Aerodynamic Torque Acting on a Butterfly Valve. Comparison and Choice of a Torque Coefficient

1999 ◽  
Vol 121 (4) ◽  
pp. 914-917 ◽  
Author(s):  
C. Solliec ◽  
F. Danbon
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Low Cost ◽  
Normalization Method ◽  
Pressure Drops ◽  
Torque Coefficient ◽  
Aerodynamic Torque ◽  
Valve Pressure

Most technological devices use butterfly valves to check the flow rate and speed, through piping. Their main advantages are their low cost, their mechanical suitability for fast operation, and their small pressure drops when they are fully open. The fluid dynamic torque about the axis of large valves has to be considered as the actuator could be overstrained. This torque is generally defined using a nondimensional coefficient KT, in which the static pressure drop created by the valve is used for normalization. When the valve is closed downstream of an elbow, the valve pressure drop is not well defined. Thus, the classic normalization method gives many ambiguities. To avoid the use of the pressure drop, we define another torque coefficient CT in which the dynamic pressure of the flow is the normalization factor instead of the pressure drop. Advantages and drawbacks of each normalization method are described in the following.

Experimental and Computational Analyses of Pressure Differentials in Flexible Ducts With Different Bent Angles

2007 ◽  
Author(s):  
Ray R. Taghavi ◽  
Wonjin Jin ◽  
Mario A. Medina
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Complex Geometry ◽  
Analysis Data ◽  
Secondary Flows ◽  
Low Flow ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Geometrical Effects ◽  
Cfd Analyses

A set of experimental analyses was conducted to determine static pressure drops inside non-metallic flexible, spiral wire helix core ducts, with different bent angles. In addition, Computational Fluid Dynamics (CFD) solutions were performed and verified by comparing them to the experimental data. The CFD computations were carried out to produce more systematic pressure drop information through these complex-geometry ducts. The experimental setup was constructed according to ASHRAE Standard 120-1999. Five different bent angles (0, 30, 45, 60, and 90 degrees) were tested at relatively low flow rates (11 to 89 CFM). Also, two different bent radii and duct lengths were tested to study flexible duct geometrical effects on static pressure drops. FLUENT 6.2, using RANS based two equations - RNG k-ε model, was used for the CFD analyses. The experimental and CFD results showed that larger bent angles produced larger static pressure drops in the flexible ducts. CFD analysis data were found to be in relatively good agreement with the experimental results for all bent angle cases. However, the deviations became slightly larger at higher velocity regimes and at the longer test sections. Overall, static pressure drop for longer length cases were approximately 0.01in.H2O higher when compared to shorter cases because of the increase in resistance to the flow. Also, the CFD simulations captured more pronounced static pressure drops that were produced along the sharper turns. The stronger secondary flows, which resulted from higher and lower static pressure distributions in the outer and inner surfaces, respectively, contributed to these higher pressure drops.

scholarly journals Grid convergence study of a cyclone separator using different mesh structures

2017 ◽  
Vol 23 (3) ◽  
pp. 311-320 ◽  
Author(s):  
R.A.F. Oliveira ◽  
G.H. Justi ◽  
G.C. Lopes
Keyword(s):  
Pressure Drop ◽  
Collection Efficiency ◽  
Fluid Dynamic ◽  
Two Phase ◽  
Mesh Structure ◽  
Pressure Drops ◽  
Regular Elements ◽  
Grid Convergence ◽  
Grid Convergence Index ◽  
Mesh Structures

In a cyclone design, pressure drop and collection efficiency are two important performance parameters to estimate its implementation viability. The optimum design provides higher efficiencies and lower pressure drops. In this paper, a grid independence study was performed to determine the most appropriate mesh to simulate the two-phase flow in a Stairmand cyclone. Computational fluid dynamic (CFD) tools were used to simulate the flow in an Eulerian-Lagrangian approach. Two different mesh structure, one with wall-refinement and the other with regular elements, and several mesh sizes were tested. The grid convergence index (GCI) method was applied to evaluate the result independence. The CFD model results were compared with empirical correlations from bibliography, showing good agreement. The wall-refined mesh with 287 thousand elements obtained errors of 9.8% for collection efficiency and 14.2% for pressure drop, while the same mesh, with regular elements, obtained errors of 8.7% for collection efficiency and 0.01% for pressure drop.

