Nov 18, 2006 detonation or ping happens at high pressures lots of throttle during acceleration. It is part of the reason why new trucks cost so much. The spark plug creates only one of them, and the other is undesired. Knocking is the noise you hear caused by detonation,which is an explosion or uncontrolled burning inside the cylinder of a reciprocating engine. The energy release must be sudden enough to cause a local accumulation of energy at the site of the explosion. Piston skirt noise happens to be louldest on the sides of the engine. Detonation definition of detonation by the free dictionary. Soto1, fumiya togashi, and rainald lohner2, 1 saic, 1710 saic drive, mclean, va 22102, usa 2 george mason university, 4400 university dr, fairfax, va 22030, usa abstract. Pdf differences between the detonation behavior of emulsion.
First, detonation parameters pressure, temperature, density, and species mass fraction are calculated for three cases where the hydrogen mass fraction in air is 1. Spontaneous combustion of the endgas, or remaining airfuel mixture in the chamber. The key difference between knocking and detonation is that, knocking brings several drawbacks to the engine such as, overheating of spark plug points, erosion of the combustion chamber surface and rough, inefficient operation whereas detonation can cause abrasion, mechanical damage and overheating in engines. An older name for the salt kno 3 potassium nitrate is saltpeter also spelled salt peter and salt. What is the difference between knocking and detonation in internal.
Knocking and detonation is physically same like nosiy sound. 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. The role of product composition in determining detonation. The high velocity knock, usually called detonation,will produce severe damage of the engine and is avoided by the electronic engine control. Occurrence of sporadic superknock is the main obstacle in the development of advanced gasoline engines. What is the difference between pinging and knocking. The phenomenon of detonation was first observed and described by harry ricardo.
The resulting knock or ping is the sound of the pistons slamming against the cylinder walls. Pdf differences between the detonation behavior of. Engines the loud pulsating noise heard within the engine cylinder of an i. It is caused due to the propagation of a high speed pressure wave created by the autoignition of end portion of unburnt fuel. The velocity of detonation in solid and liquid explosives is.
A method is proposed for determining the energy release in a combustible mixture, which is based on processing the trajectory of the expanding wave from the viewpoint of the strong explosion model. Detonation or ping happens at high pressures lots of throttle during acceleration. A simple relation between the detonation velocity of an. Detonations occur in both conventional solid and liquid explosives, as well as in reactive gases. The calculations rely on classical results of detonation theory, linked to the assumption of adiabatic expansion of the gaseous detonation products. What is the difference between knocking and detonation in. To tune an engine for maximum power, you need to understand this undesirable. Difference between knocking and detonation compare the. The mechanism of the initiation and propagation of. Prediction of detonation pressure and velocity of explosives. Thats exactly what happened to dustin ellermann, top shot season 3 champion. Endgas autoignition and detonation development in a. An explosion results from the rapid release of energy.
May 30, 2017 chain detonation what happens when a primer stack blows. The effects of detonation may be anywhere from arbitrary to severe. The difference of temperature between the gases inside the cylinder and. Kapila department of mathematical sciences, rensselaer polytechnic institute, troy, new york, 12180 may 19, 2008. A detonation wave of pressuregain combustion is a shock wave followed by a reaction zone according to the znd theory. Benchmarking it, i get anywhere between 3k10k ap with one single successful dive into enemy zergs depending on how organised they are and how soon they are able to react. Nov 18, 2011 a detonation wave is a chemical reaction wave propagating at the velocity of a shock wave along the explosive charge. A study of detonation propagation and di raction with. Pdf high boost and direct injection are the main tendency of gasoline engine.
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. Energy release in multifront detonation springerlink. Endgas autoignition and detonation development in a closed. Based on energetic considerations, we deduce a simple link between the detonation velocity d of an explosive and its gurney energy e g, namely. Numerical simulations are performed for both the detonation wave solution and its linear stability. Nov 22, 2008 the difference between detonation and deflagration. Mon number, and the difference between ron and mon is known. Study of knocking effect in compression ignition engine with. The highpressure and hightemperature of the compression stroke combine. Then, exergy efficiency is used as objective criteria of performance evaluation. The difference between knocking and detonation is that, knocking brings some several drawbacks to the engine such as, overheating of spark plug points, erosion of the combustion chamber surface and rough, inefficient operation whereas detonation can cause abrasion, mechanical damage and overheating in engines. Detonation is sometimes called knocking, but that is just confusing.
