Induction System Effects on Small-Scale Turbulence in a High-Speed Diesel Engine

1987 ◽  
Vol 109 (4) ◽  
pp. 491-502 ◽  
Author(s):  
A. E. Catania ◽  
A. Mittica
Keyword(s):  
Diesel Engine ◽  
Turbulence Intensity ◽  
High Speed ◽  
Engine Speed ◽  
Small Scale ◽  
Cylinder Wall ◽  
System Configuration ◽  
Intake System ◽  
Induction System ◽  
Scale Turbulence

The influence of the induction system on small-scale turbulence in a high-speed, automotive diesel engine was investigated under variable swirl conditions. The induction system was made up of two equiverse swirl tangential ducts, and valves of the same size and lift. Variable swirl conditions were obtained by keeping one of the inlet valves either closed or functioning, and by changing engine speed. The investigation was carried out for two induction system configurations: with both ducts operating and with only one of them operating. Two different engine speeds were considered, one relatively low (1600 rpm) and the other quite high (3000 rpm), the latter being the highest speed at which engine turbulence has been measured up to now. Cycle-resolved hot-wire anemometry measurements of air velocity were performed throughout the induction and compression strokes, under motored conditions, along a radial direction at an axial level that was virtually in the middle of the combustion chamber at top dead center. The velocity data were analyzed using the nonstationary time-averaging procedure previously developed by the authors. Correlation and spectral analysis of the small-scale turbulence so determined was also performed. The turbulence intensity and its degree of nonhomogeneity and anisotropy were sensibly influenced by the variable swirl conditions, depending on both the intake system configuration and engine speed; they generally showed an increase with increasing swirl intensity, at the end of the compression stroke. A similar trend was observed in the cyclic fluctuation of both the mean velocity and turbulence intensity. The micro time scale of turbulence was found to be almost uniform during induction and compression, showing a slight dependence on the measurement point and on the intake system configuration, but a more sensible dependence on the engine speed. No effect of the cylinder wall on turbulence was apparent.

On the Premixed Combustion in a Direct-Injection Diesel Engine

1987 ◽  
Vol 109 (2) ◽  
pp. 187-192 ◽  
Author(s):  
A. C. Alkidas
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Engine Speed ◽  
Direct Injection ◽  
Premixed Combustion ◽  
Injection Timing ◽  
Oxides Of Nitrogen ◽  
Nitrogen Emissions ◽  
Direct Injection Diesel Engine ◽  
Diffusion Burning

The factors influencing premixed burning and the importance of premixed burning on the exhaust emissions from a small high-speed direct-injection diesel engine were investigated. The characteristics of premixed and diffusion burning were examined using a single-zone heat-release analysis. The mass of fuel burned in premixed combustion was found to be linearly related to the product of engine speed and ignition-delay time and to be essentially independent of the total amount of fuel injected. Accordingly, the premixed-burned fraction increased with increasing engine speed, with decreasing fuel-air ratio and with retarding injection timing. The hydrocarbon emissions did not correlate well with the premixed-burned fraction. In contrast, the oxides of nitrogen emissions were found to increase with decreasing premixed-burned fraction, indicating that diffusion burning, and not premixed burning, is the primary source of oxides of nitrogen emissions.

The influence of inter-jet spacing and jet-swirl interaction on flame image velocimetry (FIV) derived flow fields in a small-bore diesel engine

2021 ◽  
pp. 146808742110384
Author(s):  
Jinxin Yang ◽  
Lingzhe Rao ◽  
Charitha de Silva ◽  
Sanghoon Kook
Keyword(s):  
Diesel Engine ◽  
Turbulence Intensity ◽  
High Speed ◽  
Jet Impingement ◽  
Flow Fields ◽  
Bulk Flow ◽  
Frame Rate ◽  
Wall Jet ◽  
Jet Interaction ◽  
Image Velocimetry

