GAS CORE CHARACTERISTICS OF SWIRL EFFERVESCENT ATOMIZER

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Zulkifli Abdul Ghaffar ◽  
Salmiah Kasolang ◽  
Ahmad Hussein Abdul Hamid ◽  
Diyar I. Ahmed ◽  
Khairul Imran Sainan ◽  
...  
Keyword(s):  
High Speed ◽  
Spray Angle ◽  
Orifice Diameter ◽  
Working Fluid ◽  
Core Size ◽  
Core Diameter ◽  
Factors Affecting ◽  
Effervescent Atomizer ◽  
Core Characteristics ◽  
Vane Angle

Swirl effervescent atomizer consists of two atomization mechanisms, effervescent and swirl. For a swirl-related atomizer, the air/gas core diameter was reported to be one of the factors affecting the widening of spray angle. A wider spray angle is important to provide a better spray distribution. The characteristic of gas core in an inside-out swirl effervescent atomizer was investigated as part of the study in understanding the mechanism of this type of atomization. The interaction effects between three independent parameters (i.e. swirl-generating vane angle, gas flowrate and discharge orifice diameter) on the size and characteristics of the gas core were investigated. Water and nitrogen gas were used respectively as the working fluid and atomization gas. The high-speed shadowgraph technique was utilized to record the videos of the gas core structures. The video recordings were converted to image sequences and analyzed using an image processing software. It was concluded that a larger gas core was produced with an increasing vane angle or gas flowrate. The increasing gas flowrate tends to increase the gas core size for all cases of the vane angle. Increasing the orifice diameter tends to increase the gas core size for all cases of the gas flowrate. The interaction between the orifice diameter and swirl-generating vane angle on the size of the gas core was inconclusive.

EFFECT OF GEOMETRICAL PARAMETERS INTERACTION ON SWIRL EFFERVESCENT ATOMIZER SPRAY ANGLE

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Zulkifli Abdul Ghaffar ◽  
Salmiah Kasolang ◽  
Ahmad Hussein Abdul Hamid ◽  
Ow Chee Sheng ◽  
Mimi Azlina Abu Bakar
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Spray Angle ◽  
Orifice Diameter ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
High Speed Video Camera ◽  
Effervescent Atomizer ◽  
Vane Angle ◽  
Discharge Orifice

A wider spray angle produced by an atomizer is often required in providing a better spray dispersion. The formation and wideness of the spray angle were reported to be affected by the changes in geometrical parameters. In the present study, the effect of the interaction between two geometrical parameters (swirl-generating vane angle and discharge orifice diameter) on the swirl effervescent atomizer spray angle was studied. A newly-designed swirl effervescent atomizer was developed with 30°, 45° and 60° swirl-generating vane angle and 1.5, 2.0 and 2.5mm discharge orifice diameter. The atomizer performance tests were carried out using water as the working fluid and nitrogen gas as the atomizing agent. High-speed shadowgraph technique was deployed to record the resultant sprays produced. Video recordings, acquired using a high-speed video camera, were converted to a sequence of images for further analysis using image processing software. It was found that geometrical parameters of the newly designed atomizer have a great impact on the formation and characteristics of the spray angle. The combined effect of both swirl-generating vane angle and discharge orifice diameter has produced an increase in the spray angle. The largest spray angle was observed at the largest dimension of both geometries.

Characteristics of Swirl Effervescent Atomizer Spray Angle

2014 ◽  
Vol 607 ◽  
pp. 108-111
Author(s):  
Zulkifli Abdul Ghaffar ◽  
Salmiah Kasolang ◽  
Ahmad Hussein Abdul Hamid
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Spray Angle ◽  
Working Fluid ◽  
Intensity Effect ◽  
Video Recordings ◽  
High Speed Video Camera ◽  
Swirl Intensity ◽  
Effervescent Atomizer ◽  
Vane Angle

In the application of sprays produced by an atomizer, spray angle is one of key performance parameters. A larger spray angle is often required in providing a better spray dispersion. Swirl effervescent atomizer is one of the existing atomizers with the capability to produce a large spray angle. The formation of spray angle from this atomizer however is hardly understood. A newly-designed swirl effervescent atomizer was developed and tested with different swirl-generating vane angle in order to understand the swirl intensity effect on the spray angle. Experiments were carried out based on a cold flow test approach using water as the working fluid and nitrogen gas as the atomizing agent. High-speed shadowgraph technique was deployed to record the resultant sprays produced. Video recordings, acquired using a high-speed video camera, were converted to a sequence of images for further analysis using an image processing software. It was found that the spray angle increases with the swirl-generating vane angle. Specifically, the spray angle shows an abrupt increase for the case of swirl-generating vane angle changing from 30° to 45° but visualizes only a gradual increase in the case of swirl-generating vane angle changing from 45° to 60°.

