What is length scale in turbulence?

The turbulence length scale, , is a physical quantity describing the size of the large energy-containing eddies in a turbulent flow. The turbulent length scale is often used to estimate the turbulent properties on the inlets of a CFD simulation.

What is the difference between a laminar flame and a turbulent flame?

Unlike a laminar flame, which has a propagation velocity that depends uniquely on the thermal and chemical properties of the mixture, a turbulent flame has a propagation velocity that depends on the character of the flow, as well as on the mixture properties.

What are the types of turbulent flame?

Turbulent Flame

  • Flame Speed.
  • Laminar Flame.
  • Turbulence.
  • Ignition.
  • Hydrogen.
  • Direct Numerical Simulation.
  • Flamelets.
  • Flame Front.

What is turbulent flame propagation?

Turbulent flame speed is a characteristic of the rate of propagation of a flame in a turbulent flow field, such as that in a gas turbine combustor or a reciprocating internal combustion engine.

What is time scale and length scale?

In relativistic mechanics time and length scales are related by the speed of light. In relativistic quantum mechanics or relativistic quantum field theory, length scales are related to momentum, time and energy scales through Planck’s constant and the speed of light.

How do you find the turbulent length scale?

, where L is the characteristic length. In this case, the motorBike has a characteristic length of 1.42m. So its turbulence length scale should be 1.42*0.07 = 0.0994m.

What do you understand by laminar flame?

Laminar flame speed is defined as the propagation rate of the normal flame front relative to the unburned mixture. It is an important property for a premixed flame as it embodies the fundamental information of diffusivity, reactivity, and exothermicity of the combustible hydrocarbon mixture.

What is laminar diffusion flame?

A theoretical description is presented for a laminar diffusion flame spreading against an air stream over a solid- or liquid-fuel bed. Both a thin sheet and a semi-infinite fuel bed are considered. The burning process is described as follows: The hot flame heats the unburned fuel bed, which subsequently vaporizes.

What is stationary flame?

Stationary Flame Method (Bunsen Flame) Nozzle is employed to maintain uniform velocity profile. Infinitely thin perfectly conical flame front is established. For flame to be stationary, the local burning velocity must be equal to the local flow velocity.

What is meant by flame speed?

The flame speed is defined as the speed which the unburned gas mixture move relative to and normal to the flame front.

What is flame propagation?

Flame propagation: the measurement of burning velocities of slow flames and the determination of limits of combustion.

How turbulence affect flame propagation speed?

The maximum velocity and duration of flame propagation increased with the increase in turbulence intensity. Under the same turbulence intensity, the flame propagation velocity generally augmented first and then lessened.