Search results
Results from the WOW.Com Content Network
Mass flow rate is defined by the limit [3] [4] ˙ = =, i.e., the flow of mass through a surface per time .. The overdot on ˙ is Newton's notation for a time derivative.Since mass is a scalar quantity, the mass flow rate (the time derivative of mass) is also a scalar quantity.
In combustion physics, fuel mass fraction is the ratio of fuel mass flow to the total mass flow of a fuel mixture. If an air flow is fuel free, the fuel mass fraction is zero; in pure fuel without trapped gases, the ratio is unity. [1] As fuel is burned in a combustion process, the fuel mass fraction is reduced. The definition reads as = where ...
The English unit pound mass is more commonly used than the slug, and when using pounds per second for mass flow rate, it is more convenient to express standard gravity as 1 pound-force per pound-mass. Note that this is equivalent to 32.17405 ft/s2, but expressed in more convenient units.
Mathematically, mass flux is defined as the limit =, where = = is the mass current (flow of mass m per unit time t) and A is the area through which the mass flows.. For mass flux as a vector j m, the surface integral of it over a surface S, followed by an integral over the time duration t 1 to t 2, gives the total amount of mass flowing through the surface in that time (t 2 − t 1): = ^.
Pound per hour is a mass flow unit based on the international avoirdupois pound, which is used in both the British imperial and, being a former colony of Britain, the United States customary systems of measurement. It is abbreviated as PPH, or more conventionally as lb/h. Fuel flow for engines may be expressed using this
In a nozzle or other constriction, the discharge coefficient (also known as coefficient of discharge or efflux coefficient) is the ratio of the actual discharge to the ideal discharge, [1] i.e., the ratio of the mass flow rate at the discharge end of the nozzle to that of an ideal nozzle which expands an identical working fluid from the same initial conditions to the same exit pressures.
Air-fuel ratio is the ratio between the mass of air and the mass of fuel in the air-fuel mix at any given moment. The mass is the mass of all constituents that compose the air or fuel, whether they take part in the combustion or not. For example, a calculation of the mass of natural gas as fuel — which often contains carbon dioxide (CO 2 ...
The engine does work on the air going through it and this work is in the form of an increase in kinetic energy. The increase in kinetic energy comes from burning fuel and the ratio of the two is the thermal efficiency which equals increase in kinetic energy divided by the thermal energy from the fuel (fuel mass flow rate x lower calorific value).