A Contribution to the Analysis of Turbulence Anisotropy and Nonhomogeneity in an Open-Chamber Diesel Engine

1999 ◽  
Vol 121 (2) ◽  
pp. 226-234 ◽  
Author(s):  
E. Spessa
Keyword(s):  
Diesel Engine ◽  
Specific Reference ◽  
Spectral Structure ◽  
Turbulence Structure ◽  
Time Frequency ◽  
Piston Bowl ◽  
Crank Angle ◽  
Speed Dependence ◽  
Helical Intake Port ◽  
All Speeds

Further investigation of the turbulence time-frequency spectral structure and its anisotropy and nonhomogeneity has been carried out in the combustion chamber of an automotive diesel engine with a high-squish reentrant in-piston-bowl and a helical intake port. An advanced HWA technique was applied for turbulence measurements along the injector axis, under motored engine conditions in the speed range of 600–3000 rpm. Autospectral density functions of each fluctuating velocity component, as was determined by a specific sensor-wire orientation, were evaluated in consecutive crank-angle correlation intervals during the induction, compression, and early expansion strokes. In order to study the speed dependence of the turbulence-structure anisotropy and nonhomogeneity in different portions of the engine cycle, time-scales of cycle-resolved and conventional turbulent fluctuations were analyzed as functions of the engine speed for different wire orientations, measurement locations, and correlation intervals. Anisotropy and nonhomogeneity were generally significant at low engine speeds, whereas a tendency towards isotropy and homogeneity was found by increasing the speed. With specific reference to the bowl-generated turbulence, spectral anisotropy was remarkable at all speeds in the reverse-squish flow, close to the cylinder-head wall. However, spectral nonhomogeneity was the main feature of the direct-squish flow at low engine speeds.

Soot Evolution With Cyclic Crank-Angle-Resolved Two-Color Thermometry in an Optical Diesel Engine Fueled With Biodiesel Blend and ULSD

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Kan Zha ◽  
Radu-Catalin Florea ◽  
Marcis Jansons
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Soot Formation ◽  
Soot Temperature ◽  
Soot Emission ◽  
Piston Bowl ◽  
Crank Angle ◽  
Wall Impingement ◽  
Kl Factor ◽  
Biodiesel Blend

Biodiesel is a desirable alternative fuel for the diesel engine due to its low engine-out soot emission tendency. When blended with petroleum-based diesel fuels, soot emissions generally decrease in proportion to the volume fraction of biodiesel in the mixture. While comparisons of engine-out soot measurements between biodiesel blends and petroleum-based diesel have been widely reported, in-cylinder soot evolution has not been experimentally explored to the same extent. To elucidate the soot emission reduction mechanism of biodiesel, a single-cylinder optically-accessible diesel engine was used to compare the in-cylinder soot evolution when fueled with ultra-low sulfur diesel (ULSD) to that using a B20 biodiesel blend (20% vol./vol. biodiesel ASTM D6751-03A). Soot temperature and KL factors are simultaneously determined using a novel two-color optical thermometry technique implemented with a high-speed CMOS color camera having wide-band Bayer filters. The crank-angle resolved data allows quantitative comparison of the rate of in-cylinder soot formation. High-speed spray images show that B20 has more splashing during spray wall impingement than ULSD, distributing rebounding fuel droplets over a thicker annular ring interior to the piston bowl periphery. The subsequent soot luminescence is observed by high-speed combustion imaging and soot temperature and KL factor measurements. B20 forms soot both at low KL magnitudes over large areas between fuel jets, and at high values among remnants of the fuel spray, along its axis and away from the bowl edge. In contrast, ULSD soot luminescence is observed exclusively as pool burning on the piston bowl surfaces resulting from spray wall impingement. The soot KL factor evolution during B20 combustion indicates earlier and significantly greater soot formation than with ULSD. B20 combustion is also observed to have a greater soot oxidation rate, which results in lower late-cycle soot emissions. For both fuels, higher fuel injection pressure led to lower late-cycle soot KL levels. The apparent rate of heat release (ARHR) analysis under steady skip-fire conditions indicates that B20 combustion is less sensitive to wall temperature than that observed with ULSD due to a lesser degree of pool burning. B20 was found to have both a shorter ignition delay and shorter combustion duration than ULSD.

scholarly journals Numerical investigation of injection parameters and piston bowl geometries on emission and thermal performance of DI diesel engine

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Ikhtedar Husain Rizvi ◽  
Rajesh Gupta
Keyword(s):  
Diesel Engine ◽  
Thermal Performance ◽  
Equivalence Ratio ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Injection Nozzle ◽  
Piston Bowl ◽  
Injection Parameters ◽  
Nozzle Size ◽  
Engine Emission

