Search results
Results From The WOW.Com Content Network
Air–fuel equivalence ratio, λ (lambda), is the ratio of actual AFR to stoichiometry for a given mixture. λ = 1.0 is at stoichiometry, rich mixtures λ < 1.0, and lean mixtures λ > 1.0. There is a direct relationship between λ and AFR. To calculate AFR from a given λ, multiply the measured λ by the stoichiometric AFR for that fuel.
At least one exception exists: the Russian RD-180 preburner, which burns LOX and RP-1 at a ratio of 2.72. Additionally, mixture ratios can be dynamic during launch. This can be exploited with designs that adjust the oxidizer to fuel ratio (along with overall thrust) throughout a flight to maximize overall system performance.
The oxidizer and fuel pre-burner valves operate together to throttle the engine and maintain a constant 6.03:1 propellant mixture ratio. [3] The main oxidizer and main fuel valves control the flow of liquid oxygen and liquid hydrogen into the engine and are controlled by each engine controller.
The highest specific impulse chemical rockets use liquid propellants ( liquid-propellant rockets ). They can consist of a single chemical (a monopropellant) or a mix of two chemicals, called bipropellants. Bipropellants can further be divided into two categories; hypergolic propellants, which ignite when the fuel and oxidizer make contact, and ...
Lean-burn. Lean-burn refers to the burning of fuel with an excess of air in an internal combustion engine. In lean-burn engines the air–fuel ratio may be as lean as 65:1 (by mass). The air / fuel ratio needed to stoichiometrically combust gasoline, by contrast, is 14.64:1. The excess of air in a lean-burn engine emits far less hydrocarbons.
Lower flammability limit (LFL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower explosive level (LEL). At a concentration in air lower than the LFL, gas ...
Ethanol fuel mixtures have "E" numbers which describe the percentage of ethanol fuel in the mixture by volume, for example, E85 is 85% anhydrous ethanol and 15% gasoline. Low-ethanol blends are typically from E5 to E25, although internationally the most common use of the term refers to the E10 blend. Blends of E10 or less are used in more than ...
Mixture fraction. Mixture fraction ( ) is a quantity used in combustion studies that measures the mass fraction of one stream (usually the fuel stream) of a mixture formed by two feed streams, one the fuel stream and the other the oxidizer stream. [ 1][ 2] Both the feed streams are allowed to have inert gases. [ 3]