Visual Observations of Chamber Volume Effect on Ebullience From Submerged Orifice Plates

2016 ◽  
Author(s):  
Sanjivan Manoharan ◽  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Surface Tension ◽  
Bubble Growth ◽  
High Speed ◽  
Capillary Tube ◽  
Volume Effect ◽  
Orifice Plate ◽  
Orifice Diameter ◽  
Chamber Volume ◽  
Acrylic Glass ◽  
Liquid Pools

Effect of chamber volume upstream of the orifice on ebullience from orifice plates is studied experimentally in this paper. Bubble growth from orifice plates submerged in liquid pools is captured using high speed videography. The orifice plate substrate is acrylic glass and 11 different orifice diameters (diameter range: 0.610< D0< 2.261mm) are utilized. In addition to water, ethanol-water binary mixture with surface tension of 54 mN/m is used to examine the interplay between surface tension and chamber volume effects on bubble characteristics. For an acrylic glass orifice plate with a fixed chamber volume, above a certain transition orifice diameter, the bubbles from the orifice plate are of the same size and shape as those from a capillary tube orifice. However, below this diameter, the bubbles from the orifice plate show significantly different characteristics due to the chamber volume effect. The bubbles are more spherical in shape with the apex being sharper and more pointed. The bubbles also tend to sit closer to the plate due to their abnormally large size while the growth times are much shorter. These differences are highlighted by comparing photographs of bubble growth with and without the chamber volume effect. Additionally, for the medium chamber region, an empirical correlation was proposed to predict bubble departure diameters to within ±15 %. For a fixed chamber volume, variation in surface tension showed no change in the transition orifice diameter.

Computational and Experimental Characterization of Single Bubble Dynamics in Isothermal Liquid Pools

2007 ◽  
Author(s):  
A. Subramani ◽  
S. K. Kasimsetty ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Surface Tension ◽  
Bubble Growth ◽  
High Speed ◽  
Bubble Dynamics ◽  
Great Influence ◽  
Growth Dynamics ◽  
Equivalent Diameter ◽  
Parametric Effects ◽  
Liquid Pools ◽  
Visualization Techniques

The process of bubble growth is of great influence on the bubble volume and bubble rise velocity. The overall behavior of bubbles at fluid interfaces depends strongly on bubble growth and the closely linked process of bubble detachment. In the present study, the dynamics of a single gas bubble emanating from an orifice submerged in isothermal liquid pools is investigated computationally and experimentally. The parametric effects of liquid properties, capillary diameters and air flow rates on the bubble shape, equivalent diameter, and growth times on the dynamic behavior (incipience, growth and necking) of air bubbles, in fluids of varying surface tension and viscosity, as it grows from a tip of a sub-millimeter-scale capillary orifice have been studied. Computational solutions have been obtained by solving the complete set of governing equations using Volume of Fluid (VOF) interface tracking method. The CFD model has been verified experimentally using optical high speed micro-scale flow visualization techniques. The results were analyzed in a theoretical stand point considering the various forces acting on the bubble such as forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport, and the consequent motion of the gas-liquid interface. The results obtained ascertain the role of liquid-gas interfacial forces as well as the fluid properties on the bubble growth dynamics.

Experimental Study of Chamber Volume Effect on Bubble Formation From Orifice Plates Submerged in Water

2018 ◽  
Author(s):  
Omkar S. Gokhale ◽  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Experimental Study ◽  
Bubble Size ◽  
Bubble Formation ◽  
Orifice Plate ◽  
Orifice Diameter ◽  
Equilibrium Contact Angle ◽  
Growth Time ◽  
Size And Shape ◽  
Chamber Volume ◽  
Gas Chamber

Experimental study of air bubble formation from orifice plates submerged in water pools has been carried out. Air is forced through the orifice by supplying it to a chamber connected to the orifice plate. The chamber volume plays an important role in determining the bubble growth time as well as bubble size and shape at departure. The effect of chamber volume is generally correlated in term of a dimensionless parameter, capacitance number (Nc), which is proportional to the chamber volume and is inversely proportional to the square of the orifice diameter. To better understand and characterize this effect, an experimental study is performed using ten orifice plates of diameter ranging from 0.61 mm to 2.261 mm with six different chamber volumes between 12 cc and 59 cc with the corresponding capacitance numbers varying from 0.2 to 19. The shape and size of the bubble are captured using high speed videography. The orifice plate material is acrylic glass which has an equilibrium contact angle of 38° with pure water. It was observed that the value of critical capacitance number or Nc above which the bubble evolution is affected by the gas chamber volume, is around 0.85. The bubbles are more spherical in shape, and the growth time is significantly smaller. Also, at high capacitance number (Nc > 7), the air flow in the bubble is so high that the bubble departs with a sharp apex and has a large volume. Above Nc > 10, the chamber effects plateau and further increase in gas chamber volume does not alter bubble size and shape at departure.

