Determination of Erosive Burning Effect

Compute velocity and pressure distributions along the flow direction in the port 

Compute burning rate as a function of pressure and determine po at t = tg 

Compute total mass flow rate at nozzle throat by mg = AAxVxpp 

When Po = Poj is obtained, continue to compute internal propellant grain geometry at t = ti 

The pressure peaks observed in the combustion tests shown in Fig. 14.19 are computed as a function of L/D as shown in Fig. 14.20. The peak pressures computed by means of the Lenoir-Robillard empirical equation are confirmed by the measured pressure at the head-end of the motor. It is evident thatp values predicted without erosive burning are significantly lower than the measured maximum pressures. Fig. 14.21 shows the erosive ratio, 8 = r/to, as a function of the mass flow rate per unit cross-sectional area in the port, G. The erosive ratio increases with increasing Mach number in the port at constant L/D. 

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