Measurement Based Atomization Model for Diesel Spray Evaporation and Combustion in a Matrix Burner

2011 ◽  
Author(s):  
Dieter Bohn ◽  
James Willie
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Gas Turbines ◽  
Cone Angle ◽  
Measurement Data ◽  
Droplet Size Distribution ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
The Matrix ◽  
The Right

This paper describes the development of an atomization model for implementation in a CFD solver. The model is developed for application in a matrix burner that is suitable for simulating the conditions prevailing in stationary gas turbines. The fuel considered is diesel and the matrix burner is designed using the Lean Premixed Prevaporized (LPP) concept. In this concept, the liquid fuel is first atomized, vaporized and thoroughly premixed with the oxidizer before it enters the combustion chamber. The injector used is a hollow-cone Schlick series 121–123 pressure-swirl atomizer. Extensive measurements are carried out at different atomization pressures to determine the right parameters like the nozzle diameter, atomization pressure and spray cone angle that will yield a good spray pattern. Based on the measurement data, the mass flow rate and the droplet size distribution are determined. The latter is determined by curve fitting the experimental data. The determined droplet size distribution is implemented in a Fortran subroutine that is hooked to the CFD solver. Cold flow CFD results are compared for different positions of the nozzle. The hot flow CFD results are also compared with the hot flow results obtained when the droplet size distribution is assumed to be uniform.

Numerical Simulation and Experiment of Atomization Field of Fan-Shaped Atomization Nozzle for Plant Protection UAV

2021 ◽  
Vol 14 ◽  
Author(s):  
Maohua Xiao ◽  
Yuanfang Zhao ◽  
Zhenmin Sun ◽  
Chaohui Liu ◽  
Tianpeng Zhang
Keyword(s):  
Numerical Simulation ◽  
Size Distribution ◽  
Droplet Size ◽  
Plant Protection ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Spray Cone Angle ◽  
Spray Cone

Background: There are drift and volatilization of the droplets produced by the plant protection Unmanned Aerial Vehicle (UAV) under the influence of external wind speed and its flight speed. Objective: It studied the atomization characteristics of its fan-shaped atomizing nozzle under different inlet pressures and inner cavity diameters. Methods: For the start, the Realizable k-ε turbulence model, DPM discrete phase model and TAB breakup model are used to make a numerical simulation of the spray process of the nozzle. Then, the SIMPLE algorithm is used to obtain the droplet size distribution diagram of the nozzle atomization field. At last, the related test methods are used to study its atomization performance, and the changes of atomization angle and droplet velocity under different inlet pressures and inner cavity diameters and the distribution of droplet size are discussed. Results: The research results show that under the same inner cavity diameter, as the inlet pressure increases, the spray cone angle of the nozzle and the droplet velocity at the same distance from the nozzle increase. As the distance from the nozzle increases, the droplet velocity decreases gradually, the droplet size distribution moves to the direction of small diameter, and the droplets in the anti-drift droplet size area increase. Under the same inlet pressure, as the diameter of the inner cavity increases, the spray cone angle first increases and then decreases, and the droplet velocity at the same distance from the nozzle increases. As the distance from the nozzle increases, the droplet velocity decreases gradually, the droplet size distribution moves to the direction of large diameter, and the large size droplets increase, which cannot meet the anti-drift volatilization effect. Conclusion: Under the parameter set in this study, when the inlet pressure is 0.6MPa and the inner cavity diameter is 2mm, the atomization result is the best.

scholarly journals Effect of Inlet Tangential Port Area on the Performance of Small – Scale Simplex Atomizer

2012 ◽  
Author(s):  
Selvan G. Muthu ◽  
H. S. Muralidhara ◽  
Vinod Kumar Vyas ◽  
Kanth T. P. Dinesh ◽  
S. Kumaran ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Small Scale ◽  
Sauter Mean Diameter ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Mean Diameter ◽  
Coefficient Of Discharge

An experimental investigation was conducted to study the effects of increased area of inlet tangential ports on the performance of small scale simplex atomizer. The spray characteristics of three different simplex atomizer representing increasing area of inlet tangential ports are examined using water as a working fluid. Measurements of coefficient of discharge, spray cone angle, Sauter mean diameter and droplet size distribution were carried out over wide range of injection pressure. Coriolis mass flow meter was used to measure coefficient of discharge. Spray cone angle was measured by image processing technique. Sauter mean diameter and droplet size distributions were measured by Malvern droplet sizing instrument. It was observed that with increase in area of inlet tangential ports the size of air core produced along the center line reduced, which increases the coefficient of discharge. Spray cone angle decreases with increase in area of inlet tangential ports. It was found that increase in area of inlet tangential ports reduces swirl strength inside swirl chamber, which results in increasing Sauter mean diameter. Better droplet size distribution was observed for lower area of inlet tangential port configuration. The obtained experimental results were compared with experimental correlations available in literatures. Deviations in the obtained experimental results and experimental correlations was observed. This is due to difference in the size of atomizer used and difference in experimental techniques used between the present work and other investigations.

