Knocking and detonation in ic engines pdf download

When knock, detonation, or preignition occurs, the airfuel mixture is ignited at an improper time in the cycle. Knocking should not be confused with preignitionthey are two separate events. If you can audibly hear knock, then its time to verify your tune and fuel. Nov 09, 2017 a supercharging reduces knocking in diesel engines b there can be limited supercharging in petrol engines because of detonation c supercharging at high altitudes is essential d supercharging results in fuel economy e supercharging is essential in aircraft engines. The detonation theory led many to call knock detonation but the more general term knock is preferred since the engine phenomenon includes more than the endgas energy release and since there. These help the fuel to ignite at the correct time during the. Turbocharger and supercharger to increase the output of any engine more fuel can be burned and make bigger explosion in every cycle.

Skip to content engineering interview questions,mcqs,objective questions,class notes,seminor topics,lab viva pdf free download. This video explains knocking combustion and preignition and the reasons for this irregular combustion. The mixture is ignited by the spark, normally in the centre of the cylinder, and a flame front moves from the spark towards the outside of the cylinder in a controlled burn. Theory of detonation, effect of engine variables on detonation, control of detonation. The actual volume of fresh charge admitted in 4stroke petrol. Effect of knocking in spark ignition in a fourstroke engine authors ravikant sahu1, eklabya gupta2, deepak kumar dewangan3, prakash kumar sen4, shailendra kumar bohidar5 1,2,3student bachelor of engg. Unintentional detonation when deflagration is desired is a problem in some devices. Engines aice important part b 16 marks questions, pdf books, question bank with answers key, me6016.

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. Detonation or knocking in ic engines mechanical engineering. This early before the spark plug fires ignition of fuel creates a shock wave throughout the cylinder as the burning and expanding fuelair mixture collides with the piston that is. This means that a powerful explosion is trying to expand a cylinder chamber that is shrinking in size, attempting to reverse the direction of the piston and the engine. Thus, a 2nd autoignition occurs with much more pressure rise intensity near walls. Download ebook ic engine doc success ratio in me for past 3 years gate campus. Download fulltext pdf download fulltext pdf knocking combustion in sparkignition engines article pdf available in progress in energy and combustion science 61. Detonation, or engine knock, occurs simply when fuel preignites before the piston. Detonation generally caused by fuel with a low octane rating is the tendency for the fuel to preignite or autoignite in an engines combustion chamber. Detonation, or engine knock, occurs simply when fuel preignites before the piston reaches scheduled spark ignition. This video explains the term knocking, related to internal combustion engine working on petrol.

Pdf knocking combustion in sparkignition engines researchgate. May 25, 2014 we use your linkedin profile and activity data to personalize ads and to show you more relevant ads. In a properly functioning engine, the charge burns with the flame front progressing smoothly from the point of ignition across the combustion chamber. Internal combustion ic engine study notes handwritten. Detonation suppression means for internal combustion engines us. Detonation, as is known, is a phenomenon occurring in internal combustion engines improperly adjusted or under severe conditions of operation. Investigations indicate that detonation may be controlled by retarding the rate of combustion by chemicals added to the mixture, which serve to increase its specific heat and prevent excessive temperature, and by reducing the temperature of the walls of the combustionchamber, so that the temperature of the charge previous to ignition will be lower and thus insure a normal rate of. Engines objective questions and answers pdf,interview questions,multiple choice questions,lab viva,seminar topics,online quiz important free download. In the literature, four terms are used to describe the phenomenon. Knocking also called knock, detonation or spark knock, pinking in uk english or pinging in us english in sparkignition internal combustion engines occurs when combustion of the airfuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of airfuel mixture explode outside the envelope of the normal combustion front. Phenomenon of knock in ci engine is called knocking and phenomenon of knock in petrol engine is called detonation. Knocking combustion causes major engine damage, and also reduces the efficiency. Text andor other creative content from engine knocking was copied or moved into preignition with this edit on march 11, 2018.

The most important works that carried out theoretical. Consequently, as the first few droplets injected are passing through the. Knocking combustion in sparkignition engines sciencedirect. An arrangement for suppressing detonation in internal combustion engines having control members to adjust the working conditions of said engine comprising a detonation sensitive device operative to generate a small electric current when subjected to detonation induced vibration, and means including an. What is the difference between knocking and detonation in ic. The working cycle in case of four stroke engine is completed in following number. Feb 09, 2017 knocking and detonation is physically same like nosiy sound. Many times these terms are used interchangeably though they are technically different.

