Numerical Investigation of a Globe Control Valve and Estimating its Loss Coefficient at Different Opening States

2021 ◽  
Author(s):  
Saber Rezaey
Keyword(s):  
Pressure Ratio ◽  
Functional Relation ◽  
Control Valve ◽  
Head Loss ◽  
Loss Coefficient ◽  
Rate Of Change ◽  
Minor Losses ◽  
Pressure Changes ◽  
Globe Control Valve ◽  
Oil Gas

One of the most important components of fluid transmission systems is a control valve located in the pipelines of oil, gas, etc. The primary purpose of this valve is to control the rate of fluid flow passing through it under pressure changes and the most important issue is to investigate the flow’s characteristics in order to achieve a proper geometry to control the flow rate and pressure as desired. The valves used in pipelines add to the overall head loss of the system. Therefore, valves with proper geometry can reduce these minor losses and finally decrease total energy losses. In this paper, a globe control valve is modeled and then numerically investigated to extract its functional relation, which relates pressure ratio to inlet Reynolds number, and estimate its loss coefficient at the valve’s different opening states which have not been addressed completely before and can be beneficial for the selection and usage of globe valves under certain conditions. According to the results, it is found that pressure ratio and loss coefficient are functions of inlet velocity and the valve’s opening state’s percentage, which are directly related to the valve’s geometry. When the valve opens, the rate of change in pressure ratio and loss coefficient are very sharp. Gradually, this rate decreases and the results tend to the final value at the valve’s fully opened state.

scholarly journals A Procedure for Performance Experimental Analysis of a Globe Control Valve

2018 ◽  
Author(s):  
Hesam Hoursan ◽  
Mohammad J. Moradi ◽  
Mohammad Omid Hadjiazim ◽  
Mohammad Taghi Ahmadian ◽  
Ahmad Barari
Keyword(s):  
Experimental Analysis ◽  
Control Valve ◽  
Globe Control Valve

scholarly journals Numerical simulation of minor losses coefficient on the example of elbows

2018 ◽  
Vol 180 ◽  
pp. 02093
Author(s):  
Smyk Emil ◽  
Mrozik Dariusz ◽  
Olszewski Łukasz ◽  
Peszyński Kazimierz
Keyword(s):  
Numerical Simulation ◽  
Numerical Methods ◽  
Numerical Method ◽  
Cross Section ◽  
Analytical Methods ◽  
Circular Cross Section ◽  
Experimental Methods ◽  
Loss Coefficient ◽  
Complicated Problem ◽  
Minor Losses

Determining of minor losses coefficient is very complicated problem. Analytical methods are often very difficult and experimental methods are very expensive and time-consuming. Consequently, the use of numerical methods seems to be a good solution, but there are no publications describing this issue. Therefore, the paper is describing the numerical method of determining the minor loss coefficient ξ on the example of elbows with circular cross-section.

On kinematic waves I. Flood movement in long rivers

1955 ◽  
Vol 229 (1178) ◽  
pp. 281-316 ◽  
Keyword(s):  
Shock Waves ◽  
Equations Of Motion ◽  
Functional Relation ◽  
Wave Theory ◽  
Observation Point ◽  
Rate Of Change ◽  
Kinematic Wave ◽  
Unit Distance ◽  
Kinematic Waves ◽  
The Waves

In this paper and in part II, we give the theory of a distinctive type of wave motion, which arises in any one-dimensional flow problem when there is an approximate functional relation at each point between the flow q (quantity passing a given point in unit time) and concentration k (quantity per unit distance). The wave property then follows directly from the equation of continuity satisfied by q and k . In view of this, these waves are described as ‘kinematic’, as distinct from the classical wave motions, which depend also on Newton’s second law of motion and are therefore called ‘dynamic’. Kinematic waves travel with the velocity dq/dk , and the flow q remains constant on each kinematic wave. Since the velocity of propagation of each wave depends upon the value of q carried by it, successive waves may coalesce to form ‘kinematic shock waves ’. From the point of view of kinematic wave theory, there is a discontinuous increase in q at a shock, but in reality a shock wave is a relatively narrow region in which (owing to the rapid increase of q ) terms neglected by the flow concentration relation become important. The general properties of kinematic waves and shock waves are discussed in detail in §1. One example included in §1 is the interpretation of the group-velocity phenomenon in a dispersive medium as a particular case of the kinematic wave phenomenon. The remainder of part I is devoted to a detailed treatment of flood movement in long rivers, a problem in which kinematic waves play the leading role although dynamic waves (in this case, the long gravity waves) also appear. First (§2), we consider the variety of factors which can influence the approximate flow-concentration relation, and survey the various formulae which have been used in attempts to describe it. Then follows a more mathematical section (§3) in which the role of the dynamic waves is clarified. From the full equations of motion for an idealized problem it is shown that at the ‘Froude numbers’ appropriate to flood waves, the dynamic waves are rapidly attenuated and the main disturbance is carried downstream by the kinematic waves; some account is then given of the behaviour of the flow at higher Froude numbers. Also in §3, the full equations of motion are used to investigate the structure of the kinematic shock; for this problem, the shock is the ‘monoclinal flood wave’ which is well known in the literature of this subject. The final sections (§§4 and 5) contain the application of the theory of kinematic waves to the determination of flood movement. In §4 it is shown how the waves (including shock waves) travelling downstream from an observation point may be deduced from a knowledge of the variation with time of the flow at the observation point; this section then concludes with a brief account of the effect on the waves of tributaries and run-off. In §5, the modifications (similar to diffusion effects) which arise due to the slight dependence of the flow-concentration curve on the rate of change of flow or concentration, are described and methods for their inclusion in the theory are given.

