A Correlation for Air Velocities in Cylindrical Prechambers of Diesel Engines

1981 ◽  
Vol 103 (3) ◽  
pp. 499-504 ◽  
Author(s):  
B. A. Ajakaiye ◽  
J. C. Dent
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Theoretical Analysis ◽  
Diesel Engines ◽  
Air Velocity ◽  
Additional Tool ◽  
Injection Type ◽  
Air Motion ◽  
Theory And Experiment

Theoretical analysis and measurements of air velocities in cylindrical prechambers of the indirect injection type Diesel engine are reported. Comparisons are made between the theoretical analysis and the measurements for two cylindrical prechambers tested in the present study and the results of previous investigators [4–6], A correlation is derived-to link air velocity in the cylindrical prechamber and known engine parameters. The results show that there is poor and inconsistent agreement between theory and experiment in some of the cases considered. Reasons are suggested to explain these inconsistencies. The derived correlation could serve as an additional tool for the engine designer in predicting air motion and hence combustion and heat transfer in the prechamber of indirect injection diesel engine.

Thermal modelling of modern diesel engines: proposal of a new heat transfer coefficient correlation

2011 ◽  
Vol 225 (11) ◽  
pp. 1544-1560 ◽  
Author(s):  
C A Finol ◽  
K Robinson
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Diesel Engines ◽  
Internal Combustion Engines ◽  
Operating Conditions ◽  
Boost Pressure ◽  
Simple Relationship

Existing methods for predicting heat fluxes and temperatures in internal combustion engines, which take the form of correlations to estimate the heat transfer coefficient on the gas-side of the combustion chamber, are based on methodology developed over the past 50 years, often updated in view of more recent experimental data. The application of these methods to modern diesels engines is questionable because key technologies found in current engines did not exist or were not widely used when those methods were developed. Examples of such technologies include: high-pressure common rail and variable fuel injection strategies including retarded injection for nitrogen oxides emission control; exhaust gas re-circulation; high levels of intake boost pressure provided by a single- or double-stage turbocharger and inter-cooling; multiple valves per cylinder and lower swirl; and advanced engine management systems. This suggests a need for improved predicting tools of thermal conditions, specifically temperature and heat flux profiles in the engine block and cylinder head. In this paper a modified correlation to predict the gas-side heat transfer coefficient in diesel engines is presented. The equation proposed is a simple relationship between Nu and Re calibrated to predict the instantaneous spatially averaged heat transfer coefficient at several operating conditions using air as gas in the model. It was derived from the analysis of experimental data obtained in a modern diesel engine and is supported by a research methodology comprising the application of thermodynamic principles and fundamental equations of heat transfer. The results showed that the new correlation adequately predicted the instantaneous coefficient throughout the operating cycle of a high-speed diesel engine. It also estimated the corresponding cycle-averaged heat transfer coefficient within 10 per cent of the experimental value for the operating conditions considered in the analysis.

Methods for Determining the Thermal State of Medium-Speed Diesel Engines Taking into Account Boiling of the Coolant

2020 ◽  
pp. 22-28
Author(s):  
L.L. Myagkov ◽  
V.M. Sivachev
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Thermal State ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cylinder Liner ◽  
Thermal Factor ◽  
Medium Speed ◽  
Thermal Fatigue Cracks

Forcing medium-speed diesel engines by increasing the mean effective pressure leads to an increase in the thermal factor of the engine parts. High temperatures of the cylinder head fire deck and the cylinder liner working surface cause thermal fatigue cracks in these parts as well as piston scuffing. Therefore, the development of new methods of intensifying heat transfer in the cooling gallery and refined methods for determining the engine parts thermal state is currently relevant. In both areas of research, a significant role is played by the process of coolant boiling, which significantly intensifies heat transfer in the cooling system. A review of the literature showed that the existing methods of mathematical modeling of conjugate heat transfer in the cooling cavities taking into account the boiling process have a number of significant drawbacks. This paper presents the developed mathematical model and methods for determining the thermal state of medium-speed diesel engine parts taking into account boiling of the coolant, thus making it possible to combine the advantages of both the engineering approach and numerical simulation based on computational fluid dynamics. The thermal state of a new generation medium-speed diesel engine D500 was calculated and the thermal factor of the main engine parts was estimated.

