INVESTIGATION OF RAPID ATOMIZATION AND COLLAPSE OF SUPERHEATED LIQUID FUEL SPRAY UNDER SUPERHEATED CONDITIONS

2016 ◽  
Vol 26 (12) ◽  
pp. 1361-1384 ◽  
Author(s):  
Shengqi Wu ◽  
Hujie Pan ◽  
Min Xu ◽  
David L. S. Hung ◽  
Tianyun Li
Keyword(s):  
Liquid Fuel ◽  
Fuel Spray ◽  
Superheated Liquid

Fuel Composition Effects on Forced Ignition of Liquid Fuel Sprays

2018 ◽  
Author(s):  
Sheng Wei ◽  
Brandon Sforzo ◽  
Jerry Seitzman
Keyword(s):  
Physical Properties ◽  
Liquid Fuel ◽  
Chemical Properties ◽  
Reaction Rates ◽  
High Energy ◽  
Fuel Spray ◽  
Successful Outcome ◽  
Fuel Composition ◽  
Ignition Probability ◽  
Fuel Sprays

In gas turbine combustors, ignition is achieved by using sparks from igniters to start a flame. The process of sparks interacting with fuel/air mixture and creating self-sustained flames is termed forced ignition. Physical and chemical properties of a liquid fuel can influence forced ignition. The physical effects manifest through processes such as droplet atomization, spray distribution, and vaporization rate. The chemical effects impact reaction rates and heat release. This study focuses on the effect of fuel composition on forced ignition of fuel sprays in a well-controlled flow with a commercial style igniter. A facility previously used to examine prevaporized, premixed liquid fuel-air mixtures is modified and employed to study forced ignition of liquid fuel sprays. In our experiments, a wall-mounted, high energy, recessed cavity discharge igniter operating at 15 Hz with average spark energy of 1.25 J is used to ignite liquid fuel spray produced by a pressure atomizer located in a uniform air coflow. The successful outcome of each ignition events is characterized by the (continued) presence of chemiluminescence 2 ms after spark discharge, as detected by a high-speed camera. The ignition probability is defined as the fraction of successful sparks at a fixed condition, with the number of events evaluated for each fuel typically in the range 600–1200. Ten fuels were tested, including standard distillate jet fuels (e.g., JP-8 and Jet-A), as well as many distillate and alternative fuel blends, technical grade n-dodecane, and surrogates composed of a small number of components. During the experiments, the air temperature is controlled at 27 C and the fuel temperature is controlled at 21 C. Experiments are conducted at a global equivalence ratio of 0.55. Results show that ignition probabilities correlate strongly to liquid fuel viscosity (presumably through droplet atomization) and vapor pressure (or recovery temperature), as smaller droplets of a more volatile fuel would lead to increased vaporization rates. This allows the kernel to transition to a self-sustained flame before entrainment reduces its temperature to a point where chemical rates are too slow. Chemical properties of the fuel showed little influence, except when the fuels had similar physical properties. This result demonstrates that physical properties of liquid fuels have dominating effects on forced ignition of liquid fuel spray in coflow air.

scholarly journals Group Combustion Behavior of Liquid Fuel Spray Under the Influence of Wake Flow Behind a Circular Rod.

1995 ◽  
Vol 61 (581) ◽  
pp. 317-324
Author(s):  
Kazuyoshi Nakabe ◽  
Fumiteru Akamatsu ◽  
Yukio Mizutani ◽  
Masashi Katsuki ◽  
Taizo Imoto
Keyword(s):  
Liquid Fuel ◽  
Wake Flow ◽  
Fuel Spray ◽  
Combustion Behavior ◽  
Group Combustion

scholarly journals Evaporation Characteristics of Spray in a Lean Premixed-Prevaporization Combustor for a 100 KW Automotive Ceramic Gas Turbine

1994 ◽  
Author(s):  
Youichlrou Ohkubo ◽  
Yoshinorl Idota ◽  
Yoshihiro Nomura
Keyword(s):  
Gas Turbine ◽  
Mass Fraction ◽  
Liquid Fuel ◽  
Three Dimensional ◽  
Flame Stabilization ◽  
Fuel Spray ◽  
Inlet Temperature ◽  
Lean Combustion ◽  
Swirl Chamber ◽  
Lean Premixed

Spray characteristics of liquid fuel air-assisted atomizers developed for a lean premixed-prevaporization combustor were evaluated under two kinds of conditions: in still air under non-evaporation conditions at atmospheric pressure and in a prevaporization-premixing tube under evaporation conditions with a running gas turbine. The non-evaporated mass fraction of fuel spray was measured using a phase Doppler particle analyzer in the prevaporization-premixing tube, in which the inlet temperature ranged from 873K to 1173K. The evaporation of the fuel spray in the tube is mainly controlled by its atomization and distribution. The NOx emission characteristics measured with a combustor test rig were evaluated with three-dimensional numerical simulations. A low non-evaporated mass fraction of less than 10% was effective in reducing the exhausted NOx from lean premixed-prevaporization combustion to about 1/6 times smaller than that from lean diffusion (spray) combustion. The flow patterns in the combustor are established by a swirl chamber in fuel-air preparation tube, and affect the flame stabilization of lean combustion.

