow takes shape, and the reverse flow stops until the discs are fully closed, and slamming of the check valve occurs. The non-dimensional dynamic characteristic curve of this type of dual disc check valve has a slope of about 1.624, which mirrors the response of the check valve closing to the occurrence of the water hammer in the system. Knowing the dynamic behavior can be convenient in designing and selecting a check valve and regulating piping system working conditions.

Study on the influence of structural parameters on the flow and cavitation characteristics of tandem multi-stage pressure-reducing valves

Tandem multi-stage pressure-reducing valves (TMSPRV) are widely used for piping systems in the process industry. The flow coefficient is a central factor in valve design. The cavitation was caused by the local pressure of the fluid passing through the pressure-reducing valve being lower than the saturated steam pressure. Would cause serious damage to the pipeline system. Therefore, it is important to investigate systematically the effect of throttling structure parameters on the flow and cavitation characteristics of valves. In this paper, a combination of experimental and numerical simulations was used to study the effect of different structural parameters of valves on the flow coefficient. The results showed that increasing the flow channel inclination is beneficial to enlarging the flow coefficient. Meanwhile, the effects of different structural parameters on pressure and velocity of pressure reducing valves are discussed, the results indicated that increasing the inclination of the flow channel would reduce the vortex volume at the outlet. With the increase of the chamfer, the low-pressure area caused by the vortex in the near-wall surface decreases. Numerical simulations are conducted to investigate the effect of different structural parameters on the cavitation characteristics of valves. The numerical results showed that the flow channel inclination angle is 60° and the flow channel chamfer is less than 6 mm as the optimal value. In summary, considering the influence of structural parameters on flow coefficient, flow characteristics, and cavitation characteristics. The runner inclination angle is 60°, and the runner chamfer is 4 mm as the best value. The research work in this paper could provide technical support to achieve a better fluid pressure reducing and flow state of the TMSPRV under severe working conditions.

Flow Characteristics Study of High-Parameter Multi-Stage Sleeve Control Valve

This study considers a multi-stage sleeve control valve with different opening degrees. The flow capacity of the numerical model is calculated using the actual working conditions of the control valve in a nuclear power plant as a baseline. A flow resistance test bench is then used to measure the flow capacity under each opening degree, and the flow characteristic curve is plotted to verify the accuracy of the numerical model. Based on CFX software simulations of different opening speeds, pressures, turbulent kinetic energy clouds, and set detection curves, analysis of the flow characteristics of the multi-stage sleeve valve with high parameters shows that, with an increase in the degree of opening, the valve speed will also increase. However, the speed at the socket orifice is slightly different, exhibiting a higher opening in the middle and lower openings on both sides. A maximum speed of 792.4 m/s is found in the 40% valve orifice. A maximum value of the turbulent kinetic energy of 1.4 × 10 4m2/s2 occurs in the throttle hole of the valve seat with an opening of 80%. The source of the aerodynamic noise is obtained in this study, which is of great significance to the decompression and noise reduction in multi-stage sleeve valves.

Experimental and Numerical Study on the Dynamic and Flow Characteristics of a Reciprocating Pump Valve

The structure and dynamics of a reciprocating pump liquid end affect the volumetric efficiency and net positive suction head. To match the kinematics with theoretical parameters, reciprocating pump valve motion and flow visualization tests and computational fluid dynamics (CFD) analyses were performed on a wing-guided bevel discharge valve in a horizontal quintuple single-acting reciprocating pump. The valve motion test results showed that the maximum pump valve displacement and the pump valve opening and closing durations were approximately 8.3 mm, 29 ms, and 38 ms, respectively. The corresponding flow visualization test results were 11.4 mm, 9.5 ms, and 35.5 ms. The valve closing durations obtained from the valve motion and flow visualization tests are approximately twice as high as the U-Adolph prediction. The maximum displacement obtained from the valve motion test is consistent with the U-Adolph prediction. Three-dimensional CFD analyses were performed to investigate the flow states, pressure, and velocity characteristics of the discharge valve opening. Finally, the proposed method was applied to develop a new horizontal quintuple single-acting reciprocating pump with a rated flow rate of 1250 L/min and pressure of 40 MPa. This developed pump exhibited good performance and excellent reliability.

Numerical Investigation on the Internal Flow Field of Electronic Expansion Valve as the Throttle Element

<div class="section abstract"><div class="htmlview paragraph">As one of the key components of the heat pump system, the electronic expansion valve mainly plays the role of throttling and reducing pressure in the heat pump system. The refrigerant flowing through the orifice will produce complex phase change. It is of great significance to study the internal flow field by means of CFD calculations. Firstly, a three-dimensional fluid model is established and the mesh is divided. Secondly, the phase change model is selected, the material is defined and the boundary conditions are determined. According to the principle of the fluid passing through thin-walled small holes, the flow characteristics of electronic expansion valve are theoretically analyzed. Then the flow characteristics of expansion valve are numerically calculated, and a bench for testing mass flow rate of the expansion valve is built. Then the theoretical value, CFD value and experimental value are compared to verify the correctness of the established three-dimensional fluid model. The flow rate changes of expansion valve are studied under the condition of changing geometric parameters such as the cone angle of the valve spool and the radius of circular arc at the end of the valve seat. According to the momentum theorem, the steady hydraulic force is theoretically deduced. Then the changes of steady hydraulic force are studied under the conditions of different inlet pressure and outlet pressure. At the same time, there also analyzes the effects of the conditions of different valve spool cone angle and valve seat arc radius on steady hydraulic force on the valve spool. Finally, transient analysis is carried out by using dynamic mesh technology. The speed of spool movement is defined by User Defined Function (UDF). Under constant pressure difference conditions, the influence of the spool movement on the hydraulic force and outlet flow of the valve is studied. And the change of the internal pressure field are shown.</div></div>