Spray Test of Fuel Nozzle for Lean Pre-Mixed Pre-Vaporized Combustor

2002 ◽  
Author(s):  
Tomoyoshi Nakae ◽  
Masao Saigo ◽  
Akihiro Santo ◽  
Atsushi Tanaka
Keyword(s):  
Liquid Fuel ◽  
Ambient Pressure ◽  
Droplet Size Distribution ◽  
Test Model ◽  
Air Velocity ◽  
Fuel Droplets ◽  
Fuel Flow ◽  
Fine Spray ◽  
Fuel Nozzle ◽  
Pdpa Measurement

An LPP (Lean Pre-mixed Pre-vaporized) combustor is one of the most promising systems to make it possible to reduce NOx emission drastically. To realize low NOx combustors using liquid fuel, uniformity and fine atomization of fuel droplets are essential requirements. Droplet diameters of a fuel nozzle designed for LPP combustor as determined by PDPA measurement system are presented in this paper. An annulus pre-mixing duct was employed for the LPP fuel nozzle test model. Spray tests were conducted at pressures from 0.18MPa to 0.53MPa. Pre-mixing air velocity was also varied. Data show that the test nozzle produces a fine spray. In this paper, fuel droplet size distribution and velocity are presented and effects of air pressure and velocity on atomization are discussed. SMD of fuel droplets increases with the increases of ambient pressure. This is inconsistent with the trend determined by other works. But when the effect of fuel flow rate (or fuel film thickness) is considered, these inconsistencies can be resolved.

Forced Oscillations in Combustors With Spray Atomizers

1999 ◽  
Vol 124 (1) ◽  
pp. 20-30 ◽  
Author(s):  
M. Zhu ◽  
A. P. Dowling ◽  
K. N. C. Bray
Keyword(s):  
Liquid Fuel ◽  
Pressure Fluctuations ◽  
Droplet Size Distribution ◽  
Forced Oscillations ◽  
Combustion Instabilities ◽  
Unsteady Combustion ◽  
Fuel Droplets ◽  
Rate Of Combustion ◽  
Flow Oscillations ◽  
Insight Into

Most types of combustion-driven devices experience combustion instabilities. For aeroengine combustors, the frequency of this oscillation is typically in the range 60–120 Hz and is commonly called “rumble.” The rumble oscillations involve coupling between the air and fuel supplies and unsteady flow in the combustor. Essentially pressure fluctuations alter the inlet fuel and air, thereby changing the rate of combustion, which at certain frequencies further enhances the pressure perturbation and so leads to self-excited oscillations. The large residence time of the liquid fuel droplets, at idle and subidle conditions, means that liquid and gaseous phases must both be considered. In the present work, we use a numerical model to investigate the forced unsteady combustion due to specified time-dependent variations in the fuel and air supplies. Harmonic variations in inlet air and fuel flows have been considered and the resulting unsteady combustion calculated. The influence of droplet size distribution has also been investigated. The calculations provide insight into the interaction between atomization, unsteady combustion, and flow oscillations.

Combustion Oscillations in Burners With Fuel Spray Atomisers

1999 ◽  
Author(s):  
M. Zhu ◽  
A. P. Dowling ◽  
K. N. C. Bray
Keyword(s):  
Liquid Fuel ◽  
Pressure Fluctuations ◽  
Droplet Size Distribution ◽  
Combustion Instabilities ◽  
Unsteady Combustion ◽  
Fuel Droplets ◽  
Rate Of Combustion ◽  
Aero Engine ◽  
Flow Oscillations ◽  
Insight Into

Most types of combustion-driven devices experience combustion instabilities. For aero-engine combustors, the frequency of this oscillation is typically in the range 60–120Hz and is commonly called ‘rumble’. The rumble oscillations involve coupling between the air and fuel supplies and unsteady flow in the combustor. Essentially pressure fluctuations alter the inlet fuel and air, thereby changing the rate of combustion, which at certain frequencies further enhances the pressure perturbation and so leads to self-excited oscillations. The large residence time of the liquid fuel droplets, at idle and sub-idle conditions, means that liquid and gaseous phases must both be considered. In the present work, we use a numerical model to investigate forced unsteady combustion due to specified time-dependent variations in the fuel and air supplies. Harmonic variations in inlet air and fuel flows have been considered and the resulting unsteady combustion calculated. The influence of droplet size distribution has also been investigated. The calculations provide insight into understanding the interaction between atomization, unsteady combustion and flow oscillations.

