The structure of the pressure swirl nozzle is an important factor affecting its spray performance.This work aims to study pressure swirl nozzles with different structures by experiment and simulation.In the experiment...The structure of the pressure swirl nozzle is an important factor affecting its spray performance.This work aims to study pressure swirl nozzles with different structures by experiment and simulation.In the experiment,10 nozzles with different structures are designed to comprehensively cover various geometric factors.In terms of simulation,steady-state simulation with less computational complexity is used to study the flow inside the nozzle.The results show that the diameter of the inlet and outlet,the direction of the inlet,the diameter of the swirl chamber,and the height of the swirl chamber all affect the atomization performance,and the diameter of the inlet and outlet has a greater impact.It is found that under the same flow rate and pressure,the geometric differences do have a significant impact on the atomization characteristics,such as spray angle and SMD(Sauter mean diameter).Specific nozzle structures can be customized according to the actual needs.Data analysis shows that the spray angle is related to the swirl number,and the SMD is related to turbulent kinetic energy.Through data fitting,the equations for predicting the spray angle and the SMD are obtained.The error range of the fitting equation for the prediction of spray angle and SMD is within 15% and 10% respectively.The prediction is expected to be used in engineering to estimate the spray performance at the beginning of a real project.展开更多
Pressure nozzle is commonly used in the dust-reduction techniques by spraying of underground coal mines.Based on the internal structure,the pressure nozzle can be divided into the following types:spiral channel nozzle...Pressure nozzle is commonly used in the dust-reduction techniques by spraying of underground coal mines.Based on the internal structure,the pressure nozzle can be divided into the following types:spiral channel nozzle,tangential flow-guided nozzle and X-swirl nozzle.In order to provide better guidance on the selection of nozzles for the coal mine dust-reduction systems by spraying,we designed comparing experiments to study the atomization characteristics and dust-reduction performance of four commonly used nozzles in the coal mine underground with different internal structures.From the experimental results on the atomization characteristics,both the tangential flow-guided nozzle and the X-swirl nozzle have high flow coefficients.The atomization angle is the largest in the spiral non-porous nozzle,and smallest in both the X-swirl nozzle and the spiral porous nozzle.The spraying range and the droplet velocity are inversely proportional to the atomization angle.When the water pressure is low,the atomization performance of the spiral non-porous nozzle is the best among the four types of nozzles.The atomization performance of the X-swirl nozzle is superior to other types when the water pressure is high.Under the high water pressure,the particle size of the atomized droplets is smallest in the X-swirl nozzle.Through the experiments on the dust-reduction performance of the four types of nozzles and the comprehensive analysis,the X-swirl nozzle is recommended for the coal mine application site with low water pressure in the dust-reduction system,while at the sites with high water pressure,the spiral non-porous nozzle is recommended,which has the lowest water consumption and obvious economic advantages.展开更多
The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study.The results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liq...The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study.The results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liquid volume flux under different Reynolds numbers at the near-field spray.The spray structure was visualized using a high-speed camera,and the characteristics of droplets were measured using a Phase Doppler Anemometer(PDA)in both the radial and axial directions.The tests were carried out at varying spray pressures(0.2 to 1.0 MPa),corresponding to different Reynolds numbers(5369 to 12006).It was found that when the Reynolds number rises,the liquid became more unstable after leaving the nozzle,causing the liquid film to break up faster.According to the measurements of PDA,the coalescence of droplets increased due to the centrifugal effect.What’s more,the velocity of the droplets fluctuates significantly in the radial direction,and the droplets with a smaller particle size had a higher average velocity.From the perspective of liquid distribution,the increase in Reynolds number caused the spray liquid to move in the radial direction gradually.In contrast,the liquid volume distribution changed in the radial direction more obviously than in the axial direction,growing to the maximum along the radial direction and gradually reducing.It can provide a reference for selecting operating parameters for actual agricultural spray operations and the design of electrostatic nozzles through the research on breakup and droplet characteristics.展开更多
The current article presents conceptual,preliminary and detailed aero-thermal redesign of a typical high pressure turbine nozzle guide vane.Design targets are lower coolant consumption,reduced manufacturing costs an...The current article presents conceptual,preliminary and detailed aero-thermal redesign of a typical high pressure turbine nozzle guide vane.Design targets are lower coolant consumption,reduced manufacturing costs and improved durability.These goals are sought by 25%reduction in vane count number and lower number of airfoils per segment.Design challenges such as higher airfoil loading,associate aerodynamic losses and higher thermal loads are discussed.In order to maximize coolant flow reduction and avoid higher aerodynamic losses,airfoil Mach distribution is carefully controlled.There has been an effort to limit design changes so that the proven design features of the original vane are used as much as possible.Accordingly,the same cooling concept is used with minor modifications of the internal structures in order to achieve desired coolant flow and internal heat transfer distribution.Platforms of the new design are quite similar to the original one except for cooling holes and application of thermal barrier coating(TBC).Detailed aerodynamics/heat transfer simulations reveals that the reduced trailing edge(T.E.)blockage and skin friction dominated the negative effect of increased secondary losses.As a result the reduced design performs acceptable in terms of total pressure loss and improving stage efficiency for a wide range of varying pressure ratio.Moreover,more than 20%cooling mass flow can be saved;while maximum and average metal temperatures as well as cross sectional temperature gradients have not been changed much.展开更多
基金supported by the National Key Research and Development Program(2022YFB3504000)the National Natural Science Foundation of China(22122815,21978296)the NSFC-EU project(31961133018)。
文摘The structure of the pressure swirl nozzle is an important factor affecting its spray performance.This work aims to study pressure swirl nozzles with different structures by experiment and simulation.In the experiment,10 nozzles with different structures are designed to comprehensively cover various geometric factors.In terms of simulation,steady-state simulation with less computational complexity is used to study the flow inside the nozzle.The results show that the diameter of the inlet and outlet,the direction of the inlet,the diameter of the swirl chamber,and the height of the swirl chamber all affect the atomization performance,and the diameter of the inlet and outlet has a greater impact.It is found that under the same flow rate and pressure,the geometric differences do have a significant impact on the atomization characteristics,such as spray angle and SMD(Sauter mean diameter).Specific nozzle structures can be customized according to the actual needs.Data analysis shows that the spray angle is related to the swirl number,and the SMD is related to turbulent kinetic energy.Through data fitting,the equations for predicting the spray angle and the SMD are obtained.The error range of the fitting equation for the prediction of spray angle and SMD is within 15% and 10% respectively.The prediction is expected to be used in engineering to estimate the spray performance at the beginning of a real project.