But bigger engine, which weigh more and cost more to build and maintain are not always better ii. Download link is provided and students can download the anna university me6016 advanced i. Detonation causes a very rapid pressure spike near the peak pressure point for a very brief period of time. These were then downloaded as tiff files where each image. Recently, i saw this question, which included a rather alarming quote.

Composition factor the detonation or knocking in ci engine can be reduced by using certain fuel additives which would increase the cetane number of the fuel. Effect of knocking in spark ignition in a fourstroke engine authors. Professional tuners often rely on the use of detonation cans det cans to detect knock events on highly modified engines. Us2220558a detonation suppression system for internal. A fuels octane rating is a measure of a fuels ability to resist detonation. However, the deflagration does not selfaccelerate to detonation as shown in fig. Detonation is an uncontrolled combustion event which occurs after the spark event. The spark plug creates only one of them, and the other is undesired. Aug 30, 2012 interaction of flame propagation and pressure waves during knocking combustion in sparkignition engines 21 january 2014 combustion science and technology, vol. The author describes the research work on the internalcombustion engine done recently in his laboratory in england, and presents his deductions therefrom, based upon an analysis of the evidence he has obtained to date. And ci engines in sparkignition engines, the autoignition of.

What is the meaning of knocking and detonation in i. The chipcan select between one of two sensors, if needed foraccurate monitoring or for v type engines. Main trends in detonation engine development are discussed. A limit to the extent to which compression ratio can be increased is thus set by the necessity to avoid knock. Ill add a couple of thoughts that come to mind when i think about knocking and detonation. Knocking in ic engine combustion abnormal occurring in the combustion chamber give sudden pressure rise accompanied by a metallic, hammer like sound leading to loss of performance and possible engine damages. Knocking and preignition ngk spark plug europe gmbh. Detonationpre ignition and the outboard motor one of the most common causes of major internal engine damage results from the abnormal combustion conditions that have plagued the internal combustion engine since its beginning, namely detonation and preignition, or surface ignition. Preignition causes tremendous pressure that is present for a very long time possibly the entire compression stroke. Internal combustion engines from lawrence livermore website 21 knock fundamentals knock originates in the extremely rapid release of much of the fuel chemical energy contained in. Effect of knocking in spark ignition in a fourstroke engine.

Although a huge effort was done to understand knocking combustion, what can be confirmed by many scientific publications 11, 23, knock is yet not completely understood phenomena accompanying combustion in sparkignition gasoline engines. Songtextecomknocking also knock detonation spark knock pinging or pinking. But for ci engines higher the compression ratio, lesser is the ignition delay and lesser probability of detonation or diesel knock occurring. Jul 22, 2019 the effects of detonation may be anywhere from arbitrary to severe.

Engine knock under acceleration spark knock is a pinging noise, rattling or knocking which might be heard while the engine is working hard under load passing on the highway, towing a trailer, driving up a mountain, etc. It was found that detonation can occur in modern internal combustion engines under high energy density. What is the difference between knocking and detonation. Whether an engine knocks or not depends on the outcome of a race between the normal propagation of flame throughout the unburnt charge, and the development of autoignition. Similarly, overheating may cause additional wear and tear on the engine, be relatively harmless or cause the engine to catch on fire and break. Knocking and detonation is physically same like nosiy sound. Severe detonation over an extended time can damage pistons, rods, rod bearings, and other engine parts. Mechanical engg kirodimal institute of technology raigarh c. Detonation is a problem caused by colliding flame fronts in an internal combustion engine. Knocking in spark ignition internal combustion engines occurs when combustion of some of the. Highspeed imaging from the rcm experiment showed a knocking mechanism, which has not been previously reported. What is the difference between knocking and detonation in. For fuels with low cetane number, with long ignition delay, ignition occurs late in the expansion stroke incomplete combustion, reduced power output, poor fuel conversion efficiency.

