In-cylinder Studies of Fuel Injection and Combustion from a Narrow Cone Fuel Injector in a High Speed Single Cylinder Optical Engine

Author(s):  
K. Gill ◽  
Hua Zhao
Author(s):  

The necessity of adapting diesel engines to work on vegetable oils is justified. The possibility of using rapeseed oil and its mixtures with petroleum diesel fuel as motor fuels is considered. Experimental studies of fuel injection of small high-speed diesel engine type MD-6 (1 Ch 8,0/7,5)when using diesel oil and rapeseed oil and computational studies of auto-tractor diesel engine type D-245.12 (1 ChN 11/12,5), working on blends of petroleum diesel fuel and rapeseed oil. When switching autotractor diesel engine from diesel fuel to rapeseed oil in the full-fuel mode, the mass cycle fuel supply increased by 12 %, and in the small-size high-speed diesel engine – by about 27 %. From the point of view of the flow of the working process of these diesel engines, changes in other parameters of the fuel injection process are less significant. Keywords diesel engine; petroleum diesel fuel; vegetable oil; rapeseed oil; high pressure fuel pump; fuel injector; sprayer


2008 ◽  
Vol 610 ◽  
pp. 195-215 ◽  
Author(s):  
A. ANDRIOTIS ◽  
M. GAVAISES ◽  
C. ARCOUMANIS

Flow visualization as well as three-dimensional cavitating flow simulations have been employed for characterizing the formation of cavitation inside transparent replicas of fuel injector valves used in low-speed two-stroke diesel engines. The designs tested have incorporated five-hole nozzles with cylindrical as well as tapered holes operating at different fixed needle lift positions. High-speed images have revealed the formation of an unsteady vapour structure upstream of the injection holes inside the nozzle volume, which is referred to as ‘string-cavitation’. Computation of the flow distribution and combination with three-dimensional reconstruction of the location of the strings inside the nozzle volume has revealed that strings are found at the core of recirculation zones; they originate either from pre-existing cavitation sites forming at sharp corners inside the nozzle where the pressure falls below the vapour pressure of the flowing liquid, or even from suction of outside air downstream of the hole exit. Processing of the acquired images has allowed estimation of the mean location and probability of appearance of the cavitating strings in the three-dimensional space as a function of needle lift, cavitation and Reynolds number. The frequency of appearance of the strings has been correlated with the Strouhal number of the vortices developing inside the sac volume; the latter has been found to be a function of needle lift and hole shape. The presence of strings has significantly affected the flow conditions at the nozzle exit, influencing the injected spray. The cavitation structures formed inside the injection holes are significantly altered by the presence of cavitation strings and are jointly responsible for up to 10% variation in the instantaneous fuel injection quantity. Extrapolation using model predictions for real-size injectors operating at realistic injection pressures indicates that cavitation strings are expected to appear within the time scales of typical injection events, implying significant hole-to-hole and cycle-to-cycle variations during the corresponding spray development.


2011 ◽  
Vol 133 (10) ◽  
Author(s):  
A. Valera-Medina ◽  
N. Syred ◽  
P. Bowen ◽  
A. Crayford

Swirl stabilized combustion is a technology which, for stationary combustion, consumes more than 70 to 80% of the world’s fossil fuels. There have been many reviews of this technology, but there are still many gaps in understanding. This paper focuses on the general characteristics of a 100kW swirl burner, originally designed for poor quality fuels, in terms of flame characteristic, length and pressure fluctuations, to give a relative measure of the propensity of the system to respond to outside perturbations. Studied effects include swirl number, symmetry of the swirl flow system, type of fuel injector and mode of fuel injection. A range of techniques, including High Speed Photography (HSP), Particle Image Velocimetry (PIV) and fluctuating pressure measurements were used to create flame maps, flame length detail, and relative pressure amplitudes graphs. The results are discussed in the context of potential oscillations and coupling mechanisms including the effect of the precessing vortex core (PVC), recirculation and shear flow instabilities.


