The resulting knock or ping is the sound of the pistons slamming against the cylinder walls. Modern methods in engine knock signal detection sciencedirect. Detonation or knocking in ic engines mechanical engineering. What is the difference between knocking and detonation in ic engine. Defining engine efficiency limits us department of energy. Preignition is an uncontrolled combustion event which occurs before the spark event. You have remained in right site to start getting this info. The piston is bourn due to high temperature of the unbrount charge in knocking. It the temperature of intake air in ic engines is lowered, then its efficiency will a increase b decrease. Preignition decreases performance and results in an audible pinging or knocking sound in the engine. Knock prevention and increase of reliability and efficiency of high.
Reciprocating internal combustion engines are a well established and widely used technology. As the flame propagates across combustion chamber, end gas is compressed causing pressure, temperature and density to increase. Detonation occurs when the pressure and temperature inside the cylinder become higher than the critical pressure and temperature of the fuel. The effects of detonation may be anywhere from arbitrary to severe. Abnormal combustion, more commonly known as knock or detonation, has been the limiting factor in internal combustion engine power generation since the discovery of the otto cycle itself. Knocking, in an internalcombustion engine, sharp sounds caused by premature combustion of part of the compressed airfuel mixture in the cylinder.
Both spark ignition and compression ignition engines are covered, as are those operating on fourstroke and twostroke cycles, and ranging in size from small model airplane engines to the largest stationary engines. Recently, i saw this question, which included a rather alarming quote. These were then downloaded as tiff files where each image. Read pdf ic engine m l mathur ic engine m l mathur how to change your vehicles serpentine belt, tensioner, and idler pulley proper belt tension is critical. Fresh fuel prevents gum from forming in the fuel system or on essential carburetor parts. Likewise there is a wide range of ways to classify internalcombustion engines, some of which are listed below. Engine knock, or detonation, occurs when the temperature or pressure in the. 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. Fourstroke cycle diesel engine in fourstroke cycle engines there are four strokes completing two revolutions of the crankshaft.
Detonation and knocking 80 theories of detonation 82 effect of engine variables on knock 83. As the premixed flame develops earlier in a preignition cycle, autoignition of the endgas. Pdf ic engines an pdf file to word document mac internal combustion engine is a device in which the. External combustion engines are those in which combustion takes place outside the engine where as ic engines takes place outside the engine where as ic engines combustion takes place with in the engine. 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.
This video explains knocking combustion and preignition and the reasons for this irregular combustion. The high velocity knock, usually called detonation,will produce severe damage of the engine and is avoided by the electronic engine control. Reciprocating engines include both diesel and spark ignition configurations. Under normal conditions, the combusting air and fuel mixture inside the combustion chamber ignites in a controlled manner. It was found that detonation can occur in modern internal combustion engines under high energy density conditions. The most important works that carried out theoretical. They are important for both transportation and for stationary uses. Full throttle operation with carburetor heat on can cause detonation. Ic internal combustion engines lecture note pdf notes download for the undergraduate course and an exhaust manifold generally of cast iron complete the engine assembly. It is caused due to the propagation of a high speed pressure wave created by the autoignition of end portion of unburnt fuel. 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.
The effect of knocking in piston and piston cylinder is crack and defect in piston head as shown in fig. Knocking and detonation is physically same like nosiy sound. In addition to this knocking puts a limit on the compression ratio at which an. Prolonged and intense knocking can break the piston or the engine, though it is can also endure this slight issue for thousands of miles. Effect of knocking in spark ignition in a fourstroke engine. We get asked this question a lot, and rightfully so. Phenomenon of diesel knock knocking is violet gas vibration and audible sound. Compression ratio is increased when a large volume of combustion chamber deposits accumulate in the engine. The causes of internal engine knock, and how to eliminate it. Most oem knock sensors are basically microphones tuned to listen for a specific.
What is the difference between knocking and detonation. Main trends in detonation engine development are discussed. If you dont understand exactly what each of these events are and how they occur, you wont know how to prevent them from happening, or possibly even recognizing when it happens. Internal combustion engines are classified as follows. The noise which gives the name of knocking to detonation is like. Study of knocking effect in compression ignition engine. Acces pdf ic engine by r yadav ic engine by r yadav recognizing the habit ways to get this book ic engine by r yadav is additionally useful. Worldwide production for reciprocating internal combustion engines is over 200 million units per year.
Internal combustion engine terminology and abbreviations the following terms and abbreviations are commonly used in engine technology literature. The two chemical drops normally used are, ethyl nitrate 33gmsus gallon 29gmsus gallon amyl nitrate higher the. Knocking is the noise you hear caused by detonation,which is an explosion or uncontrolled burning inside the cylinder of a reciprocating engine. Knocking and detonation are not what you want occurring in your engine 2. These are respectively, the suction, compression, power and exhaust strokes. Internal combustion engines can be classified internal combustion engines ca n be classified n be classified as c as cas continuous ic engines and ontinuous ic engines and. Phenomenon of knock in ci engine is called knocking and phenomenon of knock in petrol engine is called detonation. 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. Engines objective questions and answers pdf,interview questions,multiple choice questions,lab viva,seminar topics,online quiz important free download.
There are different types of ic engines that can be classified on the following basis. Pdf ic engines pdf ic engines pdf ic engines download. Knocking combustion in sparkignition engines article pdf available in progress in energy and combustion science 61. Powerpoint slide on knocking in ic engines compiled by raja hossain. 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. Reason, factors, comparison, gate mechanical lectures knocking, detonation. Internal combustion engine handbook sae international. The causes of internal engine knock, and how to eliminate. American technical publishers orland park, illinois. Text andor other creative content from engine knocking was copied or moved into preignition with this edit on march 11, 2018. In a properly functioning engine, the charge burns with the flame front progressing smoothly from the point of ignition across the combustion chamber. What typically happens is that when detonation occurs the piston expands excessively, scurfs in the bore along those four spots and wipes material into the.
Mathematical modeling of knocking combustion and created. Sae high efficiency ic engine symposium held 10 11 april 2011 in detroit, mi, usa while these forums focused primarily on transportation engines, the general conclusions reached are applicable to all ic engines participants in the 2010 engine efficiency colloquium 2010 engine efficiency colloquium final report edited by daw, et al. Some engines, such as liquid cooled 2stroke engines found in snowmobiles, watercraft and motorcycles, have a very common detonation failure mode. Onepiece valves are commonly used on engines that drive lighter loads, have. Detonation, or engine knock, occurs simply when fuel preignites. Pdf knocking combustion in sparkignition engines researchgate. Internal combustion ie spark ignition 81 an engine in which the combustion process in each cycle is started by use of a spark plug. There is a wide range of internal combustion engines corresponding to their many varied applications. Ill add a couple of thoughts that come to mind when i think about knocking and detonation. I c engines full notes, pdfs, lecture notes download. 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. He expressed that the knock phenomenon is similar to detonation of a. Engines the loud pulsating noise heard within the engine cylinder of an i.
Knock onset, knock intensity, superknock and preignition in spark. The effect of strokebore ratio on engine friction and economy is very small. We use your linkedin profile and activity data to personalize ads and to show you more relevant ads. 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. Ic engine most important mcq questions with answers most important mechanical engineering mcq on ic engine. What is the difference between knocking and detonation in. Knock pinging is the actual noise that can be audibly heard if detonation is bad enough. High strokebore ratio engines have equally good friction mep values as that for low strokebore ratio engine. Similarly, overheating may cause additional wearandtear on the engine, be relatively harmless or cause the engine to catch on fire and break. Internal combustion enginel is a fair summary of the opinions existing at the present time.