Characterization of a Superheated Fuel Jet in a Crossflow

2009 ◽  
Author(s):  
May Corn ◽  
Jeff Cohen ◽  
Don Hautman ◽  
Scott Thawley ◽  
Christopher Brown ◽  
...  
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Design Feature ◽  
Dew Point ◽  
Vapor Concentration ◽  
Fuel Vapor ◽  
Fuel Temperature ◽  
High Speed Imaging ◽  
Phase Doppler Interferometry ◽  
Fuel Jet

An experiment was conducted to characterize a superheated fuel jet (Jet-A) injected into an unheated crossflow. The liquid phase of the fuel jet was characterized with high speed imaging and phase Doppler interferometry while the vapor phase of the fuel was measured with infrared scattering and extinction methods. The transition from a shear-atomized to flash-atomized spray at a fuel temperature of 465°F (513K) was observed at an ambient pressure of 1 atm, which is consistent with the bubble and dew point curves predicted for JP-8. The explosive breakup that was seen in the flash-atomized spray produced sub-micron droplets with a high radial and transverse momentum that resulted in an increasing fuel vapor concentration for the same penetration height when compared with the shear-atomized case. This unique behavior makes superheated fuels an attractive design feature for fuel preparation devices that can employ flash boiling to enhance fuel atomization and mixing in a compact volume.

Characterization of a Superheated Fuel Jet in a Crossflow

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
May L. Corn ◽  
Jeffrey M. Cohen ◽  
Jerry C. Lee ◽  
Donald J. Hautman ◽  
Scott M. Thawley ◽  
...  
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Design Feature ◽  
Dew Point ◽  
Fuel Temperature ◽  
High Speed Imaging ◽  
Fuel Atomization ◽  
Phase Doppler Interferometry ◽  
Fuel Jet ◽  
Submicron Droplets

An experiment was conducted to characterize a superheated fuel jet (Jet-A) injected into an unheated crossflow of air. The liquid phase of the fuel jet was characterized with high speed imaging and phase Doppler interferometry. The transition from a shear-atomized to a flash-atomized spray at a fuel temperature of 513 K (465°F) was observed at an ambient pressure of 1 atm, which is consistent with the bubble and dew point curves predicted for JP-8. The explosive breakup that was seen in the flash-atomized spray produced submicron droplets with a high radial momentum. This unique behavior makes superheated fuels an attractive design feature for fuel preparation devices that can employ flash boiling to enhance fuel atomization and mixing in a compact volume.

scholarly journals Experimental investigation on spray characteristics of Jet A-1 and alternative aviation fuels

2021 ◽  
pp. 175682772110101
Author(s):  
Manish Kumar ◽  
Srinibas Karmakar ◽  
Sonu Kumar ◽  
Saptarshi Basu
Keyword(s):  
High Speed ◽  
Alternative Fuels ◽  
Droplet Formation ◽  
Spray Characteristics ◽  
Butyl Butyrate ◽  
Phase Doppler Interferometry ◽  
Alternative Aviation Fuels ◽  
Lower Viscosity ◽  
Fuel Jet ◽  
Atomization Characteristics

Potential alternative fuels that can mitigate environmental pollution from gas turbine engines (due to steep growth in the aviation sector globally) are getting significant attention. Spray behavior plays a significant role in influencing the combustion performance of such alternative fuels. In the present study, spray characteristics of Kerosene-based fuel (Jet A-1) and alternative aviation fuels such as butyl butyrate, butanol, and their blends with Jet A-1 are investigated using an air-blast atomizer under different atomizing air-to-fuel ratios. Phase Doppler Interferometry has been employed to obtain the droplet size and velocity distribution of various fuels. A high-speed shadowgraphy technique has also been adopted to make a comparison of ligament breakup characteristics and droplet formation of these alternative biofuels with that of Jet A-1. An effort is made to understand how the variation in fuel properties (mainly viscosity) influences atomization. Due to the higher viscosity of butanol, the SMD is higher, and the droplet formation seems to be delayed compared to Jet A-1. In contrast, the lower viscosity of butyl butyrate promotes faster droplet formation. The effects of the blending of these biofuels with Jet A-1 on atomization characteristics are also compared with that of Jet A-1.

scholarly journals Influence of Gaseous Environment on Reaction Behavior and Phase Formation in Ti/2B Reactive Multilayer Foils

2012 ◽  
Vol 1405 ◽  
Author(s):  
Robert V. Reeves ◽  
Mark A. Rodriguez ◽  
Eric D. Jones ◽  
David P. Adams
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Product Formation ◽  
Atmospheric Conditions ◽  
Bilayer Thickness ◽  
X Ray Diffraction ◽  
High Speed Imaging ◽  
Reaction Behavior ◽  
Gaseous Environment ◽  
Sputter Deposited

