The Experts below are selected from a list of 22335 Experts worldwide ranked by ideXlab platform
Sasko Dimitrov - One of the best experts on this subject based on the ideXlab platform.
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Transient response of a pilot operated pressure relief Valve with compensating control piston
2014Co-Authors: Sasko DimitrovAbstract:A subject of investigation was pilot operated pressure relief Valve with compensating control piston. Non linear mathematical model of the Valve was developed. Theoretically and experimentally the transient response of the Valve has been investigated. Using advance measurement equipment experimentally has been shown the opening of the Main Valve before the pilot Valve, i.e. opposite of the static characteristic.
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Transient response of a pilot operated pressure relief Valve
2013Co-Authors: Mihail Komitovski, Sasko DimitrovAbstract:A subject of investigation was conventional design of pilot operated pressure relief Valve. Non linear mathematical model of the Valve was developed. Theoretically and experimentally the transient response of the Valve has been investigated. Using advance measurement equipment experimentally has been shown the opening of the Main Valve before the pilot Valve, i.e. opposite of the static characteristic.
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Investigation of static characteristics of pilot operated pressure relief Valves
2013Co-Authors: Sasko DimitrovAbstract:Theoretical and experimental investigation of the static characteristics of the pilot operated pressure relief Valve is presented in this article. A mathematical model of pressure drop vs. flow depending for pilot operated pressure relief Valve is developed. An experimental test stand was created for experimental determination of the static characteristics and compared with each other which confirm the mathematical model. The results of solving the mathematical model and experimental investigation are presented in few diagrams. A few directions for improving the static characteristics are given, especially at the moment of opening of the Main Valve. Advantages and disadvantages of the static characteristics are discussed.
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Experimental verification of a mathematical model of static characteristics of pilot operated pressure relief Valves
2011Co-Authors: Sasko Dimitrov, Simeon Simeonov, Slavco CvetkovAbstract:A numerical and experimental investigation of the static characteristics of pilot operated pressure relief Valves is presented in this article. A mathematical model of a pressure drop depending on a flow in a pilot operated pressure relief Valve is developed. A test stand is created for the experimental determination of the pressure drop depending on the flow and the obtained results are compared with theoretical ones. The results of solving the mathematical model and experimental investigation are presented in a few diagrams. A few directions for improving the static characteristics are given, especially at the moment of the Main Valve of the pilot operated pressure relief Valves opening. Advantages and disadvantages of the static characteristics of both types of Valves are presented.
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Static characteristics of pilot operated pressure relief Valves with compensating control piston
2011Co-Authors: Sasko DimitrovAbstract:In this paper a mathematical model of the static characteristics for a pilot operated pressure relief Valve with compensating piston has been developed. The static characteristic has been presented in few diagrams. The influence of the compensating piston to the static characteristic has been emphasized as a manner for reducing the difference between pressure of opening of the pilot Valve and the Main Valve.
Jiang Kaiyou - One of the best experts on this subject based on the ideXlab platform.
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A Large-Flowrate On–Off Valve with Hollow Structure for High-Frequency Hydraulic Vibration and Impact System
Science of Advanced Materials, 2020Co-Authors: Shuo Liu, Yong Cai, Jiang KaiyouAbstract:In high-frequency hydraulic vibration and impact systems, the high-speed reciprocating motion of the impact piston, as controlled by the Main Valve, transfers energy to the target. Therefore, the Main Valve must have a fast response speed and strong flow capacity. A novel two-stage large-flowrate on–off Valve is developed in this study. The first stage is a small-flowrate servo Valve, and the second stage is a large-flowrate hydraulic control Valve with a hollow spool. The hollow structure not only reduces the quality of the spool and improves the Valve dynamic characteristics but also improves the flow capacity and reduces the pressure drop at the Valve port. A structural strength simulation is performed, and the deformation and stress of the spool are calculated. Then, the internal flow channel is extracted and the pressure drop characteristics of Valve are obtained by simulation. To obtain the dynamic characteristics of the Valve, the control equations of the Valve are established, and the simulation model is built in Simcenter Amesim software. Then, the structural parameters of the Valve body are optimized in this model. Finally, a prototype is developed for hydraulic vibration and impact systems. The experimental results show that the prototype works well, the opening time of the second-stage Valve is within 6 ms, and the port pressure drop at a flow rate of 1000 L/min is only 30% of the conventional opening and closing Valve of the same diameter.
M. Dunn - One of the best experts on this subject based on the ideXlab platform.
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Advanced Turbine Aerothermal Research Rig (ATARR) Monitor and Control System (MCS) Hardware Reference Manual. Version 2.
1993Co-Authors: C. Haldeman, M. DunnAbstract:Abstract : This manual is presented to WPAFB as an aid in sorting out the Monitor and Control System (MCS) hardware that was implemented by Belcan Corporation. Several revisions of the actual hardware have occurred, but until now, the documentation was scattered and not completely up-to-date. The Main goals of this manual are to: (1) Consolidate the various hardware reference manuals and coordinate the manual with the existing wiring. (2) Outline the changes made by Calspan with regards to the Main Valve activation system and the isolation Valve. (3) Provide a formal list of Calspan recommendations for the MCS system for future efforts.
