Structure of a Hollow-Cone Spray With and Without Combustion

1992 ◽  
Author(s):  
B. Chehroudi ◽  
M. Ghaffarpour
Keyword(s):  
Cone Angle ◽  
Velocity Profiles ◽  
Axial Distance ◽  
Volume Flux ◽  
Hollow Cone ◽  
Flow Rates ◽  
Drop Velocity ◽  
Radial Profiles ◽  
Fuel Nozzle ◽  
Hollow Cone Spray

A hollow-cone spray with a nominal cone angle of 30 degrees from a pressure-swirl fuel atomizer was used in a swirl-stabilized combustor. The combustor is circular in cross section, with a swirl plate and fuel nozzle axis coinciding with the axes of the chamber. kerosene is injected upward inside the chamber from the fuel nozzle. Separate swirl and dilution air flows are distributed into the chamber that pass through honeycomb flow straighteners and screens. A calculated swirl number of 1.5 is generated with the design swirl plate exit air velocity of 30 degrees with respect to the chamber axis. Effects of swirl and dilution air flow rates on the shape and stability of the flame are investigated. A Phase Doppler Particle Analyzer (PDPA) is used to measure drop size, mean and rms values of axial drop velocity, fuel volume flux, drop velocity and size distributions, and size-classified drop velocity profiles for two cases of with and without combustion and at six different axial locations from the nozzle. For the no-combustion case all air and fuel flow rates were kept at the same values as the combusting spray condition. Results for mean axial drop velocity profiles indicate widening of the spray, with slight increase in the magnitudes of the peak drop velocities due to combustion. Root mean square (RMS) values of drop velocity fluctuations decrease due to a combination of increase in gas kinematic viscosity and elimination of small drops at high temperatures. Sauter mean diameter (SMD) radial profiles at all axial locations increase with combustion due to preferential burning of small drops. Fuel volume flux profiles indicate negligible drop vaporization and/or burning up to a distance of 25mm from the nozzle. Velocity number distributions at different radial points for without combustion at an axial distance of 55mm from the atomizer are symmetric in shape only close to the peak of the mean drop velocity and show a bimodal shape around the maximum mean drop axial velocity gradient. Corresponding number distributions for the combustion case are fairly symmetric and quite different in behavior at all radial positions. Size-classified drop velocity profiles are also plotted and discussed.

scholarly journals Spray Drop Size and Velocity Measurements in a Swirl-Stabilized Combustor

1991 ◽  
Author(s):  
B. Chehroudi ◽  
M. Ghaffarpour
Keyword(s):  
Drop Size ◽  
Cone Angle ◽  
Hollow Cone ◽  
Flow Rates ◽  
Fuel Droplets ◽  
Radial Profiles ◽  
Fuel Nozzle ◽  
Pass Through ◽  
Yellow Region ◽  
Hollow Cone Spray

A pressure-swirl fuel nozzle generating a hollow-cone spray with nominal cone angle of 30 degrees is used in a swirl-stabilized combustor. The combustor is circular in cross section with swirl plate and fuel nozzle axes aligned and coinciding with the axis of the chamber. Kerosene is injected upward inside the chamber from the fuel nozzle. Separate swirl and dilution air flows are uniformly distributed into the chamber that pass through the honey comb flow straighteners and screens. Calculated swirl number of 1.5 is generated with the design swirl plate exit air velocity of 30 degrees with respect to the chamber axis. Effects of swirl and dilution air flow rates on the shape and stability of the flame are investigated. Stable and classical liquid fuel sheet disintegration zone exists close to the nozzle with no visible light followed by a luminous blue region and a mixed blue/yellow region that subsequently turns into yellow for most of the part in the flame. A Phase Doppler Particle Analyzer (PDPA) is used to measure drop size, mean and rms axial velocity for two cases of with and without combustion at six different axial locations from the nozzle. For the no-combustion case all air and fuel flow rates were kept at the same values as the combusting spray condition. Results for mean axial drop velocity profiles indicate widening of the spray due to combustion while the magnitudes of the peak velocities are slightly increased. No measurements inside the hollow-cone spray are possible due to burning of fuel droplets. Drop turbulence decreases due to combination of increase in gas kinematic viscosity and elimination of small drops at high temperatures. Sauter Mean Diameter (SMD) radial profiles at all axial locations increase with combustion due to preferential burning of small drops.

