Effect of Fuel/Air Ratio on Air Blast Simplex Nozzle Performance

1997 ◽  
Author(s):  
Michael A. Benjamin ◽  
Vincent G. McDonell ◽  
G. Scott Samuelsen
Keyword(s):  
Mechanical Design ◽  
Separated Flow ◽  
Effective Area ◽  
Spray Angle ◽  
Mass Ratio ◽  
Gas Turbine Combustor ◽  
Major Barrier ◽  
Momentum Ratio ◽  
Air Blast ◽  
Air Mass

The Air-Blast Simplex (ABS) nozzle may have significant mechanical design advantages when compared to Pure Air-Blast (PAB) designs, and attractive cost benefits. The major barrier to implementing ABS nozzles is spray collapse at high ambient pressures. The present study addresses this issue, and presents the results in a manner that is useful to the gas turbine combustor designer. The results reveal that spray collapse is not significant as long as the fuel-to-air mass ratio is maintained below about 0.3. The results also reveal two distinct curves for air effective area that are attributed to the presence or lack of flow separation in the vane/shroud assembly. In the case of the separated flow, a larger rate of decrease in effective area with increasing fuel air mass or momentum ratio is observed. These results help address ABS spray angle collapse at high pressure, and identify strategies that may adequately mitigate, or even eliminate, spray collapse in a suitably designed combustor.

Characteristics of Preheated Bio-Oil Sprays Produced by an Air-Blast Injector

2010 ◽  
Author(s):  
Heena V. Panchasara ◽  
Ajay K. Agrawal
Keyword(s):  
Laser Sheet ◽  
Inlet Temperature ◽  
Mass Ratio ◽  
Ambient Conditions ◽  
Air Blast ◽  
Visualization System ◽  
Radial Profiles ◽  
Significant Difference ◽  
Bio Oil ◽  
Temperature And Pressure

In this study the vegetable oil (VO) is preheated to reduce the kinematic viscosity, and thus, improve atomization. A commercial air-blast atomizer is used to produce the VO spray at ambient conditions of temperature and pressure. Characteristics of the resulting spray are measured using a laser sheet visualization system and a Phase Doppler Particle Analyzer system. Experiments are conducted for VO temperatures varying from 40 C to 100 C and air to liquid mass ratio (ALR) of 2.0 and 4.0. Results show a decrease in Sauter Mean Diameter with an increase in VO temperature, regardless of the ALR. Radial profiles show larger droplets migrating towards the edge of the spray and smaller droplets in the interior spray region. Results show a significant difference in distributions of mean and root mean square axial velocity profiles as the VO inlet temperature is increased for a fixed ALR. Higher VO inlet temperature and higher ALR produced a narrower spray with smaller diameter droplets and higher peak axial velocities. Overall, this study has shown that preheating VO improves atomization by producing spray with smaller diameter droplets.

Wheel-Based Stair Climbing Robot with Hopping Mechanism – Demonstration of Continuous Stair Climbing Using Vibration –

2008 ◽  
Vol 20 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Yuji Asai ◽  
◽  
Yasuhiro Chiba ◽  
Keisuke Sakaguchi ◽  
Naoki Bushida ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Stair Climbing ◽  
Design Parameters ◽  
Mass Ratio ◽  
Climbing Robot ◽  
Soft Landing ◽  
Hopping Mechanism ◽  
And Control ◽  
Two Bodies

We propose a simple hopping mechanism using vibration of a two-degrees-of-freedom (2-DOF) system for a fast stair-climbing robot. The robot, consisting of two bodies connected by springs and a wire, hops by releasing energy stored in springs and travels quickly using wheels mounted on its lower body. The trajectories of bodies during hopping change based on mechanical design parameters such as reduced mass of the two bodies, the mass ratio between the upper and lower bodies, and spring constant, and control parameters such as initial contraction of the spring and wire tension. This property allows the robot to quickly and economically climb stairs and land softly without complex control. In this paper, we propose a mathematical model of the robot and investigate required tread length for continuous hopping to climb a flight of stairs. Furthermore, we demonstrate fast stair-climbing and soft landing for a flight of stairs in experiments.