This propagation velocity increases, reaches c at radius r t. We are only beginning to understand the nonlinear interaction between chemistry and fluid mechanics that produces the rapid energy release known as detonation. Detonation postignition the heat from compression along with the radiated heat from the initial flame front causes a secondary flame front to develop this second flame front can propagate at supersonic speeds this second flame front collides with the first creating extremely high cylinder temperatures 3500 fand pressures 800 psi. The main difference in general engine performance between diesel and. You can change knock by removing spark plug wire on the affected cyl. A knocking or pinging noise may be heard at low speeds but at high speeds detonation may not be audible especially in performance or competition engines. The test mixtures used were stoichiometric hydrogen and oxygen diluted with either argon or nitrogen at subatmospheric pressures. This energy is then dissipated by a variety of mechanisms, including formation of a pressure wave. Mar 23, 2016 inevitable detonation much easier to counter in pvp. The detonation theory which holds that,under knocking conditions, the advancing flame front accelerates to sonic velocities and consumes the endgas at a rate. Clear detonation wave intervals of low pressure shown in figure 7 exist between two neighboring groups of detonation waves of high pressure and each group of detonation waves of low pressure lasts about 57 ms. If the sites you can back it up with are available, thatll be a real help, thankyou. Some or all of the primers in the vertical feeding tube can go off in a chain detonation. The presence of carburetor ice in an aircraft equipped with a fixedpitch propeller can be verified by applying carburetor heat and noting.
It works only for sorcs who know what theyre doing. Knocking and detonation are not what you want occurring in your engine 2. Differences between the detonation behavior of emulsion explosives sensitized with glass or with polymeric microballoons article pdf available in journal of physics conference series 5005. Superknock is the severe engine knock triggered by preignition. May 25, 2014 we use your linkedin profile and activity data to personalize ads and to show you more relevant ads. The spark plugs ignites the injected fuel and explosion is started. Pdf in this paper we introduce a general definition of a selfsustained detonation wave as a structure composed of a lead shock front and a following unsteady transonic flow. Prolonged and intense knocking can break the piston or the engine, though it is can also endure this slight issue for thousands of miles. This work studied endgas autoignition and detonation development in a closed chamber using 1d simulation with detailed chemistry. Detonation from latin detonare, meaning to thunder downforth is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it.
On critical conditions for detonation initiation by shock. Kasimov, theory of detonation with an embedded sonic locus, siam journal of applied mathematics, 66, no. Combustion and knocking tendency of gasoline, anhydrous ethanol and wet ethanol in. The interaction between pressure wave and chemical reaction was investigated. Numerical modeling of rocket warhead detonation and fragmentation joseph d. The causes of internal engine knock, and how to eliminate it. Explosions are either detonations or deflagrations. There is great demand for a detonation model that can accurately simulate the. Since lx17 cannot sustain detonation at less than 7. We use your linkedin profile and activity data to personalize ads and to show you more relevant ads. What is the difference between knocking and detonation in ic engine.
Difference between knocking and detonation pdf downloadgolkes. This is a detailed description of how our theory of weaklycurved slowlyvarying detonations can be used to predict critical conditions for direct initiation of detonation in various. With detonation, the spark ignites the fuelair mixture, as it should. Hydrogen fuel is an effective alternate fuel in making a pollutionfree environment with higher efficiency. Proximity detonation vs inevitable detonation elder. Detonation is the spontaneous ignition of the fuelair mixture in some part of the combustion chamber, usually furthest from the spark plug, at some time after the normal ignition of the. How controlled detonations work apparently, finding information on the internet about making bombs is easier than finding information about taking them apart. Knock onset, knock intensity, superknock and preignition in spark. In a different article, well look more closely at the normal combustion event, and explore how our use of the engine controls throttle, mixture and prop affect what. Those trade secrets especially those being developed by the military to defeat ieds are too valuable to post where the whole world can read them. A typical pressure signal and a knock signal from a knocking cycle.