An Experimental Investigation of Butterfly Valve Performance Downstream of an Elbow

1991 ◽  
Vol 113 (1) ◽  
pp. 81-85 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Mass Flow ◽  
Performance Characteristics ◽  
Flow Coefficient ◽  
Butterfly Valve ◽  
Operating Characteristics ◽  
Drop Mass ◽  
Torque Coefficient ◽  
Aerodynamic Torque

The results of an experimental investigation concerning the operating characteristics of a butterfly valve downstream of a mitered elbow are reported. Primary emphasis is given the influences of valve disk angle, valve/elbow spacing, and valve/elbow orientation on the dimensionless pressure drop, mass flow coefficient, and aerodynamic torque coefficient characteristics of the valve. The results show that when the valve is located two pipe diameters downstream of the elbow, the performance characteristics are substantially affected by the relative valve/elbow orientation. However, at a spacing of eight diameters the effect of the elbow on the valve operating characteristics is small.

scholarly journals Effect of Turn Region Treatments on the Pressure Loss Distribution in a Smooth Square Channel with Sharp 180° Bend

2004 ◽  
Vol 10 (6) ◽  
pp. 459-468 ◽  
Author(s):  
D. V. Ratna Rao ◽  
Chakka Sarat Babu ◽  
S. V. Prabhu
Keyword(s):  
Pressure Drop ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Pressure Head ◽  
Reynolds Numbers ◽  
Guide Vanes ◽  
Pressure Losses ◽  
Square Channel ◽  
Smooth Channel

An experimental investigation is carried out to study the effect of several turn treatments like single guide vane (short and long) and multiple guide vanes on the pressure drop distribution in a square cross-sectioned smooth channel with a sharp 180° bend. The sharp 180° turn is obtained by dividing a rectangular passage into two square channels using a divider wall with a rounded tip at the location where the flow negotiates the turn. The study is carried out for a divider wall thickness to hydraulic diameter(W/D)of 0.2 for Reynolds numbers of 13,500 and 17,000. The pressure drop distribution normalized with the mainstream fluid dynamic pressure head is presented for the outer surfaces. The results indicate that the shape and position of the guide vanes significantly affect the pressure losses associated with coolant flows through a sharp 180° bend. Properly shaped 180° vanes located in the center of the bend decrease the overall pressure drop by as much as 40–45% compared to the no guide vane within the bend.

Numerical Investigation for Inner Flow Fields and Structure Improvements of Medium Speed Mill

2013 ◽  
Vol 732-733 ◽  
pp. 481-486
Author(s):  
Xian Ran Zhu ◽  
Cheng Yong Liu ◽  
Liang Cheng
Keyword(s):  
Numerical Model ◽  
Pressure Drop ◽  
Numerical Investigation ◽  
Flow Rate ◽  
Static Pressure ◽  
Flow Fields ◽  
Field Conditions ◽  
Pressure Drops ◽  
Medium Speed ◽  
Commercial Code

The numerical model for ZGM95 medium speed mill is built and the inner flow fields are simulated by employing the commercial code of FLUENT. The results show that the distributions of the static pressure and the flow rate are not uniform for 36 nozzle rings due to the primary air entering the mill only from one side. Two modified structures are assumed to improve the mills performances and the corresponding models are simulated further. The flow fields are still not good enough and the pressure drop increases sharply in the mill when blocking several nozzle rings, and this structure is not recommended if the amount of pulverizer rejects is not extremely huge. The structure with double-inlet can improve the distribution of the flow fields effectively in the mill and few pressure drops of the mill increase. However, the feasibility of the double-inlet structure is also depends on the field conditions. The pressure drop will be less and the flow fields will be better when adopting the horizontal inlet duct instead of the inclined one.