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Advanced Turbine Aerothermal Research Rig (ATARR) Facility Model Operation.
1993Co-Authors: C. Haldeman, M. DunnAbstract:Abstract : This facility model is a major operating tool for the ATARR facility. It can provide information about setting the eddy-brake, Main Valve activation pressures, initial fill pressures, test gas properties as well as predicting performance. It is important to remember that the facility model is just a model, the numbers it produces are approximate. Some time has been spent with the model trying to make the predicted Main Valve performance reflect its actual motion more accurately. In the future, as systems are added, it should be possible to compare the model predictions of the torque, eddy brake temperature, etc., with data. As a result, the facility model will generally be one which changes with time. This memorandum is written to document some of the history of the model, discuss how it is run presently, and point towards future work.
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A Report on the Main Valve Bearing Rebuild for the Advanced Turbine Aerothermal Research Rig (ATARR).
1993Co-Authors: M. M. Weaver, M. DunnAbstract:Abstract : On December 16, 1992 the Main Valve in the ATARR facility seized during a run at 50 psia and 400F. Immediately prior to this problem, a run at 90 psia and 400F was successfully completed. These two tests were the first ATARR runs at high temperature. The Main Valve had been run dozens of times prior to this at room temperature without incident. However, some wear of the soft nickel coating on the cylinder was observed before the high temperature runs. This section of the Main Valve final report documents the process of rebuilding the Main Valve and includes a description of an analyses conducted to determine the possible cause or causes of the failure. The bearing redesigned process, which was based on the analysis just noted, is detailed. The actual rebuild, final inspection and testing of the Main Valve are also included to complete this section.
Yingzheng Liu - One of the best experts on this subject based on the ideXlab platform.
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Influence of a circular strainer on unsteady flow behavior in steam turbine control Valves
Applied Thermal Engineering, 2017Co-Authors: Peng Wang, Yingzheng LiuAbstract:Abstract The influence of a circular strainer on unsteady flow behavior in steam turbine control Valves, which are commonly placed between an intermediate-pressure turbine and a boiler in thermal power plants, was numerically studied. A porous-medium model, which established the dependencies of the pressure drop through the strainer on the magnitude and direction of the fluid flow’s velocity, was validated by experimental measurements in a water flow test rig. As the benchmark configuration, a Valve without a strainer was used for comparison. The turbulent steam flow in the complex serpentine channel was simulated with the implementation of the proposed porous model for the strainer. The numerical results demonstrated that placing the strainer in the Main Valve resulted in dramatic changes of the flow patterns in the Main Valve’s chamber and its diffuser, and even in the downstream throttle Valve. The complex steam flow in the Main Valve was efficiently managed by the circular strainer, significantly reducing the cross-sectional force on the Main Valve’s spindle; this is attributed to attenuated oscillation of the annular flow around the Main Valve’s seat. As for the downstream throttle Valve, the pressure drop and the fluctuating lateral force on the spindle were intensified, which was shown to be closely related to the continuous impingement of the flow onto the throttle Valve’s cavity wall. In comparison with the configuration without a strainer, the placement of the strainer in the Main Valve gave rise to a pair of intensified secondary vortices in the diffuser section behind the throttle Valve.
Shuo Liu - One of the best experts on this subject based on the ideXlab platform.
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A Large-Flowrate On–Off Valve with Hollow Structure for High-Frequency Hydraulic Vibration and Impact System
Science of Advanced Materials, 2020Co-Authors: Shuo Liu, Yong Cai, Jiang KaiyouAbstract:In high-frequency hydraulic vibration and impact systems, the high-speed reciprocating motion of the impact piston, as controlled by the Main Valve, transfers energy to the target. Therefore, the Main Valve must have a fast response speed and strong flow capacity. A novel two-stage large-flowrate on–off Valve is developed in this study. The first stage is a small-flowrate servo Valve, and the second stage is a large-flowrate hydraulic control Valve with a hollow spool. The hollow structure not only reduces the quality of the spool and improves the Valve dynamic characteristics but also improves the flow capacity and reduces the pressure drop at the Valve port. A structural strength simulation is performed, and the deformation and stress of the spool are calculated. Then, the internal flow channel is extracted and the pressure drop characteristics of Valve are obtained by simulation. To obtain the dynamic characteristics of the Valve, the control equations of the Valve are established, and the simulation model is built in Simcenter Amesim software. Then, the structural parameters of the Valve body are optimized in this model. Finally, a prototype is developed for hydraulic vibration and impact systems. The experimental results show that the prototype works well, the opening time of the second-stage Valve is within 6 ms, and the port pressure drop at a flow rate of 1000 L/min is only 30% of the conventional opening and closing Valve of the same diameter.
