Numerical modeling of rocket warhead detonation and fragmentation joseph d. What is the difference between knocking and detonation in ic. Hydrogen detonation analysis for a pwr containment vessel osamu kawabata, takuji nagayoshi, mitsuhiro kajimoto, and nobuo tanaka nupecinstitute of nuclear safety fujita kanko toranomon bldg. What is the difference between knocking and detonation in. Schematically, the detonation wave is shown in the figure here. Sep 21, 2009 aircraft piston engine preignition and detonation explanation. 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. Systematic approach to analyze and characterize preignition events.
This noise changes only slightly between iron and aluminum. Les study of deflagration to detonation mechanisms in a. Difference between knocking and detonation compare the. Resonance, which is characteristic of combustion detonation, occurs at about 6400 hertz. Examples of the engineering use of gas detonation are given. The octane rating of a given grade of gasoline is a measure of its detonation resistance. Detonation is an uncontrolled form of combustion that adds undue stress to the inside of your engine.
The detonation velocity for the mixed explosives can be estimated by a similar pathway to the detonation pressure. Detonation characteristics of hydrogen oxygen mixtures morton p. Without a high pressure spike to resonate the chamber and block, you would never hear preignition. Prediction of detonation pressure and velocity of explosives. Results in excessive pressure, temperature and unstable pressure pulse shock wave. Pdf differences between the detonation behavior of. Under normal conditions, the combusting air and fuel mixture inside the combustion chamber ignites in a controlled manner. The difference between detonation and deflagration. If the sites you can back it up with are available, thatll be a real help, thankyou. Explain the differences between burning and shock to detonation. Results in excessive pressure, temperature and unstable pressure pulse. Simulations of detonation wave propagation in rectangular. The detonation phenomenon cambridge university press, 2008.
Can you please give the answer, and maybe with a little detail. Churchill the university of michigan, ann arbor, michigan detonation velocities were measured in mixtures of hydrogen and oxygen containing 25 to 75. Detonation is an explosion at the end gasses, after combustion has begun. Safety measures must be taken to ensure that the mechanism for signal transmission is disabled until the pulse from the logging unit is required. View wk 2 from hlss 230 at american military university.
As they often learn cylinder chamber combustion processes can quickly gravitate to. Detonation occurs when excessive heat and pressure in the combustion chamber cause the airfuel mixture to autoignite. Knocking and detonation is physically same like nosiy sound. In contrast to conventional engine knocking in gasoline engines, which is typically controlled by knock control algorithms in the ecu, preignition is considered. Supersonic high pressure shock front ahead of the reaction zone i. The most relevant aspects of advanced experimental investigations of gas detonation and its mathematical simulation are presented. 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. Feb 09, 2017 knocking and detonation is physically same like nosiy sound. Knocking should not be confused with preignitionthey are two separate events. This causes a brief, but intense, spike in cylinder pressure. Detonation also called spark knock is an erratic form of combustion that can cause head gasket failure as well as other engine damage. The only sign of preignition is white smoke pouring out the tailpipe and the engine quits running. Dec 30, 20 knocking is the sound of a destroyed bearing.
The difference between a nuclear weapon detonation and a. Relation between sparkignition engine knock, detonation waves. 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. Prediction of detonation pressure and velocity of xplosives 83 can be obtained when p emaxi is known. A detonation wave is a chemical reaction wave propagating at the velocity of a shock wave along the explosive charge. This video explains knocking combustion and preignition and the reasons for this irregular combustion. As nouns the difference between explosion and deflagration is that explosion is a violent release of energy sometimes mechanical, nuclear, or chemical while deflagration is the act of deflagrating. However, the relationship between the two different types of structures is unclear, which requires further clarification. 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. Gas detonation and its application in engineering and. Subsonic, typically 1 ms and 7 to 10 bar starting at ambient pressure detonation.
It is the phenomena of generation of shock wave due to impulsive energy transfer. The strong increase of knock intensity at the earliest st could be explained by such a transition, leading locally to very high pressure levels in the. Nov 18, 2011 a detonation wave is a chemical reaction wave propagating at the velocity of a shock wave along the explosive charge. I installed the sniper efi on a 383 backed by a 700r4 in an 85 c10. Detonation definition and meaning collins english dictionary.