scholarly journals Pitot Tube-Based Icing Detection: Effect of Ice Blocking on Pressure

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Xianglian Lv ◽  
Jie Guan ◽  
Shengkun Wang ◽  
Haiyang Zhang ◽  
Shijie Xue ◽  
...  
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Detection System ◽  
Low Cost ◽  
Pitot Tube ◽  
Detection Methods ◽  
Pressure Drops ◽  
Aerial Vehicle ◽  
Pressure Output ◽  
Detection Effect

This study aims at addressing a problem on icing detection for Unmanned Aerial Vehicle (UAV for short) because traditional icing detection methods are costly and bulky. Toward this end, a pitot-based icing detection method is proposed, and the effect of different types of icing blocking on pressure is firstly reported. An icing detection system based on the pitot tube is designed and fabricated. Icing wind tunnel results indicate that if the pitot tube is blocked by glaze ice, then the total pressure of the pitot tube decreases gradually and remains unchanged and less than static pressure. However, if the pitot tube is blocked by rime ice, then the total pressure drops to the same level as the static pressure. If the pitot tube is blocked by non-ice organic materials, then the total pressure suddenly drops to the same level as the static pressure and remains unchanged. Furthermore, if the pitot tube contacts the water droplets but does not freeze, the total pressure output value fluctuates slightly. The effect of icing on pressure is caused by differences in ice microstructure, temperature, and flow velocity. At the same time, the proposed method offers a facile and low-cost approach for UAV icing detection.

scholarly journals Flow Simulation and Model Analysis of Efficiency and Pressure Ratio Behaviors in GT4086 Turbocharger Compressor

Mechanika ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 293-300 ◽  
Author(s):  
Mohammad Omidi
Keyword(s):  
Pressure Drop ◽  
Global Minimum ◽  
Static Pressure ◽  
Mass Parameter ◽  
Pressure Ratio ◽  
Flow Simulation ◽  
Model Analysis ◽  
Global Maximum ◽  
Pressure Drops ◽  
Specific Speed

The present paper seeks to model and simulate the function of a centrifugal GT4082 compressor and evaluates the effects of losses in the impeller, volute, and diffuser. It is also examined the mass parameter effect on the efficiency drop at different speeds. The total and static pressure drops are also examined in the volute and diffuser. Based on the experiments, the efficiency drops in these parts modeled at different mass parameters and speeds discovered to be maximized in the volute and diffuser at a specific speed. A global minimum was observed in the overall pressure drop and a global maximum in the static pressure drop versus a mass parameter.

scholarly journals Pressure Drop Distribution in Smooth and Rib Roughened Square Channel with Sharp 180° Bend in the Presence of Guide Vanes

2004 ◽  
Vol 10 (2) ◽  
pp. 99-114 ◽  
Author(s):  
Venkata Ratna Rao.D ◽  
S. V. Prabhu
Keyword(s):  
Pressure Drop ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Pressure Head ◽  
Guide Vanes ◽  
Square Channel ◽  
Constant Pitch ◽  
Mainstream Flow ◽  
Rib Roughened

An experimental investigation is carried out to study the effect of several turn treatments like single guide vane (short and long) and multiple guide vanes on the pressure drop distribution in smooth and rib roughened square channels with a sharp 180° bend. The sharp 180° turn is obtained by dividing a rectangular passage into two square channels using a divider wall with a rounded tip at the location where the flow negotiates the turn. In rib roughened channels, ribs are configured on the top and bottom surfaces in a symmetric arrangement with an angle of 90° to the mainstream flow. Rib height-to-hydraulic diameter ratio(e/D)is maintained constant at 0.14 with a constant pitch-to-rib height ratio(P/e)of 10. The pressure drop distribution normalized with the mainstream fluid dynamic pressure head is presented for the outer surfaces. Results suggest that 90° multiple guide vanes result in the decrease of overall pressure drop by around 40% in smooth square channels. However, a reduction in overall pressure drop by only 15% is achievable through guide vanes in rib roughened square channels.

