A Study of Supercritical Jet Fuel Injection

2007 ◽  
Author(s):  
R. R. Rachedi ◽  
L. Crook ◽  
P. E. Sojka
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cone Angle ◽  
Density Ratio ◽  
Swirl Number ◽  
Penetration Length ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

An experimental investigation was conducted to examine the behavior of supercritical fluid (SCF) jets injected into supercritical environments. The behavior of the fluid, JP-10, was studied after it was passed through a pressure-swirl atomizer and entered a nitrogen environment. SCF jet behavior was characterized by the jet cone angle and penetration length. Cone angle and penetration length are reported as functions of density ratio (defined as the ratio of density of the injected fuel to the nitrogen environment), fuel mass flow rate, and pressure-swirl atomizer internal geometry. The density ratio was varied by altering the reduced temperature of the fuel (1.01<Tr<1.10) and nitrogen environment, while keeping the fuel reduced pressure constant at 1.05. Fuel mass flow rate ranged from 1.0 to 3.0 g/s (7.94 to 23.8 lbs/hr). Pressure-swirl atomizer internal geometry was varied by controlling the swirl number, ranging from straight bore to Sn=1.0. It was found that increasing the swirl number for a SCF fluid has the largest effect on jet cone angle, followed by a change in the density ratio; the mass flow rate had the least effect. The penetration length of the SCF jet increased when either the mass flow rate or density ratio increased. The mass concentration field significantly widens when the swirl number of the injector increased, as opposed to changes in the mass flow rate or density ratio which were found to have little effect.

Hybrid Pressure-Swirl/Twin-Fluid Atomizer for Emission Controls

2006 ◽  
Author(s):  
Andrew C. S. Lee ◽  
Paul E. Sojka
Keyword(s):  
Flow Field ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Drop Size ◽  
Air Flow ◽  
Exit Plane ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

An experimental study was conducted to characterize the performance of a hybrid atomizer used in emission control devices. Characterization included drop size distribution, measured using a forward light-scattering instrument, the air flow field (axial and radial velocities), measured using 2-D PIV, and turbulence characteristics of the air flow field, measured using LDA. The air flow field showed characteristics common to turbulent free round jets beyond approximately 8 exit orifice diameters from the atomizer exit plane. The centerline velocity increased with an increase in mass flow rate, while radial velocities were two orders of magnitude smaller than centerline values. The jet spreading factor initially increased with an increase in axial distance from the exit; however, it stabilized at a value of 0.09 at z/Do=11.8. Turbulence intensity along the jet centerline stabilized at 25% at z/Do=7.9. Drop size data showed complex dependencies on liquid and air mass flow rates, and on internal geometry. The influence of liquid mass flow rate on drop size was significantly smaller for the hybrid atomizer than for the pressure swirl atomizer component housed inside the hybrid unit, thus indicating a higher turndown ratio for the hybrid device. Drop size distributions produced by the hybrid atomizer showed multiple peaks, indicating there is more than one important atomizing mechanism. Finally, reducing the gap between the pressure-swirl atomizer and the exit plane of the outer casing resulted in a reduction in drop size.

An Experimental Study of Swirling Supercritical Hydrocarbon Fuel Jets

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
R. R. Rachedi ◽  
L. C. Crook ◽  
P. E. Sojka
Keyword(s):  
Flow Rate ◽  
Mass Concentration ◽  
Cone Angle ◽  
Density Ratio ◽  
Concentration Field ◽  
Hydrocarbon Fuel ◽  
Fuel Flow Rate ◽  
Swirl Number ◽  
Penetration Length ◽  
Fuel Flow

An experimental investigation was conducted to examine the behavior of swirling supercritical hydrocarbon fuel (SCF) jets injected into nitrogen environments whose temperatures and pressures exceeded the fuel critical values. Measurements of jet full-cone angle, mass concentration field, and penetration length were made using a schlieren system; the images were captured by a high-speed digital camera and processed using the camera’s software, plus MATLAB codes. Test parameters were the internal geometry of the pressure-swirl nozzle, fuel flow rate, and density ratio. The density ratio was varied by altering the reduced temperature of the injected fluid and nitrogen environment. SCF injections were studied at reduced temperatures (Tjet/Tcrit with both reported in Kelvin) ranging between 1.01 and 1.10, a reduced pressure (pjet/pcrit with both reported in bars) of 1.05, and fuel flowrates of 1.0 g/s, 2.0 g/s, and 3.0 g/s. The variable internal geometry pressure-swirl atomizer produced jets having swirl numbers (SN) of 0 (straight bore), 0.25, 0.50, and 1.00 (high swirl). As expected, increasing the swirl number for a SCF jet had by far the largest effect on jet cone angle, followed by a change in the density ratio; changing the fuel flow rate had very little effect. The SCF jet penetration length increased when either the fuel flow rate or density ratio increased. The mass concentration profiles demonstrated the jets to be self-similar in nature, and correlation to a Gaussian profile showed the mass concentration field to be independent of swirl number, density ratio, and fuel flow rate. Finally, it was found that there was a linear relationship between the jet half-width and the swirl number. The current study characterized the behavior of swirling hydrocarbon fuel SCF jets for the first time. Aspects of jet behavior similar to that of gas jets include: Gaussian mass concentration profiles and jet boundaries that scale with swirl number. Finally, CO2 was found to be a suitable surrogate fluid for hydrocarbon fuels since the behavior of the hydrocarbon SCF jets was similar to that of CO2 SCF jets.