Phenomenon of knock in ci engine is called knocking and phenomenon of knock in petrol engine is called detonation. Pdf relationship between superknock and preignition. Investigating knock in an industrial sparkignition engine by large. What can happen when the bottommost primer in a primer feed tube goes off. It was found that preignition most commonly initiated in the area surrounding. Knocking in spark ignition internal combustion engines occurs when combustion of some of the. 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. The usage of hydrogen in compression ignition engine leads to production of. In a detonation, the reaction front moves at a speed greater than the speed of sound, driving the shock front immediately preceding it. 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.
The most significant difference between superknock and conventional knock is the. Coexistence of detonation with deflagration in rotating. The detonation velocity for the mixed explosives can be estimated by a similar pathway to the detonation pressure. The main goal of this paper is to analyze the exergy losses during the shock and rarefaction wave of hydrogenair mixture. The damage from an explosion is caused by the dissipating energy. A series of experiments supported by numerical simulations are reported on the interaction between a planar incident shock and a single obstacle. Can you please give the answer, and maybe with a little detail. Feb 09, 2017 knocking and detonation is physically same like nosiy sound. The main aim of the study was to determine the conditions under which a reflected detonation was. Dynamics of high soundspeed metal con ners driven by non. I agree with your oppion about the difference between kocking combusion and detonation. A detonation wave is a chemical reaction wave propagating at the velocity of a shock wave along the explosive charge. Unintentional detonation when deflagration is desired is a problem in some devices. Detonation or knocking in ic engines mechanical engineering.
Upon teardown, forensic analysis would reveal the telltale signs of both detonation and preignition damage, although its the preignition that ultimately did the engine in. Prediction of detonation pressure and velocity of xplosives 83 can be obtained when p emaxi is known. The causes of internal engine knock, and how to eliminate. Detonation occurs after ignition and causes an explosion of the mixture, rather than a smooth burn. By utilizing a rapid compression machine, events of preignition and superknock in a closed system under high temperature and high pressure were captured by synchronous highspeed direct photography and pressure measurement, with the results demonstrating that the mechanism of super. The difference between detonation and deflagration. Detonation is basically a phenomenon which is similar to the many explosions taking place at the same moment. Forces and severe heat that result from the occurrence of either will usually require the complete teardown and repair of the engine. This produce knocking sound and hence called knocking. Detonation always comes after normal combustion has been started by the spark plug. Knock, detonation, pinging, preignition, etc are basically two things. Detonation instability of continuously rotating detonation. There is this thing called inflation that causes the price of most things to go up a few percentages every year. Normal combustion expands out, but the gasses on the edge of the flame front compress and begin combusting spontaneously.
The science of high explosives is basically a coupling of chemistry and fluid mechanics. Scary experience, but thankfully dustin was not injured. The wave trajectory in the case of critical initiation of multifront detonation in a combustible mixture is compared with the trajectory of a blast wave generated by the same initiator in an inert. A study of detonation propagation and di raction with compliant con nement j.
Ill add a couple of thoughts that come to mind when i think about knocking and detonation. It is known that the experimental diagnostic tools available to study detonation fronts are. Detonation waves are combustion fronts triggered by a strong shock and sustained by a chemical reaction 1,2. The role of product omposition in determining detonation velocity. Detonation is a problem caused by colliding flame fronts in an internal combustion engine. Detonation is an explosion at the end gasses, after combustion has begun. What is the difference between knocking and detonation. Chain detonation what happens when a primer stack blows. By utilizing a rapid compression machine, events of preignition and superknock in a closed system under high temperature and high pressure were captured by synchronous highspeed direct photography and pressure measurement, with the results demonstrating that the mechanism of superknock. What is the difference between knocking and detonation in ic. Proximity detonation vs inevitable detonation elder scrolls.
Dec 30, 20 knocking is the sound of a destroyed bearing. However, the relationship between the two different types of structures is unclear, which requires further clarification. The distinction must again be drawn between the explosive decomposition of a crystal in nernst, theoretical chemistry, p. Detonation engines have higher thermal efficiency than deflagration engines conventional engines, such as rocket engines and airbreathing engines because detonation has a lower entropy production than deflagration. Detonation and preignition are two unique conditions that can severely damage an aircraft engine. Study of knocking effect in compression ignition engine. 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. Simulations of detonation wave propagation in rectangular. Superknock is a manifestation of developing detonation which can be. Detonation is different, but creates the same problems as preignition.
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