基金Financial support for this work,provided by the National Natural Science Foundation of China(No.51574123)the Hunan Provincial Natural Science Foundation of China(No.2017JJ3076)Hunan Graduate Research and Innovation Project(No.CX2018B661),are gratefully acknowledged.
文摘Pressure nozzle is commonly used in the dust-reduction techniques by spraying of underground coal mines.Based on the internal structure,the pressure nozzle can be divided into the following types:spiral channel nozzle,tangential flow-guided nozzle and X-swirl nozzle.In order to provide better guidance on the selection of nozzles for the coal mine dust-reduction systems by spraying,we designed comparing experiments to study the atomization characteristics and dust-reduction performance of four commonly used nozzles in the coal mine underground with different internal structures.From the experimental results on the atomization characteristics,both the tangential flow-guided nozzle and the X-swirl nozzle have high flow coefficients.The atomization angle is the largest in the spiral non-porous nozzle,and smallest in both the X-swirl nozzle and the spiral porous nozzle.The spraying range and the droplet velocity are inversely proportional to the atomization angle.When the water pressure is low,the atomization performance of the spiral non-porous nozzle is the best among the four types of nozzles.The atomization performance of the X-swirl nozzle is superior to other types when the water pressure is high.Under the high water pressure,the particle size of the atomized droplets is smallest in the X-swirl nozzle.Through the experiments on the dust-reduction performance of the four types of nozzles and the comprehensive analysis,the X-swirl nozzle is recommended for the coal mine application site with low water pressure in the dust-reduction system,while at the sites with high water pressure,the spiral non-porous nozzle is recommended,which has the lowest water consumption and obvious economic advantages.
基金support provided by National Natural Science Foundation of China(Grant No.31971797)National Natural Science Foundation of China(Grant No.32271997)+3 种基金China Agriculture Research System of MOF and MARA(CARS-26)General Program of Guang-dong Natural Science Foundation(2021A1515010923)Guangdong Provincial Special Fund For Modern Agriculture Industry Technology Innovation Teams(Grant No.2023KJ108)Key-Area Research and Development Program of Guangdong Province(2023B 0202090001).
文摘The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study.The results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liquid volume flux under different Reynolds numbers at the near-field spray.The spray structure was visualized using a high-speed camera,and the characteristics of droplets were measured using a Phase Doppler Anemometer(PDA)in both the radial and axial directions.The tests were carried out at varying spray pressures(0.2 to 1.0 MPa),corresponding to different Reynolds numbers(5369 to 12006).It was found that when the Reynolds number rises,the liquid became more unstable after leaving the nozzle,causing the liquid film to break up faster.According to the measurements of PDA,the coalescence of droplets increased due to the centrifugal effect.What’s more,the velocity of the droplets fluctuates significantly in the radial direction,and the droplets with a smaller particle size had a higher average velocity.From the perspective of liquid distribution,the increase in Reynolds number caused the spray liquid to move in the radial direction gradually.In contrast,the liquid volume distribution changed in the radial direction more obviously than in the axial direction,growing to the maximum along the radial direction and gradually reducing.It can provide a reference for selecting operating parameters for actual agricultural spray operations and the design of electrostatic nozzles through the research on breakup and droplet characteristics.
文摘The current article presents conceptual,preliminary and detailed aero-thermal redesign of a typical high pressure turbine nozzle guide vane.Design targets are lower coolant consumption,reduced manufacturing costs and improved durability.These goals are sought by 25%reduction in vane count number and lower number of airfoils per segment.Design challenges such as higher airfoil loading,associate aerodynamic losses and higher thermal loads are discussed.In order to maximize coolant flow reduction and avoid higher aerodynamic losses,airfoil Mach distribution is carefully controlled.There has been an effort to limit design changes so that the proven design features of the original vane are used as much as possible.Accordingly,the same cooling concept is used with minor modifications of the internal structures in order to achieve desired coolant flow and internal heat transfer distribution.Platforms of the new design are quite similar to the original one except for cooling holes and application of thermal barrier coating(TBC).Detailed aerodynamics/heat transfer simulations reveals that the reduced trailing edge(T.E.)blockage and skin friction dominated the negative effect of increased secondary losses.As a result the reduced design performs acceptable in terms of total pressure loss and improving stage efficiency for a wide range of varying pressure ratio.Moreover,more than 20%cooling mass flow can be saved;while maximum and average metal temperatures as well as cross sectional temperature gradients have not been changed much.