This study applies Flame Image Velocimetry (FIV) to show the in-flame flow field development with an emphasis on the jet-jet interaction and jet-swirl interaction phenomena in a single-cylinder small-bore optically accessible diesel engine. Two-hole nozzle injectors with three different inter-jet spacing angles of 45°, 90° and 180° are prepared to cause different levels of jet-jet interaction. The engine has a swirl ratio of 1.7, which is used to evaluate jet-swirl interaction of the selected 180° inter-jet spacing nozzle. High-speed soot luminosity imaging was performed at a high frame rate of 45 kHz for the FIV processing. For each inter-jet spacing angle, a total of 100 individual combustion cycles were recorded to address the cyclic variations. The ensemble averaged flow fields are shown to illustrate detailed flow structures while the Reynolds decomposition using spatial filtering is applied to analyse turbulence intensity. The results showed reduced bulk flow magnitude and turbulence intensity at smaller inter-jet spacing, suggesting the two opposed wall-jet heads colliding immediately after the jet impingement on the wall can cause flow suppression effects. This raised a concern on the mixing as lower inter-jet spacing creates more fuel-rich mixtures in the jet-jet interaction region. Despite lower flow magnitude, the cyclic variation was also estimated higher for narrower inter-jet spacing, which is another drawback of the significant jet-jet interaction. Regarding the jet-swirl interaction, the wall-jet head penetrating on the up-swirl side showed lower bulk flow magnitude as the counter-flow arrangement suppressed the flow, similar with the narrower interact-jet spacing results. However, the turbulence intensity was measured higher on the up-swirl side, suggesting the relatively weaker swirl flow vectors opposed to the penetrating wall-jet head could in fact enhance the mixing.

scholarly journals Airflow Characteristics Investigation of a Diesel Engine for Different Helical Port Openings and Engine Speeds

2021 ◽  
Vol 53 (3) ◽  
pp. 210306
Author(s):  
Willyanto Anggono ◽  
Mitsuhisa Ichiyanagi ◽  
Reina Saito ◽  
Gabriel J. Gotama ◽  
Chris Cornelius ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Turbulence Intensity ◽  
Engine Speed ◽  
Control Valve ◽  
Swirl Ratio ◽  
Airflow Velocity ◽  
Mean Velocity ◽  
Image Velocimetry ◽  
Port Opening ◽  
The Difference

Intake airflow characteristics are essential for the performance of diesel engines. However, previous investigations of these airflow characteristics were mostly performed on two-valve engines despite the difference between the airflow of two-valve and four-valve engines. Therefore, in this study, particle image velocimetry (PIV) investigations were performed on a four-valve diesel engine. The investigations were conducted under different engine speeds and helical port openings using a swirl control valve (SCV). The results suggest that the position of the swirl center does not significantly shift with different engine speeds and helical port openings, as the dynamics of the flow remained closely similar. The trends of the airflow characteristics can be best observed during the compression stroke. A higher engine speed increases the angular velocity of the engine more compared to the increase of the airflow velocity and results in a lower swirl ratio of the flow. On the other hand, a higher engine speed leads to a higher mean velocity and the variation of velocity results in a larger turbulence intensity of the flow. Increasing the helical port opening brings a reduction in the swirl ratio and turbulence intensity as more airflow from the helical port disturbs the airflow from the tangential port.

Knock criteria for aviation diesel engines

2016 ◽  
Vol 18 (7) ◽  
pp. 752-762 ◽  
Author(s):  
Rik D Meininger ◽  
Chol-Bum M Kweon ◽  
Michael T Szedlmayer ◽  
Khanh Q Dang ◽  
Newman B Jackson ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
High Speed ◽  
Thermal Stresses ◽  
Cetane Number ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Cylinder Wall ◽  
Analysis Model ◽  
Element Analysis

The objective of this study was to develop knock criteria for aviation diesel engines that have experienced a number of malfunctions during flight and ground operation. Aviation diesel engines have been vulnerable to knock because they use cylinder wall coating on the aluminum engine block, instead of using steel liners. This has been a trade-off between reliability and lightweighting. An in-line four-cylinder four-stroke direct-injection high-speed turbocharged aviation diesel engine was tested to characterize its combustion at various ground and flight conditions for several specially formulated Jet A fuels. The main fuel property chosen for this study was cetane number, as it significantly impacts the combustion of the aviation diesel engines. The other fuel properties were maintained within the MIL-DTL-83133 specification. The results showed that lower cetane number fuels showed more knock tendency than higher cetane number fuels for the tested aviation diesel engine. In this study, maximum pressure rise rate, or Rmax, was used as a parameter to define knock criteria for aviation diesel engines. Rmax values larger than 1500 kPa/cad require correction to avoid potential mechanical and thermal stresses on the cylinder wall coating. The finite element analysis model using the experimental data showed similarly high mechanical and thermal stresses on the cylinder wall coating. The developed diesel knock criteria are recommended as one of the ways to prevent hard knock for engine developers to consider when they design or calibrate aviation diesel engines.

