Understanding Lift Force Discontinuity of Pressure Safety Valve

Abstract A pressure safety valve (PSV) is a safety valve designed to protect a vessel or a system during an overpressure event. For pressure safety valve to perform its function, the lift force as one of the key factors influencing the overall performance must be predicted. However, the lift force shows discontinuity with the increase of the valve opening under certain situations. This discontinuity could cause a series of problems, such as dynamic instability. In order to deeply explore the mechanism of the discontinuities numerical and experimental investigation were performed on a direct operated PSV in this paper. A test rig was constructed to measure the steady state lift forces at different valve openings. The working fluid was air and the valve body was removed. To obtain the details of the flow inside the valve, a series of computational fluid dynamics (CFD) simulations were conducted. The simulation indicated that the changing flow pattern is the main cause of the lift force discontinuity and the flow pattern is very sensitive to the valve nozzle thickness and the position of the adjustment ring. Thus, the lift force discontinuity could be weakened or even eliminated by proper valve design.

Investigations of Inducers Operating With High Rotational Speed

Journal of Fluids Engineering ◽

10.1115/1.4041730 ◽

2018 ◽

Vol 141 (4) ◽

Cited By ~ 1

Author(s):

Björn Gwiasda ◽

Matthias Mohr ◽

Martin Böhle

Keyword(s):

Rotational Speed ◽

Test Bench ◽

Pressure Rise ◽

Working Fluid ◽

Cfd Simulations ◽

High Rotational Speed ◽

Rotating Speed ◽

Performance Pressure ◽

Suction Performance

Suction performance, pressure rise, and efficiency for four different inducers are examined with computational fluid dynamics (CFD) simulations and experiments performed with 18,000 rpm and 24,000 rpm. The studies originate from a research project that includes the construction of a new test bench in order to judge the design of the different inducers. This test bench allows to conduct experiments with a rotational speed of up to 40,000 rpm and high pressure ranges from 0.1 bar to 40 bar with water as working fluid. Experimental results are used to evaluate the accuracy of the simulations and to gain a better understanding of the design parameter. The influence of increasing the rotating speed from 18,000 rpm to 24,000 rpm on the performance is also shown.

The Aerodynamics of a Diabolo

10.31224/osf.io/azmxu ◽

2021 ◽

Author(s):

Darren Jia

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Angular Momentum ◽

Flow Pattern ◽

High Spin ◽

Angular Speed ◽

Geometric Shape ◽

Cfd Simulations ◽

Resistive Torque ◽

Diabolo is a popular game in which the object can be spun at up to speeds of 5000 rpm. This high spin velocity gives the diabolo the necessary angular momentum to remain stable. The shape of the diabolo generates an interesting air flow pattern. The viscous air applies a resistive torque on the fast spinning diabolo. Through computational fluid dynamics (CFD) simulations it's shown that the resistive torque has an interesting dependence on the angular speed of the diabolo. Further, the geometric shape of the diabolo affects the dependence of torque on angular speed.

Three-Dimensional CFD Analysis of a Spring-Loaded Pressure Safety Valve From Opening to Re-Closure

ASME 2010 Pressure Vessels and Piping Conference: Volume 5 ◽

10.1115/pvp2010-25024 ◽

2010 ◽

Cited By ~ 3

Author(s):

Xue Guan Song ◽

Lei Cui ◽

Young Chul Park

Keyword(s):

Safety Valve ◽

Three Dimensional ◽

Cfd Model ◽

Flow Features ◽

Valve Opening ◽

Multiple Domains ◽

Future Work ◽

Mesh Technique ◽

Detailed Picture

We describe the dynamic analysis of a spring-loaded pressure safety valve (PSV) using a moving mesh technique and transient analysis in computational fluid dynamics (CFD). Multiple domains containing pure structural meshes are generated to ensure that the correlative mesh could change properly without negative volumes. With a geometrically accurate CFD model including the PSV and vessel rather than only the PSV, the entire process from valve opening to valve re-closure is presented. A detailed picture of the compressible fluid flowing through the PSV is obtained, including flow features in the very small seat region. In addition, the forces on the disc and its motion are monitored. Results from the model were very useful in investigating the dynamic and fluid characteristics of the PSV. Our practical CFD model has the potential to reduce the costs and risks associated with the development of new pressure safety valve designs. Future work will focus on improving the spring stiffness and seat region to eliminate or reduce vibration during the re-closure process.