scholarly journals Spray Characteristics and Internal Flow Structures of Swirl Effervescent Atomizer

2018 ◽  
Vol 7 (3.11) ◽  
pp. 58
Author(s):  
Z A. Ghaffar ◽  
S Kasolang ◽  
Ahmad H. A. Hamid
Keyword(s):  
Internal Flow ◽  
Operating Conditions ◽  
Spray Angle ◽  
Orifice Diameter ◽  
Flow Structures ◽  
Spray Characteristics ◽  
Core Diameter ◽  
Breakup Length ◽  
Effervescent Atomizer ◽  
High Level

Spray characteristics and internal flow structures of an atomizer are important parameters in indicating their performances. Both parameters are affected by the operating conditions and atomizer geometries. This study investigates the effect of operating parameters and atomizer geometries on spray angle, breakup length and gas core diameter of swirl effervescent atomizer. This work is conducted specifically to find the most critical parameters that will produce the required spray characteristics and internal flow structure. The atomizer performance tests were carried out using water as the working fluid and nitrogen gas as the atomizing agent. High-speed shadowgraph technique was utilized to record the videos of the spray and internal flow structures. The video recordings were converted to image sequences and analyzed using image processing software. Geometrical parameters were found to be more dominant for characterizing the resultant sprays, but operating conditions was more critical in affecting the internal flow structures. The widest spray angle (~25°) and shortest breakup length (~10mm) were observed at the high level of swirl-generating vane angle and discharge orifice diameter. Gas core diameter expanded up to 1.13mm at the high level of GLR.  

An Experimental Investigation on the Effect of Various Swirl Atomizer Orifice Geometries on the Air Core Diameter

2012 ◽  
Vol 225 ◽  
pp. 32-37 ◽  
Author(s):  
Mohd Syazwan Firdaus Mat Rashid ◽  
Ahmad Hussein Abdul Hamid ◽  
Chee Sheng Ow ◽  
Zulkifli Abdul Ghaffar
Keyword(s):  
Fuel Injection ◽  
Injection Pressure ◽  
High Strength ◽  
Orifice Diameter ◽  
Working Fluid ◽  
Core Diameter ◽  
Air Core ◽  
Liquid Atomization ◽  
Swirl Atomizer ◽  
Discharge Orifice

Liquid atomization is a process of changing the liquid into small droplets. There are many applications which are related to liquid atomization including fuel injection in combustion systems and also in agricultural sprays. In pressure swirl atomizer, the liquid is injected into the atomizer through tangential port and a swirling motion is formed inside the swirl chamber. In high strength of swirling motion, an air core will be visible inside the atomizer. The liquid is then discharged from the orifice to form a spray which breaks up the liquid into small droplets. The objective of this research is to investigate the effect of various orifice geometries on the air core diameter. The injection pressure was varied in the range of 2 to 8 bar and water was used as the working fluid. Experiment data shows that the air core diameter increases as the injection pressure increased, regardless the discharge orifice diameter and discharge orifice length. It also found that the air core diameter increases as the discharge orifice length decreases and the discharge orifice diameter increases.

scholarly journals Influence of orifice geometry on atomization characteristics of pressure swirl atomizer

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042095018
Author(s):  
Huilong Zheng ◽  
Zhaomiao Liu ◽  
Kaifeng Wang ◽  
Jiayuan Lin ◽  
Zexuan Li
Keyword(s):  
High Speed ◽  
Cone Angle ◽  
Spray Angle ◽  
Orifice Diameter ◽  
High Speed Photography ◽  
Spray Cone Angle ◽  
Experimental Conditions ◽  
Spray Cone ◽  
Velocity Magnitude ◽  
Pressure Swirl

