In the simplest view, combustion instability can be thought of as pressure swings in the engine caused by the multiple streams of liquid oxygen and rocket fuel combining and igniting at extremely high pressures in such a way that causes violent vibrations.
How do you control the combustion instability?
The principle of ‘antisound’ is used to construct a method for the suppression of combustion instabilities. This active instability control (AIC) method uses external acoustic excitation by a loudspeaker to suppress the oscillations of a flame.
What is thermoacoustic instability?
Thermoacoustic instability, also known as combustion instability, has been encountered in the development and operation of practical devices including rocket engines, gas turbines, boilers, and aeroengines, manifesting itself with large-amplitude pressure oscillations, which may cause detrimental consequences.
What is chugging instability?
Chugging is a low frequency instability that is normally attributed to an interaction between the combustion process and propellant feed system elasticity, and excludes interaction with primary structure. … Buzzing can cause triggering of higher frequency instabilities, but is not normally destructive itself.
What is combustion efficiency of boiler?
Combustion efficiency is a measure of how effectively the heat content of a fuel is transferred into usable heat. The stack temperature and flue gas oxygen (or carbon dioxide) concentrations are primary indicators of combustion efficiency. … The table relates stack readings to boiler performance.
Can combustion happen on the moon?
If oxygen is presnt on moon then combustion take place but if unable to fulfil oxygen then can’t possible.
What is flame stability?
In house and industrial applications flame stability is achieved by attaching the flame to a simple device known as a burner. Flame stabilization is usually accomplished by causing some of the combustion products to recirculate and hence to continually ignite the fuel mixture.
How does a flame holder work?
A flame holder is a component of a jet engine designed to help maintain continual combustion. … A flame holder creates a low-speed eddy in the engine to prevent the flame from being blown out. The design of the flame holder is an issue of balance between a stable eddy and drag.
What is combustion oscillation?
The oscillation is sustained when a rise in combustion-chamber pressure causes the mean gas temperature to increase, often because it reduces the air-inflow rate. … When the mechanism is understood the cure for an unwanted pulsation becomes relatively simple.
What is thermoacoustic effect?
Thermoacoustics is the interaction between temperature, density and pressure variations of acoustic waves. … Thermoacoustic effects can be observed when partly molten glass tubes are connected to glass vessels. Sometimes spontaneously a loud and monotone sound is produced.
What is good combustion?
Perfect combustion is simply a mixture of fuel and oxygen, with both being completely consumed in the burning process. … Having just the right amount of oxygen (no more, no less) is called the stoichiometric point, or stoichiometric combustion. The stoichiometric point is also called the 100% air point.
What is good combustion efficiency?
Various combustion processes produce combustion efficiencies from 0% to 95+%. … Combustion Processes and Their Combustion Efficiency Ranges.
| Combustion Process | Efficiency Range |
|---|---|
| Induced Draft Furnace “Medium Efficiency” | 74-82% |
| Boiler with Gas-powered Burner | 75-83% |
| Condensing Furnace (Gas & Oil) “High Efficiency” | 75-90+% |
•
What causes high CO in a boiler?
If the oxygen level is set too low and something changes the combustion process can become ‘fuel rich’ as there is insufficient oxygen for all the fuel to burn. This can cause high levels of CO to be generated and in the extreme enough fuel to enter the boilers flue and ignite (explode) outside the combustion chamber.
Can there be fire without oxygen?
A fire cannot burn without oxygen. … The burning that a star does, then, is a nuclear reaction, and not a chemical one like the fires on Earth (when a candle burns, the atoms themselves remain unchanged: just the molecules are affected).
Can you have a fire in space?
Fires can’t start in space itself because there is no oxygen – or indeed anything else – in a vacuum. Yet inside the confines of spacecraft, and freed from gravity, flames behave in strange and beautiful ways. They burn at cooler temperatures, in unfamiliar shapes and are powered by unusual chemistry.
Will a candle burn in zero gravity?
A candle can burn in zero gravity, but the flame is quite a bit different. Fire behaves differently in space and microgravity than on Earth.
What is the essential condition for flame stability?
5.04. Flame stability is fundamental to good combustion in flames. … Fuel properties important for good flame stability are volatile release and the quality of volatile matter. The physical size of the fuel is important as is the steadiness of the feed system.
What is flame flashback?
When a flammable mixture of fuel gas and air or oxygen is present in a gas line upstream of a welding or cutting blowpipe, flame can flash back into the gas line, and there is the possibility of a serious accident. A flame or flashback arrestor is a safety device designed to stop a flame in its tracks.
What causes flame lift off?
Excessive primary air can cause flames to lift and blow-off the burner ports. … Also, any factor which increases flow velocity from ports contributes to lifting flames. Overrating of burners is also a cause. The normal cure for lifting flames is the reduction of primary air input to the burner.
Can annular combustor?
Like the can type combustor, can annular combustors have discrete combustion zones contained in separate liners with their own fuel injectors. Unlike the can combustor, all the combustion zones share a common ring (annulus) casing. Each combustion zone no longer has to serve as a pressure vessel.
What does a flame stabilizer do?
Flame stabilization techniques vary by engine type but typically have a bluff body to impart a recirculation zone of hot combustion gases around the fuel injectors and compressed air inlet to prevent flameout.
Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with Sun’Agri and INRAE in Avignon between 2019 and 2022. My thesis aimed to study dynamic agrivoltaic systems, in my case in arboriculture. I love to write and share science related Stuff Here on my Website. I am currently continuing at Sun’Agri as an R&D engineer.