CFD Simulations and PIV Measurements for Optimization of Flow Pattern in a Sieve Plate Extraction Column

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.391-392.1464 ◽

2011 ◽

Vol 391-392 ◽

pp. 1464-1468

Author(s):

Chang Chun Duan ◽

Chun Jiang Liu ◽

Xi Gang Yuan

Keyword(s):

Flow Pattern ◽

Reverse Flow ◽

Continuous Phase ◽

Extraction Column ◽

Sieve Plate ◽

Cfd Simulations ◽

Flow Area ◽

Piv Measurements ◽

Image Velocimetry ◽

Present work deals with the optimization for flow pattern of continuous phase in a sieve plate extraction column using both computational fluid dynamics (CFD) simulations and particle image velocimetry (PIV) measurements. Firstly single-phase simulation was conducted for the traditional column and it was found that there was a very large reverse flow area between every two plates. Then step by step, by changing the downcomer structure, consisting of inclining downcomers, adding baffles, slotting downcomers and baffles and adjusting the number and size of slots, the reverse flow area was decreased and thereby the flow pattern of continuous phase was optimized. Finally, an optimal flow pattern was obtained with reverse flow area greatly reduced. In order to prove the validity of the simulation results, PIV experiments of two columns were carried out and it was found that the results of simulations and experiments are in good agreement.

A Study on High-Output Resonance-Driven Piezoelectric Micropumps Using Active Check Valves

Journal of Robotics and Mechatronics ◽

10.20965/jrm.2004.p0171 ◽

2004 ◽

Vol 16 (2) ◽

pp. 171-177 ◽

Cited By ~ 5

Author(s):

Jung-Ho Park ◽

◽

Kazuhiro Yoshida ◽

Chikara Ishikawa ◽

Shinichi Yokota ◽

...

Keyword(s):

Tap Water ◽

Check Valve ◽

Effective Size ◽

Working Fluid ◽

Valve Body ◽

Pump Chamber ◽

Valve Opening ◽

Optimal Values ◽

Basic Characteristics ◽

High Output

A novel high-output resonance-driven piezoelectric micropump using two active check valves in place of conventional passive check valves used in inlet and outlet is proposed. It actively controls opening/closing of check valves using piezoelectric actuator synchronizing with expansion/contraction of pump chamber. A prototype micropump is fabricated with an effective size of 17×8×1mm3. When tap water is used as the working fluid, pumping characteristics of the fabricated pump are experimentally investigated using an adequate timing control for valve opening/closing. From experimental results, it is ascertained that optimal values of the phase shift for the voltage to drive the pump chamber to realize a miniaturized but powerful micropump are 15° in inlet check valve and 195° in outlet. Based on obtained results, a sheet active shuttle valve that has a unified valve body for inlet and outlet check valves is newly proposed. A micropump with an effective size of 10×10×10mm3is fabricated and the basic characteristics are experimentally investigated.

The Effects of the Presence of a Kitchen House on the Wind Flow Surrounding a Low-Rise Building

Energies ◽

10.3390/en13236243 ◽

2020 ◽

Vol 13 (23) ◽

pp. 6243

Author(s):

Siti Noratikah Che Deraman ◽

Saddam Hussein Abo Sabah ◽

Shaharudin Shah Zaini ◽

Taksiah A. Majid ◽

Amin Al-Fakih

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Flow Pattern ◽

Air Flow ◽

Flow Characteristics ◽

Wind Flow ◽

Cfd Simulations ◽

The Core ◽

Gap Height

Most Malaysian rural houses are categorized as non-engineered buildings and vulnerable to damage during events such as windstorms due to the fact that these houses lack engineering considerations. These houses are characterized by having an attached kitchen house, and many of these houses were previously damaged by thunderstorms. The current research investigated the air flow characteristics changes surrounding these houses as a result of the presence of the kitchen. The roof pitch, position, gap height, and overhang were investigated using computational fluid dynamics (CFD) simulations. The results showed that the kitchen position at the center resulted in a slight increase in the suction on the ridge of the roof; however, it significantly altered the flow pattern in the windward and leeward directions. The results also showed that the roof overhang, roof pitch, and kitchen position contributed severely to the damage of the rural house. Moreover, the highest suction occurred at the roof ridge when the kitchen was located at the center of the rural house (Cp = −2.28). Therefore, the authors believe that it is more advantageous to have a kitchen connected to the core as it reduces the pressure on the roof of the core during thunderstorm events.

