scholarly journals Investigation on the Characteristics of a Combination Microflow Control Valve

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yuqi Wang ◽  
Xinhui Liu ◽  
Jinshi Chen ◽  
Yafang Han ◽  
Siyuan Liu ◽  
...  
Keyword(s):  
Flow Rate ◽  
Structural Parameters ◽  
Flow Characteristics ◽  
Control Valve ◽  
Hydraulic Systems ◽  
Flow Area ◽  
Port Area ◽  
Rate Fluctuation ◽  
Calculation Results ◽  
Flow Regulator

Flow control valves have broad application prospects in aviation hydraulic systems. This paper proposes a combination microflow control valve (CMCV) instead of the traditional valve to optimize the performance. Influences of structural parameters of CMCV on its characteristics are numerically investigated to determine the static and dynamic characteristics of CMCV. The calculation results indicate that there is a negative feedback control between stages of the flow regulator, the orifice pressure drop is compensated, and the flow regulation deviation is reduced. The orifice area and the flow regulator valve port area have significant effects on flow characteristics. The diameter of orifice, the spring stiffness, the number of throttle holes, and the ultimate displacement of sleeve are positively correlated with the flow rate stability value of the valve. The valve port flow area gradient and initial overlap of the flow regulator affect the flow rate fluctuation range and response time of CMCV.

Development of Novel Particle Excitation Flow Control Valve for Stable Flow Characteristics

2016 ◽  
Vol 10 (4) ◽  
pp. 540-548 ◽  
Author(s):  
Daisuke Hirooka ◽  
◽  
Tomomi Yamaguchi ◽  
Naomichi Furushiro ◽  
Koichi Suzumori ◽  
...  
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Control Valve ◽  
Flow Control Valve ◽  
Different Types ◽  
Valve Opening ◽  
Working Principle ◽  
Stable Flow ◽  
Air Flow Control

The authors have previously developed a compact, light-weight air flow control valve, which realizes continuous flow control. The vibration produced by a piezoelectric device (PZT) was used to excite particles confined in a flow channel to control the valve opening for the developed control valve. Therefore, the voltage applied to the PZT can be changed to continuously control the flow rate. A new working principle was developed for the control valve to stabilize flow rate characteristics. Different types of particles were used to change the valve opening condition. A prototype was manufactured to demonstrate the effectiveness of the control valve.

An Investigation Into the Characteristics of a Two Dimensional “2D” Flow Control Valve

2001 ◽  
Vol 124 (1) ◽  
pp. 214-220 ◽  
Author(s):  
J. Ruan ◽  
R. Burton ◽  
P. Ukrainetz
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Structural Parameters ◽  
Control Valve ◽  
Favorable Effect ◽  
Flow Control Valve ◽  
Two Dimensional ◽  
System Pressure ◽  
Hydrostatic Force ◽  
2D Flow

In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli’s forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve (defined as a two dimensional or “2D” flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve’s static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.

An Investigation Into the Characteristics of a “2D” Flow Control Valve

2000 ◽  
Author(s):  
J. Ruan ◽  
R. Burton ◽  
P. Ukrainetz
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
High Speed ◽  
Structural Parameters ◽  
Control Valve ◽  
Favorable Effect ◽  
Flow Control Valve ◽  
System Pressure ◽  
Hydrostatic Force ◽  
2D Flow

Abstract In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli’s forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve, (defined as a “2D” flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve’s static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.

Effects of Control Valve's Structure Parameters on the Circulation Characteristics for an Electronic Unit Pump

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Wan-Lin Zhao ◽  
Guo-Xiu Li ◽  
Lan Wang ◽  
Hong-Meng Li ◽  
Jie Wang ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
High Precision ◽  
Mass Flow ◽  
Flow Rate ◽  
Fuel Injection ◽  
Flow Characteristics ◽  
Control Valve ◽  
Electronic Unit ◽  
Electronic Unit Pump ◽  
Circulation Characteristics

The control valve is an essential component of electronic unit pump (EUP) fuel injection systems; it controls the flow rate with high-precision electrical signals. Thus, high precision and flexibility are required in the working process of a fuel injection system. The flow capacity (indicated by mass flow rate) of a control valve is an important technical indicator in the discharge of EUP fuel injection systems. In this study, the transient flow characteristics within control valve during the discharge of an EUP were evaluated using a computational fluid dynamics (CFD) approach. Three essential structural parameters of EUP control valve were investigated, and their effects on circulation characteristics were evaluated. The variation trends were observed, and the changes in significant physical parameters and crucial physical field distributions were analyzed. During the investigation, the visualization of internal flow of control valve provided more detailed information of flow fields. This study shows the effect of each parameter on flow characteristics and indicates that cavitation is the lowest for the case of 0.20 mm valve core lift; the length of slit is the shortest for the case of 7 mm seal diameter, therefore, the mass flow rate of export is the highest; at 139 deg seal cone angles, fuel velocity is the highest, therefore, 139 deg is the best seal cone angle.

