Pilot Pipe and Damping Orifice Arrangements Analysis of a Pilot-Control Globe Valve

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Jin-yuan Qian ◽  
Jia-yi Wu ◽  
Zhi-xin Gao ◽  
Zhi-jiang Jin
Keyword(s):  
Energy Consumption ◽  
Pressure Distribution ◽  
Lower Energy ◽  
Flow Resistance ◽  
Flow Characteristics ◽  
Incoming Flow ◽  
Local Flow ◽  
Flow Capacity ◽  
Bottom Face ◽  
Globe Valve

Abstract Compared to conventional globe valves, the pilot-control globe valve (PCGV) possesses advantages of lower energy consumption and higher space utilization. In order to analyze the effects of pilot pipe and damping orifice arrangements, this work proposes four PCGVs and conducts simulations to compare their overall performances, overall flow characteristics, and local flow characteristics around the valve core. In general, the arrangement of the pilot pipe has larger effects on the hydroperformances of PCGVs than the arrangement of the damping orifice. The pipe-parallel-mounted type PCGV performs better in hydroperformance than the pipe-perpendicular-mounted type PCGV, and thus is recommended in practice. As the specified valve core travel increases, the flow resistance of PCGVs decreases and the flow capacity of PCGVs increases. However, overlarge specified valve core travel has little effects on the flow resistance and flow capacity of PCGVs. Besides, the increased specified valve core travel could effectively reduce the wear induced by the uneven pressure distribution on the external lateral face of valve core, but it has little effect on the wear induced by the uneven pressure distribution on the bottom face. For all pipe-perpendicular-mounted type PCGVs, the variation of axial force imposed on the valve core relative to the specific valve core travel presents similar tendencies under different incoming flow velocity within the scope of the investigation, which could be concluded into a fitting equation. This work could be referred for the optimization of PCGVs and other similar valves.

scholarly journals Experimental Study on Pressure Distribution and Flow Coefficient of Globe Valve

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 875 ◽  
Author(s):  
Quang Khai Nguyen ◽  
Kwang Hyo Jung ◽  
Gang Nam Lee ◽  
Sung Bu Suh ◽  
Peter To
Keyword(s):  
Reynolds Number ◽  
Pressure Distribution ◽  
Full Range ◽  
Flow Characteristics ◽  
National Standards ◽  
Flow Coefficient ◽  
Test Loop ◽  
Close Range ◽  
Valve Opening ◽  
Globe Valve

In this study, the pressure distribution and flow coefficient of a globe valve are investigated with a series of experiments conducted in a flow test loop. The experiments are performed on a three-inch model test valve from an eight-inch ANSI (American National Standards Institute) B16.11—Class 2500# prototype globe valve with various pump speeds and full range of valve openings. Both inherent and installed flow characteristics are measured, and the results show that the flow coefficient depends not only on the valve geometry and valve opening but also on the Reynolds number. When the Reynolds number exceeds a certain value, the flow coefficients are stable. In addition, the pressures at different positions in the upstream and the downstream of the valve are measured and compared with recommendation per ANSI/ISA-75.01 standard. The results show that, in single-phase flow, the discrepancies in pressure between different measurement locations within close range of 10 nominal diameter from the valve are inconsiderable.

scholarly journals Dynamic flight load measurements with MEMS pressure sensors

2021 ◽  
Author(s):  
Christian Raab ◽  
Kai Rohde-Brandenburger
Keyword(s):  
Pressure Distribution ◽  
Pressure Sensors ◽  
Flow Characteristics ◽  
Flight Test ◽  
Measurement Technology ◽  
Test Program ◽  
Aerodynamic Pressure ◽  
Pressure Distributions ◽  
Time Histories ◽  
Mems Pressure Sensors