scholarly journals Analisis Airfoil Double-Slot Flap LS(01)-0417 MOD Dengan Airfoil Tanpa Flap Nasa SC(2) 0610

2018 ◽  
Vol 11 (2) ◽  
pp. 49
Author(s):  
Gaguk Jatisukamto ◽  
Mirna Sari
Keyword(s):  
Computational Fluid Dynamic ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Airflow Velocity ◽  
The Difference ◽  
The Stability

Kestabilan pesawat terbang ditentukan oleh desain airfoil sayap dan ekor. Perbedaan kecepatan aliran udara antara permukaan atas dan bawah airfoil menghasilkan perbedaan tekanan sehingga akan memberikan gaya angkat (lift) pada sayap. Perbedaan tekanan udara pada permukaan sayap dinyatakan dengan pressure coefficient (Cp), yaitu perbedaan tekanan statik lokal dengan tekanan statik aliran bebas. Koefisien lift (Cl) adalah rasio antara gaya angkat (lift) dengan tekanan dinamis. Peningkatan angka CL sebesar 20,4% pada riset sebelumnya diperoleh berdasarkan simulasi penambahan flap. Tujuan penelitian ini adalah membandingkan hasil simulasi airfoil double slot flap LS(01)-0417 MOD  dengan airfoil NASA SC(2) 0610 yang tanpa flap dan mencari korelasi antara sudut serang (?) dengan koefisien lift (Cl ).Metodologi penelitian dilakukan dengan simulasi Computational Fluid Dynamic (CFD). Hasil penelitian dapat disimpulkan bahwa koefisien lift CL untuk airfoil double slot flap LS(01)-0417 MOD menghasilkan CL = 1,498 sedangkan dengan sudut serang ? = 16o sedangkan airfoil NASA SC(2) 0610 tanpa flap memiliki nilai CL = 1,095 dengan sudut serang 13o. The stability of the aircraft is ordered by the airfoil design of the wings and the tail. The difference in flow velocity between the surface and the bottom of the airfoil will produce styles that will present lift  on the wings. The difference in airflow velocity between the top and bottom surfaces of the airfoil produces a pressure difference so it will provide lift (lift) on the wing. The lift coefficient (CL) is the ratio between lift with dynamic pressure. The difference of air pressure on the wing surface is expressed by pressure coefficient (Cp), the difference of local static pressure with free flow static pressure. The lift coefficient (Cl) is the ratio of lift to dynamic pressure. An increase in CL value of 20.4% in previous research was obtained based on the simulation of flap addition. The purpose of this research is comparison between airfoil double slot flap LS (01)-0417 MOD with airfoil NASA SC (2) 0610 without flap and search between angle of attack (?) with coefficient of lift (Cl). Method research is done by Computational Fluid Dynamic (CFD). The result of this research can be concluded that lift coefficient CL for double slot airfoil flap LS (01)-0417 MOD yield CL = 1,498 while with angle of attack ? = 16o while airfoil NASA SC (2) 0610 without flap have value CL = 1,095 with angle of attack 13o

The Performance of Two Butterfly Valves Mounted in Series

1991 ◽  
Vol 113 (3) ◽  
pp. 419-423 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
System Performance ◽  
Combined Effect ◽  
Operating Characteristics ◽  
Dimensionless Pressure ◽  
Mass Flowrate ◽  
In Series ◽  
Torque Coefficient ◽  
Aerodynamic Torque

The results of an experimental investigation concerning the operating characteristics of two similar butterfly valves mounted in series are reported. Emphasis is given to the influence of the upstream valve disk angle, the downstream valve disk angle, the relative valve orientation, and the spacing between the valves. The dimensionless pressure drop, the mass flowrate coefficient, and the aerodynamic torque coefficient of each valve are used to characterize the system performance. The results show that the operating characteristics are strongly tied to the combined effect of the two valve disk angles. With noted exceptions, the valve disk orientation and spacing are secondary influences.

Sign in / Sign up

Export Citation Format

Share Document