Periodic liquid fuel sprays combustion processes and their damping of combustion instabilities

2000 ◽  
Author(s):  
R. Heising ◽  
E. Lubarsky ◽  
M. Neumaier ◽  
Y. Neumeier ◽  
B. Zinn
Keyword(s):  
Liquid Fuel ◽  
Combustion Instabilities ◽  
Fuel Sprays ◽  
Combustion Processes

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.

KESAN SUDUT PUSARAN TERHADAP PEMBENTUKAN EMISI MENGGUNAKAN DWI PEMUSAR UDARA ALIRAN JEJARIAN

2017 ◽  
Vol 79 (2) ◽  
Author(s):  
Muhammad Roslan Rahim ◽  
Mohammad Nazri Mohd Jaafar
Keyword(s):  
Temperature Profile ◽  
Liquid Fuel ◽  
Swirling Flow ◽  
Environmentally Friendly ◽  
Adverse Impact ◽  
Nox Emissions ◽  
Combustion System ◽  
Fuel Sprays ◽  
Low Emission

Combustion of liquid fuel sprays produces NOX, CO and other emissions that have an adverse impact on the environment and humans. This study is conducted to produce low-emission combustion with the use of double radial swirler. Swirling flow burning will enhance the mixing of fuel and air to produce a flame that is more stable and efficient. In this study, weak swirler with an angle of 30º is set as a primary swirler and strong swirlers each with an angle of 40º, 50º and 60º are set as the secondary swirler. Combinations of these swirlers helped the mixing of fuel and air during combustion. The results show, the combination of swirlers 30º/60º produced the highest temperature profile, the best flames, more stable and shorter than other combinations. NOX emissions for the combination of swirlers 30º/60º at stoichiometric are 15.6% lower than the combinations of swirlers 30º/40º. Other emissions such as CO, also shows 8.4% of reduction in the combination of swirlers 30º/60º. These results indicated that double swirlers helped in reducing emissions during combustion and also producing an environmentally friendly combustion system.

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