expansion ratio


expansion ratio

[ik′span·shən ‚rā·shō] (fluid mechanics) For the calculation of the mass flow of a gas out of a nozzle or other expanding duct, the ratio of the nozzle exit section area to the nozzle throat area, or the ratio of final to initial volume. (mechanical engineering) In a reciprocating piston engine, the ratio of cylinder volume with piston at bottom dead center to cylinder volume with piston at top dead center.