scholarly journals Study on impedance size optimization of one way surge tank in long distance water suply system

2020 ◽  
Author(s):  
Xuyun Chen ◽  
Jian Zhang ◽  
Xiaodong Yu ◽  
Sheng Chen ◽  
Lin Shi
Keyword(s):  
Pressure Drop ◽  
Water Flow ◽  
Negative Pressure ◽  
Water Hammer ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Characteristic Line ◽  
Surge Tank ◽  
Long Distance ◽  
The One

Abstract The size of the impedance hole of the one-way surge tank will affect its protection against water hammer. In this paper, a mathematical model of one-way surge tank with impedance is established based on characteristic line method. The pressure-reducing penetration formula of one-way surge tank including impedance loss and the calculation formula of make-up water flow are deduced. Based on these formulas, the influence of impedance hole diameter ratio (ratio of impedance hole of one-way surge tank to diameter of water pipeline) on water hammer protection effect is analyzed, and the reasonable value range of impedance hole diameter ratio is given. The correctness of the theoretical analysis results is verified by an engineering example. The results show that the pressure and flow relationship derived from the formula are consistent with the numerical simulation results. The penetration pressure drop of the one-way surge tank is inversely proportional to the impedance size. When the impedance hole diameter ratio is less than 0.2, the penetration pressure drop will cause serious negative pressure. The make-up water flow is proportional to the size of the impedance hole, and the make-up water volume should be reduced while ensuring that the pipeline has no negative pressure.

Cavitation at Sharp Edge Multi-Hole Baffle Plates

2011 ◽  
Author(s):  
G. J. Holt ◽  
D. Maynes ◽  
J. Blotter
Keyword(s):  
Water Flow ◽  
Plate Thickness ◽  
Diameter Ratio ◽  
Cavitation Number ◽  
Hole Diameter ◽  
Loss Coefficient ◽  
Sharp Edge ◽  
Baffle Plate ◽  
Cavitation Inception ◽  
Critical Cavitation

This paper reports results of an experimental investigation of cavitation caused by water flow through sharp edge multi-hole baffle plates at high speeds and large pressure drops. Such cavitation can be destructive to industrial systems due to the induced pipe wall vibrations that result. Incipient and critical cavitation numbers are design limits that are frequently needed in the design of systems implementing baffle plate type geometries to prevent adverse cavitation effects. The overall baffle plate loss coefficient, point of cavitation inception, and point where critical cavitation occurs are functions of baffle hole size, number of holes, and plate thickness. Sixteen total baffle plates were considered in the study with hole sizes ranging from 0.16 cm to 2.54 cm, total through area ranging between 11% and 60%, plate thickness ranging from 0.32–0.635 cm, and number of holes ranging from 4 to 1800. The plates were mounted in the test section of a 10.2 cm diameter schedule 40 pipe closed water flow loop. The focus of this paper is on how the influencing parameters affect the loss coefficient and the point of cavitation inception. The results show a complex dependency between the baffle plate loss coefficient with total through area ratio and the thickness to baffle hole diameter ratio. In general the loss coefficient decreases with increasing openness and increasing thickness to hole diameter ratio. A model based on the data is proposed to predict the loss coefficient for multi-holed baffle plates. Further, the data show that the cavitation number at the point of cavitation inception increases with increasing openness. However, with regard to the thickness to hole diameter ratio, the cavitation number at inception exhibits a local maximum at a ratio between 0.5 and 1.0. Models to allow prediction of the point of cavitation inception and the point where critical cavitation begins are presented in the paper.