The Behavior of Liquid Fuel Sprays in Acoustically-Forced Air Swirler Flows

2012 ◽  
Author(s):  
Wookyung Kim ◽  
Shiling Zhang ◽  
Paul Palies ◽  
Jeffrey Cohen ◽  
Scott Liljenberg ◽  
...  
Keyword(s):  
Mass Flow ◽  
Liquid Fuel ◽  
Ambient Pressure ◽  
Stokes Number ◽  
Fuel Spray ◽  
Fuel Mass ◽  
Fuel Droplets ◽  
Air Mixing ◽  
Acoustic Forcing ◽  
Cfd Analyses

The effects of air flow forcing on fuel spray characteristics in a premixing swirler were assessed using ambient-pressure experiments and CFD (LES) analyses. Experimental measurements were performed using phase-locked Phase-Doppler Interferometry on two different swirler/mixer designs. The CFD analyses employed an advanced spray modeling technique to track the surface of the liquid fuel. The swirler designs chosen were representative of advanced low-emissions combustor concepts that emphasize thorough fuel/air mixing for Jet-A fuel. Significant post-processing of the results was performed in order to extract the response of the fuel spray mass flow rate fluctuations and fuel/air ratio to acoustic forcing. The results demonstrated that i) acoustic air forcing did not significantly change the atomization process, but did influence the unsteady transport of fuel droplets within the swirler flow field, ii) the level of fuel mass flow fluctuation was higher for one swirler and the level of fuel/air ratio fluctuations was higher for the other swirler and iii) the different behaviors between the two swirlers are primarily caused by the discrepant alignment of fuel and air distribution and the dissimilar droplet Stokes number which governs the unsteady transport. CFD results were interrogated to help understand the root causes of the observed phenomena. These showed that, for the swirler in which fuel mass flow fluctuations were observed, the swirl number was modulated by the acoustic forcing.

NONEQUILIBRIUM DIFFUSION COMBUSTION OF LIQUID FUEL DROPLETS AND SPRAYS MODELING

2012 ◽  
Vol 43 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Nickolay N. Smirnov ◽  
V. F. Nikitin ◽  
V. V. Tyurenkova
Keyword(s):  
Liquid Fuel ◽  
Diffusion Combustion ◽  
Fuel Droplets

scholarly journals Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1229
Author(s):  
Hongtao Zhang ◽  
Zhihua Wang ◽  
Yong He ◽  
Jie Huang ◽  
Kefa Cen
Keyword(s):  
Burning Rate ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Ambient Pressure ◽  
Interactive Effects ◽  
Propagation Time ◽  
High Speed Camera ◽  
Single Droplet ◽  
Fuel Droplets ◽  
Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

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.

scholarly journals An experimental study on the effects of swirling oxidizer flow and diameter of fuel nozzle on behaviour and light emittance of propane-oxygen non-premixed flame

2017 ◽  
Vol 21 (3) ◽  
pp. 1453-1462 ◽  
Author(s):  
Alireza Javareshkian ◽  
Sadegh Tabejamaat ◽  
Soroush Sarrafan-Sadeghi ◽  
Mohammadreza Baigmohammadi
Keyword(s):  
Reynolds Numbers ◽  
Flame Length ◽  
Nozzle Diameter ◽  
Fuel Flow ◽  
Maximum Value ◽  
Fuel Nozzle ◽  
Flame Shape ◽  
The Stability ◽  
Blue Flame

In this study, the stability and the light emittance of non-premixed propane-oxygen flames have been experimentally evaluated with respect to swirling oxidizer flow and variations in fuel nozzle diameter. Hence, three types of the vanes with the swirl angles of 30?, 45?, and 60? have been chosen for producing the desired swirling flows. The main aims of this study are to determine the flame behaviour, light emittance, and also considering the effect of variation in fuel nozzle diameter on combustion phenomena such as flame length, flame shape, and soot free length parameter. The investigation into the flame phenomenology was comprised of variations of the oxidizer and fuel flow velocities (respective Reynolds numbers) and the fuel nozzle diameter. The results showed that the swirl effect could change the flame luminosity and this way could reduce or increase the maximum value of the flame light emittance in the combustion zone. Therefore, investigation into the flame light emittance can give a good clue for studying the mixing quality of reactants, the flame phenomenology (blue flame or sooty flame, localized extinction), and the combustion intensity in non-premixed flames.

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.

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