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Windage is a force created on an object by friction when there is relative movement between air and the object. Windage loss is the reduction in efficiency due to windage forces. For example, electric motors are affected by friction between the rotor and air. [1] Large alternators have significant losses due to windage
heat loss from steam before entering the nozzle, deflection of flow in the nozzle, boundary layer development in the nozzle, turbulence in the nozzle, and; the friction in the nozzle which reduces the available enthalpy drop. Hence, the actual velocity leaving the nozzle is less than that obtained with isentropic expansion.
The friction loss is customarily given as pressure loss for a given duct length, Δp / L, in units of (US) inches of water for 100 feet or (SI) kg / m 2 / s 2. For specific choices of duct material, and assuming air at standard temperature and pressure (STP), standard charts can be used to calculate the expected friction loss.
Friction and windage, 5–15%; Iron or core losses, 15–25%; Stator losses, 25–40%; Rotor losses, 15–25%; Stray load losses, 10–20%. For an electric motor, the efficiency, represented by the Greek letter Eta, [49] is defined as the quotient of the mechanical output power and the electric input power, [50] calculated using this formula:
In laminar flow, friction loss arises from the transfer of momentum from the fluid in the center of the flow to the pipe wall via the viscosity of the fluid; no vortices are present in the flow. Note that the friction loss is insensitive to the pipe roughness height ε: the flow velocity in the neighborhood of the pipe wall is zero.
In an electrical or electronic circuit or power system part of the energy in play is dissipated by unwanted effects, including energy lost by unwanted heating of resistive components (electricity is also used for the intention of heating, which is not a loss), the effect of parasitic elements (resistance, capacitance, and inductance), skin effect, losses in the windings and cores of ...
An engine has many moving parts that produce friction. Some of these friction forces remain constant (as long as the applied load is constant); some of these friction losses increase as engine speed increases, such as piston side forces and connecting bearing forces (due to increased inertia forces from the oscillating piston).
In fluid dynamics, the Darcy friction factor formulae are equations that allow the calculation of the Darcy friction factor, a dimensionless quantity used in the Darcy–Weisbach equation, for the description of friction losses in pipe flow as well as open-channel flow.