Modeling and Analysis of a Pressure Compensated Flow Control Valve

2005 ◽  
Author(s):  
Minter Cheng
Keyword(s):  
Response Time ◽  
Flow Control ◽  
Transient Response ◽  
Flow Rate ◽  
Control Valve ◽  
Spring Constant ◽  
Flow Control Valve ◽  
Hydraulic Systems ◽  
System Pressure ◽  
Control Accuracy

In hydraulic systems, flow control valve is used to regulate the flow of fluid to actuators by adjusting the valve opening. However, the inlet and the outlet pressures of the valve are not always remaining constant. Any change in pressure will alter the flow rate through the valve and alter the actuator speed consequently. Pressure compensated flow control valves are often used in hydraulic systems when accurate speed control is required under varying supply or load pressures. The basic structure of the pressure compensated flow control valve is by incorporating a compensating spool to maintain a constant pressure drop across the metering orifice. Under ideal circumstance, the actuator speed can be constant and controllable, regardless of load or system pressure changes. However, in practical applications, any system or load pressures variations will cause force unbalance on valve compensating spool and affect the control accuracy. The steady and dynamic response of the flow control valve plays an important role on hydraulic system behavior. Therefore, analyzing and understanding of the valve steady and dynamic behaviors is very important. In this study, the steady and dynamic performance of a pressure compensated flow valve is simulated numerically by solving the characteristic equations. The parameters studied in this research are biased spring constant, pre-compressed spring length, spool mass, and the damping orifice characteristics. The simulation results show that the flow force is identified as the key factor to affect the control accuracy. Increasing the spring constant as well as the pre-compressed spring length will increase the steady flow rate and reduce the transient response time. Decreasing the damping orifice opening or the discharge coefficient will increase the transient response time. The spool mass has practically no effect on the flow rate.

Computational fluid dynamics and experimental analysis on flow rate and torques of a servo direct drive rotary control valve

2018 ◽  
Vol 233 (1) ◽  
pp. 213-226 ◽  
Author(s):  
Muzhi Zhu ◽  
Shengdun Zhao ◽  
Jingxiang Li ◽  
Peng Dong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Characteristics ◽  
Control Valve ◽  
Direct Drive ◽  
Flow Area ◽  
Novel Structure ◽  
System Pressure ◽  
Opening And Closing ◽  
Dynamics Method

This paper aims to analyze the flow characteristics and fluid torques in a direct drive rotary control valve with a novel structure, and based on the computational fluid dynamics method, the advantages of improved structure are verified. With the establishment of the valve structure and the simulation model, the sliding mesh model and moving region grid are applied to simulate the complete opening and closing process of the valve at dynamic conditions. The results present that the fluid torques generate resistance torques during the increasing process of flow area while providing driving torques in the decreasing period of flow area, which is consistent with the theoretical analysis. In addition, the flow regulation of the fluid chamber is conducted with the computational fluid dynamics method and experimental test, which exhibited disagreement due to the oil leakage phenomenon. The simulation results and experimental results both convince the pressure and flow characteristics, and the improved valve model shows decreased fluid torques of around 17% compared with the original one under the system pressure of 6 MPa.

scholarly journals In vitro testing of explanted shunt valves in hydrocephalic patients with suspected valve malfunction

2021 ◽  
Author(s):  
Christoph Bettag ◽  
Christian von der Brelie ◽  
Florian Baptist Freimann ◽  
Ulrich-Wilhelm Thomale ◽  
Veit Rohde ◽  
...  
Keyword(s):  
Flow Rate ◽  
Clinical Symptoms ◽  
Obstructive Hydrocephalus ◽  
Flow Characteristics ◽  
Normal Pressure ◽  
Diagnostic Tools ◽  
Programmable Valve ◽  
Significant Difference ◽  
Valve Malfunction

