Engines aice books lecture notes syllabus part a 2 marks with answers me6016 advanced i. Knocking combustion in sparkignition engines sciencedirect. 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. Engines only air is compressed through a high compression ratio 14. Engine knocking refers to the metallic sound an engine can produce when pressure is applied to the gas pedal. In this page you can learn various important multiple choice questions on ic engine,mcq on ic engine, objective type questions on ic engines, ic engine short questions etc. Top because this position is at the top of most engines not always, and dead because the piston stops at this point. The factors that affect the flame propagations are. And ci engines in sparkignition engines, the autoignition of. In this article, well examine the causes of engine knock and discuss some ways to soothe a noisy motor. When an engine pings, it releases pollution into the environment in. Topdeadcenter tdc position of the piston when it stops at the furthest point away from the crankshaft.
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 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 intermittent ic engines. But ci engines work at constant pressure and has a compression ratio of 16 20. Jul 22, 2019 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. The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft. 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. Its more common in some engines than in others some are particularly prone such problems, while others are more resistant. Detonation or knocking in ic engines mechanical engineering. Knocking in ic engine combustion abnormal occurring in the combustion chamber give sudden pressure rise accompanied by a metallic, hammer like sound. Internal combustion ic engine study notes handwritten. This video explains the term knocking, related to internal combustion engine working on petrol.
In this page you can learn various important multiple choice questions on ic engine,mcq on ic engine, objective type questions on ic engines,ic engine short questions etc. In four stroke engines, one power stroke is generated for two revolutions of crank shaft. Fuel is injected into the cylinders late in compression stroke through one or more injectors into highly compressed air in the combustion chamber. Knocking combustion research is crucially important because it determines engine durability, fuel consumption, and power density, as well as noise and emission performance. The noise may be a hollow knocking sound or more of a rattling soundin either case, its not a sound you want to hear. What is the difference between knocking and detonation in. C engines multiple choice questions with answers set 02 practice test.
When cylinders have the correct balance of air and fuel, fuel will burn in small, regulated pockets instead of all at once. The volume of the air used is about 10,000 galgal of fuel. To understand the underlying principles of operation of different ic engines and components. Dec 05, 20 knocking in ci ingine takes place due to ignition lagif ignition lag is short then it is desirerable but if ingnition lag period is long then it cause vibration in engine,due to sudden pressure. Pdf knock is technically defined as an audible noise associated with autoignition of a region of the fuelair mixture ahead of the moving. Thermofluids and turbomachinery assignment 20112012 6 p a g e performance characteristics table test no 1 2 3 4 5 6 7 8 raw torque nm 6. A hmh flame speed is obtained in diesel engine when air fuel ratio is a uniform throughout the mixture b chemically correct mixture c about 35% rich mixture d about 10% rich mixture e about 10% lean mixture. Knocking combustion in sparkignition engines article pdf available in progress in energy and combustion science 61. What is the meaning of knocking and detonation in i.
Unfiltered air may contain millions of particles of abrasive dust and other matter, which could cause rapid wear. Internal combustion engine performance characteristics. For a cylinder 10 cm in diameter, the time required for a pressure disturbance. 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. Higher flame propagation velocities can achieve higher combustion efficiency and fuel economy. Study of knocking effect in compression ignition engine with. Ci engines are often called diesel engines, especially in the nontechnical community. Faster burning engines high turbulence are less sensitive to changes in mixture composition, p and t than slower burning engines. Engines multiple choice questions and answers pdf 101.
The two distinct types of ic engines used for either mobile or stationary operations are. There is evidence that the phenomenon of knock in sparkignition engines is connected with the production of peroxides in the last part of the fuelair mixture to be burnt. But for ci engines higher the compression ratio, lesser is the ignition delay and lesser probability of detonation or diesel knock occurring. 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. 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.
Following conditions are necessary for combustion to take place 1. Engines aice important part b 16 marks questions, pdf books, question bank with answers key, me6016. If the temperature of intake air in internal combustion engine increases, then its efficiency will. These ic engine study notes will help you to get conceptual deeply knowledge about it. After each pocket burns, it creates a little shock, igniting the next pocket and continuing the cycle. Effect of knocking in spark ignition in a fourstroke engine. However in case of two stroke engines, the cycle is completed in one revolution of. Detonation in the internal combustion engine is a phenomenon which occurs in the cylinder charge undr certain operating conditions. The aim of this project is detecting knock during combustion of biodieselhydrogen fuel and also the knock is suppressed by timed injection of diethyl ether dee with biodieselhydrogen fuel for different loads. Engines the loud pulsating noise heard within the engine cylinder of an i.
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. An ic engine uses large quantities of air for combustion, the ratio being 1415 lb of air for every lb of fuel bursts. Feb 24, 2014 the aim of this project is detecting knock during combustion of biodieselhydrogen fuel and also the knock is suppressed by timed injection of diethyl ether dee with biodieselhydrogen fuel for different loads. In continuous ic in continuous ic engines engines engines products of products of. Knocking occurs when fuel burns unevenly in your engines cylinders. Engine knock arises from autoignition of the end gas. Basic characteristics of engine knocking combustion. 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. Mar 28, 2017 this video explains the term knocking, related to internal combustion engine working on petrol. C engines the working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft a 12 b 1 c 2 d 4 e 8.
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