Study on the improvement of flow characteristics for the optimal design of minimum flow valve with labyrinth channel

2014 ◽  
Author(s):  
Na Zhang ◽  
Zhaozheng Lv ◽  
Jing Huang ◽  
Lisheng Zhang ◽  
Yanhui Li
Keyword(s):  
Optimal Design ◽  
Flow Characteristics ◽  
Minimum Flow ◽  
Labyrinth Channel ◽  
Flow Valve

Spring Stiffness Selection Criteria for Nozzle Check Valves Employed in Compressor Stations

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
K. K. Botros
Keyword(s):  
Selection Criteria ◽  
Hydrodynamic Force ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Check Valve ◽  
Compressor Station ◽  
Force Coefficient ◽  
Minimum Flow ◽  
High Pressure Ratio ◽  
Open Position

Nozzle type check valves are often employed in compressor stations in three locations: compressor outlet, station discharge, and station bypass. The fundamental design concept of these valves is based on creating a converging diverging flow through the valve internal geometry such that a minimum area is achieved at a location corresponding to the back of the check valve disk at the fully open position. This will ensure maximum hydrodynamic force coefficient which allows the valve to be fully open with minimum flow. Spring forces and stiffness determine the performance of this type of check valves and impact the overall operation and integrity of the compressor station. This paper examines the effects of various spring characteristics and stiffness in relation to the compressor and station flow characteristics. The results show that when the spring forces are higher than the maximum hydrodynamic force at minimum flow, the disk will not be at the fully open position, which will give rise to disk fluttering and potential for cyclic high velocity impact between components of the internal valve assembly. This could lead to self destruction of the check valve and subsequent risk of damage to the compressor unit itself. The paper also points to the fact that the spring selection criteria for a unit check valve are different than that for station and bypass check valves. An example of a case study with actual field data from a high pressure ratio compressor station employing this type of check valves is presented to illustrate the associated dynamic phenomena and fluid-structure interaction within the internal assembly of the check valve.

Fluid-Structure Coupling Analysis of Traveling Wave Micro-Pump

2013 ◽  
Vol 662 ◽  
pp. 572-575
Author(s):  
Chang Zhi Wei
Keyword(s):  
Optimal Design ◽  
Traveling Wave ◽  
Driving Force ◽  
Channel Wall ◽  
Flow Characteristics ◽  
Driving Voltage ◽  
Micro Channel ◽  
Coupling Analysis ◽  
Fluid Structure ◽  
Micro Pump

The generation method of traveling wave and the driving force source in straight micro channel were investigated based on the vibration theory. The analysis shows that the driving force in traveling wave micro-pump is closely related to the fluctuations of the channel wall and there is traveling standing wave along the straight micro channel. Through fluid-structure coupling analysis, flow characteristics in straight micro channel are obtained as well as the outlet velocity. The average outlet velocity is about several hundreds of nanometers percent second if only the mechanical force is considered. The influence of the driving voltage on the velocity is also analyzed to provide guidance on the optimal design of the traveling wave micro-pump.

Comparison of the annual minimum flow and the deficit below threshold approaches: case study for the province of New Brunswick, Canada

2009 ◽  
Vol 36 (9) ◽  
pp. 1421-1434 ◽  
Author(s):  
Loubna Benyahya ◽  
Daniel Caissie ◽  
Fahim Ashkar ◽  
Nassir El-Jabi ◽  
Mysore Satish
Keyword(s):  
Weibull Distribution ◽  
New Brunswick ◽  
Generalized Pareto Distribution ◽  
Flow Characteristics ◽  
Low Flow ◽  
Likelihood Method ◽  
Data Series ◽  
Parameter Estimates ◽  
Minimum Flow ◽  
The Right

A low-flow frequency analysis using the annual minimum flow (AMF) and the deficit below threshold (DBT) approaches was carried out for 30 hydrometric stations across the province of New Brunswick. The AMF method considers only the annual minimum events, and the DBT method considers all low flows below a certain threshold (or truncation level). In the present study, the DBT method characterizes low flow in terms of deficit intensity, which is becoming increasingly important in both water and aquatic resources management. The annual minimum series were fitted using the three-parameter Weibull distribution (AMF–WEI3), and the intensity data series were fitted using the two-parameter Weibull distribution (DBT–WEI2) and the generalized Pareto distribution (DBT–GP). All parameter estimates were obtained using the maximum likelihood method. The AMF–WEI3 and DBT–GP approaches provided a good fit to at-site data in terms of annual minimum flow and deficit intensity, respectively. However, the present study showed that the DBT–WEI2 approach underestimated the right tail of low-flow intensity. The Anderson–Darling statistic was also calculated for the data series and can provide insight into which distribution may adequately model the low-flow characteristics. A regionalization study was also performed using the AMF–WEI3 and DBT–GP methods.

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