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The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values. A fundamental specification for such engines, it is measured two ways: the static compression ratio, calculated based on the volume of the cylinder when the piston is at the bottom of ...
In aeronautical engineering, overall pressure ratio, or overall compression ratio, is the ratio of the stagnation pressure as measured at the front and rear of the compressor of a gas turbine engine. The terms compression ratio and pressure ratio are used interchangeably. [1] Overall compression ratio also means the overall cycle pressure ratio ...
The efficiency of an engine is defined as ratio of the useful work done to the heat provided. where, is the heat absorbed and is the work done. Please note that the term work done relates to the power delivered at the clutch or at the driveshaft. This means the friction and other losses are subtracted from the work done by thermodynamic ...
However, a real diesel engine will be more efficient overall since it will have the ability to operate at higher compression ratios. If a petrol engine were to have the same compression ratio, then knocking (self-ignition) would occur and this would severely reduce the efficiency, whereas in a diesel engine, the self ignition is the desired ...
The engine can produce any compression ratio from 8:1 to 14:1. The highest torque is achieved at 8:1, giving high acceleration, while the best gas mileage (fuel efficiency) is achieved at 14:1. The electronic engine controller responds to the pressure on the gas pedal, in real-time, altering the compression ratio seamlessly.
This "simulated" Atkinson cycle is most notably used in the Toyota 1NZ-FXE engine from the early Prius and the Toyota Dynamic Force engines. The effective compression ratio is reduced—for the time the air is escaping the cylinder freely rather than being compressed—but the expansion ratio is unchanged (i.e., the compression ratio is smaller ...
The engine pressure ratio (EPR) is the total pressure ratio across a jet engine, measured as the ratio of the total pressure at the exit of the propelling nozzle divided by the total pressure at the entry to the compressor. [1] Jet engines use either EPR or compressor/fan RPM as an indicator of thrust. [2] When EPR is used, the pressures are ...
Cylinder capacities may range from 10 cm 3 or less in model engines up to thousands of liters in ships' engines. [7] The compression ratio affects the performance in most types of reciprocating engine. It is the ratio between the volume of the cylinder, when the piston is at the bottom of its stroke, and the volume when the piston is at the top ...