Effect of Liquid/Gas Density Ratio on Primary Jet Breakup of Pressure Swirl Atomizer: Experimental and Numerical Study

2019 ◽  
Author(s):  
Edin Michael ◽  
Santhosh Kumar Keerthi ◽  
Krishna Kant ◽  
Pankaj Kolhe ◽  
Raja Banerjee ◽  
...  
Keyword(s):  
Numerical Study ◽  
Cone Angle ◽  
Density Ratio ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Gas Density ◽  
Jet Breakup ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Abstract This work reports experimental and numerical study of primary jet breakup of a pressure swirl atomizer. Experiments were performed in a constant volume spray chamber and the spray pattern was characterized as a function of different liquid/gas density ratios which was achieved by changing the ambient pressure. The liquid/gas density ratio was varied between ≈ 102 to 103 and the axial Reynold number was maintained at 6 × 103. Diffused backlight imaging in conjunction with high speed videography was used to visualize the spray. Parameters like spray cone angle, spray breakup length and flapping frequency was estimated. Additionally, POD analysis was performed to find the sheet instability modes. A corresponding numerical study using Coupled Level Set VOF method was performed keeping the liquid/gas density ratio of 10 and 102 to simulate the primary jet breakup using an in-house two-phase solver developed using OpenFOAM libraries. The solver was validated by following the numerical work of Fuster et al. Effect of computational mesh size on parameters like spray cone angle, breakup length was estimated.

The Effects of Tip Clearance on Performance of a Heavy Duty Multi Stages Axial Turbine

2012 ◽  
Author(s):  
Mohammad Reza Shirzadi ◽  
Hossein Saeidi
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Large Scale ◽  
Tip Clearance ◽  
Heavy Duty ◽  
Penetration Length ◽  
Axial Turbine ◽  
Commercial Code

In this article aerodynamic effects of tip clearance on a heavy duty axial turbine are studied. Three different tip clearances are considered for each rotor. For simplicity, a simple tip profile is assumed and cooling air is not modeled. Aerodynamic behavior of all stages is studied in terms of polytropic efficiency, leakage mass flow, secondary and total losses, penetration length, and total mass flow rate for different pressure ratios. Also three well established correlations of tip clearance loss are compared with CFD results to obtain the best model for performance calculation of such a large-scale turbine. The steady states, viscous and compressible flow governing equations representing the flow field with k-epsilon turbulence model are solved using commercial code ANSYS CFX.12. Useful data are presented to predict the variation of efficiency of each individual rotor, as well as entire turbine, as a function of relative tip gap (k/h). This information may be useable in design and troubleshooting. According to the results, even though pressure drop in rear stages across tip gap is lower than pressure drop in front stages, leakage mass flow rate is considerably high for this LP stages. Consequently, tip clearance losses of rear stages have significant effect on the entire turbine efficiency.

Pressure-Scaling of Pressure-Swirl Atomizer Cone Angles

2006 ◽  
Author(s):  
D. R. Guildenbecher ◽  
R. R. Rachedi ◽  
P. E. Sojka
Keyword(s):  
Pressure Drop ◽  
Ambient Pressure ◽  
Cone Angle ◽  
Subsequent Increase ◽  
Gas Entrainment ◽  
A Value ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer ◽  
Measure Cone

An experimental investigation was conducted to study the effects of increased ambient pressure (up to 6.89 MPa) and increased nozzle pressure drop (up to 2.8 MPa) on the cone angles for sprays produced by pressure-swirl atomizers having varying amounts of initial swirl. This study extends the classical results of DeCorso and Kemeny [1]. Shadow photography was used to measure cone angles at x/D0=10, 20, 40, and 60. Our lower pressure results for atomizer swirl numbers of 0.50 and 0.25 are consistent with those of DeCorso and Kemeny [1], who observed a decrease in cone angle with an increase in a pressure drop-ambient density product until a minimum cone angle was reached at ΔPρair1.6~200. Results for atomizers having higher swirl numbers do not match the DeCorso and Kemeny [1] results as well, suggesting that their correlation be used with caution. Another key finding is that an increase in ΔPρair1.6 to a value of 1000 leads to continued decreases in cone angle, but that a subsequent increase to 4000 has little effect on cone angle. Finally, there was little influence of atomizer pressure drop on cone angle, in contrast to findings of previous workers. These effects are hypothesized to be due to gas entrainment.