A Steady-State Air Motion Study in a V-6 Uniflow Scavenged Two-Stroke Diesel Engine

1988 ◽  
Vol 110 (3) ◽  
pp. 503-508
Author(s):  
T. D. Doan ◽  
E. F. Crawford ◽  
S. J. Hinkle
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Airflow Rate ◽  
Maximum Difference ◽  
Motion Study ◽  
Air Motion ◽  
Insight Into

This paper presents new insight into the causes of cylinder-to-cylinder variation in swirl torque and airflow in uniflow scavenged, two-stroke diesel engines. A V-6 model of such an engine was investigated as a flow rig under steady-state conditions. These variations were found to be primarily caused by the effect of the airbox walls on the air motion. The maximum difference in the baseline cylinder-to-cylinder swirl torque and airflow rate was 11 and 3.5 percent, respectively. Two airbox design modifications, resulting from the study, in turn demonstrated increased cylinder airflow rate and reduced cylinder-to-cylinder swirl torque variation on the flow rig.

LDA Measurement and a Theoretical Analysis of the In-Cylinder Air Motion in a DI Diesel Engine

1985 ◽  
Author(s):  
Shin Matsuoka ◽  
Takeyuki Kamimoto ◽  
Tomonori Urushihara ◽  
Yoshihiro Mochimaru ◽  
Hideo Morita
Keyword(s):  
Diesel Engine ◽  
Theoretical Analysis ◽  
Di Diesel Engine ◽  
Air Motion ◽  
Lda Measurement

A Model for Drilled Cooling in the Valve Bridge of Cylinder Head

2011 ◽  
Vol 52-54 ◽  
pp. 338-342
Author(s):  
Xiao Liu ◽  
Wei Zheng Zhang ◽  
Chang Hu Xiang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Theoretical Analysis ◽  
Transfer Coefficient ◽  
Cylinder Head ◽  
3D Model ◽  
Numerical Study ◽  
The Mathematical Model

To evaluate the efficiency of drilled cooling in the valve bridge of cylinder head, theoretical analysis for the drilled cooling is carried out, and a mathematical model for the enhanced cooling is presented based on a simplified 3D model. The mathematical model is validated by numerical study on the heat transfer with and without drilled cooling, which is carried out through fluid-solid coupling. The correlation between the velocity in the drilled passage and heat transfer coefficient was also analyzed. The results can be used to solve the heat transfer in enhanced diesel engine.

The Need for Excellence

1989 ◽  
Vol 203 (1) ◽  
pp. 1-18
Author(s):  
C C J French
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Internal Combustion Engine ◽  
Diesel Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
World Market ◽  
The Future

The 1988 President gives a brief resume of his education and apprenticeship and then goes on to review his career at Ricardo Consulting Engineers. He describes some of the projects with which he has been involved, including a torpedo engine, a recycle diesel engine, heat transfer in engines, two-cycle diesel engines and the Atlas research engine. He discusses the future of the reciprocating internal combustion engine and concludes by emphasizing the need for engineering excellence in an increasingly competitive world market.

scholarly journals IMPROVING FUEL EFFICIENCY OF MARINE SWIRL-CHAMBER DIESEL ENGINE BY INCREASED THERMAL RESISTANCE OF HEAT TRANSFER

2019 ◽  
pp. 80-87
Author(s):  
Alexander Fedorovich Dorokhov ◽  
Pavel Aleksandrovitch Dorokhov
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Thermal Resistance ◽  
Combustion Chamber ◽  
Fuel Consumption ◽  
Diesel Engines ◽  
Fuel Efficiency ◽  
Working Fluid ◽  
Gas Temperature ◽  
Swirl Chamber