On the noise sources of the unsuppressed high-speed jet

1971 ◽  
Vol 50 (1) ◽  
pp. 21-31 ◽  
Author(s):  
K. A. Bishop ◽  
J. E. Ffowcs Williams ◽  
W. Smith
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Large Scale ◽  
Jet Noise ◽  
Jet Flow ◽  
Scale Model ◽  
Small Scale ◽  
Noise Sources ◽  
Supersonic Transport ◽  
Scale Turbulence

The paper describes an interpretation of jet-noise theory and scale-model experiments to highlight physical properties of jet-noise sources at very high speed. The study is prompted by current efforts to suppress the noise of supersonic transport aircraft.The principal noise sources are shown to be very large-scale wave-like undulations of the jet flow that travel downstream at supersonic speed for a distance of several jet diameters. These motions are relatively well ordered and are probably more akin to recognizable instabilities of a laminar flow than the confused small-scale turbulence. Because of this we postulate a model of the noise generating motions as the instability products of a jet flow of low equivalent Reynolds number. This Reynolds number is based on an eddy viscosity and can be further reduced by artificially increasing the small-scale turbulence level. This step would tend to stabilize the flow and inhibit the formation of large-scale noise producing eddies.

scholarly journals Estimates of the turbulence intensity and power density of an asymmetrical tidal flow under variability of wind forcing

2019 ◽  
Vol 55 (2) ◽  
pp. 61-72
Author(s):  
K. A. Korotenko ◽  
A. V. Sentchev
Keyword(s):  
Power Density ◽  
Turbulence Intensity ◽  
Tidal Flow ◽  
Acoustic Doppler Current Profiler ◽  
Wind Forcing ◽  
Small Scale ◽  
Reynolds Stresses ◽  
Direct Measurements ◽  
Current Profiler ◽  
Scale Turbulence

A high-frequency (1.2 MHz) four-beam Acoustic Doppler Current Profiler (ADCP) moored on the seabed has been used for direct measurements of turbulence in a shallow coastal zone of the eastern English Channel. From the measurements conducted, 5 tidal cycles covering calm and storm periods were selected. Impacts of the tidal cycle asymmetry and the variability of wind forcing on the turbulence intensity, Reynolds stresses, and the power density of the flow are assessed quantitatively. A comparison of the energy characteristics of the tidal flow during calm and storm periods revealed that the power density of the stream during the storm was about half of that during the calm period. Wave bias correction of Reynolds stresses allows estimating a contribution of small-scale turbulence to its total intensity.

Experimental Study of Heat Transfer in a Direct Injection Diesel Engine

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
P. Raghu ◽  
R. Sundarrajan ◽  
R. Rajaraman ◽  
M. Ramaswamy ◽  
B. Sathyanaryanan
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Diesel Engine ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Engine Speed ◽  
Direct Injection ◽  
Cylinder Wall ◽  
Direct Injection Diesel Engine ◽  
Wide Range

An experimental study has been established to understand the effective cylinder wall heat transfer rate and temperature of a direct injection diesel engine. Temperatures were calculated under a wide range of load at different locations in the cylinder block and cylinder head of the engine using pre-arranged thermocouples to acquire the temperature gradient and consequently realize the equivalent heat transfer rate, cylinder wall temperatures, heat transfer co-efficient and engine speed. Diesel and biodiesel blends (B20 and B100) are used as fuels and the temperature readings are found using a ‘k-type’ thermocouple and temperature readings are noted. Raise in the cylinder temperature is observed as the engine torque increases for the diesel and biodiesel. As the engine speed increases, the exhaust gas velocity involved in and out of the engine will increases and this lead to an increase in the heat transfer co-efficient for diesel and biodiesel.

scholarly journals Analysis of Combustion Characteristics of Waste Plastic Disposal Fuel (WPDF) and Tire Derived Fuel (TDF)

2015 ◽  
Vol 773-774 ◽  
pp. 600-604 ◽  
Author(s):  
Mohd Herzwan Hamzah ◽  
Abdul Adam Abdullah ◽  
Agung Sudrajat ◽  
Nur Atiqah Ramlan ◽  
Nur Fauziah Jaharudin
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Ignition Delay ◽  
High Speed ◽  
Engine Speed ◽  
Fossil Fuel ◽  
Motor Vehicle ◽  
Peak Pressure ◽  
Combustion Characteristics ◽  
Waste Plastic