Powerpoint slide on knocking in ic engines compiled by raja hossain. Download as pptx, pdf, txt or read online from scribd. When the airfuel charge ignites out of time and elsewhere in the chamber, a separate and undesired flame front ignites after the spark plug fires. Heavy knock detonation rapid combustion of stoichiometric mixture at. 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 former pages history now serves to provide attribution for that content in the latter page, and it must not be deleted so long as the latter page exists. Counterweight oil pan camshaft cam lobes intake valve engine coolant crankshaft rocker arm cover rocker arm valve spring cylinder head exhaust valve. Knocking combustion in sparkignition engines article pdf available in progress in energy and combustion science 61.

It is an inherent problem that plagues internal combustion engines, and it has been studied intensively for decades. The effects of detonation may be anywhere from arbitrary to severe. The two chemical drops normally used are, ethyl nitrate. Full throttle operation with carburetor heat on can cause detonation. Similarly, overheating may cause additional wearandtear on the engine, be relatively harmless or cause the engine to catch on fire and break. Combustion may be defined as a relatively rapid chemical combination of hydrogen and carbon in fuel with oxygen in air resulting in liberation of energy in the form of heat. Knocking, in an internalcombustion engine, sharp sounds caused by premature combustion of part of the compressed airfuel mixture in the cylinder. External combustion engine internal combustion engine combustion of airfuel is outside the engine cylinder in a boiler. Phenomenon of diesel knock 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. Knock onset, knock intensity, superknock and preignition in spark. In addition, detonation could be initiated near the walls in ic engines if the energy density is high enough. It is caused due to the propagation of a high speed pressure wave created by the autoignition of end portion of unburnt fuel. Prolonged and intense knocking can break the piston or the engine, though it is can also endure this slight issue for thousands of miles. Oct 02, 2017 knocking or detonation or pre ignition what is knocking detonation pre ignition.

Another way to add power is to make a normal sized engine more efficient. In internal combustion engines it is called engine knocking or pinging or pinking, and it causes a loss of power, excessive heating, and eventual engine failure in some cases. In addition to this knocking puts a limit on the compression ratio at which an. Evaluation of knock intensity and knock limited thermal efficiency of different combustion chambers in stoichiometric operation lng engine 2 april 2019 effects of boretostroke ratio on the efficiency and knock characteristics in a singlecylinder gdi engine. Engines the loud pulsating noise heard within the engine cylinder of an i. What is the difference between knocking and detonation in ic engine. This autoignitioninduced flow pushes back the sparkignited flame front and creates a further negative curvature.

Pdf knocking combustion research is crucially important because it. Study of knocking effect in compression ignition engine with. This abnormal combustionqs commonly known as knocking combustion. Hit and miss governing of ic engine in this video, i.

In the flames of internal combustion engine there is constant thermal emission and linear emission resulting from tran sitions of molecules from higher to lower electron states. Us2738782a detonation suppression means for internal. Knocking or also called detonation in ic engines, in ignition spark engine, occurs when the incorrect ignition of the air fuel mixture in the some cylinder occurs while other cylinders correctly combust and produce the power stroke at the correct time. When knocking combustion occurs, highfrequency pressure oscillations can be observed. Engines aice books lecture notes syllabus part a 2 marks with answers me6016 advanced i. Here, a deflagration starts the combustion similar to the preignition observed in ic engines. Knocking and detonation are not what you want occurring in your engine 2. Detonation means the sudden and violent knocks experienced in an internal combustion engine by engineering means, this knock is set up by a highpressure wave giving loud pulsating noise this occurs when it strikes against cylinder walls, cylinder head, and piston. Knock control benefits vehicle engines work more efficiently and produce more power when operating near the detonation limit. We use your linkedin profile and activity data to personalize ads and to show you more relevant ads. Pressure waves accompanying detonation in the internal. It was found that detonation can occur in modern internal combustion engines under high energy density conditions. 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. The noise which gives the name of knocking to detonation is like.

It the temperature of intake air in ic engines is lowered, then its efficiency will a increase b decrease. Not only is preignition far more damaging, but its also much harder to detect. Scribd is the worlds largest social reading and publishing site. Feb 24, 2014 the usage of hydrogen in compression ignition engine leads to production of knocking or detonation because of its lower ignition energy, wider flammability range, and shorter quenching distance. Under normal conditions, the combusting air and fuel mixture inside the combustion chamber ignites in a controlled manner.