Combustion Terminology
Adiabatic Combustion—An ideal combustion reaction taking place without any heat exchange between the products of combustion and the environment.
Aerosol—A suspension of fine solid or liquid particles in a gas.
Autoignition Temperature—The minimum temperature at which a combustible material will self-ignite without a spark or flame.
Autoignition Time (AIT)—The time required for a combustible material to auto-ignite at a specific temperature and pressure.
B2H2 Fuel Ratio—The ratio of combustible material to air, expressed as the ratio of the lower flammability limit of the material (B2H2) to the upper flammability limit of air (O2H2).
Burning Velocity—The rate of propagation of a flame front through a combustible material.
Chemical Kinetics—The study of the speed at which chemical reactions occur.
Deflagration—A rapid combustion reaction in which the flame front propagates through an unconfined medium at a subsonic velocity.
Detonation—A rapid combustion reaction in which the flame front propagates through an unconfined medium at a supersonic velocity.
Diffusion Flame—A nearly adiabatic reaction in which the combustion products mix with the unburned gases in the reaction zone.
Equivalence Ratio—The ratio of the mass of fuel to the mass of oxidizer required for stoichiometric combustion.
Flammability Limits—The minimum and maximum fuel-to- air ratios, expressed as the ratio of the lower flammability limit of the material to the upper flammability limit of air.
Flame Spread Rate—The rate at which a flame front propagates through an unconfined medium.
Heat of Combustion—The energy released during the combustion of a given amount of material.
Ignition Delay—The time between the introduction of a fuel/air mixture into a reaction chamber and the onset of flame propagation.
Ignition Energy—The energy required to initiate a combustion reaction.
Limiting Oxygen Index—The amount of oxygen, expressed as a percentage, required to support combustion between the lower and upper flammability limits of a given material.
Nozzle Efficiency—The ratio of the kinetic energy of the combustion products to the thermal energy of the reaction chamber.
Reaction Zone—The area in which the chemical reaction of a combustion process occurs.
Spontaneous Ignition Temperature—The minimum temperature at which a combustible material will spontaneously ignite in a given environment.
Stoichiometry—The ratio of the mass of fuel to the mass of oxidizer required for complete combustion.
Thermal Degradation Temperature (Td)—The temperature at which a combustible material begins to decompose.
Thermal Expansion—The increase in the volume of a material due to increased temperature.
Thermal Radiation—The transfer of heat via electromagnetic waves.
Q2: Mechanical Design Terminology
Ancillary Elements—Components or subsystems of a mechanical system that do not directly contribute to its primary function.
Applied Loads—The forces acting on a component, structure, or system.
Axial Load—A force acting along the axis of a system or component.
Bearing—A mechanical device that transmits load between two components while allowing them to move relative to one another.
Bending Stress—The stress set up in a component due to a bending moment.
Casting—A manufacturing process in which a fluid material is poured into a mold and allowed to solidify.
Coefficient of Friction—The ratio of the force of friction between two surfaces to the normal force between them.
Contact Stress—The stress set up in a component due to contact between two surfaces.
Deflection—The displacement of a component or structure caused by an applied load.
Elastic Limit—The maximum stress that a component can be subjected to without permanent deformation.
Fatigue—A material failure caused by repeated cyclic loading.
Fluid Power—The use of a liquid or gas to transfer, store, and control energy.
Force—A vector quantity expressing the strength of an external fault acting on a system.
Hardening—A process used to increase the strength of a metal by increasing the number of dislocations in its crystal structure.
Joints—The parts of a system or component that provide physical connections between parts or subsystems.
Lubrication—The use of a lubricant to reduce friction between two surfaces and provide protection against wear.
Manufacturing Tolerances—The allowable deviation between a component and its specified design dimensions.
Moment—A force acting at a distance from a reference point, causing rotation about that point.
Power Transmission—The use of mechanical components to transfer power from one system to another.
Shear Stress—The stress set up in a component due to shear forces.
Static Loads—Forces that act continuously on a system or component.
Stiffness—A measure of the stiffness of a system or component under an applied load.
Strain—The deformation of a component due to an applied load.
Strength—The ability of a material to withstand loads.
Stress—The internal force set up in a component due to an applied load.
Tensile Stress—The stress set up in a component due to a tensile force.
Torsional Stress—The stress set up in a component due to a twisting force.
Vibration—The periodic motion of a system or component due to an applied force.
Wear—The gradual decrease in the size of a component due to use or exposure to an external environment.