AbstractTightening noose on engine emission norms compelled manufacturers globally to design engines with low emission specially NOx and soot without compromising their performance. Amongst various parameters, shape of piston bowls, injection pressure and nozzle diameter are known to have significant influence over the thermal performance and emission emanating from the engine. This paper investigates the combined effect of fuel injection parameters such as pressure at which fuel is injected and the injection nozzle size along with shape of piston bowl on engine emission and performance. Numerical simulation is carried out using one cylinder naturally aspirated diesel engine using AVL FIRE commercial code. Three geometries of piston bowls with different tumble and swirl characteristics are considered while maintaining the volume of piston bowl, compression ratio, engine speed and fuel injected mass constant along with equal number of variations for injection nozzle size and pressures for this analysis. The investigation corroborates that high swirl and large turbulence kinetic energy (TKE) are crucial for better combustion. TKE and equivalence ratio also increased as the injection pressure increases during the injection period, hence, enhances combustion and reduces soot formation. Increase in nozzle diameter produces higher TKE and equivalence ratio, while CO and soot emission are found to be decreasing and NOx formation to be increasing. Further, optimization is carried out for twenty-seven cases created by combining fuel injection parameters and piston bowl geometries. The case D2H1P1 (H1 = 0.2 mm, P1 = 200 bar) found to be an optimum case because of its lowest emission level with slightly better performance.

A Computational Investigation of Piston Bowl Geometry for a Large Bore Two-Cycle Diesel Engine

2011 ◽  
Author(s):  
Jonathan Dolak ◽  
Deep Bandyopadhyay
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Simulation Software ◽  
Spray Angle ◽  
Tier 2 ◽  
Piston Bowl ◽  
Cylinder Test ◽  
Advanced Combustion ◽  
Combustion Simulation ◽  
Reduce Emissions

The objective of this research was to optimize an Electro-Motive Diesel (EMD) large-bore, two-cycle diesel engine (710 cubic inches of displacement per cylinder) at high load to minimize soot, nitrogen oxide (NOx) and fuel consumption. The variables considered were the number of spray-hole nozzles per injector, including spray angle and piston bowl geometry, for a range of injection pressures. Analytical simulations were conducted for a calibrated EMD 710 Tier 2 engine and a few of the top-performing cases were studied in detail. CONVERGE™, a commercially available, advanced combustion simulation software was used in this analysis. A surface deforming tool, Sculptor®, was used to obtain various piston bowl geometries. MiniTab® was utilized for statistical analysis. Results show that optimal combinations of injection variables and piston bowl shape exist to simultaneously reduce emissions and fuel consumption compared to Tier 2 EMD 710 engines. These configurations will be further tested in a single-cylinder test cell and presented later. This investigation shows the importance of bowl geometry and spray targeting on emissions and fuel consumption for large-bore, two-stroke engines with high power density.

scholarly journals Multiresolution analysis of vibration signals acquired from locomotive Diesel engine for classification of engine states basing on signal statistical parameters

2017 ◽  
Vol 168 (1) ◽  
pp. 68-72
Author(s):  
Piotr BOGUŚ ◽  
Mateusz CIESZYŃSKI ◽  
Jerzy MERKISZ
Keyword(s):  
Diesel Engine ◽  
Complex Analysis ◽  
Statistical Parameters ◽  
Vibration Signals ◽  
Time Frequency ◽  
Significant Difference ◽  
Before And After ◽  
On Line ◽  
Locomotive Diesel

The paper presents a method of classification of locomotive Diesel engine states basing on vibration signals taken from an engine body and using chosen statistical parameters calculated for the original signal and it wavelet multiresolution components. The researches presented in the paper concern estimation of an engine states before and after a general repair. The target application of the presented researches is an on-line diagnostic system which can complement standard OBD systems. To this purpose the applied methods should not base on complex analysis of some spectral, time-frequency or scalogram plots but rather on choosing single diagnostic parameters which are suitable for the fast on-line diagnostic. The results have showed the significant difference in distinguishing of engine work before and after a general repair using some chosen statistical parameters applied to vibration signals.

scholarly journals Influence of Chemical Composite Additive on Combustion and Emission Characteristics of a Diesel Engine using Waste Plastic Oil as Fuel and Modified Piston Bowl

2018 ◽  
Vol 34 (6) ◽  
pp. 2806-2813
Author(s):  
Pappula Bridjesh ◽  
Pitchaipillai Periyasamy ◽  
Narayanan Kannaiyan Geetha
Keyword(s):  
Experimental Investigation ◽  
Diesel Engine ◽  
Combustion Chamber ◽  
Emission Characteristics ◽  
Soy Lecithin ◽  
Physiochemical Properties ◽  
Waste Plastic ◽  
Piston Bowl ◽  
Waste Plastic Oil ◽  
Engine Combustion

This experimental investigation is an endeavour to substitute diesel with WPO as fuel on a diesel engine. Enhancing the physiochemical properties of WPO or with hardware modifications on the engine, the performance of engine could not be improved up to the mark. The physiochemical properties of WPO are enhanced by the use of composite additive, which is a mixture of soy lecithin and 2-ethylhexyl nitrate and to improve the in-cylinder air motion; subsequently to increase the swirl and turbulence, standard hemispherical combustion chamber is modified to toroidal spherical grooves combustion chamber. The results of combined effect of modifying the combustion chamber and addition of composite additive suggest that improvements in engine-out emissions can be obtained from current diesel engines by enhancing physiochemical properties of fuel and matching geometry of combustion chamber. Engine combustion and emission characteristics under various loads for various fuels under test are as well studied.

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