Asymmetric Transverse Acoustic Excitation of a Hollow Cone Spray Sheet With Air Swirl

2019 ◽  
Author(s):  
Rohit R. Bhattacharjee ◽  
Aravind I. Babu ◽  
Satyanarayanan R. Chakravarthy
Keyword(s):  
Cone Angle ◽  
Acoustic Excitation ◽  
Hollow Cone ◽  
Breakup Length ◽  
Swirl Angle ◽  
Transverse Acoustic ◽  
Spray Axis ◽  
Acoustic Forcing ◽  
Pressure Swirl ◽  
Hollow Cone Spray

Abstract The objective of this study was to experimentally observe the effects of externally perturbing a hollow cone spray sheet with acoustic excitation. These effects were quantified by measuring changes in the spray breakup length, swirl angle, and oscillatory behaviour of the sheet edge. We used a pressure swirl nozzle embedded into a swirler with 60° vane angles and a geometric swirl no. of SG = 0.981. Water was used to produce a hollow cone spray sheet and air was used as our swirler agent. For asymmetric forcing, only one side of the spray chamber was attached to a transverse duct (aligned perpendicular to the spray axis) along with two speakers. The duct harmonics were found to be 115 Hz, 204 Hz, and 313 Hz. Our experimental modes were also found to be comparable with results obtained numerically using the acoustic solver package from ANSYS. Our results show that for most cases the spray edges, cone angle, and breakup length responds to the acoustic forcing. While the cone angle increased with air swirl, for some cases without acoustic forcing the breakup length increased with air swirl.

scholarly journals Species Concentrations in a Model Gas Turbine Combustor

1993 ◽  
Author(s):  
M. Ghaffarpour ◽  
B. Chehroudi
Keyword(s):  
Gas Turbine ◽  
Axial Position ◽  
Concentration Profiles ◽  
Flame Zone ◽  
Hollow Cone ◽  
Gaseous Species ◽  
Species Concentration ◽  
Drop Velocity ◽  
Concentration Changes ◽  
Hollow Cone Spray

To investigate the combustion characteristics of hollow-cone spray flames somewhat similar to those occurring in the primary zone of gas turbine combustion chambers or within oil burners, a swirl-stabilized combustor was designed. The combustor is circular in cross section, with a swirl plate and fuel nozzle axis coinciding with the axes of the combustor. Separate swirl and dilution air flows are distributed into the combustor that pass through honeycomb flow straighteners and screens. A kerosene spray was generated by a simplex atomizer with a nominal initial-spray-angle of 30 degrees. Swirling air with swirl number of 1.5 was produced from a swirl plate. A Phase Doppler Particle Analyzer (PDPA) was used to measure the drop size, mean and rms values of axial drop velocity with and without combustion. Air and fuel flow rates and other conditions were kept identical for reacting and non-reacting cases to investigate effects of combustion alone on the spray. A thermocouple was used to measure the average uncorrected temperature in this turbulent spray flame. A water-cooled stainless-steel gas sampling probe was designed to be used with a gas chromatograph (GC) to measure the gaseous species concentrations in this combustor. Results for mean axial drop velocity profiles indicate widening of the spray, with slight increase in the magnitudes of the peak drop velocities due to combustion. No measurements of this type are possible inside the hollow-cone spray due to burning of fuel droplets within the flame zone. Root-Mean-Square (RMS) values of drop velocity fluctuations decrease due to combination of increase in gas kinematic viscosity and elimination of small drops at high temperatures. Sauter Mean Diameter (SMD) radial profiles at all axial locations increase with combustion as compared to the no-combustion case due to preferential burning of small drops. At the initial stages of combustion near the atomizer, the gas species concentration changes due to droplet evaporation, decomposition of fuel, reaction, and mixing with extra air. At the end of the visible flame zone, away from the nozzle, no significant amounts of methane and hydrogen have been observed. The gas concentration profiles at this axial position are flat within the burned gas zone. The species concentration profiles measured in the burned gas zone near the nozzle and along the spray centerline axis are similar to those of turbulent gaseous-fuel diffusion flame.

Effect of Azimuthal Velocity Fluctuation on Hollow Cone Spray

2017 ◽  
Author(s):  
Aravind I. Babu ◽  
Satya Chakravarthy
Keyword(s):  
Velocity Fluctuation ◽  
High Speed ◽  
Cone Angle ◽  
Azimuthal Velocity ◽  
Mean Flow ◽  
Hollow Cone ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Velocity Fluctuations ◽  
Hollow Cone Spray

This paper reports an experimental investigation on the effect of imposed azimuthal velocity fluctuation on the spray characteristics of a hollow cone spray produced from a pressure-swirl nozzle. This effect is inferred by performing experiments separately on 0° and 60° axial straight vane swirlers oriented concentric to the spray nozzle for the air-flow subjected to upstream acoustic forcing. The hollow cone spray is subjected to external excitation using a loudspeaker at two different frequencies and two amplitudes. These frequencies correspond to the resonant frequencies of the plenum. The 60° vane swirler, when subjected to acoustic excitation, produces axial and azimuthal velocity fluctuation downstream of the swirler, whereas the 0° swirler produces only axial velocity fluctuation downstream of the swirler. In both 60° and 0° swirlers, the downstream velocity fluctuation due to acoustic disturbances propagate at the speed of sound. In addition, the velocity fluctuations produced due to the excitation are convected by the mean flow. This results in a combined effect of velocity fluctuations at the swirler exit. The hollow cone spray responds more readily to excitation at low frequencies than higher frequencies. This is observed from the high-speed shadowgraph images. The high-speed shadowgraph images acquired are processed to extract spray cone angle. The phase averaged spray cone angle fluctuates for different phase angle within an acoustic cycle. The analysis of the high-speed shadowgraph images shows that the cone angle fluctuation amplitude is higher for the 0° swirler as compared to the 60° swirler. The variation of the liquid sheet thickness and breakup length due to excitation is captured using high-speed planar laser induced fluorescence. The study clearly demonstrates that azimuthal velocity fluctuation affects the spray formation process.

