Simulations of Valve Operation in High Pressure Facilities

2007 ◽  
Author(s):  
Vineet Ahuja ◽  
Ashvin Hosangadi ◽  
Peter Cavallo ◽  
Jeremy Shipman
Keyword(s):  
Operating Conditions ◽  
Property Variation ◽  
Grid Approach ◽  
Testing Data ◽  
Variable Displacement ◽  
Numerical Formulation ◽  
Liquid Rocket ◽  
Valve Operation ◽  
Multi Phase ◽  
Real Fluids

An innovative technique for simulating moving valve problems in liquid rocket testing facilities using cryogenic working fluids has been developed. This strategy uses a novel library grid approach in conjunction with an elasticity based grid movement solver with a multi-element unstructured CFD framework. The numerical formulation is based on a compressible gas-liquid framework that accurately models cavitation and multi-phase mixture acoustics while accounting for real fluids property variation. Demonstration of transient moving valve simulations for valve configurations operated at NASA SSC have been carried out for two different valves with very different plug operating profiles. The results are in good agreement with testing data for variable displacement plug motion as well as quasi-steady simulations for slow operating valves. Valve response to varying operating conditions such as plug speed can be predicted using the developed tool. This technique can also serve to analyze problems of valve stall, valve timing/scheduling and can reduce need for expensive activation runs at test facilities.

Performance Analysis of Gas-Expanded Lubricants in a Hybrid Bearing Using Computational Fluid Dynamics

2015 ◽  
Author(s):  
Brian K. Weaver ◽  
Gen Fu ◽  
Andres F. Clarens ◽  
Alexandrina Untaroiu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Phase Behavior ◽  
Ambient Pressure ◽  
Operating Conditions ◽  
Full Potential ◽  
Dissolved Carbon ◽  
Bearing Stiffness ◽  
Multi Phase ◽  
Stiffness And Damping

Gas-expanded lubricants (GELs), tunable mixtures of synthetic oil and dissolved carbon dioxide, have been previously shown to potentially increase bearing efficiency, rotordynamic control, and long-term reliability in flooded journal bearings by controlling the properties of the lubricant in real time. Previous experimental work has established the properties of these mixtures and multiple numerical studies have predicted that GELs stand to increase the performance of flooded bearings by reducing bearing power losses and operating temperatures while also providing control over bearing stiffness and damping properties. However, to date all previous analytical studies have utilized Reynolds equation-based approaches while assuming a single-phase mixture under high-ambient pressure conditions. The potential implications of multi-phase behavior could be significant to bearing performance, therefore a more detailed study of alternative operating conditions that may include multi-phase behavior is necessary to better understanding the full potential of GELs and their effects on bearing performance. In this work, the performance of GELs in a fixed geometry journal bearing were evaluated to examine the effects of these lubricants on the fluid and bearing dynamics of the system under varying operating conditions. The bearing considered for this study was a hybrid hydrodynamic-hydrostatic bearing to allow for the study of various lubricant supply and operating conditions. A computational fluid dynamics (CFD)-based approach allowed for a detailed evaluation of the lubricant injection pathway, the flow of fluid throughout the bearing geometry, thermal behavior, and the collection of the lubricant as it exits the bearing. This also allowed for the study of the effects of the lubricant behavior on overall bearing performance.

Multi-Phase Flow and Condensation in Proton Exchange Membrane Fuel Cells

2002 ◽  
Author(s):  
John M. Stockie
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Transport Processes ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Phase Flow ◽  
Multi Phase Flow ◽  
Multi Phase ◽  
Exchange Membrane

The porous electrodes in a proton exchange membrane fuel cell are characterized by multi-phase flow, involving liquid water and multispecies gases, that are undergoing both condensation and catalyzed reactions. Careful management of liquid water and heat in the fuel cell system is essential for optimizing performance. The primary focus of this study is thus on condensation and water transport, neither of which have yet been studied in as much detail as other aspects of fuel cell dynamics. We develop a two-dimensional model for multi-phase flow in a porous medium that captures the fundamental transport processes going on in the electrodes. The governing equations are discretized using a finite volume approach, and numerical simulations are performed in order to determine the effect of changing operating conditions on fuel cell performance.