AbstractThe determination of structural loads plays an important role in the certification process of new aircraft. Strain gauges are usually used to measure and monitor the structural loads encountered during the flight test program. However, a time-consuming wiring and calibration process is required to determine the forces and moments from the measured strains. Sensors based on MEMS provide an alternative way to determine loads from the measured aerodynamic pressure distribution around the structural component. Flight tests were performed with a research glider aircraft to investigate the flight loads determined with the strain based and the pressure based measurement technology. A wing glove equipped with 64 MEMS pressure sensors was developed for measuring the pressure distribution around a selected wing section. The wing shear force determined with both load determination methods were compared to each other. Several flight maneuvers with varying loads were performed during the flight test program. This paper concentrates on the evaluation of dynamic flight maneuvers including Stalls and Pull-Up Push-Over maneuvers. The effects of changes in the aerodynamic flow characteristics during the maneuver could be detected directly with the pressure sensors based on MEMS. Time histories of the measured pressure distributions and the wing shear forces are presented and discussed.

On the time scales and structure of Lagrangian intermittency in homogeneous isotropic turbulence

2019 ◽  
Vol 867 ◽  
pp. 438-481 ◽  
Author(s):  
R. Watteaux ◽  
G. Sardina ◽  
L. Brandt ◽  
D. Iudicone
Keyword(s):  
Time Scales ◽  
Isotropic Turbulence ◽  
Flow Characteristics ◽  
Residence Times ◽  
Particle Trajectories ◽  
Local Flow ◽  
Available Energy ◽  
Homogeneous And Isotropic Turbulence ◽  
History Of ◽  
Optimum Manner

We present a study of Lagrangian intermittency and its characteristic time scales. Using the concepts of flying and diving residence times above and below a given threshold in the magnitude of turbulence quantities, we infer the time spectra of the Lagrangian temporal fluctuations of dissipation, acceleration and enstrophy by means of a direct numerical simulation in homogeneous and isotropic turbulence. We then relate these time scales, first, to the presence of extreme events in turbulence and, second, to the local flow characteristics. Analyses confirm the existence in turbulent quantities of holes mirroring bursts, both of which are at the core of what constitutes Lagrangian intermittency. It is shown that holes are associated with quiescent laminar regions of the flow. Moreover, Lagrangian holes occur over few Kolmogorov time scales while Lagrangian bursts happen over longer periods scaling with the global decorrelation time scale, hence showing that loss of the history of the turbulence quantities along particle trajectories in turbulence is not continuous. Such a characteristic partially explains why current Lagrangian stochastic models fail at reproducing our results. More generally, the Lagrangian dataset of residence times shown here represents another manner for qualifying the accuracy of models. We also deliver a theoretical approximation of mean residence times, which highlights the importance of the correlation between turbulence quantities and their time derivatives in setting temporal statistics. Finally, whether in a hole or a burst, the straining structure along particle trajectories always evolves self-similarly (in a statistical sense) from shearless two-dimensional to shear bi-axial configurations. We speculate that this latter configuration represents the optimum manner to dissipate locally the available energy.

scholarly journals Effects of the Geometric Parameters of Mixer on the Mixing Process of Foam Concrete Mixture and Its Energy Efficiency

2020 ◽  
Vol 10 (22) ◽  
pp. 8055
Author(s):  
Sergey A. Stel’makh ◽  
Evgenii M. Shcherban’ ◽  
Anatolii I. Shuiskii ◽  
Al’bert Yu. Prokopov ◽  
Sergey M. Madatyan ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Lower Energy ◽  
Geometric Parameters ◽  
Concrete Mixture ◽  
Mixing Process ◽  
Conical Part ◽  
Foam Concrete ◽  
Optimal Range ◽  
Optimal Values

The paper studies the influence of the geometric parameters of the mixer on the mixing process, the construction of the mixing body, its location in the mixer bulk, and the mixer shape and geometry. The technique of calculating the power spent on mixing the foam concrete mixture is described. The effects of the ratio of the mixture height to the mixer diameter, the number and width of reflective partitions, and the shape of the conical part of the mixer on the homogeneity of the foam concrete mixture and the power consumption are considered. The optimal ratios of the foam concrete mixture height to the mixer diameter have been determined. Moreover, the optimal range of the ratios of the partition width to the mixer diameter has been established, in order to obtain a homogeneous foam concrete mixture throughout the volume with lower energy consumption. The optimal values of the angle of the mixer conical part for the preparation of a foam concrete mixture have been determined.

