The engine system is the heart of the smoke generator. The pulse jet engine does four things:
Develops heat to vaporize the fog oil.
Develops thrust to force the vaporized fog oil into the atmosphere.
Develops suction to open the engine valve and draw successive fuel air mixtures into the combustion
Develops pressure to drive the fog oil pump.
The engine system consists of an engine head assembly, blanket, engine tube assembly, outer shell,
cooling baffle, front cover, inner and outer discharge baffles, and discharge cover assembly.
The engine head assembly (Figure 3) consists of a machine bolt, a backstop washer, an engine
valve backstop, a 16-petal engine valve, an engine head, a flowjector, and a metering jet. The engine
head assembly is accessible after opening the front cover. The engine valve is circular in shape and is
equipped with 16 petals. It is held to the rear of the engine head by a backstop, recessed washer, and a
machine bolt. The flowjector is a device through which fuel is introduced to the mixing chamber in the
engine head. It consists of an air tube and body with three fuel spray orifices. The fuel metering jet,
which is installed in the end of the flowjector, meters the flow of fuel from the fuel tube.
Figure 3. Engine head assembly.
The engine tube is a trombone-shaped assembly that serves as a combustion chamber and exhaust
tube. The engine head is attached to the front end of the combustion chamber by the engine head
adapter. The engine tube conducts exhaust gases and vaporized fog oil to the space inside the engine
tube housing assembly. The engine tube housing assembly is flanged at each end for attaching the
engine tube and cooling baffle assembly at the engine head end, and for attaching the inner and outer
discharge baffle assemblies at the smoke outlet end. The baffle assembly is welded to the flange on the
engine tube housing assembly. The outer discharge baffle consists of a dome-shaped plate with three
outlet nozzles welded to it. The outer discharge baffle, a gasket, and a backup ring are bolted to the
flange on the engine tube housing. A discharge cover assembly is fastened to the smoke outlet end of
the outer shell. The front cover is mounted on the engine head section of the engine by a hinge. It can
be opened for access to the engine head, float bowl, float bowl toggle valve, or to other components
mounted on the front of the engine. The cover is held partly open by a stop when the engine is being
operated. It is closed when the generator is being transported or is in storage.