Author(s):  
Weilin Zeng ◽  
Xu He ◽  
Senjia Jin ◽  
Hai Liu ◽  
Xiangrong Li ◽  
...  

High-speed photography, two-color method, and thermodynamic analysis have been used to improve understanding of the influence of pilot injection timing on diesel combustion in an optical engine equipped with an electronically-controlled, common rail, high-pressure fuel injection system. The tests were performed at four different pilot injection timings (30 degree, 25 degree, 20 degree, and 15 degree CA BTDC) with the same main injection timing (5 degree CA BTDC), and under 100MPa injection pressure. The engine speed was selected at 1200 rev/min, and the whole injection mass was fixed as 27.4 mg/stroke. The experimental results showed that the pilot injection timing had a strong influence on ignition delay and combustion duration: advancing the pilot injection timing turned to prolong the ignition delay and shorten the combustion duration. The combustion images indicated that when pilot injection was advanced, the area of luminous flames decreased. The results of two-color method suggested pilot injection timing significantly impacted both the soot temperature distribution and soot concentration (KL factor) within the combustion chamber. 30 degree CA BTDC was the optimal pilot injection timing for in-cylinder soot reduction.


Author(s):  
Anatoli Borissov ◽  
James J. McCoy

Both physical and mathematical models were built to describe the main processes in large-bore gas engines. Based on the detail modeling and analysis of cylinder airflow, fuel injection, mixing, combustion and NOx generation, it was possible to pinpoint the problem of abnormal NOx production, even for lean mixtures, that occurs in these engines. In addition, analysis of the experimental data of jet mixing using high-speed photographic evidence, as well as engine performance data, has helped in the understanding of the mixing process. This has resulted in the development of a new way of the mixing of fuel and air utilizing multiple-nozzle supersonic injection. The fuel injection system is designed to optimize the mixing of the methane fuel with the air in the cylinder of a large bore natural gas engine. The design goals of low-pressure (<130 psi), all-electronic valve actuation, and optimal mixing were all achieved with a unique valve/nozzle arrangement. Later, a laser induced fluorescence method was used to take high-speed photographs of the development of the fuel jet exiting the newly developed supersonic electronic fuel injector (SSEFI). This result, together with the results of numerous experimental testing of SSEFI on different engines (GMVH-6, GMW-10, V-250, UTC-165) are presented as evidence of the success of the SSEFI application for the improvement of engine performance, engine control and NOx reduction.


1990 ◽  
Vol 112 (3) ◽  
pp. 422-430 ◽  
Author(s):  
J. Workman ◽  
G. M. Beshouri

Single-cylinder testing of an Electronic Pilot Fuel Injection (EPFI) system (reported in Part I) indicated that a 45 percent reduction in NOx emissions could be obtained with a 3 percent improvement in fuel consumption by replacing the mechanical system, delivering 6 percent pilot, with the EPFI at 2.9 percent delivery. Further optimization testing of this system at pilot levels down to 0.7 percent over a wide range of timings and air/fuel ratios resulted in even further reductions in NOx emissions without fuel penalty. The EPFI system can yield NOx emissions levels significantly below 2 g/BHP-h with an improvment in fuel consumption of at least 3–4 percent, and probably yield emissions level as low as 0.5 g/BHP-h without substantial penalties in efficiency or operability.


2012 ◽  
Vol 482-484 ◽  
pp. 1943-1946
Author(s):  
Li Dan Chen ◽  
Huang Xiang Shan

Through the discussion of main shortages of the high-speed electromagnetic valve used in electronic fuel injection system, the author introduced a new design thought of fuel injector based on 2D technology. Axial displacement of controlling valve was used to control the volume of gushing oil, while radial revolution of spool valve was used to change the time of injection. Additionally, mathematic modeling and MATLAB simulating indicated that, the injector designed based on 2D technology acquired the advantages of quick response and also realized the ideal shape of fuel injection rate.


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