Transient 3D CFD Simulation of a Stationary Vane, Oil Free, Rotary Compressor

Periodica Polytechnica Mechanical Engineering ◽

10.3311/ppme.13890 ◽

2019 ◽

Vol 63 (4) ◽

pp. 308-318 ◽

Cited By ~ 1

Author(s):

Balázs Farkas ◽

Jenő Miklós Suda

Keyword(s):

Cfd Simulation ◽

Piston Compressor ◽

Working Fluid ◽

Rotary Compressor ◽

Heat Sources ◽

Cfd Model ◽

Cfd Simulations ◽

Rolling Piston ◽

Good Agreement

The evaluation of a newly designed oil-free rotary compressor is presented based on transient 3D Computational Fluid Dynamics (CFD) simulations. The simulations are performed at low compression ratios and low pressure ratios and low rotational speeds. To place the results into context, the data presented in related literature was processed and summarized. The methods related to the CFD model of the newly designed compressor were developed, summarized and evaluated. The accessed CFD data are in good agreement with the results of the former rolling piston compressor related investigations. The oil free operation prevents the contamination of the working fluid from lubricant. Since the compressor is planned to work in open cycle within the sensitive environment of thermal heat sources contamination free operation has to be accomplished. However, oil-free operation also results in significantly lower performance based on the modelling results.

Numerical Study of Heat Pipes Effects to a 3-Dimensional Room With Natural Driven Ventilation

Volume 6B: Energy ◽

10.1115/imece2014-37705 ◽

2014 ◽

Author(s):

Z. Abdullah ◽

B. P. Huynh ◽

A. Idris

Keyword(s):

Heat Exchanger ◽

Heat Pipe ◽

Flow Pattern ◽

Numerical Study ◽

Heat Pipes ◽

Working Fluid ◽

3 Dimensional ◽

Sharp Edges ◽

Pipe Heat

A Computational Fluid Dynamics (CFD) software package is used to investigate numerically a 3-dimensional rectangular-box room installed with heat pipes heat exchanger (HPHE). Heat pipe heat exchanger utilizing refrigerant by mean of working fluid is installed on top of a room. The air-side heat transfer and the flow pattern of a thermo-siphon heat pipes is studied with a natural driven ventilation of a building. Different opening of the inlet and outlet air where the heat pipe was installed are tested with round edges opening as well as sharp edges. The standard RANS k–ε turbulence model is used. Results with different setting of heat pipe and opening characteristic, air flow rate and flow pattern as well as its temperature effects are examined.

The Aerodynamics of a Diabolo

10.31219/osf.io/48jzy ◽

2021 ◽

Author(s):

Darren Jia

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Angular Momentum ◽

Flow Pattern ◽

High Spin ◽

Angular Speed ◽

Geometric Shape ◽

Cfd Simulations ◽

Resistive Torque ◽

Scaled Experiments and CFD Simulations Supporting the Design of the Spallation Neutron Source Mercury Target

10.1115/imece2000-2081 ◽

2000 ◽

Author(s):

W. David Pointer ◽

Mark W. Wendel ◽

Jason M. Crye ◽

Arthur E. Ruggles ◽

David K. Felde ◽

...

Keyword(s):

Neutron Source ◽

Cfd Simulation ◽

Complete Characterization ◽

Experimental Program ◽

Working Fluid ◽

Spallation Neutron Source ◽

Cfd Simulations ◽

Liquid Mercury ◽

Abstract A combination of experimental and computational methods is necessary to adequately characterize the flow patterns in the liquid mercury target of the Spallation Neutron Source (SNS). Since liquid mercury is completely opaque and corrosive to many materials, the use of liquid mercury as the working fluid makes complete characterization of the flow field by experiment difficult. Furthermore, flow asymmetries and quasi-periodic instabilities that are observed in early target flow experiments are difficult to capture in computational fluid dynamics (CFD) simulations of the system. Therefore, an experimental program using several scaled experiments is combined with CFD simulation for the design and development of the SNS mercury target.