Procedure:

• Combustible mixture is filled in the tube
• On ignition at one end, the flame propagates through the tube

Features:

• Inner dia of tube should be greater than the quenching diameter
• The flame is planar in the beginning and curved towards downstream, due to buoyancy
• Natural convection distorts the planar flame front due to difference in densities
• Friction at the tube wall is also a reason for parabolic shape of the flame

The burning velocity is given by