Characteristics of Leeward Shear Layer Structure of Hollow-Cone Spray in Gaseous Crossflow

AIAA Journal ◽  
2021 ◽  
Vol 59 (1) ◽  
pp. 405-409
Author(s):  
Haibin Zhang ◽  
Shilin Gao ◽  
Bofeng Bai ◽  
Yechun Wang
Keyword(s):  
Shear Layer ◽  
Layer Structure ◽  
Hollow Cone ◽  
Hollow Cone Spray

Effects of Fuel Nozzle Condition on Gas Turbine Combustion Chamber Exit Temperature Distributions

2010 ◽  
Author(s):  
Kristen Bishop ◽  
William Allan
Keyword(s):  
Combustion Chamber ◽  
Ambient Pressure ◽  
Cone Angle ◽  
Operating Conditions ◽  
Spray Cone Angle ◽  
Mixing Processes ◽  
Spray Cone ◽  
Temperature Distributions ◽  
Fuel Nozzle ◽  
Exit Temperature

The effects of fuel nozzle condition on the temperature distributions experienced by the nozzle guide vanes have been investigated using an optical patternator. Average spray cone angle, symmetry, and fuel streaks were quantified. An ambient pressure and temperature combustion chamber test rig was used to capture exit temperature distributions and to determine the pattern factor. The rig tests matched representative engine operating conditions by matching Mach number, equivalence ratio, and fuel droplet size. It was observed that very small deviations (± 10° in spray cone angle) from a nominal distribution in the fuel nozzle spray pattern correlated to increases in pattern factor, apparently due to a degradation of mixing processes, which created larger regions of very high temperature core flow and smaller regions of cooler temperatures within the combustion chamber exit plane. The spray cone angle had the most measureable influence while the effects of spray roundness and streak intensity had slightly less influence. Comparisons were made with published studies conducted on the combustion chamber geometry, and recommendations were made for fuel nozzle inspections.

Analysis of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector Performance in Optical and Metal Research Engines

2017 ◽  
Author(s):  
Carlo Beatrice ◽  
Giacomo Belgiorno ◽  
Gabriele Di Blasio ◽  
Ezio Mancaruso ◽  
Luigi Sequino ◽  
...  
Keyword(s):  
High Pressure ◽  
Hollow Cone ◽  
Metal Research ◽  
Hollow Cone Spray

Sampling of High-Quality Wet Steam from Steam Mains Operating at 11·4 Bar Pressure

1973 ◽  
Vol 187 (1) ◽  
pp. 381-393 ◽  
Author(s):  
D. J. Ryley ◽  
M. J. Holmes
Keyword(s):  
Static Pressure ◽  
Water Mass ◽  
Cone Angle ◽  
Wet Steam ◽  
High Quality ◽  
Flow Rates ◽  
Further Development ◽  
Half Cone ◽  
Steam Main ◽  
Half Cone Angle

A venturi device was employed to strip and entrain liquid from the wall of a 3 in (7·5 cm) diameter steam main prior to isokinetic sampling. By injecting heated water into dry steam the wetness fraction was controlled between 1 and 5 per cent. Venturi convergence half-cone angles of 20, 30, 40 and 50° were employed and steam flow rates varied from 360–730 kg/h (800–1600 1b/h). Observations were made of the distribution through the test section of static pressure, recovered temperature and film thickness (for pressure 3·8 bar (55 1b/in2 absolute) only). Sampling across a diameter showed that under the most advantageous conditions the ratio, aggregate mass of entrained water: mass of injected water did not exceed 23 per cent. The optimum venturi half-cone angle lay between 40 and 50°. While capable of further development, the stripping-sampling principle seems unlikely to lead to significant improvements in wet steam sampling for quality.

A dealiasing method for use with ultrasonic pulsed Doppler in measuring velocity profiles and flow rates in pipes

2015 ◽  
Vol 26 (8) ◽  
pp. 085301 ◽  
Author(s):  
Hideki Murakawa ◽  
Ei Muramatsu ◽  
Katsumi Sugimoto ◽  
Nobuyuki Takenaka ◽  
Noriyuki Furuichi
Keyword(s):  
Velocity Profiles ◽  
Pulsed Doppler ◽  
Flow Rates

Validation of a CFD Model of a Hollow-Cone Spray with Gasoline Fuel Blends

2011 ◽  
Author(s):  
Lars Schmidt ◽  
Jason King ◽  
John Stokes ◽  
James Mullineux ◽  
Calvin R.Ramasamy ◽  
...  
Keyword(s):  
Cfd Model ◽  
Hollow Cone ◽  
Fuel Blends ◽  
Hollow Cone Spray
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