Study on Setting of One-Way Surge Tank in Long Water Supply Engineering

2008 ◽  
Author(s):  
Jianyong Hu ◽  
Jian Zhang ◽  
Weihua Lu ◽  
Shibo Ma
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Water Supply ◽  
Negative Pressure ◽  
Water Hammer ◽  
Surge Tank ◽  
Proper Place ◽  
Column Separation ◽  
Important Measure ◽  
Engineering Principle

One-way surge tank is an important measure of water hammer protection in long water supply engineering. It can control the negative pressure efficiently and prevent pipeline from column separation. Setting one-way surge tank in proper place along pipeline is relative to the safety of long water supply engineering. Principle of Setting one-way surge tank is made through theoretical analysis detailedly. It is obviously that result of theoretical analysis is conservative because attenuation of water hammer is ignored, but theoretical analysis provide an proper approach for setting one-way surge tank. Based on result of theoretical analysis, optimization setting is obtained through numerical simulation.

scholarly journals Surge Tank Analysis for Water Hammer Remedy for Long Distance Pipeline

2018 ◽  
Vol 11 (3) ◽  
pp. 47-53
Author(s):  
Nisreen J. Rasheed
Keyword(s):  
Friction Factor ◽  
Method Of Characteristics ◽  
Transient Flow ◽  
Water Hammer ◽  
Pipeline System ◽  
Surge Tank ◽  
Governing Equations ◽  
Long Distance ◽  
Several Variables ◽  
The Impact

Various protection methods can be used for protecting the pipeline system from the impact of water hammer. Which includes the use of special materials for supporting the pipeline and the installation of special devices such as surge tanks, relief valves, and air chambers. In this study, to protect the pipeline system and reduce the effect of water hammer, surge tank has been used. Governing equations of transient flow with and without surge tank is numerically simulated using MATLAB software. Sensitivity analysis was investigated using several variables such as pipe diameter, wave’s velocity and friction factor. Method of characteristics (MOC) was implemented in this study. It was found that the diameter and friction factor of pipe have a significant impact on the results of transient flow and surge tank compared to the effect of wave’s velocity. It has been reached that the capacities of surge tanks at diameter (1m), are (1475m3) at first, second and fourth stages, (1360m3) at third and fifth stages and (570m3) at sixth stage. And at diameter (1.2m), the capacities are (1700m3), (1530m3) and (1475m3) at first, second and third stages respectively. But at diameter (1.4m), the capacities are (1590m3) at first and second stages. For all values of wave’s velocity, the capacities of surge tanks are (1760m3), (1530m3) and (1420m3) at first, second and third stages respectively. But the capacities of surge tanks at friction factor (0.007) are (1810m3), (1585m3) and (1245m3) at first, second and third stages respectively. However, for the capacity of surge tanks at the friction factor (0.008), it was mentioned when the surge tanks capacity of the diameter (1.2m) was mentioned. And when the friction factor is (0.009), the capacities are (1460m3) at first stage, (1415m3) at second and third stages and (570m3) at fourth stage

Analytical solutions for predicting the maximum pressure drop after pump failure in long-distance water supply project

2018 ◽  
Vol 18 (6) ◽  
pp. 1926-1936 ◽  
Author(s):  
Cheng-yu Fan ◽  
Jian Zhang ◽  
Xiao-dong Yu
Keyword(s):  
Pressure Drop ◽  
Water Supply ◽  
Safety Assessment ◽  
Water Hammer ◽  
Maximum Pressure ◽  
Long Distance ◽  
Pump Failure ◽  
Pipe System ◽  
Protection Scheme ◽  
Maximum Pressure Drop

Abstract The water hammer caused by pump failure in a long-distance pressurized pipe system generally poses a severe threat to the safety of the whole system. The maximum pressure drop at the pump end of the discharge line is significant for the safety assessment of the pipelines. In this study, the characteristics of the pump-stopping water hammer and its propagation in the pipelines are analyzed. The formula for predicting the maximum pressure drop is deduced based on the Method of Characteristics and the complete characteristics of the pumps. The application conditions of the formula and the solution procedures are presented as well. In addition, two engineering cases are introduced and the results calculated by the formula are compared with those resulting from the numerical simulation, and the agreement is satisfactory. The formula presented in this study is of simple form, practical and of high precision, and can provide a theoretical basis for the water hammer protection scheme of a long-distance water supply project.

