Testing the modified generator resulted in a marked
improvement of power output as shown in Figure 6. The generator
output power improved over 600 Watts and the power curves were
less erratic than in the previous test.
The open circuit voltage temperature profile showed some
improvement from the first test series, however, it still indicated that
there was a problem with the gas boundary layer and it was suspected
that heat transfer problem was associated with lack of turbulence in
the exhaust gas as it exited the turbocharger drive turbines.
The heat transfer fins had been made discontinuous, they were
placed in line because of both the time required and the cost of
changing the casting core mold to offset the fins. It was decided to
install swirl fins on the center displacement body to increase the gas
turbulence. This was accomplished by welding two types of fins to
the shell of the hollow displacement body, the first row was a single
set of curved blades to start the swirl and the second type consisted
of four rows of angled straight blades to sustain the swirl as shown
in Figure 7.