Teaching Rate of Change and Problem Solving to High School Students With High Incidence Disabilities at Tier 3

2019 ◽  
pp. 073194871988734
Author(s):  
Kaitlin Bundock ◽  
Leanne S. Hawken ◽  
Sharlene A. Kiuhara ◽  
Breda V. O’Keeffe ◽  
Robert E. O’Neill ◽  
...  
Keyword(s):  
High School ◽  
High School Students ◽  
Problem Solving ◽  
Students With Disabilities ◽  
Instructional Strategies ◽  
Conceptual Understanding ◽  
Functional Relation ◽  
Rate Of Change ◽  
Probe Design ◽  
School Students

Implementing an integrated sequence of concrete-representational-abstract depictions of mathematics concepts (CRA-I) can improve the mathematics achievement of students with disabilities, and explicit instructional strategies involving problem-solving heuristics and student verbalizations can help facilitate students’ conceptual understanding of mathematics. Combining CRA-I and explicit instructional strategies may increase students’ conceptual understanding and ability to express mathematical reasoning through writing. This study included three ninth-grade students with disabilities, and employed a multiple-probe design across-participants to investigate a functional relation between an explicit instructional strategy within a CRA-I framework and high school students’ with disabilities proficiency in solving rate of change problems. Results showed that all three students improved their mathematics scores (combined Tau-U effect size = 0.77, p < .001) and maintained improvements during a 1- to 7-week post-instruction phase. Implications for research and practice related to mathematics instruction and intervention specifically for students with learning disabilities are discussed.

Contraction/Expansion Effects in 90° Miter Bends in Rectangular Xurographic Microchannels

2011 ◽  
Author(s):  
Lam Nguyen ◽  
John Elsnab ◽  
Tim Ameel
Keyword(s):  
Reynolds Number ◽  
Critical Reynolds Number ◽  
Area Ratio ◽  
Loss Coefficient ◽  
Sidewall Roughness ◽  
Cross Sectional ◽  
Loss Coefficients ◽  
Minor Losses ◽  
High Reynolds ◽  
Reported Data

Xurography is an inexpensive rapid prototyping technology for the development of microfluidic systems. Imprecision in the xurographic tape cutting process can result in undesired changes in channel dimensions near features that require a change in cutting direction, such as 90° miter bends. An experimental study of water flow in rectangular xurographic microchannels incorporating 90° miter bends with different channel widths in each leg is reported. A set of twelve microchannels, with channel depth approximately 105 micrometers and aspect ratio ranging from 0.071 to 0.435, were fabricated from double-sided adhesive Kapton® polyimide tape and two rectangular glass plates. The channels were reinforced with a mechanical clamping system, enabling high Reynolds number, Re, flows (up to Re = 3200) where Re was based upon hydraulic diameter and average velocity. Reported data include friction factor and critical Reynolds number for straight microchannels and loss coefficients for flow through 90° miter bends that contain either a contraction or expansion with cross-sectional area ratios of 0.5, 0.333 and 0.2. The critical Reynolds number, Recr, ranged from 1750 to 2300 and was found to be dependent on channel defects such as sidewall roughness, adhesive droplets, and corner imperfections. Loss coefficients through 90° miter bends with expansion decrease rapidly for Re < Recr. At the transition, the loss coefficient suddenly drops and approaches an asymptotic value for Re > Recr. For 90° miter bends with contractions, loss coefficients gradually decrease with increasing Re for 150 < Re < 1400. In addition, the loss coefficient decreases with decreasing area ratio through the contraction or expansion. The minor loss coefficient data were found to be dependent on Reynolds numbers and area ratio of contraction/expansion at the bend. The results suggest that the effect of the contraction/expansion was the dominant mechanism for minor losses in the 90° miter bend.

scholarly journals Head loss coefficient through sharp-edged orifices

2016 ◽  
Vol 49 (6) ◽  
pp. 062009 ◽  
Author(s):  
Nicolas J. Adam ◽  
Giovanni De Cesare ◽  
Anton J. Schleiss ◽  
Sylvain Richard ◽  
Cécile Muench-Alligné
Keyword(s):  
Head Loss ◽  
Loss Coefficient ◽  
Head Loss Coefficient
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