Axial and Radial Variation of Spray Characteristics of a Small-Scale Simplex Atomizer

2014 ◽  
Author(s):  
Muthuselvan Govindaraj ◽  
Muralidhara Halebidu Suryanarayana ◽  
Vinod Kumar Vyas ◽  
Jeyaseelan Rajendran ◽  
Rajeshwari Natarajan ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Radial Direction ◽  
Cone Angle ◽  
Injection Pressure ◽  
Droplet Size Distribution ◽  
Axial Direction ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Injection Pressures

Simplex atomizer is widely used in the liquid fuel combustion devices in aerospace and power generation industries. An experimental work was conducted, to study variation of SMD and droplet size distribution along axial and radial directions of the spray for different injection pressures. Malvern spray analyzer is used in the present investigation. Four different atomizer configurations of increasing atomizer constant (K) are examined using water and kerosene. Spray cone angle is measured for different configurations at different injection pressures (up to 30 bar) using image processing technique. In the case of atomizer with lower K, spray cone angle continuously increases with injection pressure. In the case of atomizer with higher K, initially spray cone angle increases significantly, but remains almost constant after 16 bar. Variation of SMD and droplet size distribution along axial direction of the spray is compared between water and kerosene spray. SMD variation along the axial direction of spray clearly shows the continuous brakup of droplets along axial direction of the spray. In the case of water spray, SMD rapidly decreases along the axial direction up to 30 mm from the orifice exit, and gradually decreases up to 120 mm. In the case of kerosene spray, SMD rapidly decreases along the axial direction up to 40 mm from the orifice exit, after that SMD fluctuates along the axial direction up to 100 mm from the orifice exit. This fluctuation is due to evaporation of smaller droplets (50 microns) of kerosene. Span also continuously fluctuates after 40 mm from the orifice exit in the case of kerosene spray. Variation of SMD and droplet size distribution along radial direction of the spray is compared for different injection pressure and configurations of simplex atomizer. Increase in injection pressure, increases the disruptive aerodynamic force, which reduces the radial peak value of SMD and widens the radial profile. With decrease in atomizer constant (K), swirl strength inside the swirl chamber increases, which in turn increases the spray cone angle. SMD variation along the radial direction of spray showed more uniform droplet diameter distribution for lower atomizer constant (K) configurations. Reducing the atomizer constant improves the atomization quality more effectively than increasing the injection pressure.

scholarly journals Atomization Quality of Twin Fluid Atomizers for Gas Turbines

1982 ◽  
Author(s):  
M. M. Elkotb ◽  
M. A. Elsayed Mahdy ◽  
M. E. Montaser
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Gas Turbines ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Diameter Ratio ◽  
Air Pressure ◽  
Sauter Mean Diameter ◽  
Flow Number ◽  
Mean Diameter

A detailed investigation of the effect of nozzle/needle diameter ratio, normal fuel area, swirler degree, air pressure, fuel pressure on flow number, cone angle and droplet size distribution of external mixing twin fluid atomizers is given in this paper. Forty atomizers have been constructed to prevent mutual effect of various parameters. Flow number and cone angle are found to increase with nozzle/diameter ratio, and to decrease with the increase of air pressure. Optimum fuel flow is obtained at swirler angle 30-deg, while cone angle increases with increase of swirler angle. Sauter mean diameter decreases with the increase of air pressure and decrease of fuel pressure. Suitable functions are derived for droplet size distribution, Sauter mean diameter, and flow number. They are suitable to predict the geometry of the atomizer and to be used also in a prediction model for the calculation of fuel concentration and heat release.

Study of Two Miniature Air-Assist Atomizers With Radial and Axial Air Swirlers

2006 ◽  
Author(s):  
Y. Levy ◽  
V. Sherbaum ◽  
V. Ovcharenko ◽  
V. Nadvani
Keyword(s):  
Droplet Size ◽  
Droplet Diameter ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Spray Angle ◽  
Air Velocity ◽  
Liquid Pressure ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Air Channels

The performances of two types of miniature air-assist atomizers were investigated; one with air being directed to the liquid spray through radial-tangential air channels and the other with air supplied through a small axial swirler. The study has shown that droplet size is reduced significantly when the air velocity increases up to about 50 m/s. However, further increase in air velocity has only a weak effect on the droplet size. In the absence of air supply, elevating the liquid pressure causes a reduction in the droplet diameter. The maximum values of the droplet mass flux shifts to the spray periphery with increasing of air velocity. In the air-assist operational regime, the liquid pressure has a slight effect on SMD however; the spray cone angle is increased significantly and can achieve values of up to 120 degrees for low liquid pressure drop. The larger spray angle at comparable droplet size distribution makes the atomizers with the radial air swirlers more favorable for small jet engines.