Design and Testing of an Adjustable Linkage for a Variable Displacement Pump

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Shawn R. Wilhelm ◽  
James D. Van de Ven
Keyword(s):  
High Efficiency ◽  
Operating Conditions ◽  
The Novel ◽  
Hydraulic Pump ◽  
Low Friction ◽  
Transmission Angle ◽  
Displacement Pump ◽  
Order Of Magnitude ◽  
Variable Displacement ◽  
Design And Testing

A variable displacement hydraulic pump/motor with high efficiency at all operating conditions, including low displacement, is beneficial to multiple applications. Two major energy loss terms in conventional pumps are the friction and lubrication leakage in the kinematic joints. This paper presents the synthesis, analysis, and experimental validation of a variable displacement sixbar crank-rocker-slider mechanism that uses low friction pin joints instead of planar joints as seen in conventional variable pump/motor architectures. The novel linkage reaches true zero displacement with a constant top dead center position, further minimizing compressibility energy losses. The synthesis technique develops the range of motion for the base fourbar crank-rocker and creates a method of synthesizing the output slider dyad. It is shown that the mechanism can be optimized for minimum footprint and maximum stroke with a minimum base fourbar transmission angle of 30 deg and a resultant slider transmission angle of 52 deg. The synthesized linkage has a dimensionless stroke of 2.1 crank lengths with a variable timing ratio and velocity and acceleration profiles in the same order of magnitude as a comparable crank-slider mechanism. The kinematic and kinetic results from an experimental prototype linkage agree well with the model predictions.

Improving the Traditional RCA Methodology to Design a Most Efficient and Reliable Valve for LDPE Hypercompressors Leveraging Experimental Data From Test Bench Simulation: A Real Case Study

2013 ◽  
Author(s):  
Carmelo Maggi ◽  
Leonardo Tognarelli ◽  
Riccardo Bagagli ◽  
Jan Wojnar
Keyword(s):  
Failure Modes ◽  
Good Accuracy ◽  
Deep Understanding ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Gas Composition ◽  
Pressure Losses ◽  
Valve Operation

The behavior of the valves of Hypercompressors on LDPE plants is challenging to predict because it depends on many factors and often the expected and macroscopic gas parameters, such as pressure, temperature and gas composition are not sufficient to properly evaluate the valve behavior in the field. In fact valve operation is highly dependent on local phenomena such as localized pressure losses and presence of vortexes which are in turn influenced by the geometry of the valve and by its behavior. To better understand all these phenomena it is needed to characterize these valves through experimental tests aimed at defining, with a good accuracy, the valve dimensionless parameters Cd (drag coefficient) and Ks (flow coefficient) as a function of the geometry of the valve itself. If the coefficients Cd and Ks are not accurate, the expected behavior of the valve may be completely different from the evidence of the field and could not properly explain certain types of failure modes. With a more accurate evaluation of Cd and Ks, some types of damage which in first hypothesis would seem caused by factors external to the valve, in reality are proven to be intrinsically related to valve design and often dependent on valve malfunctioning. As a final step, through to a deep understanding of the valve behavior in the field an improvement of valve reliability and efficiency can be achieved through optimization of the design for various operating conditions.

Simulations of Unsteady Valve Systems

2005 ◽  
Author(s):  
V. Ahuja ◽  
A. Hosangadi ◽  
P. A. Cavallo ◽  
R. J. Ungewitter ◽  
J. D. Shipman
Keyword(s):  
Dynamic Instability ◽  
Fluid Dynamic ◽  
Control Valve ◽  
Industrial Facilities ◽  
Control Valves ◽  
Grid Adaption ◽  
Instability Modes ◽  
Multi Phase Flow ◽  
Valve Operation ◽  
Multi Phase