A Comparison of Air-Blast and Flow-Blurring Injectors Using Phase Doppler Particle Analyzer Technique

2009 ◽  
Author(s):  
Benjamin M. Simmons ◽  
Heena V. Panchasara ◽  
Ajay K. Agrawal
Keyword(s):  
Vegetable Oil ◽  
Laser Sheet ◽  
High Viscosity ◽  
Spray Angle ◽  
Ambient Conditions ◽  
Air Blast ◽  
New Novel ◽  
Significant Difference ◽  
Phase Doppler Particle Analyzer ◽  
Temperature And Pressure

Recent research on biofuels for power generation has typically focused on biodiesel because the biodiesel feedstrock, e.g., vegetable oil, poses significant combustion problems related to poor atomization. Existing injectors cannot effectively atomize high viscosity fuels such as vegetable oil. However, a new, novel flow-blurring (FB) injector concept has shown promise in overcoming the atomization problems. In this study, a FB injector is compared to a commercial air-blast (AB) injector operated with water at ambient conditions of temperature and pressure. Laser sheet visualization and Phase Doppler Particle Analyzer (PDPA) systems are used to obtain the spray characteristics for a range of air to liquid (ALR) ratios. Results show significant difference in distributions of Sauter Mean Diameters (SMDs), and mean and root-mean square axial velocity for the two injectors operated at a fixed ALR. In comparison to the AB injector, the FB injector produced spray with smaller SMDs, a smaller SMD range over the spray volume, higher RMS and mean axial velocities in the center region, and a compact spray with spray angle nearly independent of ALR. Results show that the FB injector is an effective way of atomizing liquids at relatively low ALRs compared to a traditional AB injector, without the additional pressure drop penalty.

scholarly journals Air-Blast Atomization of Coal-Water Mixture and Application to a Fuel Atomizer with Wide Spray Angle.

1991 ◽  
Vol 70 (11) ◽  
pp. 1075-1081
Author(s):  
Nobuki NAGAI ◽  
Takao INAMURA ◽  
Hideto INAGAKI
Keyword(s):  
Spray Angle ◽  
Water Mixture ◽  
Air Blast

scholarly journals Numerical Study of the Effects of Twin-Fluid Atomization on the Suspension Plasma Spraying Process

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 224
Author(s):  
Mehdi Jadidi ◽  
Sara Moghtadernejad ◽  
Jack Hanson
Keyword(s):  
Plasma Spraying ◽  
Fine Particles ◽  
Numerical Study ◽  
Suspension Plasma Spraying ◽  
Solid Particles ◽  
Droplet Breakup ◽  
Flight Behavior ◽  
Spray Angle ◽  
Injection System ◽  
Air Blast

Suspension plasma spraying (SPS) is an effective technique to enhance the quality of the thermal barrier, wear-resistant, corrosion-resistant, and superhydrophobic coatings. To create the suspension in the SPS technique, nano and sub-micron solid particles are added to a base liquid (typically water or ethanol). Subsequently, by using either a mechanical injection system with a plain orifice or a twin-fluid atomizer (e.g., air-blast or effervescent), the suspension is injected into the high-velocity high-temperature plasma flow. In the present work, we simulate the interactions between the air-blast suspension spray and the plasma crossflow by using a three-dimensional two-way coupled Eulerian–Lagrangian model. Here, the suspension consists of ethanol (85 wt.%) and nickel (15 wt.%). Furthermore, at the standoff distance of 40 mm, a flat substrate is placed. To model the turbulence and the droplet breakup, Reynolds Stress Model (RSM) and Kelvin-Helmholtz Rayleigh-Taylor breakup model are used, respectively. Tracking of the fine particles is continued after suspension’s fragmentation and evaporation, until their deposition on the substrate. In addition, the effects of several parameters such as suspension mass flow rate, spray angle, and injector location on the in-flight behavior of droplets/particles as well as the particle velocity and temperature upon impact are investigated. It is shown that the injector location and the spray angle have a significant influence on the droplet/particle in-flight behavior. If the injector is far from the plasma or the spray angle is too wide, the particle temperature and velocity upon impact decrease considerably.