Mining and militarysetting requirements to match the applicationgurney energies, overpressures, role of metallization, simple models. As far as the engine itself is concerned, one of the key differences between detonation and preignition is that an engine can be designed and built to tolerate lighttomoderate detonation, but not necessarily so with preignition. Knock, detonation, pinging, preignition, etc are basically two things. Since lx17 cannot sustain detonation at less than 7. Detonation noun the noun detonation has 2 senses 1. Since both can be highly destructive and both generally lead to explosions of something. Detonation is sometimes called knocking, but that is just confusing. There is sometimes confusion between detonation and preignition that we will try to explain. Hydrogen detonation analysis for a pwr containment vessel. What is the difference between knocking and detonation in ic engine. What is the difference between knocking and detonation in internal. The higher the octane number, the better able the fuel is to resist.
It is spontaneous combustion of end gas remaining charge in the combustion chamber. The engine community pushes ever nearer to the limits of power output. 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. This noise of detonation is commonly called spark knock. The autoignition theory which states that when the airfuel mixture in the end gas region is compressed to sufficiently high pressure and temperature the fuel. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem. Detonation occurs after ignition and causes an explosion of the mixture, rather than a smooth burn.
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. With detonation, the spark ignites the fuelair mixture, as it should. Kasimov, theory of detonation with an embedded sonic locus, siam journal of applied mathematics, 66, no. 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. 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. Also known as ping or spark knock, detonation takes place after the spark plug has fired and a portion of the airfuel mixture has been consumed in the normal combustion process. Knocking and detonation are not what you want occurring in your engine 2. Thats the biggest difference between detonation and preignition when looking at piston failures.
This paper will compare and contrast detonation in ideal and in highly nonideal explosives. The phenomenon of detonation was first observed and described by harry ricardo during experiments carried out between 1916 and 1919 to discover the reason for. In a detonation, the reaction front moves at a speed greater than the speed of sound, driving the shock front immediately preceding it. Detonation can cause the temperatures inside the cylinder head to rise to the melting point of the components inside it, with the piston usually going first. Detonation is also called an engine knock, knocking, or pinging because of the. Nov 15, 2019 colloquially, any explosion is generally called a detonation. Unintentional detonation when deflagration is desired is a problem in some devices. Phenomenon of knock in ci engine is called knocking and phenomenon of knock in petrol engine is called detonation. 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. 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. Detonations occur in both conventional solid and liquid explosives, as well as in reactive gases.
Cline introduction all high output engines are prone to destructive tendencies as a result of over boost, misfueling, mistuning and inadequate cooling. Explosions are either detonations or deflagrations. Neither, however, is desirable as neither aids in combustion stability and control. Colloquially, any explosion is generally called a detonation. An explosion results from the rapid release of energy. We get asked this question a lot, and rightfully so. Pdf differences between the detonation behavior of emulsion. Dec 16, 2017 namaskaar dosto iss video me mene detonation or knocking ko explain kra h umeed krta hu aapko video pasand aaegi. In the frame of the wave, the fresh mixture enters the shock at speed d, starts burning in the reaction zone until completely. A mild detonation will simply heat the engine but if it is severe, it may even result in fracture of the piston or other damages to the engine. Detonation is different, but creates the same problems as preignition. If there is no indication of gun detonation, repeat steps 7. There is great demand for a detonation model that can accurately simulate the.
The phenomenon of detonation was first observed and described by harry ricardo. Analysis of five shots of knocking combustion, taken with the naca highspeed. Ill add a couple of thoughts that come to mind when i think about knocking and detonation. So the pinging you hear is actually the structure of the engine reacting to the pressure spikes. If there is still no indication of gun detonation following step 7. 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. Structure of a detonation from high speed photography and soot tubes 3d cellular structure, constantly changing cell width. Ideal explosives, represented here by a tatb binder system, have relatively flat. Understanding how the magnetos work maintenance mondays mzeroa flight training duration. Knocking in spark ignition internal combustion engines occurs when combustion of some of the. Detonation or knocking in the internal com bustion engine is considered as a problem in engineering and as a problem in. This energy is then dissipated by a variety of mechanisms, including formation of a pressure wave. What is the difference between knocking and detonation. 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.
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