Hydraulic Transient Prevention with Dipping Tube Hydropneumatic Tank

2013 ◽  
Vol 316-317 ◽  
pp. 762-765 ◽  
Author(s):  
Rong He Wang ◽  
Zhi Xun Wang ◽  
Feng Zhang ◽  
Ji Long Sun ◽  
Xiao Xue Wang ◽  
...  
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Water Hammer ◽  
Surge Tank ◽  
Air Velocity ◽  
Long Distance ◽  
Comparison Results ◽  
Low Costs ◽  
Gas Volume ◽  
Subroutine Package

The dipping tube hydropneumatic tank is one of the most efficient equipments to prevent water hammer in water distribution and long distance transmission pipe systems. Due to its low costs and easy to maintain features, dipping tube hydropneumatic tank has many irreplaceable advantages, however it is difficult to determine the correct size and gas volume for real world engineering applications. This paper presents a robust method to solve the problems from theory and application. Based on the Method of Characteristics (MOC) equations, this paper derives the equations for modeling dipping tube hydropneumatic tanks in water distribution systems to prevent water hammer. The equations include MOC, differential orifice head loss equation, gas law, air mass, air velocity and etc. The IBMs scientific subroutine package (SSP) is applied to solve the equations by deriving to the form of X=f (X). The method has been integrated into HAMMER. This paper also presents an example to illustrate the methods of determining the tank size, and the comparison results with sealed hydropneumatic tank and surge tank equipment.

Analysis of the precipitation reactor-separation equipment system. Continuous reactor and the rotary vacuum filter operating at the selected negative pressure drop

1981 ◽  
Vol 46 (10) ◽  
pp. 2364-2370 ◽  
Author(s):  
Otakar Söhnel
Keyword(s):  
Pressure Drop ◽  
Negative Pressure ◽  
Continuous Reactor ◽  
Vacuum Filter ◽  
Continuous Precipitation ◽  
Derived Relations ◽  
Filtration Area ◽  
Separation Equipment ◽  
Unit Output ◽  
Rotary Vacuum

An analysis has been performed of the continuous precipitation reactor - rotary vacuum filter system (operating at the selected negative pressure drop) on the basis of the unit output. Filtration area necessary for separation of the product from the precipitation reactor is a function of the mean residence time of suspension in the reactor, concentration of the precipitating solutions, porosity of the filtration cake and the filtration negative pressure drop. Application of the derived relations is demonstrated on the continuous precipitation of Mg(OH)2.

scholarly journals Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Dillon Alexander Wilson ◽  
Kul Pun ◽  
Poo Balan Ganesan ◽  
Faik Hamad
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bubble Diameter ◽  
Diameter Ratio ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Flow Rates ◽  
Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

scholarly journals Study on the Leakage and Inter-Stage Pressure Drop Characteristics of Two-Stage Finger Seal

2021 ◽  
Vol 11 (5) ◽  
pp. 2239
Author(s):  
Hailin Zhao ◽  
Hua Su ◽  
Guoding Chen ◽  
Yanchao Zhang
Keyword(s):  
Pressure Drop ◽  
Pressure Difference ◽  
Radial Displacement ◽  
Mean Square ◽  
The Finite Element Method ◽  
Axial Pressure ◽  
Two Stage ◽  
One Stage ◽  
The One ◽  
Lower Contact

To solve the high leakage and high wear problems faced by sealing devices in aeroengines under the condition of high axial pressure difference, the two-stage finger seal is proposed in this paper. The finite element method and computational fluid dynamics (FEM/CFD) coupling iterative algorithm of the two-stage finger seal is developed and validated. Then the performance advantages of two-stage finger seal compared to the one-stage finger seal are studied, as well as the leakage and the inter-stage pressure drop characteristics of two-stage finger seal are investigated. Finally, the measure to improve the inter-stage imbalance of pressure drop of two-stage finger seal is proposed. The results show that the two-stage finger seal has lower leakage and lower contact pressure than the one-stage finger seal at high axial pressure difference, but there exists an inter-stage imbalance of pressure drop. Increasing the axial pressure difference and the root mean square (RMS) roughness of finger element can aggravate the imbalance of pressure drop, while the radial displacement excitation of rotor has little influence on it. The results also indicate that the inter-stage imbalance of pressure drop of the two-stage finger seal can be improved by increasing the number of finger elements of the 1st finger seal and decreasing the number of finger elements of the 2nd finger seal.

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