scholarly journals Influence of viscosity, surface tension, and inclination angle on motion of long bubbles in closed tubes

1966 ◽  
Vol 25 (4) ◽  
pp. 821-837 ◽  
Author(s):  
E. E. Zukoski
Keyword(s):  
Experimental Study ◽  
Surface Tension ◽  
Inclination Angle ◽  
Bubble Velocity ◽  
Vertical Tubes

An experimental study has been made of the motion of long bubbles in closed tubes. The influence of viscosity and surface tension on the bubble velocity is clarified. A correlation of bubble velocities in vertical tubes is suggested and is shown to be useful for the whole range of parameters investigated. In addition, the effect of tube inclination angle on bubble velocity is presented, and certain features of the flow are described qualitatively.

An Experimental Study on Improvement in Thermal Efficiency of Mesh Wick Heat Pipe

2014 ◽  
Vol 592-594 ◽  
pp. 1423-1427 ◽  
Author(s):  
G. Kumaresan ◽  
S. Venkatachalapathy ◽  
Indraneel C. Naik
Keyword(s):  
Experimental Study ◽  
Heat Pipe ◽  
Inclination Angle ◽  
Tilt Angle ◽  
Thermal Efficiency ◽  
Cuo Nanoparticles

This study aims to investigate the influence of inclination angle and concentration of nanoparticles on the improvement in heat pipe thermal efficiency. Spherical shaped, 40 nm size CuO nanoparticles are used in this study and its physical and thermal chracteristics are investigated. The results are compared with a heat pipe using DI water at horizontal position.The thermal efficiency is improved by increasing the tilt angle and mass of particles dispersed in DI water. The improvement in thermal efficiency obtained are 20.59, 35.92 and 32.57% respectively for 0.5, 1.0 and 1.5 wt% of CuO nanofluids and 60° inclination angle.

scholarly journals The effect of surface tension on steadily translating bubbles in an unbounded Hele-Shaw cell

2017 ◽  
Vol 473 (2201) ◽  
pp. 20170050 ◽  
Author(s):  
Christopher C. Green ◽  
Christopher J. Lustri ◽  
Scott W. McCue
Keyword(s):  
Surface Tension ◽  
Numerical Solutions ◽  
Bubble Velocity ◽  
Number Of Solutions ◽  
Branch Number ◽  
Single Solution ◽  
Countably Infinite ◽  
Prime Function ◽  
Hele Shaw Cell ◽  
Effect Of Surface

New numerical solutions to the so-called selection problem for one and two steadily translating bubbles in an unbounded Hele-Shaw cell are presented. Our approach relies on conformal mapping which, for the two-bubble problem, involves the Schottky-Klein prime function associated with an annulus. We show that a countably infinite number of solutions exist for each fixed value of dimensionless surface tension, with the bubble shapes becoming more exotic as the solution branch number increases. Our numerical results suggest that a single solution is selected in the limit that surface tension vanishes, with the scaling between the bubble velocity and surface tension being different to the well-studied problems for a bubble or a finger propagating in a channel geometry.

Evaluation of General Correlations for Heat Transfer During Boiling of Saturated Liquids in Tubes and Annuli

2005 ◽  
Author(s):  
M. Mohammed Shah
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Large Deviations ◽  
Boiling Heat Transfer ◽  
Mean Deviation ◽  
Data Sets ◽  
Vapor Quality ◽  
Dimensional Parameters ◽  
Vertical Tubes ◽  
Reduced Pressures

Six of the most verified correlations for boiling heat transfer were compared to data for horizontal and vertical tubes and annuli. The correlations evaluated were: Chen (1966), Shah (1982), Gungor and Winterton (1986), Liu & Winterton (1991), Kandlikar (1990), and Steiner and Taborek (1992). The database used to evaluate these correlations included 29 fluids: water, refrigerants, cryogens, organic and inorganic chemicals. The data cover reduced pressures from 0.005 to 0.783, mass flux from 28 to 11071 kg/m2s, vapor quality from 0 to 0.95, and boiling number from 0.000026 to 0.00742. The correlations of Shah and Gungor & Winterton gave the best agreement with data with a mean deviation of about 17.5%, only a couple of data sets showing large deviations. The paper presents and discusses the results of this study. Included are tables giving the range of dimensional and non-dimensional parameters covered by each experimental study.

scholarly journals Experimental study of immersion ratio and shaft inclination angle in the performance of a surface-piercing propeller

2019 ◽  
Vol 10 (1) ◽  
pp. 153-167
Author(s):  
Seyyed Mostafa Seyyedi ◽  
Rouzbeh Shafaghat ◽  
Mohioddin Siavoshian
Keyword(s):  
Experimental Study ◽  
Free Surface ◽  
Surface Water ◽  
Inclination Angle ◽  
Superior Performance ◽  
Design Parameters ◽  
Water Tunnel ◽  
Hydrodynamic Coefficients ◽  
Thrust And Torque ◽  
Surface Piercing Propeller

Abstract. Surface-piercing propellers have been widely used in light and high-speed vessels because of their superior performance. Experimental study of these propellers is one of the most reliable and accurate ways which can provide details about the performance and effect of different design parameters on the performance of the surface-piercing propellers. In this research, a five-blade surface-piercing propeller was tested in the free surface water tunnel of Babol Noshirvani University of Technology in order to expand the available experimental data and database for future engineering designs. The effects of immersion ratio and shaft inclination angle on the propeller's efficiency and hydrodynamic coefficients were examined. A free surface water tunnel and a calibrated dynamometer with the measurability of the thrust forces and the torque of a propeller were used for this purpose. Comparing the obtained results with the existing semi-experimental equations shows that the equations presented in various geometric conditions are not accurate enough, and developing the existing database is necessary. The details of the obtained results showed that the hydrodynamic coefficients of the thrust and torque increased by increasing the immersion ratio, but the coefficient of hydrodynamic thrust and efficiency reduced. The results also indicated that the coefficient of torque increased by increasing the shaft inclination angle. The highest efficiency of the propeller was achieved in the range of 40 %–50 % immersion ratios at all angles of shaft inclination. For all immersion ratios, the maximum and minimum efficiencies were obtained at 0 and 15 shaft inclination angles, respectively. The best efficiency of the propeller was at 50 % immersion ratio and zero shaft inclination angle.

Effect of inclination angle on the performance of a shell and tube heat storage unit – An experimental study

2017 ◽  
Vol 112 ◽  
pp. 1497-1509 ◽  
Author(s):  
N. Kousha ◽  
M.J. Hosseini ◽  
M.R. Aligoodarz ◽  
R. Pakrouh ◽  
R. Bahrampoury
Keyword(s):  
Experimental Study ◽  
Inclination Angle ◽  
Heat Storage ◽  
Storage Unit ◽  
Shell And Tube
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