Measurement of Flow Fluctuation in the Flow Standard Facility Based on Singular Value Decomposition

In order to accurately evaluate the flow stability of the flow standard facility, the flow fluctuation in the standard facility needs to be accurately measured. However, the flow fluctuation signal is always superimposed with the fluctuation signal of the measuring flowmeter or measurement system (mainly noise), which leads to inaccurate measurement of the flow fluctuation and even an unreliable evaluation result of the flow stability. In addition, when there are multiple fluctuation sources, flow fluctuations with different frequencies are superimposed together, which is extremely unfavorable for evaluating the impact of flow fluctuation with different single frequencies. In this paper, a new measuring method was proposed to obtain the fluctuation signal and the flow fluctuation based on singular value decomposition (SVD). Simulation experiments on the fluctuation signal (single frequency and multiple frequencies) under different levels of noise were conducted, and simulation results showed that the proposed method could accurately obtain the fluctuation signal and the flow fluctuation, even under high noise. Finally, an experimental platform was set-up based on a water flow standard facility and a flow fluctuation generator, and experiments on the output signal of a venturi flowmeter were carried out. The experiment results showed that the proposed method could effectively obtain the fluctuation signal and accurately measure the flow fluctuation.

Analisis Konstruksi Pipa Pompa Suction 112-JB

The 101-JTC condenser tank has excess steam condensate due to the addition of admission steam from 101-JT. Therefore, it is necessary to design a piping system that connects 101-JTC condenser tank with the 112-JB pump to drain the condensed excess steam. The designed piping system will encounter a dynamic response caused by fluid flow fluctuation over the time. This dynamic response causes the pipe to experience stress. To find out the resulting voltage which will not cause damage or failure, it is necessary to estimate the safety factor in a piping system that has been given static and dynamic loading. This research uses the fluid structure interaction or FSI method with the help of ANSYS software as a simulation tool. The results of this study are, the flow in the pipe causes an impact load which makes the structure vibrate freely damped. The resulting dynamic response describes, the structure displacement amplitude decreases with increasing time. This indicates a stable vibration. Finally, when viewed from the value of stress against time, the fatigue that occurs in the pipe structure induce a stress below the stress limit on Goodman diagram. It can be estimated that the structure has no service life limit. The fatigue safety factor is 7.1.

Time-lapse graphical representation methods for mapping of Intermittent Rivers and Ephemeral Streams (IRES)

Flow data visualizations describe runoff, flooding or drought, showing the interconnectivity and complexity of water data issues or water management problems. Intermittent Flow Rivers constitute more than half of the length of the global river network and their presence is expanding in response to climate change. A new approach is developed to visualize the flow of the Intermittent Rivers and Ephemeral Streams (IRES) based on the creation of time-lapse videos. Two statistical methods, the Natural Breaks and Equal Interval one, are used and evaluated for the creation of the mapping content. The flow dataset of IRES for the island of Crete (in Greece) is used as a case study for a six-year period. The results of both methods are used as an input to create the time-lapse videos of IRES. The videos show the flow fluctuation and cessation during a six-year period and the differences between the two methods.

Flow Control for a Two-Stage Proportional Valve with Hydraulic Position Feedback

The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve. Essentially, the Valvistor valve is a proportional throttle valve and the flow fluctuates with the change of load pressure. The flow fluctuation severely restricts the application of the Valvistor valve. In this paper, a novel flow control method the Valvistor valve is provided to suppress the flow fluctuation and develop a high performance proportional flow valve. The mathematical model of this valve is established and linearized. Fuzzy proportional-integral-derivative (PID) controller is adopted in the closed-loop flow control system. The feedback is obtained by the flow inference with back-propagation neural network (BPNN) based on the spool displacement in the pilot stage and the pressure differential across the main orifice. The results show that inference with BPNN can obtain the flow data fast and accurately. With the flow control method, the flow can keep at the set point when the pressure differential across the main orifice changes. The flow control method is effective and the Valvistor valve changes from proportional throttle valve to proportional flow valve. For the developed proportional flow valve, the settling time of the flow is very short when the load pressure changes abruptly. The performances of hysteresis, linearity and bandwidth are in a high range. The linear mathematical model can be verified and the assumptions in the system modeling is reasonable.

Modeling and theoretical study of relief chamfer method for reducing the flow ripple of a spool valves distribution radial piston pump

This paper presents a study of flow ripple reduction method of a spool valves distribution radial piston pump (SVDRPP). Relief chamfers are adopted to prolong and moderate the opening processes of the delivery spool valves, thus to relieve the pressure surges as well as the consequent flow ripples, vibrations and noises. The mathematical model of this method is established and multiple numerical simulations are conducted to analyze the mechanism as well as the effectiveness of this method. According to the simulation results, different relief chamfer angles have varying influences on flow ripple reduction. Remarkable reduction of flow fluctuation from 43.4% to 36% could be achieved, when the relief chamfer angle is set around 30°. Comparisons between the relief chamfer method and the time delay method indicate that the former has better compatibility to the load pressure lower than the rated value; while the latter has better compatibility to the higher load pressure.