The safe and reliable operation of industrial facilities and high pressure test stands for engine and component testing is largely dependent on the smooth performance of control valves. However, such valves frequently experience pressure oscillations from hydrodynamic instabilities, cavitation and unsteady valve operation. In this paper, we present a series of high fidelity computational simulations of control valves primarily to understand the physics associated with the dominant instability modes. A generalized multi-element framework with sub-models for grid adaption, grid movement and multi-phase flow dynamics was used to carry out the simulations. We discuss the methodology in detail with the example of transient analyses of a gaseous hydrogen control valve and capture the fluid dynamic instability that results from valve operation. Additionally, we provide detailed analyses of a modal instability that is observed in the operation of a pressure regulator valve. In both cases, the instabilities are not localized and manifest themselves as a system wide phenomena leading to oscillations in mass flow and/or undesirable chatter.

Comparison and Evaluation of Analytical Structural Solutions With EPRI Safety Valve Test Results

1985 ◽  
Vol 107 (4) ◽  
pp. 380-386
Author(s):  
L. C. Smith ◽  
T. M. Adams
Keyword(s):  
Safety Valve ◽  
Structural Response ◽  
Operating Conditions ◽  
Test Results ◽  
Test Configuration ◽  
Program Testing ◽  
Piping Systems ◽  
Solution Methods ◽  
Verification Process ◽  
Valve Operation

All operating plant licensees and applicants are required to verify the acceptability of plant specific pressurizer safety valve piping systems for valve operation transients by testing per NUREG-0737 (issued November, 1980) and all subsequent U.S. NRC generic follow-up letters. Of particular concern was the operability of the safety valves and the acceptability of the downstream piping when subjected to the dynamic thermal hydraulic loadings associated with these transients. To aid in this verification process the Electric Power Research Institute (EPRI) conducted an extensive program testing different safety valves subjected to varying operating conditions. Downstream piping loads associated with the various loading cases were also measured. This paper presents and compares analytically determined solutions for the structural response of the test configuration to actual test results. A brief description of the methods used to generate the thermal hydraulic loads is presented but the major emphasis is on the piping dynamic response. Discussed are the piping and support modeling techniques, the dynamic solution methods and the load application methods employed. Analytically calculated piping stresses, support loads, displacements, and valve nozzle loads are compared to the test results.

scholarly journals METHODOLOGY OF EXPERIMENTAL INVESTIGATIONS OF VALVE OPERATION

2019 ◽  
Vol 5 ◽  
pp. 56-63
Author(s):  
Natig Sabir Seyidahmadov
Keyword(s):  
Research Result ◽  
Independent Study ◽  
Operating Conditions ◽  
Valve Plate ◽  
Experimental Investigations ◽  
Compressor Station ◽  
Safe Operation ◽  
Special Equipment ◽  
Valve Operation ◽  
Gas Lift

Tightness, as well as the reliability of the valve plate, is a complex property of the effective operation of compressor cylinders of the first stage and, in general, gas-engine reciprocating compressors. The issue of valve plate tightness is a subject of independent study, since technical and economic efficiency depends on their work. In this connection, only some data obtained under operating conditions are presented in this work. As a research result, it is found that, taking into account the identified requirements for the gas lift system, in order to effectively increase the operating hours of valves with increased tightness of the plate, it is necessary to check and purge the valves. Therefore, each valve in the gas lift compressor station, without subjecting them to cleaning, is first recommended to check for leaks. To confirm the feasibility of checking valve tightness, special equipment is offered for each gas-lift compressor station, a purge chamber, on which the tightness of valve plates is checked. The usefulness and importance of the purge chamber is in preparation of the valve at the gas lift compressor station, which contributes to increased efficiency, safe operation, normal tightness and reliability of its operation.

scholarly journals Computational Prediction of Primary Breakup in Fuel Spray Nozzles for Aero-Engine Combustors

