Papers by Keyword: Valve

Abstract: In this paper the fracture problem of exhaust valve of the piston engine was investigated. Visual inspection showed that on the fractured surface of the valve the beach marks, typical for fatigue failure were observed. The crack origin was not covered by corrosion products or material defects. In order to explain the reasons of damage of the valve, the non-linear finite element method was utilized. The numerical model composed of the poppet valve, the guide and the seat face was defined. In the analysis both the mechanical load resulting from the valve spring and also the thermal load arising from a non-uniform temperature field were defined. The loads were at first defined separately in order to check which load component has a dominant influence on the stress level. In third load case (which represents the operational thermo-mechanical engine conditions) the mentioned loads were defined simultaneously. The results of performed computations showed that the operational dynamic stress (in the critical zone of the valve where the crack appeared) is more than 12 times lower than the yield stress of the material. It means that the premature fatigue fracture of the valve was probably caused by any phenomenon concerned with the increase of the operational stress in the valve. The additional observation of the second (non-damaged) valve from the same engine head showed that the carbon deposit was located on the valve face. The results of the stress analysis of the valve with additional carbon particle showed, that in the valve stem a high bending stress was observed.

Abstract: Findings are presented from the tests of balanced control valve mounted on the steam piping with experimental turbine. The forces applied on the spindle are recorded and compared to design calculation. The forces are evaluated from the pressures on a servo drive piston or they are measured directly using force transducers. The real operational characteristics are compared with characteristics defined for constant inlet pressure.

Abstract: The valve is an important control unit in all kinds of fluid conveying system, which has formed a series product. The design of the valve product follows the characteristic process, and there is a strong correlation between its components. Using knowledge engineering related theory and method, through mining and presentation about the field design knowledge and structure knowledge of the pressure valve, implements the pressure valve parametric variant design templates by using the top-down design and parametric design technology on the NX platform. It can greatly improve the design efficiency and quality through the rapid variant design of series of the valve with the template.

Abstract: The paper brings in an original solution of proportional hydraulic flow control valve, which can function with both simple and differential command. The static adjustment characteristic of this equipment is analyzed. Also, two systems that integrate the discussed equipment are taken into account.

Abstract: A hybrid numerical method of combining Large Eddy Simulation (LES) and Lighthill’s acoustic analogy theory is utilized to simulate the flow-induced noise at low Mach numbers. The aerodynamic noise generated by flow through a cavity, which is similar to a valve, is simulated and the results are validated by comparing with the open literature. In the simulation, the turbulent flow is computed with LES. After this, the flow field simulation results are used to compute the flow-induced noise with Lighthill’s acoustic analogy theory based on the commercial software ACTRAN. Finally, the simulation results of the flow-induced noise, including the sound pressure level and the peak frequencies, are analyzed and compared with experimental data. It is validated that the hybrid method of combining LES and Lighthill’s acoustic analogy theory used in this paper is feasible and reliable in engineering applications.

Abstract: The paper combines CFD simulation and high-speed observation experiments to analyze the forming mechanism of high-speed cavitation flowing inside V-groove. It is found that the formation and development of cavitation are greatly affected by the cavitation nucleus, and subjected to two flow patterns, shear flow and vortex. When the groove is shallow or valve opening is small, cavitation inception occurs in the strong shear region near the throttling edge, which is related to the separation of boundary layer and the wall attachment effect. As the depth of the valve port increases, the reflux becomes stronger at the back of the throttling edge, which complements the low pressure area generated from the fluid separation. At the same time the pulsation is formed in the downstream due to the large longitudinal velocity gradient, resulting in vortex, and the area of ​​low pressure in the center of vortex also leads to the generation of cavitation.

Abstract: This paper expounded the necessities of third party inspection for liquefied natural gas project valves. The third party inspection methods are introduced in detail. Tests and operations on each item are analyzed.

Abstract: The air separation part aims to clean up the air and separate air, it provides the demand gas for the factory. This process is automatically controlled by the progress which we code. The operating time and the valves reaction at each stage have strict requirements. If the operating time fails to meet requirements or the valve operations are improper, it will make the index of the air separation failed. Thus it will cause the whole process interruption and cause huge losses. Therefore, we must ensure that each valve operation of molecular sieve can be effectively controlled and monitored.

Abstract: Directional control valves start, stop or change the direction of flow in compressed air applications. To understand the different applications of compressed air and how valves are used, one must first have knowledge of the kinds and types of valves used by industries. This paper studies local valve control of the electro-hydraulic system. The slow response of hydraulic control valve usually becomes the hold-up of whole system performance. Although fast valves (e.g. high-bandwidth servo-valves) are available, they are far more expensive than slow valves (e.g. proportional directional control valves). To improve the performance of proportional directional control valves, three different types of controllers are synthesized. Firstly, based on the pole zero cancellation technique, an open loop compensator is designed which requires the accurate valve dynamic model information; Secondly, a full state feedback adaptive robust controller (ARC) is synthesized, which effectively takes into account the effect of parametric uncertainties and uncertain nonlinearities such as friction force and flow force. Finally, an output feedback ARC controller is synthesized to address the problem of un measurable states. Keywords: valve, hydraulic device, Simulink.

Abstract: To make Nuclear Power Plants (NPP) more acceptable by the public, there is a need to conform to the stringent safety criteria evolved continuously. Among the several safety aspects, the seismically induced effects call more attention at the present scenario. But the adequate full scale testing of the critical components can render a more realistic simulation. Extensively shake table testing is used for the seismic qualification and research purposes. It provides the means to excite structures in such a way that they are subjected to conditions representative of true earthquake ground motions. The seismic qualification tests were conducted as per the test procedure given in IEEE STD 344-1987 standards: IEEE recommended practice for seismic qualification of class 1E equipment for Nuclear Power Generating Station. Valves are one of the active components in the SFR system. The seismic operability of active components can be established only by shake table testing. Shake table testing includes fixing of the equipment into the shake table, exiting the table with a seismic excitation equal to or larger than the design earthquake, resonance search test in all the three directions for 1 to 50 Hz to identify the system frequencies and assessment of the functionality and structural integrity of the valve during and at the end of the test. The valve that has been experimentally qualified completed type test for OBE & SSE cycles, the same will not be utilized in the reactor application. The methodology involved in the seismic qualification of the unconventional valve presented in this paper. Among the various shake table experiments carried out for the seismic qualification unconventional valves, the experiment carried out for the Inclined Fuel Transfer Machine (IFTM) Gate valve is referred in this paper for the above purpose. It is one of the unconventional type large in size and heavy gate valve available in the SFR system