Wetting and Capillarity Effects On Bubble Formation From Orifice Plates Submerged in Pools of Water

2021 ◽  
Author(s):  
Sanjivan Manoharan ◽  
Raj M. Manglik ◽  
Milind A. Jog
Keyword(s):  
Contact Angle ◽  
Bubble Growth ◽  
High Speed ◽  
Bubble Formation ◽  
Minimum Energy ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Orifice Diameter ◽  
Capillary Length ◽  
Critical Contact

Abstract An experimental study of bubble growth from submerged orifice plates in pools of water is carried out to scale and correlate the effects of surface wettability and orifice diameter D0 on ebullience. Measurements of bubble growth on surfaces with nine different contact angles (38° ≤ θ ≤ 128°) with varying air flow rates (1 to 300 ml/min) were made using high speed videography and image processing. In the static or constant-volume regime, below a critical contact angle θc, the bubble base remains attached to the orifice and the equivalent departure diameter Db is independent of contact angle θ. On the other hand, above the critical contact angle, the bubble base spreads on the surface resulting in larger Db. For θ &gt; θc, Db is strongly dependent on θ and increases with it. Using minimum energy method, it is shown that the wettability effects can be scaled and correlated by a modified capillary length, defined as a function of the Laplace length and contact angle. The proposed correlation provides predictions of Db that agree with experimental data of this study as well as those available in the literature to within ±15 %. Moreover, for a hydrophobic surface when D0 &gt; twice the modified capillary length, the bubble grows inside the orifice; for a hydrophilic surface this scales with twice the capillary length and effect of θ is not seen.

Effect of Dual Frequency Ultrasound on the Bubble Formation in a Capillary Tube

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Benwei Fu ◽  
Nannan Zhao ◽  
Guoyou Wang ◽  
Hongbin Ma
Keyword(s):  
Bubble Growth ◽  
High Speed ◽  
Capillary Tube ◽  
Bubble Formation ◽  
Single Frequency ◽  
Quartz Tube ◽  
Outer Diameter ◽  
Dual Frequency ◽  
Heating Section ◽  
Frequency Ultrasound

A visual experimental investigation was conducted to determine the effect of dual frequency ultrasound on the bubble formation and growth in a capillary quartz tube. Two piezoelectric ceramics were used in this experiment. They were made of Pb-based lanthanum-doped zirconate titanates (PLZTs). The PLZTs were placed on a quartz tube with an inner diameter of 2 mm and an outer diameter of 3 mm. The capillary tube was vacuumed first and then charged with water using a filling ratio of 70%. The ultrasonic sound was applied to the heating section of a capillary tube. The bubble formation and growth were recorded by a high speed camera. As shown in figures, when the ultrasound with a single frequency of either 154 kHz or 474 kHz was applied, only one bubble was generated. When the dual frequencies of 154 kHz and 474 kHz were applied, more bubbles were generated. The speed of the bubble growth with dual frequency ultrasound was much higher than that with a single frequency. When a dual frequency ultrasound (154 kHz and 474 kHz) was used, the nucleation sites for bubble formation were significantly increased and the bubble growth rate enhanced.

Mili-Scale Visualization of Bubble Growth-Translation and Droplet Impact Dynamics

2006 ◽  
Vol 128 (8) ◽  
pp. 736-736 ◽  
Author(s):  
R. M. Manglik ◽  
M. A. Jog ◽  
A. Subramani ◽  
K. Gatne
Keyword(s):  
Surface Tension ◽  
Video Processing ◽  
High Speed ◽  
Digital Video ◽  
Capillary Tube ◽  
Droplet Impact ◽  
Stainless Steel Surface ◽  
Air Bubble ◽  
Processing Software ◽  
The Impact

The dynamic behavior of an air bubble, emanating from a 0.32 mm i.d., 0.64 mm o.d., vertical capillary-tube orifice with a bubble interval of 0.22–0.28 s at constant pressure and adiabatic (T=25°C) conditions, as well as droplet impact and spreading on a hydrophobic surface are characterized. Images of the mili-scale spatial-temporal evolution of bubbles (embryonic appearance at orifice tip → growth and detachment → translation) as well as droplets were acquired using a high-speed (5000 frames/s) digital video camera fitted with a 8× optical zoom lens. It was triggered through a computer interface to record continuous high-speed video from which any desired frame can be captured by digital-video-processing software; the equivalent departure diameter was estimated by area-averaging using image processing software. The impact, spreading, and recoil behaviors of ethanol and water droplets on a horizontal stainless steel surface are depicted in Fig. 1. For constant Weber number (We∼10), the spreading and recoil dynamics in the two cases are significantly different. Higher wettability of ethanol promotes greater spreading and dampens recoil in comparison with that seen in water. Figure 2 depicts the growth of an air bubble in pools of ethanol and water. While displaying similar ebullience, a bubble of smaller size and surface age is produced in low-surface-tension ethanol. Dynamic shape variations of the air bubble as it translates upwards in the pool are seen in Fig. 3. From a nearly spherical, tear-drop bubble, the shape changes to an oblate ellipsoid during translation, and surface tension effects are manifest only in the size of respective bubbles.