Numerical Analysis of Pressure Swirl Atomizer

2015 ◽  
Vol 798 ◽  
pp. 190-194
Author(s):  
Mehmet Kahraman ◽  
Guven Komurgoz ◽  
Ibrahim Ozkol
Keyword(s):  
Cone Angle ◽  
Computational Cost ◽  
Internal Flow ◽  
Combustion Engines ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Atomization quality of liquids has a great importance on the performance of combustion engines. In this study the internal flow phenome of pressure swirl atomizer is investigated by using numerical method. The design of swirl atomizer is performed based on the requested atomizer characteristics which are sauter mean diamer (SMD), spray cone angle and break up length. Prediction and understanding of liquid film dynamics in the atomizer inside are the fundamental ways to explore atomizer performance. The purpose of this study is to estimate the air core size and film thickness in pressure swirl atomizer by setting single phase numeric computations. This article concludes that the CFD validated swirl atomizer design can be achieved with the lower computational cost using stream function methodology.

Study on the dynamic response of a pressure swirl injector to ramp variation of mass flow rate

2018 ◽  
Vol 152 ◽  
pp. 449-457 ◽  
Author(s):  
Peng Cheng ◽  
Qinglian Li ◽  
Huiyuan Chen ◽  
Zhongtao Kang
Keyword(s):  
Dynamic Response ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Swirl Injector ◽  
Pressure Swirl

Experimental Investigations of Performance Parameters of Pressure Swirl Atomizer for Kerosene Type Fuel

2009 ◽  
Author(s):  
Saurabh Dikshit ◽  
Salim Channiwala ◽  
Digvijay Kulshreshtha ◽  
Kamlesh Chaudhari
Keyword(s):  
Drop Size ◽  
Mechanical Energy ◽  
Cone Angle ◽  
Experimental Investigations ◽  
Performance Parameters ◽  
Spray Cone ◽  
Spray Penetration ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

The process of atomization is one in which a liquid jet or sheet is disintegrated by the kinetic energy of the liquid itself, or by exposure to high velocity air or gas, or as a result of mechanical energy applied externally. Combustion of liquid fuels in engines and industrial furnaces is dependent on effective atomization to increase the specific surface area of the fuel and thereby achieve high rate of mixing and evaporation. The pressure swirl atomizer is most common type atomizer used for combustion in gas turbine engines and industrial furnaces. The spray penetration is of prime importance for combustion designs. Over penetration of the spray leads to impingement of the fuel on walls of furnaces and combustors. On the other hand, if spray penetration is inadequate, fuel–air mixing is unsatisfactory. Optimum engine performance is obtained when the spray penetration is matched to the size and geometry of combustors. Methods for calculating penetration are therefore essential to sound engine design. Equally important are the spray cone angles and the drop size distribution in the sprays. An attempt is being made to experimentally investigate pressure swirl atomizer performance parameters such as spray cone angle, penetration length and drop size at different injection pressures ranging from 6 bar to 18 bar.

scholarly journals Effect of Low Ambient Pressure on Spray Cone Angle of Pressure Swirl Atomizer

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhengyan Guo ◽  
Yi Jin ◽  
Kai Zhang ◽  
Kanghong Yao ◽  
Yunbiao Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Cone Angle ◽  
Spray Angle ◽  
High Speed Photography ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Pressure swirl atomizers are widely used in gas turbine combustor; this paper is aimed at researching the effect of low ambient pressure (0.1 MPa to 0.01 MPa, lower than an atmosphere) on the spray cone angle of pressure swirl atomizer. The spray angle is captured by high-speed photography; then, an image post program is used to process the spray angle magnitude. A mathematical model of a single droplet’s movement and trajectory based on force analysis is proposed to validate the spray angle variation. The maximum variation of the spray cone angle, which is observed when fuel supply pressure drop through the atomizer is 1 MPa as the ambient pressure decreases from 0.1 MPa to 0.01 MPa, is found to be 23.9%. The experimental results show that the spray cone angle is expected to increase with the ambient pressure decrease; meanwhile, mathematical results agree well with this trend.

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