AbstractDiagnosis of symptomatic valve malfunction in hydrocephalic patients treated with VP-Shunt (VPS) might be difficult. Clinical symptoms such as headache or nausea are nonspecific, hence cerebrospinal fluid (CSF) over- or underdrainage can only be suspected but not proven. Knowledge concerning valve malfunction is still limited. We aim to provide data on the flow characteristics of explanted shunt valves in patients with suspected valve malfunction. An in vitro shunt laboratory setup was used to analyze the explanted valves under conditions similar to those in an implanted VPS. The differential pressure (DP) of the valve was adjusted stepwise to 20, 10, 6, and 4 cmH2O. The flow rate of the explanted and the regular flow rate of an identical reference valve were evaluated at the respective DPs. Twelve valves of different types (Codman CertasPlus valve n = 3, Miethke Shuntassistant valve n = 4, Codman Hakim programmable valve n = 3, DP component of Miethke proGAV 2.0 valve n = 2) from eight hydrocephalic patients (four male), in whom valve malfunction was assumed between 2016 and 2017, were replaced with a new valve. Four patients suffered from idiopathic normal pressure (iNPH), three patients from malresorptive and one patient from obstructive hydrocephalus. Post-hoc analysis revealed a significant difference (p < 0.001) of the flow rate between each explanted valve and their corresponding reference valve, at each DP. In all patients, significant alterations of flow rates were demonstrated, verifying a valve malfunction, which could not be objectified by the diagnostic tools used in the clinical routine. In cases with obscure clinical VPS insufficiency, valve deficiency should be considered.

Investigation of suction flow characteristic in the inertance hydraulic converters for efficiency improvement

2021 ◽  
pp. 095965182110248
Author(s):  
Xiaoming Chen ◽  
Yuchuan Zhu ◽  
Travis Wiens ◽  
Doug Bitner ◽  
Minghao Tai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Flow Characteristic ◽  
Performance Indicator ◽  
Flow Characteristics ◽  
Check Valve ◽  
Analytical Models ◽  
Switching Frequency ◽  
Experimental Measurements ◽  
Efficiency Improvement ◽  
Suction Flow

The inertance hydraulic converter relies on fluid inertance to modulate flow or pressure and is considered to be a competitive alternative to the conventional proportional hydraulic system due to its potential advantage in efficiency. As the quantification of fluid inertance, the suction flow characteristic is the crucial performance indicator for efficiency improvement. To explore the discrepancy between the passive inertance hydraulic converter featured by the check valve and the active inertance hydraulic converter driven by an equivalent 2/3 way fast switching valve in regard to suction flow characteristics, analytical models of the inertance hydraulic converters were established in MATLAB/Simulink. The validated models of the respective suction components were incorporated in the overall analytical models and their suction flow characteristics were theoretically and experimentally discussed. The analytical predictions and experimental measurements for the current configurations indicated that the active inertance hydraulic converter yields a larger transient suction flow rate than that of the passive inertance hydraulic converter due to the difference of the respective suction components. The suction flow characteristic can be modulated using the supply pressure and duty cycle, which was confirmed by experimental measurements. In addition, the suction flow characteristics are heavily affected by the resistance of the suction flow passage and switching frequency. There is a compromise between the resistance and switching frequency for inertance hydraulic converters to achieve large suction flow rate.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

Numerical Simulation of Cavitating Flow in a Francis Turbine

2008 ◽  
Author(s):  
Lingjiu Zhou ◽  
Zhengwei Wang ◽  
Yongyao Luo ◽  
Guangjie Peng
Keyword(s):  
Numerical Simulation ◽  
Transport Equation ◽  
Flow Rate ◽  
Suction Side ◽  
Cavitating Flow ◽  
Francis Turbine ◽  
Efficiency Change ◽  
Experiment Data ◽  
Calculation Results ◽  
Vapor Fraction

The 3-D unsteady Reynolds averaged Navier-tokes equations based on the pseudo-homogeneous flow theory and a vapor fraction transport-equation that accounts for non-condensable gas are solved to simulate cavitating flow in a Francis turbine. The calculation results agreed with experiment data reasonably. With the decrease of the Thoma number, the cavity first appears near the centre of the hub. At this stage the flow rate and the efficiency change little. Then the cavity near the centre of the hub grows thick and the cavities also appear on the blade suction side near outlet. With further reduce of the Thoma number the cavitation extends to the whole flow path, which causes flow rate and efficiency decrease rapidly.

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