The exit nozzle, which is located downstream
from the combustion chamber has its entrance diameter equal to the diameter of
the combustion chamber. Nozzle exit diameter is dependent upon combustion
chamber temperature and can be determined mathematically. Such mathematical
treatment is beyond the scope of this monograph. A good "rule of thumb"
that the practical designer can use to obtain this dimension is make the nozzle exit area approximately 1.4 times
greater than the diffuser entrance area. The nozzle exit area is a critical
dimension and this value can best be determined by trial and error (varying the
area until the highest thrust value is obtained). However, the above stated
empirical factor will give a reasonably close value.
During operation, the high combustion temperature and centrifugal force cause the body structure to warp out of round and seek a "tear drop" shape, thus destroying the performance of the engine. To prevent such warpage a base plate may be welded to the combustion chamber prior to welding the diffuser and exit nozzle to the combustion chamber.
A rotor mounted fuel tank as shown in Fig #9 eliminates the rotary seal and pumping equipment necessary to lift fuel from the fuel tank up to the rotor hub but it complicates rotor stability, works a hardship in refueling and does not provide fuel flow adjustment while the rotor is in operation. Therefore, this system is recommended for test equipment only.
During operation, the high combustion temperature and centrifugal force cause the body structure to warp out of round and seek a "tear drop" shape, thus destroying the performance of the engine. To prevent such warpage a base plate may be welded to the combustion chamber prior to welding the diffuser and exit nozzle to the combustion chamber.
A rotor mounted fuel tank as shown in Fig #9 eliminates the rotary seal and pumping equipment necessary to lift fuel from the fuel tank up to the rotor hub but it complicates rotor stability, works a hardship in refueling and does not provide fuel flow adjustment while the rotor is in operation. Therefore, this system is recommended for test equipment only.
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