Experiment 4

Experiment 4

Study of Combustion of Composite Propellant Aim: To determine the effects of chamber pressure on combustion using numerical methods. Theory: The burn rate of a composite propellant is a function of composition, particle size (AP and Al), chamber pressure, initial temperature of propellant and lateral flow velocity in the chamber. Composite propellant combustion is predominantly controlled by the diffusion flame. Temperature and Pressure variations in burn rate are given by these equations

r / rT0  exp[ T (Tin  T0 )]

T 

d ln r 2 (r2  r1 ) ~ dT (r1  r2 ) (Tin 2  Tin1 )

Variation of Flame temperature with changes in chamber pressures is observed by a numerical simulation.

Procedure: The program is fed with desired initial conditions which are given below. The flame temperature patterns are obtained for different chamber pressures. Longitudinal Grid Size = 0.1 microns Lateral Grid Size

= 1 micron

Initial Temperature = 300 K Starting grid number of Each AP Particle = 0004 Ending grid number of Each AP Particle = 0008 Changes in rate of burning are observed and graphed at different temperatures. For Tin = 300K Chamber Pressure( in atm) Burn rate( in mm/s)

5

10

15

20

0.00147

0.00206

0.00262

0.00316

For Tin = 350K Chamber 5 10 15 Pressure( in atm) Burn rate( in 0.00169 0.00234 0.00295 mm/s) Observations: These are the flame temperature patterns observed at Tin = 300K. Pc = 5 atm

20 0.00354

Pc = 10 atm

Pc = 15 atm

Pc = 20 atm

Dependence of burn rate over Chamber Pressure is plotted for different Tin.

Conclusion: Flame Temperature increases with increase in Chamber Pressure.

AE06B012 AE06B009 AE06B013 AE06B010