ABSTRACTThe effects of surrounding gaseous environment on the reaction behaviors and product formation for sputter-deposited Ti/2B reactive multilayers are reported. With the surrounding environment set to different air pressures, from atmospheric conditions to 10-4 Torr, Ti/2B samples were reacted in a self-propagating mode, and the average reaction wave velocities were determined through high-speed imaging. Propagation speeds for 3.0 μm-thick multilayers were in the range of 10.89 to 0.05 m/s depending on bilayer thickness (i.e., reactant layer periodicity) and ambient pressure. X-ray diffraction analysis showed that single-phase TiB2 forms within multilayers that have small bilayer thickness. Multilayers that have a large bilayer thickness developed a mixture of TiB2, TiB and TiO2.

Measurement of Air-Fuel Mixing in a Diesel Spray at Engine Relevant Conditions Using UV-VIS DBI Diagnostic

2021 ◽  
Author(s):  
Conner Godbold ◽  
Farzad Poursadegh ◽  
Oleksandr Bibik ◽  
Caroline Genzale
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Liquid Droplet ◽  
Ultra Violet ◽  
Orifice Diameter ◽  
Diesel Spray ◽  
Vapor Concentration ◽  
Fuel Vapor ◽  
Diesel Combustion ◽  
Concentration Data

Abstract Due to the non-premixed nature of diesel combustion, mixing prior to the reaction zone has proven to be one of the primary factors in emissions formation. Therefore, the advancement of diagnostics used to measure mixing fields in diesel applications is imperative for a greater understanding of how in-cylinder emissions mitigation techniques operate. Towards this goal, we have recently demonstrated the use of a high-speed two-wavelength extinction imaging measurement, UV-VIS DBI, for time-resolved measurements of mixing in a diesel spray. This diagnostic operates by back-lighting the spray with ultra-violet and visible illumination. The visible illumination is selected at a non-absorbing wavelength, such that the visible light is only attenuated by liquid droplet scattering, enabling discrete detection of the liquid-vapor mixture and pure vapor phases of the spray. For this work, Ultraviolet and visible light are generated using a ND:YAG pumped frequency-doubled tunable dye laser operating at 9.9 kHz . The simultaneous UV-Visible illumination is used to back-illuminate a vaporizing diesel spray, and the resulting extinction of each signal is recorded by a pair of high-speed cameras. Using an aromatic tracer (naphthalene, BP = 218 °C) in a base fuel of dodecane (BP = 215–217 °C), the UV illumination (280 nm) is absorbed along the illumination path through the spray, yielding a projected image of line-of-sight optical depth that is proportional to the projected fuel vapor concentration in the pure vapor region of the spray. In this paper, a new method of determining the absorption coefficient for the pure-vapor phase of the spray will be discussed, along with showing how an Inverse-Abel transform can be used to compute planar concentration data from the projected concentration data yielded by the diagnostic. This diagnostic and data processing is applied to diesel sprays from two Bosch CRI3-20 ks1.5 single-orifice injectors (140 μm and 90 μm orifice diameters) injecting into a nonreacting high-pressure and temperature nitrogen environment using a constant-flow, optically-accessible spray chamber operating at 60 bar and 900 K. The mixing data produced agrees well with previously existing mixing data, which further instills confidence in the diagnostic, and gives the diesel combustion community access to mixing field data for a 140 μm orifice diameter injector at a 60 bar and 900 K condition.

A Multi-Wavelength Extinction Imaging Diagnostic for Quantifying Diesel Spray Mixing at Engine-Relevant Conditions

2020 ◽  
Author(s):  
Conner Godbold ◽  
Farzad Poursadegh ◽  
Oleksandr Bibik ◽  
Carlos De La Camara Castillo ◽  
Caroline Genzale
Keyword(s):  
High Speed ◽  
Rayleigh Scattering ◽  
Mie Scattering ◽  
Light Extinction ◽  
Diesel Spray ◽  
Vapor Concentration ◽  
Fuel Vapor ◽  
Ic Engine ◽  
Projected Image ◽  
Liquid Spray