scholarly journals Numerical Study of Heat Transfer Intensification in a Circular Tube Using a Thin, Radiation-Absorbing Insert. Part 1: Thermo-Hydraulic Characteristics

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4596
Author(s):  
Piotr Bogusław Jasiński
Keyword(s):  
Heat Transfer ◽  
Flow Resistance ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Cylindrical Tube ◽  
Radiation Absorption ◽  
Fluid Temperature ◽  
Gas Temperature ◽  
Insert Size ◽  
Channel Diameter

The presented paper, which is the first of two parts, shows the results of numerical investigations of a heat exchanger channel in the form of a cylindrical tube with a thin insert. The insert, placed concentrically in the pipe, uses the phenomenon of thermal radiation absorption to intensify the heat transfer between the pipe wall and the gas. Eight geometric configurations of the insert size were numerically investigated using CFD software, varying its diameter from 20% to 90% of the pipe diameter and obtaining the thermal-flow characteristics for each case. The tests were conducted for a range of numbers Re = 5000–100,000 and a constant temperature difference between the channel wall and the average gas temperature of ∆T = 100 °C. The results show that the highest increase in the Nu number was observed for the inserts with diameters of 0.3 and 0.4 of the channel diameter, while the highest flow resistance was noted for the inserts with diameters of 0.6–0.7 of the channel diameter. The f/fs(Re) and Nu/Nus(Re) ratios are shown on graphs indicating how much the flow resistance and heat transfer increased compared to the pipe without an insert. Two methods of calculating the Nu number are also presented and analysed. In the first one, the average fluid temperature of the entire pipe volume was used to calculate the Nu number, and in the second, only the average fluid temperature of the annular portion formed by the insert was used. The second one gives much larger Nu/Nus ratio values, reaching up to 8–9 for small Re numbers.

One-pot three-step mechanically assisted synthesis and catalytic performance of tripodal metallic complexes

2021 ◽  
Author(s):  
Rima Tedjini ◽  
Raquel Viveiros ◽  
Teresa Casimiro ◽  
Vasco D.B. Bonifácio
Keyword(s):  
Energy Consumption ◽  
Lower Energy ◽  
Catalytic Performance ◽  
Green Technology ◽  
Waste Reduction ◽  
One Pot ◽  
Reaction Conversion

Mechanosynthesis is an emergent green technology that proceeds under solventless or vestigial solvent conditions. Major advantages relay in waste reduction and lower energy consumption, without compromising or enhancing reaction conversion....

Experimental and Numerical Investigations on Flow Characteristics of the KVLCC2 at 30° Drift Angl

2015 ◽  
Author(s):  
Moustafa Abdel-Maksoud ◽  
Volker Müller ◽  
Tao Xing ◽  
Serge Toxopeus ◽  
Frederick Stern ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Turbulence Modeling ◽  
Flow Characteristics ◽  
Flow Structures ◽  
Local Flow ◽  
Drift Angle ◽  
Vortical Structures ◽  
Ship Model ◽  
University Of Technology ◽  
Global And Local