The article considers ship swirl-chamber diesel engines used in shipbuilding as the main and auxiliary engines. Two reasons for low profitability of the swirl chamber diesel engines are highlighted: large heat losses of the cooling working fluid due to the extended heat transfer surface of the chamber, and significant aerodynamic energy losses of compressed air during its passage through a relatively narrow channel connecting the piston chamber with the combustion chamber and the flow of gases from the swirl chamber on top the piston space. There have been proposed the methods for improving the operational performance of swirl-chamber diesels in production, in particular, their fuel efficiency. The scheme of the swirl-chamber and a section of the swirl-chamber cylinder head are presented. It has been stated that the total coefficient of thermal conductivity can be reduced if the wall of the swirl- chamber is made multi-layer. The layouts of a multi-layer cylinder-spherical wall of a swirl combustion chamber with a titanium cylinder-spherical insertion and thermal insulation of a vortex combustion chamber are given. The total thermal resistance of the spherical wall was calculated, heat loss through the multilayer spherical wall was determined, gas temperature in the vortex chamber was calculated, according to the average cycle temperature diagram. It was inferred that the amount of heat removed from the working fluid to cooling through the thermally insulated wall of the swirl-chamber will be 40% less than the amount of heat released to the cooling through the wall of the swirl-chamber of a commercial diesel engine. The difference in heat will be used to increase the indicator gas operation, which, with the same cyclic fuel supply, will lead to a decrease in the specific indicator fuel consumption, and at a constant level of internal engine losses - to a decrease in the specific effective fuel consumption.

scholarly journals Numerical determination of the velocity fields of the working medium in the combustion chamber of a marine high-speed diesel engine

2020 ◽  
pp. 92-97
Author(s):  
Б.И. Руднев ◽  
О.В. Повалихина
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Combustion Chamber ◽  
Convective Heat ◽  
Diesel Engines ◽  
High Speed ◽  
Velocity Fields ◽  
Marine Diesel Engine ◽  
Working Medium ◽  
Marine Diesel

Современные тенденции развития судовых дизелей связаны, прежде всего с улучшением их энергетических и экологических характеристик. Это обуславливает появление ряда проблем, важнейшая из которых – возрастание теплонапряженности деталей, образующих камеру сгорания. Высокие локальные тепловые потоки на поверхностях крышки цилиндра, поршня и втулки являются одной из главных причин, снижающих эксплуатационную надежность форсированных судовых дизелей. Достоверность расчетной оценки теплового и напряженно-деформированного состояния деталей, образующих камеру сгорания, определяется главным образом правильностью задания локальных граничных условий со стороны рабочего тела. Учитывая, что доля конвективного теплового потока в суммарном теплообмене достигает в среднем за рабочий цикл 60 – 70%, становится очевидной актуальность разработки надежных расчетно-теоретических методов определения полей скоростей рабочего тела в камере сгорания судовых дизелей. Целью данной статьи является дальнейшее совершенствование математической модели локального конвективного теплообмена в камере сгорания высокооборотного судового дизеля. Показано, что внешнее течение рабочего тела в камере сгорания может быть описано уравнениями Эйлера. Представлены поля скоростей рабочего тела в функции угла поворота коленчатого вала, полученные численным методом. Приведены изотермы и изобары рабочего тела, позволяющие более глубоко проанализировать физику процесса конвективного теплообмена в камере сгорания судового высокооборотного дизельного двигателя. Modern trends in the development of marine diesel engines are associated primarily with the improvement of their energy and environmental characteristics. This gives rise to a number of problems, the most important of which is an increase in the combustion intensity. High local heat fluxes on the surfaces of the cylinder head, piston and liner are one of the main reasons that reduce the operational reliability of boosted marine diesel engines. The reliability of the calculated estimate of the thermal and stress-strain state of parts that form the combustion chamber is mainly determined by the correctness of setting the local boundary conditions from the part of the working medium. Taking into account that the share of convective heat flux in the total heat exchange reaches, on average, 60 - 70% for a working cycle, it becomes obvious the urgency of developing reliable computational and theoretical methods for determining the velocity fields of the working medium in the combustion chamber of marine diesel engines. The purpose of this article is to further improve the mathematical model of local convective heat transfer in the combustion chamber of a high-speed marine diesel engine. It is shown that the external flow of the working medium in the combustion chamber can be described by the Euler equations. The velocity fields of the working medium as a function of the angle of rotation of the crankshaft obtained by the numerical method are shown. Isotherms and isobars of the working medium are given, which allow a more in-depth analysis of the physics of the convective heat transfer process in the combustion chamber of a high-speed marine diesel engine.

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