The spray characteristics of the pressure swirl nozzle are experimentally studied using particle dynamics analysis (PDA) and high-speed photography system in this paper, specifically focusing on the dependence of geometrical dimensions of orifice on the spray SMD, velocity magnitude and droplet distribution, and the spray cone angle. It is indicated that the increase of orifice diameter makes the initial swirling velocity lower and the spray liquid film thicker. When the spray cone is fully expanded, the flow rate of 900 μm orifice diameter nozzle increases by 30–40% and the SMD of 900 μm orifice diameter nozzle increases by 8.5% compared with that of 700 μm orifice diameter nozzle. According to the experimental conditions, the relationship between Re and spray angle was calculated as θ = 29.97*Re0.087, ignoring the factors that had little influence on spray angle. The decrease of the orifice length makes the distance of gas-medium shearing action shorten so that thinner oil film near wall cannot be formed by the extrusion of air core, leading to the swirling intensity reducing and the suction effect weakened. The spray cone angle of the 450 μm orifice length atomizer is about 5° smaller than the nozzle of 500 μm orifice length, and more small SMD droplets are not sucked, resulting in the distribution range of spray SMD declining.

scholarly journals Geometrical Scaling of Antiresonant Hollow-Core Fibers for Mid-Infrared Beam Delivery

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 420
Author(s):  
Ang Deng ◽  
Wonkeun Chang
Keyword(s):  
Structural Parameters ◽  
Transmission Band ◽  
Confinement Loss ◽  
Hollow Core ◽  
Core Size ◽  
Core Diameter ◽  
Mid Infrared ◽  
The Core ◽  
Tubular Type ◽  
Beam Delivery

We numerically investigate the effect of scaling two key structural parameters in antiresonant hollow-core fibers—dielectric wall thickness of the cladding elements and core size—in view of low-loss mid-infrared beam delivery. We demonstrate that there exists an additional resonance-like loss peak in the long-wavelength limit of the first transmission band in antiresonant hollow-core fibers. We also find that the confinement loss in tubular-type hollow-core fibers depends strongly on the core size, where the degree of the dependence varies with the cladding tube size. The loss scales with the core diameter to the power of approximately −5.4 for commonly used tubular-type hollow-core fiber designs.

Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Bo Wang ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Xin Hui ◽  
Jibao Li
Keyword(s):  
High Speed ◽  
Inlet Temperature ◽  
Main Stage ◽  
Ignition Process ◽  
High Speed Camera ◽  
Fuel Distribution ◽  
Fuel Droplets ◽  
Planar Laser ◽  
Cfd Method ◽  
Vane Angle

In order to balance the low emission and wide stabilization for lean premixed prevaporized (LPP) combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20 deg and 30 deg are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30 deg vane angle case is better than that of the 20 deg vane angle case. High-speed camera, planar laser induced fluorescence (PLIF), and computational fluids dynamics (CFD) are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30 deg vane angle case is much larger than that of the 20 deg vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30 deg vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30 deg is suggested for the better fuel distribution when designing a centrally staged combustor.

Reynolds-averaged Navier–Stokes simulation of hydrofoil effects on hydrodynamic coefficients of a catamaran in forced oscillation

2016 ◽  
Vol 231 (2) ◽  
pp. 364-383
Author(s):  
Amin Najafi ◽  
Mohammad Saeed Seif
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Navier Stokes ◽  
Hydrodynamic Coefficients ◽  
Laboratory Equipment ◽  
Factors Affecting ◽  
High Frequencies ◽  
Frequency Independent ◽  
Reynolds Averaged Navier Stokes

Determination of high-speed crafts’ hydrodynamic coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Also, it can be useful and effective in controlling the vessel instabilities. The main purpose of this study is to determine the coefficients of longitudinal motions of a planing catamaran with and without a hydrofoil using Reynolds-averaged Navier–Stokes method to evaluate the foil effects on them. Determination of hydrodynamic coefficients by experimental approach is costly and requires meticulous laboratory equipment; therefore, utilizing the numerical methods and developing a virtual laboratory seem highly efficient. In this study, the numerical results for hydrodynamic coefficients of a high-speed craft are verified against Troesch’s experimental results. In the following, after determination of hydrodynamic coefficients of a planing catamaran with and without foil, the foil effects on its hydrodynamic coefficients are evaluated. The results indicate that most of the coefficients are frequency-independent especially at high frequencies.

Record high-speed short-range transmission over 1 mm core diameter POF employing DMT modulation

2010 ◽  
Vol 35 (5) ◽  
pp. 730 ◽  
Author(s):  
H. Yang ◽  
S. C. J. Lee ◽  
C. M. Okonkwo ◽  
S. T. Abraha ◽  
H. P. A. van den Boom ◽  
...  
Keyword(s):  
High Speed ◽  
Short Range ◽  
Core Diameter

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

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