The contents of this page are from "ELEMENTS OF FRASCA ROTARY ENGINE DESIGN*"
*Copyright © 1998 by Joseph F. Frasca

DISCUSSION OF THE BASIC ENGINE ELEMENTS AND OPERATION

To familiarize you with the engine technology a brief discussion of the Frasca rotary engine, and its operating principles along with a glossary of terms follows.

The contents of this page are from "ELEMENTS OF FRASCA ROTARY ENGINE DESIGN*"
*Copyright © 1998 by Joseph F. Frasca

GLOSSARY

COMPRESSION RATIO : is a VVC's (Volume Varying Chamber; i.e. working chamber) maximum to minimum volume ratio in the compression undulation of a FRE (Frasca Rotary Engine).
It is also the maximum to minimum volume ratio of a VVC in the combustion undulation of a non-tuned FRE

DUMP PRESSURE: is the pressure of the VVC immediately before communication with exhaust porting.
The higher the dump pressures the greater the noise generated by the sudden gas expansion in the exhaust system.

EXPANSION RATIO: is the maximum to minimum volume ratio of a VVC in two cycle engines.
It is also said  ratio in the combustion undulation of a tuned 4 cycle FRE.

FACE SURFACE: is the annular cavity surface of the engine casing.

FRE: Frasca Rotary Engine.

GAP: is the clearance between the partition edge at the rotor wave surface and the wave surface.

PGAP: is the clearance between a partition and its slot at the engine annular cavity and the clearance between relatively moving surfaces at the inner and outer circumference boundaries of the annular cavity.

PURGING: occurs in the engine with an air intake(s) (scoop) on its rotor which supplies fresh air to VVC in the FRE annular cavity exhaust region(s). The fresh air cleans the VVC, completes exhaust gas combustion and cools the VVC.

TUNED ENGINE: is 4 cycle FRE that has a maximum to minimum VVC volume ratio in the compression undulation that is different from said ratio in the combustion undulation.
In usual circumstances the ratio will be larger in the combustion undulation to permit lower dump pressures and temperatures and increased power .

VVC: is Volume Varying Chamber.
The VVC are the FRE's working chambers.

WAVE SURFACE: is the annular cavity surface on the engine rotor.


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