Abstract The mixing of fuel and air in the combustion chamber of an IC engine is crucial to emissions formation. Therefore, developing effective diagnostic techniques for measuring mixing is critical for progressing IC engines. Existing methodologies for the optical measurement of air-fuel mixing, including Rayleigh scattering and Laser Induced Fluorescence (LIF), have demonstrated various diagnostic-implementation challenges, high uncertainties under engine-relevant environments, and strong interferences from the liquid spray which prevents their use in near-spray measurements. This work presents the use of an alternative approach based on a laser-absorption/scattering technique called Ultraviolet-Visible Diffuse Back-Illumination (UV-Vis DBI) to quantify local equivalence ratio in a vaporizing diesel spray. Ultraviolet and visible light are generated using a ND:YAG pumped frequency-doubled tunable dye laser operating at 9.9 kHz. The simultaneous UV-Visible illumination is used to back-illuminate a vaporizing diesel spray, and the resulting extinction of each signal is recorded by a pair of high-speed cameras. Using an aromatic tracer (naphthalene, BP = 218 °C) in a base fuel of dodecane (BP = 215–217 °C), the UV illumination (280 nm) is absorbed along the illumination path through the spray, yielding a projected image of line-of-sight optical depth that is proportional to the path-average fuel vapor concentration in the vapor region of the spray. The visible illumination is chosen at a non-absorbing wavelength (560 nm), such that the light extinction is only due to liquid scattering, yielding a projected image of the liquid spray. A key advantage of the method is that the absorption coefficient of the selected tracer is relatively independent of temperature and pressure for 280-nm illumination, reducing measurement uncertainties at engine-relevant conditions. Measurements are also achievable in near-spray vapor regions since there is no mie-scattering interference from the liquid spray. The diagnostic is applied to measure the fuel-air mixing field of a diesel spray produced by a Bosch CRI3-20 ks1.5 single-orifice injector (90 μm diameter) similar to ECN Spray A. Measurements are conducted in a non-reacting high-pressure and temperature nitrogen environment using a constant-flow, optically-accessible spray chamber operating at 60 bar and 900 K. The results are evaluated against existing ECN mixing measurements based on Rayleigh scattering. The diagnostic yields centerline and radial mixture fraction measurements that match the ECN Rayleigh measurements within uncertainty bounds.

Autoignition Limits of Hydrogen at Relevant Reheat Combustor Operating Conditions

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
J. Fleck ◽  
P. Griebel ◽  
A.M. Steinberg ◽  
M. Stöhr ◽  
M. Aigner ◽  
...  
Keyword(s):  
Flue Gas ◽  
Gas Turbines ◽  
High Speed ◽  
Initial Position ◽  
Operating Conditions ◽  
Dominant Factor ◽  
High Speed Imaging ◽  
Lean Premixed Combustion ◽  
Fuel Jet ◽  
Image Velocimetry

The use of highly reactive fuels in the lean premixed combustion systems employed in stationary gas turbines can lead to many practical problems, such as unwanted autoignition in regions not designed for combustion. In the present study, autoignition characteristics for hydrogen, diluted with up to 30 vol. % nitrogen, were investigated at conditions relevant to reheat combustor operation (p = 15 bar, T >1000 K, hot flue gas, relevant residence times). The experiments were performed in a generic, optically accessible reheat combustor, by applying high-speed imaging and particle image velocimetry. Autoignition limits for different mixing section (temperature, velocity) and fuel jet (N2 dilution) parameters are described. The dominant factor influencing autoignition was the temperature, with an increase of around 2% leading to a reduction of the highest possible H2 concentration without “flame-stabilizing autoignition kernels” of approximately 16 vol. %. Furthermore, the onset and propagation of the ignition kernels were elucidated using the high-speed measurements. It was found that the ability of individual autoignition kernels to develop into stable flames depends on the initial position of the kernel and the corresponding axial velocity at that position. While unwanted autoignition occurred prior to reaching the desired operating point for most investigated conditions, for certain conditions the reheat combustor could be operated stably with up to 80 vol. % H2 in the fuel.

Autoignition Limits of Hydrogen at Relevant Reheat Combustor Operating Conditions

2011 ◽  
Author(s):  
Julia Fleck ◽  
Peter Griebel ◽  
Adam M. Steinberg ◽  
Michael Sto¨hr ◽  
Manfred Aigner ◽  
...  
Keyword(s):  
Flue Gas ◽  
Gas Turbines ◽  
High Speed ◽  
Initial Position ◽  
Operating Conditions ◽  
Dominant Factor ◽  
High Speed Imaging ◽  
Lean Premixed Combustion ◽  
Fuel Jet ◽  
Image Velocimetry

