A study on performance and emissions of a 4stroke ic engine operating on landfill gas with the addition of h2, co. May 03, 2017 knocking is a phenomenon of generating unwanted pressure wave which create unpleasant sound and can damage engine wall during combustion in engines. In this article, i am going to explain the various factors which will affect the combustion process. The factors which affect the flame propagations are the factors wh ich affect the flame propagations are ich affect the flame propagations are 111. The engine parameters which affect the density are as follows. Discuss these whether the engine parameters can be controlled by the engine operator or ecu to mitigate the knocking conditions. Increasing the inlet pressure increases the overall pressure. Sep 05, 2014 such, a situation produces extreme pressure differentials and violent gas vibration known as knocking diesel knock, and is evidenced by audible knock. The expansion ratio which may or may not equal to the compression ratio determines how much work is.
Increasing the load opens the throttle valve more and thus the density. Preparation of fuelair mixture is done outside the engine cylinder and formation of a homogeneous mixture is normally not completed in the inlet manifold. Sometimes the mixture must be altered for a given installation to compensate for the effect of cowl design, cooling airflow, or other factors on engine cooling. The final fuelair mixture curves take into account economy, power, engine cooling, idling characteristics, and all other factors that affect combustion. Engine trouble, engine knocking, factors affecting knocking. Stages of combustion, delay period, ignition lag and the factors affecting it, detonation in c. Prolonged and intense knocking can break the piston or the engine, though it is can also endure this slight issue for thousands of miles. Each event may be one or more knocking cycles mechanism not yet defined oil, deposit.
Turbulence and engine speedturbulence and engine speed 555. Effect of knocking in spark ignition in a fourstroke engine. A sdvosb service disabled veteran owned small business. Effect of knocking in spark ignition in a fourstroke engine authors ravikant sahu1, eklabya gupta2. What is knocking and detonation in the petrol and diesel. Knocking is a phenomenon of generating unwanted pressure wave which create unpleasant sound and can damage engine wall during combustion in engines. Engines only air is compressed through a high compression ratio 14. Factors affecting auto ignition delay or engine detonation. There are many factors that affect the occurrence of knocking, including mechanical, electrical. Best multiple nonlinear model factors for knock engine. Figure 1050 note the spread at idle between an open stack and an exhaust collector ring installation for engines that are otherwise identical. Sketch the constructional layout of battery ignition system in details.
Fuel is injected into the cylinders late in compression stroke through one or more injectors into highly compressed air in the combustion chamber. Measured data premixed combustion phase combustion of the fuel which has mixed with air within flammability limits. Engines aice syllabus question bank lecture notes syllabus part a 2 marks with answers part b 16 marks question bank with answer, all the materials are listed below for the students to make use of it and score good maximum marks with our study materials. The effects of detonation may be anywhere from arbitrary to severe. Knocking is violet gas vibration and audible sound produced by extreme pressure differentials leading to the very rapid rise during the early part of uncontrolled second phase of combustion. Knocking and combustion noise analysis springerlink.
Fuel is injected into the cylinders late in compression stroke through one or more injectors into highly compressed air. Practical diesel engines have cr between 14 and 22. Curve fitting technique was used in construction of the model, and also akaike information criterion aic was used as a test in choosing the best model. Performance of an automobile engine is based on the various factors that affect combustion in engines. From the above discussion on knock, it may be seen that four major factors are involved in either producing or preventing knock. Effect of knocking in spark ignition in a fourstroke engine authors ravikant sahu1. What is knocking in engine and how to get rid of this problem. The main goal of this paper is to construct a new mathematical model and study the behavior of the factors affecting the problem of knocking in internal combustion engines.
Factors that influence ignition delay in diesel engine are compression ratio, inlet air temperature, coolant temperature, jacket water temperature, fuel temperature, intake pressure, airfuel ratio and engine size. In ci engines knocking occurs in the beginning of combustion. New model for knock factors optimization in internal. These ideal engine cycle analysis results show that expansion. Results of the figure indicates that the model rpm and torque combination is ideal for two of the factors affecting the. Unit ii compression ignition engines9 diesel fuel injection systems stages of combustion knocking factors affecting knock direct and indirect injection systems combustion chambers fuel spray behaviour spray structure and spray penetration. The air motion so organized inside the combustion chamber and the turbulence of the air passes across the fuel jet tears it into fine particles. Knocking in spark ignition internal combustion engines occurs when combustion of some of the. This in turn increase the maximum pressure during the combustion and creates a tendency to knock 11. Similarly, overheating may cause additional wearandtear on the engine, be relatively harmless or cause the engine to catch on fire and break. Knocking also knock, detonation, spark knock, pinging or pinking in spark ignition internal combustion engines occurs when combustion of some of the airfuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but one or more pockets of airfuel mixture explode outside the envelope of the normal combustion front.
