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  2. Propeller theory - Wikipedia

    en.wikipedia.org/wiki/Propeller_theory

    A propeller imparts momentum to a fluid which causes a force to act on the ship. [1] The ideal efficiency of any propulsor is that of an actuator disc in an ideal fluid. This is called the Froude efficiency and is a natural limit which cannot be exceeded by any device, no matter how good it is.

  3. Propulsive efficiency - Wikipedia

    en.wikipedia.org/wiki/Propulsive_efficiency

    The propulsive efficiency is always less than one, because conservation of momentum requires that the exhaust have some of the kinetic energy, and the propulsive mechanism (whether propeller, jet exhaust, or ducted fan) is never perfectly efficient. It is greatly dependent on exhaust expulsion velocity and airspeed.

  4. Advance ratio - Wikipedia

    en.wikipedia.org/wiki/Advance_ratio

    It helps in understanding the efficiency of the propeller at different speeds and is particularly useful in the design and analysis of propeller-driven vehicles.It is the ratio of the freestream fluid speed to the propeller, rotor, or cyclorotor tip speed. When a propeller-driven vehicle is moving at high speed relative to the fluid, or the ...

  5. Specific impulse - Wikipedia

    en.wikipedia.org/wiki/Specific_impulse

    When calculating specific impulse, only propellant carried with the vehicle before use is counted, in the standard interpretation. This usage best corresponds to the cost of operating the vehicle. For a chemical rocket, unlike a plane or car, the propellant mass therefore would include both fuel and oxidizer. For any vehicle, optimising for ...

  6. Disk loading - Wikipedia

    en.wikipedia.org/wiki/Disk_loading

    In reciprocating and propeller engines, disk loading can be defined as the ratio between propeller-induced velocity and freestream velocity. [citation needed] Lower disk loading will increase efficiency, so it is generally desirable to have larger propellers from an efficiency standpoint.

  7. Blade element momentum theory - Wikipedia

    en.wikipedia.org/wiki/Blade_Element_Momentum_Theory

    Whereas the streamtube area is reduced by a propeller, it is expanded by a wind turbine. For either application, a highly simplified but useful approximation is the Rankine–Froude "momentum" or "actuator disk" model (1865, [1] 1889 [2]). This article explains the application of the "Betz limit" to the efficiency of a ground-based wind turbine.

  8. Euler's pump and turbine equation - Wikipedia

    en.wikipedia.org/wiki/Euler's_pump_and_turbine...

    The Euler pump and turbine equations are the most fundamental equations in the field of turbomachinery.These equations govern the power, efficiencies and other factors that contribute to the design of turbomachines.

  9. Blade element theory - Wikipedia

    en.wikipedia.org/wiki/Blade_element_theory

    Consider the element at radius r, shown in Fig. 1, which has the infinitesimal length dr and the width b. The motion of the element in an aircraft propeller in flight is along a helical path determined by the forward velocity V of the aircraft and the tangential velocity 2πrn of the element in the plane of the propeller disc, where n represents the revolutions per unit time.