Modelling of Liquid Fuel Spray in Non-Isothermal Environments

2014 ◽  
Author(s):  
Ogheneruona E. Diemuodeke ◽  
Ilai Sher
Keyword(s):  
Liquid Fuel ◽  
Fuel Spray

CHANGES IN THE AREA BRIGHTNESS OF DIESEL FUEL SPRAY ZONES

2016 ◽  
Vol 3 (1) ◽  
pp. 506-509
Author(s):  
Кулманаков ◽  
S. Kulmanakov ◽  
Кирюшин ◽  
I. Kiryushin
Keyword(s):  
Diesel Fuel ◽  
Liquid Fuel ◽  
Pressure Range ◽  
Injection Pressure ◽  
Fuel Spray ◽  
Experimental Setup ◽  
Jet Injection ◽  
Axial Section ◽  
Fuel Jet ◽  
Fuel Stream

The article contains a description of the experimental setup and the stent-speed video atomized fuel stream, applicable for the study of the jet sputtering process liquid fuel. In axial section shows information about the dynamics of the area of the normalized luminance zones in the diesel fuel jet injection pressure range of 60 MPa to 180 MPa

Modeling of Internal and Near-Nozzle Flow for a Gasoline Direct Injection Fuel Injector

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Kaushik Saha ◽  
Sibendu Som ◽  
Michele Battistoni ◽  
Yanheng Li ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Liquid Fuel ◽  
Numerical Study ◽  
Direct Injection ◽  
Computational Cost ◽  
Volume Averaging ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Superheated Liquid ◽  
Fuel Injector ◽  
Flash Boiling

A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multihole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from the engine combustion network (ECN). Simulations have been carried out for a fixed needle lift. The effects of turbulence, compressibility, and noncondensable gases have been considered in this work. Standard k–ε turbulence model has been used to model the turbulence. Homogeneous relaxation model (HRM) coupled with volume of fluid (VOF) approach has been utilized to capture the phase-change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine nonflashing and evaporative, nonflashing and nonevaporative, and flashing conditions. Noticeable hole-to-hole variations have been observed in terms of mass flow rates for all the holes under all the operating conditions considered in this study. Inside the nozzle holes mild cavitationlike and in the near-nozzle region flash-boiling phenomena have been predicted when liquid fuel is subjected to superheated ambiance. Under favorable conditions, considerable flashing has been observed in the near-nozzle regions. An enormous volume is occupied by the gasoline vapor, formed by the flash boiling of superheated liquid fuel. Large outlet domain connecting the exits of the holes and the pressure outlet boundary appeared to be necessary leading to substantial computational cost. Volume-averaging instead of mass-averaging is observed to be more effective, especially for finer mesh resolutions.

Investigation of Fuel Spray Propagation, Combustion and Soot Formation/Oxidation in a Single Cylinder Medium Speed Diesel Engine

2012 ◽  
Author(s):  
Fridolin Unfug ◽  
Uwe Wagner ◽  
Kai W. Beck ◽  
Juergen Pfeil ◽  
Ulf Waldenmaier ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
High Speed ◽  
Liquid Fuel ◽  
Combustion Process ◽  
Fuel Spray ◽  
Soot Concentration ◽  
Single Cylinder ◽  
Medium Speed ◽  
532 Nm

To fulfil strict emission regulations and the need for higher efficiency of future Diesel engines require an optimized combustion process. Optical investigations represent a powerful tool for getting a better understanding of the ongoing processes. For medium speed Diesel engines, optical investigations are relatively rare or not available. The “Institut für Kolbenmaschinen” (IFKM) and MAN Diesel & Turbo SE performed extensive optical in-situ investigations of the injection and combustion process of a MAN 32/44 CR single cylinder medium speed Diesel engine that provide previously unavailable insights into the ongoing processes. The optical investigations aimed on fuel spray visualization, high-speed soot luminescence measurement and two colour pyrometry applied for five combustion chamber regions. To apply the optical measurement techniques, two optical accesses were designed. Access no. 1 is placed near the cylinder liner. Access no. 2 is located close to the injector in a 46° angle to the cylinder vertical axis. An insert was used which consists of an illumination port and a visualization endoscope. Additionally some special nozzle designs were used beside the standard nozzle, which have one separated nozzle hole. This enables a simultaneous view from both optical accesses on the same flame cone. For Mie-Scattering investigation a pulsed Nd:YAG-Laser with 532 nm wavelength was used for illumination and a CCD-camera with an upstream 532 nm optical filter was used for visualization. This combination allows observing the liquid fuel distribution even after start of combustion. Penetration depth of liquid fuel spray was analysed for different swirl numbers, intake manifold pressures, injection timings and injection pressures. High-speed flame visualization was done by two CMOS cameras which were mounted at two different optical accesses with view on the same flame cone. Due to this application a simultaneous measurement of the flame distribution of two different views was possible. This enables a 3-dimensional investigation of the flame propagation process. In addition, the advanced two colour pyrometry was applied for five different regions of the same flame cone. Due to a calibration after each measurement the absolute radiant flux can be calculated and thus the absolute temperature and soot concentration. With this procedure it was possible to give a real temperature and soot concentration distribution of the flame cone. To provide more detailed information about the combustion process, selected engine operation points were simulated with a modified version of the CFD code KIVA3v-Release2 at the IFKM. The simulated results were compared to the measured data.

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