Abstract:
An investigation has been made into the feasibility of predicting mean
convective heat transfer coefficients for the nozzles of solid propellant rocket
engines. The principle of the method used was constant flow calorimetry;
the surface of a copper nozzle was heated with a flow of hot water, and cooled
by air flow through the nozzle. Heat transfer coefficients were then derived
from measurements of water flow, water temperature drop and nozzle surface
temperatures. For a range of Reynolds numbers, the mean convective heat
transfer for a star-shaped conduit could be expressed by the following equation: -
Nu = 0.1976 Re
0.631
Pr
0.333
For a cigarette-burning charge the mean convective heat transfer could be
expressed by the following equation : -
= 0.7013 Re
0.491
Pr
0.333
The flow pattern into the nozzle was studied using a water flow visualisation
rig involving both photographic and direct viewing techniques. In addition,
investigations into the temperature and pressure distributions along the nozzle
surface at ambient conditions were carried out using a perspex nozzle fitted
with surface thermocouples and pressure tappings.