Experimental and Numerical Studies of Diesel Spray Evaporation and Combustion in a Gas Turbine Matrix Burner

2009 ◽  
Author(s):  
Dieter Bohn ◽  
James F. Willie ◽  
Nils Ohlendorf
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Cone Angle ◽  
Spray Angle ◽  
Test Rig ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Flow Simulations ◽  
Air Inlet

Lean gas turbine combustion instability and control is currently a subject of interest for many researchers. The motivation for running gas turbines lean is to reduce NOx emissions. For this reason gas turbine combustors are being design using the Lean Premixed Prevaporized (LPP) concept. In this concept, the liquid fuel must first be atomized, vaporized and thoroughly premixed with the oxidizer before it enters the combustion chamber. One problem that is associated with running gas turbines lean and premixed is that they are prone to combustion instability. The matrix burner test rig at the Institute of Steam and Gas Turbines at the RWTH Aachen University is no exception. This matrix burner is suitable for simulating the conditions prevailing in stationary gas turbines. Till now this burner could handle only gaseous fuel injection. It is important for gas turbines in operation to be able to handle both gaseous and liquid fuels though. This paper reports the modification of this test rig in order for it to be able to handle both gaseous and liquid primary fuels. Many design issues like the number and position of injectors, the spray angle, nozzle type, droplet size distribution, etc. were considered. Starting with the determination of the spray cone angle from measurements, CFD was used in the initial design to determine the optimum position and number of injectors from cold flow simulations. This was followed by hot flow simulations to determine the dynamic behavior of the flame first without any forcing at the air inlet and with forcing at the air inlet. The effect of the forcing on the atomization is determined and discussed.

Investigation on Flat-Fan Spray Characterization in High-Speed Air Coflow for Gas Turbine Online Water Washing Application

2021 ◽  
Author(s):  
Kiran Kumar ◽  
Vasudev Chaudhari ◽  
Srikrishna Sahu ◽  
Ravindra G. Devi
Keyword(s):  
Droplet Size ◽  
Gas Turbines ◽  
High Speed ◽  
Numerical Models ◽  
Cone Angle ◽  
Operating Conditions ◽  
Spray Characteristics ◽  
Spray Cone ◽  
Water Washing ◽  
Spray Characterization

Abstract Fouling in compressor blades due to dirt deposition is a major issue in land-based gas turbines as it impedes the compressor performance and degrades the overall engine efficiency. The online water washing approach is an effective alternate for early-stage compressor blade cleaning and to optimize the time span between offline washing and peak availability. In such case, typically a series of flat-fan nozzles are used at the engine bell mouth to inject water sprays into the inflowing air. However, optimizing the injector operating conditions is not a straightforward task mainly due to the tradeoff between blade cleaning effectiveness and material erosion. In this context, the knowledge on spray characteristics prior to blade impingement play a vital role, and the experimental spray characterization is crucial not only to understand the basic process but also to validate numerical models and simulations. The present paper investigates spray characteristics in a single flat-fan nozzle operated in the presence of a coflowing air within a wind-tunnel. A parametric investigation is carried out using different air flow velocity in the tunnel and inlet water temperature, while the liquid flow rate was maintained constant. The spray cone angle and liquid breakup length are measured using back-lit photography. The high-speed shadowgraphy technique is used for capturing the droplet images downstream of the injector exit. The images are processed following depth-of-filed correction to measure droplet size distribution. Droplet velocity is measured by the particle tracking velocimetry (PTV) technique. As both droplet size and velocity are known, the cross-stream evolution of local droplet mass and momentum flux are obtained at different axial locations which form the basis for studying the effectiveness of the blade cleaning process due to droplet impingement on a coupon coated with foulant of known mass.

Atomization Characteristics of Jatropha-Derived Alternative Aviation Fuels From Aircraft Engine Injector

2017 ◽  
Author(s):  
Ramachandran Sakthikumar ◽  
Deivandren Sivakumar ◽  
B. N. Raghunandan ◽  
John T. C. Hu
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Cone Angle ◽  
Fuel Spray ◽  
Jet Fuels ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Atmospheric Air ◽  
Atomization Characteristics

Search for potential alternative jet fuels is intensified in recent years to meet stringent environmental regulations imposed to tackle degraded air quality caused by fossil fuel combustion. The present study describes atomization characteristics of blends of jatropha-derived biofuel with conventional aviation kerosene (Jet A-1) discharging into ambient atmospheric air from a dual-orifice atomizer used in aircraft engines. The biofuel blends are characterized in detail and meet current ASTM D7566 specifications. The experiments are conducted by discharging fuel spray into quiescent atmospheric air in a fuel spray booth to measure spray characteristics such as fuel discharge behavior, spray cone angle, drop size distribution and spray patternation at six different flow conditions. The characteristics of spray cone angle are obtained by capturing images of spray and the measurements of spray drop size distribution are obtained using laser diffraction particle analyzer (LDPA). A mechanical patternator system comprising 144 measurement cells is used to deduce spray patternation at different location from the injector exit. A systematic comparison on the atomization characteristics between the sprays of biofuel blends and the 100% Jet A-1 is presented. The measured spray characteristics of jatropha-derived alternative jet fuels follow the trends obtained for Jet A-1 sprays satisfactorily both in qualitative and quantitative terms.

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