22.2. The detonation process is based on repetitive explosions or detonations of oxygen-fuel gas mixtures, rather than the continuous burning of a combustion flame, as in the HVOF process. Oxygen and acetylene are loaded into a long, water-cooled barrel with powder. The mixture is ignited and it explodes.
Table of Contents
What are the two theories of detonation?
There are two types of detonation: ideal detonation and nonideal detonation. This chapter focuses on ideal, that is, one dimensional, detonation theories, including the Chapman-Jouguet (CJ) theory and the Zeldovich-Neumann-Dรถring (ZND) theory.
What is detonation energy?
Detonation Pressure is a measure of the product’s shock wave energy, influenced by the product’s density (latent energy) and detonation velocity (rate of energy release).
What are detonation waves?
A detonation is a supersonic combustion wave that consists of a shock wave driven by energy release from closely coupled chemical reactions. These waves travel at many times the speed of sound, often reaching speeds of Mach 5, as in the case of a hydrogenโair fuel mixture.
What are the effects of detonation?
Detonation has negative effects throughout the engine. Light detonation may cause premature wear on bearings and bushings. Severe or prolonged detonation can cause damage to the cylinder head and pistons.
How do you identify detonation?
What Are the Symptoms of Detonation? Detonationโsometimes called knock or pre-ignitionโis a pinging sound that can sometimes be heard during acceleration and throttle tip-in. Unlike normal exhaust noise, detonation is a higher-pitched, raspy note that emanates from the engine compartment.
What is difference between explosion and detonation?
An explosion is a rapid expansion in volume associated with an extremely vigorous outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known as detonations and travel through shock waves.
What is difference between detonation and knocking?
Knocking vs Detonation Knocking is the making sharp sounds due to uneven combustion of fuel in the cylinder of a vehicle engine. Detonation is the process of pre-ignition or auto-ignition of a fuel in an engine’s combustion chamber.
What are the 3 types of explosives?
- blasting and bulk explosives (explosives used for commercial blasting applications or for their manufacture);
- perforating explosives (intended for use in the oil and gas well industry);
- special-application explosives (high explosives used for other applications, including primary explosives).
What is detonation factor?
It is defined as the ratio between the weight of the explosive and the explosion volume, i.e., the space in which the explosive is detonated. If 10 g of RDX is loaded in an enclosed space of 20 cc, the value of ฮ will be equal to 10 g/20 cc = 0.5 g/cc.
Is detonation a chemical change?
A detonation is a very special type of ex- plosion. It is a rapid chemical reaction, initiated by the heat accompanying a shock compression, which liberates sufficient energy, before any expan- sion occurs, to sustain the shock wave.
Does detonation need oxygen?
An explosive is a chemical material that is capable of extremely rapid combustion resulting in an explosion or detonation. Since an adequate supply of oxygen cannot be drawn from the air, a source of oxygen must be incorporated into the explosive mixture.
What is detonation temperature?
Detonation products of high explosives are obtained at high pressures and temperatures simultaneously, which covers a wide range of pressures, โผ1โ100 GPa, and temperatures, โผ1000โ5000 K [1].
What is meant by velocity of detonation?
Explosive velocity, also known as detonation velocity or velocity of detonation (VoD), is the velocity at which the shock wave front travels through a detonated explosive. Explosive velocities are always faster than the local speed of sound in the material.
Why is detonation velocity important?
The velocity of detonation (VOD) is one of the most important properties of explosives. It is essential that the explosive in the field condition detonates at its optimum rate and induces sufficient detonation pressure leading to good fragmentation.
How can we suppress detonation?
Detonation can be prevented by any or all of the following techniques: retarding ignition timing. the use of a fuel with high octane rating, which increases the combustion temperature of the fuel and reduces the proclivity to detonate.
Which is not effect of detonation?
Right Answer is: B Pre-ignition: Due to local overheating of spark plug & this pre-ignition increases detonation. Power output & efficiency decreases: Power output & thermal efficiency decreases due to abnormal combustion.
What is detonation in fuel?
Detonation – Detonation, as the name suggests, is an explosion of the fuel-air mixture inside the cylinder. It occurs after the compression stroke near or after top dead center. During detonation, the fuel/air charge (or pockets within the charge) explodes rather than burning smoothly.
What is the difference between detonation and combustion?
Detonation differs from normal combustion in its ignition mechanism and in the supersonic velocity of 2โ5 kilometres per second for gases and 8โ9 kilometres per second for solid and liquid explosives. Detonation is impossible when the energy loss from the reaction zone exceeds a certain limit.
Which of the following is the best definition of detonation?
A detonation is a large or powerful explosion. Detonation is the action of causing a device such as a bomb to explode.
What are the 2 types of explosions?
- Chemical: Chemical explosions occur due to either decomposition or combination reactions, which are both exothermic reactions.
- High-Order Explosives: These explosives cause destructive shock waves, such as dynamite.
What are the different types of detonator?
There are three categories of electrical detonators: instantaneous electrical detonators (IED), short period delay detonators (SPD) and long period delay detonators (LPD).
How do mechanical factors affect detonation?
- Compression ratio: The pressure and temperature at the end of compression increases with increase in compression ratio.
- Supercharging:
- Increasing inlet temperature:
- Increase in load:
- Advancing the spark:
- Flame travel distance:
- Spark plug location:
- Engine size:
What is the difference between detonation and pre-ignition?
Detonation causes a very rapid pressure spike near the peak pressure point for a very brief period of time. Pre-ignition causes tremendous pressure that is present for a very long time โ possibly the entire compression stroke. Not only is pre-ignition far more damaging, but it’s also much harder to detect.
Which acid is used in explosive?
Picric acid is used in the production of explosives, matches, and electric batteries. It is also used in etching copper and manufacturing colored glass, in the leather industry, and in the synthesis of dyes.