The increase of industrial activities and motor vehicles globally causes rise demands in fossil fuel as energy sources. Since fossil fuel is non-renewable energy, many researches have been conducted to reduce the reliance to this fossil fuel. In conjunction, the number of waste plastic and tires around the world is increasing as a result of modern application and increasing number of motor vehicle. This type of waste is hard to decays and commonly dumped onto open landfills. Utilization of waste tires and plastics can produce alternative fuel that potentially can be used in diesel engine. In this paper, the combustion characteristics of two waste source fuels known as waste plastic disposal fuel (WPDF) and tire disposal fuel (TDF) are discussed. The combustion characteristics of both fuels are compared to diesel fuel. WPDF and TDF used in this experiment are pure concentrated and not blended with diesel fuel. The experiment is conducted using single cylinder YANMAR TF120M diesel engine. The engine is operated at constant load at 20 Nm and variable speed ranged from 1200 rpm to 2400 rpm. The combustion characteristics that discussed in this paper are ignition delay and peak pressure. Both characteristic are measured at two engine speed region which is low speed (1200 rpm) and high speed (2100 rpm). From the results obtained, it can be observed that WPDF has comparable ignition delay compared to diesel fuel while TDF has longest ignition delay compared to WPDF and diesel fuel. TDF also produce highest peak pressure compared to other tested fuels. Moreover, TDF is not suitable for high speed application since it cause backfire when engine speed reach 2200 rpm.

The Effect of In-Cylinder Turbulence on Lean, Premixed, Spark Ignited Engine Performance

2015 ◽  
Author(s):  
Baine Breaux ◽  
Chris Hoops ◽  
William Glewen
Keyword(s):  
High Speed ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Engine Performance ◽  
Small Scale ◽  
Cylinder Wall ◽  
Lean Burn ◽  
Combustion Duration ◽  
Rate Of Heat Release ◽  
Operational Constraints

The intensity and structure of in-cylinder turbulence is known to have a significant effect on internal combustion engine performance. Changes in flow structure and turbulence intensity result in changes to the rate of heat release, cylinder wall heat rejection, and cycle-to-cycle combustion variability. This paper seeks to quantify these engine performance consequences and identify fundamental similarities across a range of high-speed, medium-bore, lean-burn, spark-ignited reciprocating engines. In-cylinder turbulence was manipulated by changing the extent of intake port-induced swirl as well as varying the level of piston-generated turbulence. The relationship between in-cylinder turbulence and engine knock is also discussed. Increasing in-cylinder turbulence generally reduces combustion duration, but test results reveal that increasing swirl beyond a critical point can cause a lengthening of burn durations and greatly reduced engine performance. This critical swirl level is related to the extent of small-scale, piston generated turbulence present in the cylinder. Increasing in-cylinder turbulence generally leads to reduced cycle-to-cycle variability and increased detonation margin. The overall change in thermal efficiency was dependent on the balance of these factors and wall heat transfer, and varied depending on the operational constraints for a given engine and application. Single cylinder engine test data, supported with three dimensional CFD results are used to demonstrate and explain these basic combustion engine principles.

The Effect of In-Cylinder Turbulence on Lean, Premixed, Spark-Ignited Engine Performance

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Baine Breaux ◽  
Chris Hoops ◽  
William Glewen
Keyword(s):  
High Speed ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Engine Performance ◽  
Small Scale ◽  
Cylinder Wall ◽  
Lean Burn ◽  
Combustion Duration ◽  
Rate Of Heat Release ◽  
Operational Constraints

The intensity and structure of in-cylinder turbulence is known to have a significant effect on internal combustion engine performance. Changes in flow structure and turbulence intensity result in changes to the rate of heat release, cylinder wall heat rejection, and cycle-to-cycle combustion variability. This paper seeks to quantify these engine performance consequences and identify fundamental similarities across a range of high-speed, medium-bore, lean-burn, spark-ignited reciprocating engines. In-cylinder turbulence was manipulated by changing the extent of intake port-induced swirl as well as varying the level of piston-generated turbulence. The relationship between in-cylinder turbulence and engine knock is also discussed. Increasing in-cylinder turbulence generally reduces combustion duration, but test results reveal that increasing swirl beyond a critical point can cause a lengthening of burn durations and greatly reduced engine performance. This critical swirl level is related to the extent of small-scale, piston-generated turbulence present in the cylinder. Increasing in-cylinder turbulence generally leads to reduced cycle-to-cycle variability and increased detonation margin (DM). The overall change in thermal efficiency was dependent on the balance of these factors and wall heat transfer, and varied depending on the operational constraints for a given engine and application. Single cylinder engine test data, supported with three-dimensional computational fluid dynamics (CFD) results, are used to demonstrate and explain these basic combustion engine principles.

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