2017 ◽  
Author(s):  
Thilo Ferdinand Dauch ◽  
Samuel Braun ◽  
Lars Wieth ◽  
Geoffroy Chaussonnet ◽  
Marc Christoph Keller ◽  
...  
Keyword(s):  
Computing Time ◽  
Three Dimensional ◽  
Computational Prediction ◽  
Operating Conditions ◽  
Fuel Spray ◽  
Two Phase ◽  
Aero Engine ◽  
Particle Hydrodynamics ◽  
Primary Breakup ◽  
Multi Phase

Primary breakup of liquid fuel in the vicinity of fuel spray nozzles as utilized in aero-engine combustors is numericallyinvestigated. As grid based methods exhibit a variety of disadvantages when it comes to the prediction of multi- phase flows, the ”Smoothed Particle Hydrodynamics“ (SPH)-method is employed. The eligibility of the method to analyze breakup of fuel has been demonstrated in recent publications by Braun et al, Dauch et al and Koch et al [1, 2, 3, 4]. In the current paper a methodology for the investigation of the two-phase flow in the vicinity of fuel spray nozzles at typical operating conditions is proposed. Due to lower costs in terms of computing time, 2D predictions are desired. However, atomization of fluids is inherently three dimensional. Hence, differences between 2D and 3D predictions are to be expected. In course of this study, predictions in 2D and based on a 3D sector are presented.Differences in terms of gaseous flow, ligament shape and mixing are assessed.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4693 

scholarly journals WearGP: A UQ/ML Wear Prediction Framework for Slurry Pump Impellers and Casings

2020 ◽  
Author(s):  
Anh Tran ◽  
Yan Wang ◽  
John Furlan ◽  
Krishnan V. Pagalthivarthi ◽  
Mohamed Garman ◽  
...  
Keyword(s):  
High Performance ◽  
Computational Cost ◽  
Operating Conditions ◽  
Wear Prediction ◽  
Wear Rates ◽  
Computing Platform ◽  
Multi Phase ◽  
Performance Computing ◽  
Low Computational Cost ◽  
High Computational Cost

Abstract Dedicated to the memory of John Furlan. Wear prediction is important in designing reliable machinery for slurry industry. It usually relies on multi-phase computational fluid dynamics, which is accurate but computationally expensive. Each run of the simulations can take hours or days even on a high-performance computing platform. The high computational cost prohibits a large number of simulations in the process of design optimization. In contrast to physics-based simulations, data-driven approaches such as machine learning are capable of providing accurate wear predictions at a small fraction of computational costs, if the models are trained properly. In this paper, a recently developed WearGP framework [1] is extended to predict the global wear quantities of interest by constructing Gaussian process surrogates. The effects of different operating conditions are investigated. The advantages of the WearGP framework are demonstrated by its high accuracy and low computational cost in predicting wear rates.

Mathematical Modeling of a Variable Displacement Axial Piston Pump

1999 ◽  
Author(s):  
Jeff W. Dobchuk ◽  
Richard T. Burton ◽  
Peter N. Nikiforuk ◽  
Paul R. Ukrainetz
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Specific Effects ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Wide Range ◽  
Variable Displacement ◽  
Axial Piston

Abstract The variable displacement axial piston pump has been the subject of much research, having been studied from the controls, noise reduction, and design perspectives. The resulting body of research is large and very diverse in content. A review of the available publications was conducted for this paper in order to identify those works that would be most helpful in developing a complete and accurate mathematical model of an axial piston pump. Most of the available publications can be classified into one of two general groups; those describing a small group of components to understand specific phenomena or those describing the entire pump for control or design purposes. The significant mathematical developments in various publications regarding specific phenomena, particularly those works involving nonlinear friction or pressure transients, were identified by the authors in this paper. When the mathematical developments of the phenomena specific effects are combined with the widely accepted kinematics equations for the pump, an accurate numerical model can be developed. Works on linearized lumped parameter models and parameter sensitivity were examined for this paper and the limitations of these types of models were addressed. While linearized models offer mathematical simplicity, they suffer from poor accuracy over a wide range of operating conditions and do not reflect instantaneous swashplate dynamics. This paper offers insight into the required complexity of a mathematical model that is necessary to achieve a desired accuracy as well as providing the appropriate references to develop that model.

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