Effect of Dual Frequency Ultrasound on the Bubble Formation in a Capillary Tube

2016 ◽  
Author(s):  
Benwei Fu ◽  
Nannan Zhao ◽  
Guoyou Wang ◽  
Hongbin Ma
Keyword(s):  
Bubble Growth ◽  
High Speed ◽  
Capillary Tube ◽  
Bubble Formation ◽  
High Speed Camera ◽  
Dual Frequency ◽  
Heating Section ◽  
Nucleation Sites ◽  
Ultrasonic Sound ◽  
Frequency Ultrasound

A visual experimental was conducted to determine the effect of dual frequency ultrasound on the bubble formation and growth in a capillary quartz tube. The ultrasonic sound was applied to the heating section of a capillary tube by using electrically-controlled piezoelectric ceramics made of Pb-based lanthanum-doped zirconate titanates (PLZTs). The bubble formation and growth were recorded by a high speed camera. Experimental results show that the bubble formation and growth depend on PLZT frequency. When a dual frequency ultrasound (154 kHz and 474 kHz) was used, the nucleation sites for bubble formation were significantly increased and the bubble growth rate enhanced.

Experimental Study of Single-Bubble Dynamics in Isothermal Liquid Pools: Effects of Fluid Properties, Orifice Diameter and Flow Rate

2007 ◽  
Author(s):  
A. Subramani ◽  
M. A. Jog ◽  
R. M. Manglik
Keyword(s):  
Surface Tension ◽  
Flow Rate ◽  
High Speed ◽  
Bubble Dynamics ◽  
Processing System ◽  
Single Bubble ◽  
Orifice Diameter ◽  
Growth Time ◽  
Interfacial Behavior ◽  
Fluid Properties

The dynamics of a single bubble as it grows at and eventually detaches from the tip of submerged capillary orifices in isothermal pools of pure liquids of varying fluid properties is studied experimentally. The transient interfacial behavior around the evolving isolated bubble (from inception through growth, necking, and detachment) is mapped by means of optical micro-scale flow visualization that uses a high-speed high-resolution digital camera and image processing system. Parametric effects of capillary orifice diameter (do = 0.32, 1.0, and 1.76 mm), air flow rate (2 ≤ Q˙ ≤ 20 ml/min), and liquid properties (surface tension and viscosity), on the bubbling signature (growth time, departure diameter, and bubble interval) are explored and highlighted. It is found that bubble evolution, in a first order scaling, can be correlated by a balance of forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport at the transient gas-liquid interface.

Effect of Pressure on Bubble Growth Within Liquid Droplets at the Superheat Limit

1982 ◽  
Vol 104 (4) ◽  
pp. 750-757 ◽  
Author(s):  
C. T. Avedisian
Keyword(s):  
Vapor Bubble ◽  
Bubble Growth ◽  
High Speed ◽  
Ambient Pressure ◽  
Organic Liquid ◽  
Liquid Droplets ◽  
Growth Data ◽  
Two Phase ◽  
Photographic Evidence ◽  
Good Agreement

A study of high-pressure bubble growth within liquid droplets heated to their limits of superheat is reported. Droplets of an organic liquid (n-octane) were heated in an immiscible nonvolatile field liquid (glycerine) until they began to boil. High-speed cine photography was used for recording the qualitative aspects of boiling intensity and for obtaining some basic bubble growth data which have not been previously reported. The intensity of droplet boiling was found to be strongly dependent on ambient pressure. At atmospheric pressure the droplets boiled in a comparatively violent manner. At higher pressures photographic evidence revealed a two-phase droplet configuration consisting of an expanding vapor bubble beneath which was suspended a pool of the vaporizing liquid. A qualitative theory for growth of the two-phase droplet was based on assuming that heat for vaporizing the volatile liquid was transferred across a thin thermal boundary layer surrounding the vapor bubble. Measured droplet radii were found to be in relatively good agreement with predicted radii.

scholarly journals Analysis and control of flow at suction connection in high-speed centrifugal pump

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668529 ◽  
Author(s):  
Wen-wu Song ◽  
Li-chao Wei ◽  
Jie Fu ◽  
Jian-wei Shi ◽  
Xiu-xin Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
High Speed ◽  
Internal Flow ◽  
Orifice Plate ◽  
Centrifugal Pumps ◽  
Pressure Area ◽  
Negative Effect ◽  
And Control ◽  
Experimental Data Analysis

The backflow vortexes at the suction connection in high-speed centrifugal pumps have negative effect on the flow field. Setting an orifice plate in front of the inducer is able to decrease the negative effect caused by backflow vortexes. The traditional plate is able to partially control the backflow vortexes, but a small part of the vortex is still in the inlet and the inducer. Four new types of orifice plates were created, and the control effects on backflow vortexes were analyzed. The ANSYS-CFX software was used to numerically simulate a high-speed centrifugal pump. The variations of streamline and velocity vectors at the suction connection were analyzed. Meanwhile, the effects of these plates on the impeller pressure and the internal flow field of the inducer were analyzed. Numerically, simulation and experimental data analysis methods were used to compare the head and efficiency of the high-speed pumps. The results show that the C-type orifice plate can improve the backflow vortex, reduce the low-pressure area, and improve the hydraulic performance of the high-speed pump.

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