The use of highly reactive fuels in the lean premixed combustion systems employed in stationary gas turbines can lead to many practical problems, such as unwanted autoignition in regions not designed for combustion. In the present study, autoignition characteristics for hydrogen, diluted with up to 30 vol. % nitrogen, were investigated at conditions relevant to reheat combustor operation (p = 15 bar, T > 1000 K, hot flue gas, relevant residence times). The experiments were performed in a generic, optically accessible reheat combustor, by applying high-speed imaging and Particle Image Velocimetry (PIV). Autoignition limits for different mixing section (temperature, velocity) and fuel jet (N2 dilution) parameters are described. The dominant factor influencing autoignition was the temperature, with an increase of around 2% leading to a reduction of the highest possible H2 concentration without “flame-stabilizing autoignition kernels” of approximately 16 vol. %. Furthermore, the onset and propagation of the ignition kernels were elucidated using the high-speed measurements. It was found that the ability of individual autoignition kernels to develop into stable flames depends on the initial position of the kernel and the corresponding axial velocity at that position. While unwanted autoignition occurred prior to reaching the desired operating point for most investigated conditions, for certain conditions the reheat combustor could be operated stably with up to 80 vol. % H2 in the fuel.

scholarly journals We -T classification of diesel fuel droplet impact regimes

2018 ◽  
Vol 474 (2215) ◽  
pp. 20170759 ◽  
Author(s):  
Hesamaldin Jadidbonab ◽  
Ilias Malgarinos ◽  
Ioannis Karathanassis ◽  
Nicholas Mitroglou ◽  
Manolis Gavaises
Keyword(s):  
Surface Temperature ◽  
High Speed ◽  
Ambient Pressure ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
High Speed Imaging ◽  
Two Phase ◽  
Post Impact ◽  
T Classification ◽  
The Impact

A combined experimental and computational investigation of micrometric diesel droplets impacting on a heated aluminium substrate is presented. Dual view high-speed imaging has been employed to visualize the evolution of the impact process at various conditions. The parameters investigated include wall-surface temperature ranging from 140 to 400°C, impact Weber and Reynolds numbers of 19–490 and 141–827, respectively, and ambient pressure of 1 and 2 bar. Six possible post-impact regimes were identified, termed as Stick, Splash, Partial-Rebound, Rebound, Breakup-Rebound and Breakup-Stick , and plotted on the We-T map. Additionally, the temporal variation of the apparent dynamic contact angle and spreading factor have been determined as a function of the impact Weber number and surface temperature. Numerical simulations have also been performed using a two-phase flow model with interface capturing, phase-change and variable physical properties. Increased surface temperature resulted to increased maximum spreading diameter and induced quicker and stronger recoiling behaviour, mostly attributed to the change of liquid viscosity.

Investigation of GTL-Like Jet Fuel Composition on GT Engine Altitude Ignition and Combustion Performance: Part II—Detailed Diagnostics

2011 ◽  
Author(s):  
Thomas Mosbach ◽  
Gregor C. Gebel ◽  
Patrick Le Clercq ◽  
Reza Sadr ◽  
Kumaran Kannaiyan ◽  
...  
Keyword(s):  
High Speed ◽  
Operating Conditions ◽  
Research Centre ◽  
Fuel Injector ◽  
Fuel Temperature ◽  
High Speed Imaging ◽  
Combustion Behavior ◽  
Combustion Performance ◽  
Ignition And Combustion ◽  
Spectrally Resolved

The ignition and combustion performance of different synthetic paraffinic kerosenes (SPKs) under simulated altitude relight conditions were investigated at the altitude relight test rig at the Rolls-Royce Strategic Research Centre in Derby. The conditions corresponded to a low stratospheric flight altitude between 25,000 and 30,000 feet. The combustor under test was a twin-sector representation of an advanced gas turbine combustor and fuel injector. Five different SPKs and Jet A-1 were tested at different mass flow rates of air and fuel, and at two different sub-atmospheric air pressures and temperatures. The fuel temperature was kept approximately constant. Simultaneous high-speed imaging of the OH* and CH* chemiluminescence, and of the broadband luminosity was used to visualize both the transient flame initiation phenomena and the combustion behavior of the steady burning flames. In addition, flame luminosity spectra were recorded with a spectrometer to obtain spectrally resolved information concerning the different chemiluminescence bands and the soot luminosity. These investigations were performed in conjunction with the comparative evaluation of the ignition and stability regimes of the five SPKs, which is the subject of a separate complementary paper [1]. We found that the observed flame initiation phenomena, the overall combustion behavior and the different ratios of the chemiluminescence from the OH*, CH* and C2* radicals were not strongly dependent on the fuels investigated. But, the SPK flames showed for all combustor operating conditions significantly lower soot luminosities than the corresponding Jet A-1 flames, indicating a potential benefit of the SPK fuels.

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