A Stochastic Immersed Model of Breakup Characteristics in Dense Air Atomization Flow Field

2020 ◽  
Author(s):  
Tian Deng ◽  
Xingming Ren ◽  
Yaxuan Li
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Large Scale ◽  
Gas Flow ◽  
Liquid Core ◽  
Average Diameter ◽  
Simulation Method ◽  
Spray Angle ◽  
Random Structure ◽  
Momentum Ratio

Abstract For the low-speed liquid injected into the high-speed strong turbulent gas flow in the same direction, the atomization is a transient-intensive spray, and there are many factors affecting and controlling the atomization. In this paper, the distribution and characteristics of the liquid breakup in the air atomized flow field are analyzed. A stochastic immersed model to simulate the liquid core is developed, in which, the liquid core is regarded as an immersed porous medium with a random structure, and the probability of existence is used to simulate the position of the liquid core. The initial fragmentation mechanism of the air blast atomization is applied as the global variables of the stochastic process. Using the above stochastic immersed model, combined with the Large Eddy Simulation method, the numerical simulation of the downstream flow field of a coaxial jet air atomizing nozzle is carried out. Additional force is added to the momentum equation in the LES model. Instantaneous air velocity at the air-liquid interface is characterized by instantaneous liquid phase velocity at the same time. The size of the initial atomized droplet satisfies a probability distribution, and once the large droplets are formed, the Lagrangian method is used to track the droplets. The comparison between the simulation results and the experimental results shows that this stochastic immersed model can quickly capture the information of length and position of the liquid nucleus. When the gas-liquid momentum ratio M is 3∼10000, the liquid core length can be predicted more accurately. When M>10, the prediction result is much better than phenomenological model. This model is capable of capturing flow field structures such as recirculation zones and large-scale vortices. The results of initial spray angle from experiment expression give slightly better agreement with this model. Increasing the momentum ratio leads to decreasing of the initial spray angle. The particle size of the droplets near the nozzle can be accurately predicted, especially when the gas velocity is large (bigger than 60 m/s), and the average diameter prediction error of the droplets is less than 10%.

Experimental Study of a Solid-Gas Jet Issuing Into a Transverse Stream

1978 ◽  
Vol 100 (3) ◽  
pp. 333-338 ◽  
Author(s):  
R. N. Salzman ◽  
S. H. Schwartz
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Single Phase ◽  
Gas Jet ◽  
Plume Dispersion ◽  
Correlation Equations ◽  
Mass Ratio ◽  
Air Mass ◽  
Air Jet ◽  
Particulate Distribution

The results of an experimental investigation of the trajectory and dispersion of a solid-gas (silicate-air) jet injected into a transverse stream are presented. The centerline and the spread of the jet were defined by the particulate distribution as sampled with an isokinetic probe. The jets of this study had a solid to air mass ratio on the order of 15:1. Correlation equations obtained for the trajectory are similar to those reported in the literature for single phase jets. Equations are also obtained for plume dispersion.

scholarly journals Evaluation of Atomization Characteristics of Second Generation Biodiesel Using Air Blast Atomizer

2018 ◽  
Vol 7 (4.35) ◽  
pp. 772
Author(s):  
Gopinathan Muthaiyah ◽  
Kumaran Palanisamy
Keyword(s):  
Gas Turbine ◽  
Second Generation ◽  
High Viscosity ◽  
Spray Angle ◽  
Biodiesel Fuel ◽  
Sauter Mean Diameter ◽  
Evaporation Time ◽  
Air Blast ◽  
Mean Diameter ◽  
Atomization Characteristics