Sparkignition engines normally use volatile liquid fuels. Superknock combustion in highly boosted spark ignition engines with random. Pdf new model for knock factors optimization in internal. Internal combustion engines, lecture 3 ideal cycle analysis. Fuel droplets, which remain in suspension, continue to evaporate and mix with air even during suction and compression processes. Unfortunately flame velocities for most of fuel range between. Under normal operating conditions, combustion is initiated towards the. Factors that effect ignition delay in diesel engine. Pdf statistical analysis for multiple nonlinear knock. Whether or not knock occurs depends on engine fuel vehicle factors and ambient conditions temperature, humidity. Higher flame propagation velocities can achieve higher combustion efficiency and fuel economy. Ice internal combustion engines 2161902 gtu syllabus. Sep, 2016 factors that influence ignition delay in diesel engine are compression ratio, inlet air temperature, coolant temperature, jacket water temperature, fuel temperature, intake pressure, airfuel ratio and engine size.
The ability to maximize power and fuel economy by optimizing model contain factors like temp, tps, rpm, torque. Diesel fuel injection systems stages of combustion knocking factors affecting knock. Engines aice important part b 16 marks questions, pdf books, question bank with answers key, me6016. The combustion of an i heap engine is bounding at the top by the cylinder head, inlet valve, exhaust valve and spark plug. The same reason also affects the power output which is observable at the time of acceleration. The factors affecting the combustion in engine cylinder. So, we have understood that in a spark ignition engine combustion is initiated, you know i mean. Partthrottle knock is a transient phenomenon and is a nuisance to the driver. Knocking is characterized by extreme pressure differentials and violent gas vibrations evidenced by audible knock. Factors affecting delay period in ci engines 3 injection timing advance. In order to decrease the tendency of knock it is necessary to decrease the ignition delayand. Unit i spark ignition engines 9 mixture requirements fuel. Stages of combustion, delay period ignition lag and the factors affecting it.
These mixtures must be enriched 20 to 30 percent when open stacks, instead of collector rings radial engines are used on the same engine. Knocking combustion in sparkignition engines sciencedirect. A study on performance and emissions of a 4stroke ic. Then, influencing factors of autoignition and pressure oscillations are presented based on numerical simulation and optical diagnostics, including discussion of. Use knock sensor to control spark retard so as to operate close to engine knock limit 7. Fuel consumption of engine increases drastically as heat energy is lost during knocking. Note that the performance conditions for the two types of engines diesel and gasoline are somewhat similar, except for some differences due to factors dealing with fuel and ignition.
Unfortunately flame velocities for most of fuel range between 1030 msecond. Stages of combustion, ignition lag and the factors affecting the ignition lag. Jul 22, 2019 the effects of detonation may be anywhere from arbitrary to severe. Pdf knocking combustion in sparkignition engines researchgate. The pressure and temperature at the end of compression increases with increase in compression ratio. Factors affecting fuel conversion efficiency these ideal engine cycle analysis results show that expansion ratio rc and gas composition through the ratio of specific heats both affect the cycles fuel conversion efficiency because. A comparison of the principal conditions which influence the performance of internal combustion engines is given in table 51. It occurs due to selfignition of unburned charge into combustion chamber. The tendency of the engine to knock is affecting by the shape of the combustion chamber. Mar, 2016 1st let me clarify that knocking is much more pronounced in petrol engines i. Knock is most critical at wot and at low speed because of its persistence and potential for damage. Hhigher igher combustion efficiency and fuel economy can be achieved by higher flame propagation velocities.
What is knocking in engine and how to get rid of this. The role of changes in some key operating variables affecting the production of the pollutants co, no x and unburned hydrocarbons are examined and some guidelines for reducing the undesirable emissions are. In this study, we will address the problem of knocking in internal combustion engines, and some of the factors affecting the knocking, through the study of the power of the effect of each factor. Pdf knocking combustion research is crucially important because it determines engine durability, fuel. Download link is provided and students can download the anna university me6016 advanced i. Engines aice books lecture notes syllabus part a 2 marks with answers me6016 advanced i. As a mechanical engineer it is very much essential.
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