Investigations of flow characteristics around ship hulls at large drift angle are very important for understanding the motion behavior of ships during maneuvers. At large drift angles, the flow is dominated by strong vortical structures and complex three-dimensional separations. An accurate prediction of these flow structures is still a challenge for modern computational fluid dynamics (CFD) solvers. Hull forms with high block coefficients are blunt and have strong curvatures, which leads to large area flow separations over smooth surfaces. These areas are sensitive to the relative angle between the flow and the ship motion direction. The paper is concerned with a collaborative computational study of the flow behavior around a double model of KVLCC2 at 30 degrees drift angle and Fr=0 condition, including analysis of numerical methods, turbulence modeling and grid resolution, and their effects on the mean flow and separation onset as well as formation of the vortical structures. This research is an outcome of a multi-year collaboration of five research partners from four countries. The overall approach adopted for the present study combines the advantages of CFD and EFD with the ultimate goal of capturing the salient details of the flow around the bluff hull form. The experiments were performed at the low - speed wind tunnel of the Hamburg University of Technology (TUHH). The main features of the global and local flow were captured in the experimental study. To determine the global flow characteristics, two different flow visualization techniques were used. The first one is a smoke test, which allows the visualization of vortex structures in vicinity of the ship model. The second test is a classic oil film method, which yields the direction of the limiting wall streamlines on the surface of the model. The analysis of the experimental results helped identify the separation zones on the ship model. To resolve the local flow-fields, LDA and PIV measurements were carried out in a selected number of measuring sections. Subsequently, the EFD and CFD results for the global and local flow structures were compared and analyzed. The numerical simulations were carried out by 5 institutions: Iowa Institute of Hydraulic Research of the University of Iowa (IIHR), USA, Maritime Research Institute Netherlands (MARIN), The Netherlands, Hamburg University of Technology (TUHH), Germany, Naval Surface Warfare Center, Carderock Division (NSWCCD) West Bethesda, USA and Swedish Defense Research Agency (FOI), Sweden. For the comparison with the experimental results, seven submissions of steady and unsteady CFD results are included in the present study. The participating codes include CFDShip-Iowa, ReFRESCO, FreSCo+, Edge, OpenFOAM (FOI) and NavyFoam. The size of the computational grids varies between 11 and 202 million control volumes or nodes. The influence of turbulence modeling on the predicted flow is studied by a wide variety of models such as isotropic eddy viscosity models of k-w family, Explicit Algebraic Reynolds Stress Model (EARSM), hybrid RANS-LES (DES), and LES. Despite notable differences in the grid resolutions, numerical methods, and turbulence models, the global features of the flow are closely captured by the computations. Noticeable differences among the computations are found in the details of the local flow such as the vortex strength and the location and extent of the flow separations.

Preliminary Study of Vascular Endothelial Ca2+ Response to Elevated Temperature

2000 ◽  
Author(s):  
Aaron Schen ◽  
Lisa X. Xu
Keyword(s):  
Endothelial Cells ◽  
Cardiac Output ◽  
Flow Resistance ◽  
Vascular Endothelial Cells ◽  
Cytosolic Calcium ◽  
Thermal Regulation ◽  
Vascular Endothelial ◽  
Local Flow ◽  
Preliminary Study ◽  
Diameter Change

Abstract The thermal regulation of tissue is controlled by the sympathetically mediated redistribution of cardiac output and change in local flow resistance of arterioles. The diameter change of the vessel from its resting level is governed by the state of the contractile proteins in vascular smooth muscle which can be influenced by the concentration of free cytosolic calcium ([Ca2+]i) in the vascular endothelial cells (Falcone, 1995).

Numerical Study on Flow Characteristics in High Multi-Stage Pressure Reducing Valve

2017 ◽  
Author(s):  
Fu-qiang Chen ◽  
Zhi-xin Gao ◽  
Jin-yuan Qian ◽  
Zhi-jiang Jin
Keyword(s):  
Energy Consumption ◽  
Numerical Study ◽  
Research Work ◽  
Flow Characteristics ◽  
Temperature Fields ◽  
Turbulent Dissipation ◽  
Technological Support ◽  
Multi Stage ◽  
Valve Opening ◽  
Pressure Reducing Valve

In this paper, a new high multi-stage pressure reducing valve (HMSPRV) is proposed. The main advantages include reducing noise and vibration, reducing energy consumption and dealing with complex conditions. As a new high pressure reducing valve, its flow characteristics need to be investigated. For that the valve opening has a great effect on steam flow, pressure reduction and energy consumption, thus different valve openings are taken as the research points to investigate the flow characteristics. The analysis is conducted from four aspects: pressure, velocity, temperature fields and energy consumption. The results show that valve opening has a great effect on flow characteristics. No matter for pressure, velocity or temperature field, the changing gradient mainly reflects at those throttling components for all valve openings. For energy consumption, in the study of turbulent dissipation rate, it can be found that the larger of valve opening, the larger of energy consumption. It can be concluded that the new high multi-stage pressure reducing valve works well under complex conditions. This study can provide technological support for achieving pressure regulation, and benefit the further research work on energy saving and multi-stage design of pressure reducing devices.

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