Biodiesel is one of the well-known renewable fuels that can be produced from organic oils and animal fats. Biodiesel fuel that meets ASTM D6751 fuel standards can replace diesel for reciprocating engine. On the other hand, biodiesel can also be considered for gas turbine application in power generation. Nevertheless, inferior properties of biodiesel such as high viscosity, density and surface tension results in inferior atomization and high emission which consequently hinders the fuel for gas turbine utilisation and generate higher emission pollutants. Therefore, this work focused on the evaluation of atomization characteristics of second generation biodiesel which is produced using microwave assisted post treatment scheme. The atomisation characteristics of second generation biodiesel was evaluated using air blast atomiser in terms of spray angle and spray length. Subsequently, numerical evaluation was performed to evaluate sauter mean diameter and droplet evaporation time of second generation biodiesel.  The results show, atomization characteristics of second generation biodiesel has improved in terms of spray angle and spray length, sauter mean diameter and shorter evaporation time compared to biodiesel which is commonly referred to as first generation biodiesel and fossil diesel.

Challenges in Aero Gas Turbine Combustor Development

2009 ◽  
Author(s):  
Dalton Maurya ◽  
G. N. Jayaprakash ◽  
C. Badarinath
Keyword(s):  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Inlet Temperature ◽  
Chromium Alloy ◽  
Design Development ◽  
Gas Turbine Combustor ◽  
Air Blast ◽  
Turbine Engine ◽  
Nickel Chromium ◽  
Annular Combustor

The Hot End Technologies Directorate (HETD) of Gas Turbine Research Establishment (GTRE) has the mandate to design, development and delivery of airworthy combustor and afterburner modules for a military aero gas turbine engine. In order to meet the mandate, the directorate takes the overall responsibility of design to manufacture of the combustion systems. This paper addresses the challenges faced in the development of combustor module. A short annular combustor with air blast atomizer is incorporated in the engine and it is a very important equipment of a gas turbine engine, wherein the heat energy is added to get Turbine Inlet Temperature (TET). It comprises of a pre-diffuser, a dump diffuser, outer annulus, inner annulus and a flame tube. There has been a basic liner, which was used in earlier engines and there was a shortfall in terms of performance parameters — allowable profile and pattern factors. To improve the performance, in collaboration with the M/s Central Institute of Aviation Motors (CIAM), Moscow, Russia, the liner was redesigned [1]. The secondary holes were totally blocked, primary and dilution holes were altered and it was incorporated with a new dome with a modified curvature. A new air blast atomizer with a swirler having an outer and inner pintle was incorporated. The basic liner was incorporated with these modifications and making this dome out of the high temperature resistance nickel chromium alloy was challenging and it was realized. The liner assemblies incorporating all the welding details have been realized within the GTRE. The combustor system was tested for ground light up to 4.3 km. The light up time was of the order of 5 s. The pressure loss was of the order of 4.9% at a combustor inlet Mn of 0.30. The circumferential and radial pattern factor for the modified liner is of 0.36 and 0.14 respectively.

scholarly journals Experimental Investigations of Flow Field and Atomization Field Characteristics of Pre-Filming Air-Blast Atomizers

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2800 ◽  
Author(s):  
Xiongjie Fan ◽  
Cunxi Liu ◽  
Yong Mu ◽  
Kaixing Wang ◽  
Yulan Wang ◽  
...  
Keyword(s):  
Flow Field ◽  
Liquid Film ◽  
High Speed ◽  
Experimental Investigations ◽  
Mass Rate ◽  
Air Blast ◽  
Air Mass ◽  
Fuel Mass ◽  
Field Organization ◽  
Particle Imaging

Flow field, atomization field characteristics, and liquid film breakup behaviors of a pre-filming air-blast atomizer are investigated using PIV (Particle Imaging Velocimetry), PLIF (Fuel Planar Laser Induced Fluorescence), and high-speed shadowgraph technique under different air mass rates (ma), fuel mass rates (mf), and fuel temperatures (T). The influence of structures constituting the pre-filming air-blast atomizer on the flow field organization and atomization field organization are investigated too. The results illustrate that air-blast atomizer structures have a great difference on the flow fields and atomization fields. Air-blast atomizer structures have great differences on the liquid film breakup processes too. Flow field structure and atomization structure are mainly determined by the swirler structure, whereas there are seldom influences of air mass rate and fuel mass rate on them. The results of the mechanisms of flow field organization and atomization field organization in this study can be used to support the design of new low-emission combustor.

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