Aero formulas: Difference between revisions

From NPrize
Jump to navigationJump to search
(density)
(→‎List of equations: adding dH(S,p))
Line 139: Line 139:
|-
|-
|style="background:white"| {{SERVER}}/images/formulas_mirror/entropy_dueqtdsmpdv.png
|style="background:white"| {{SERVER}}/images/formulas_mirror/entropy_dueqtdsmpdv.png
|[https://en.wikipedia.org/wiki/Entropy Entropy]
|[https://en.wikipedia.org/wiki/Internal_energy Internal energy] change related to [https://en.wikipedia.org/wiki/Entropy entropy]
|Internal energy related to entropy variation for a closed system in thermal equilibrium ([https://en.wikipedia.org/wiki/Fundamental_thermodynamic_relation fundamental thermodynamic relation]).
|Internal energy related to entropy variation for a closed system in thermal equilibrium ([https://en.wikipedia.org/wiki/Fundamental_thermodynamic_relation fundamental thermodynamic relation]).
|-
|style="background:white"| {{SERVER}}/images/formulas_mirror/dheqtds.png
|[https://en.wikipedia.org/wiki/Enthalpy Enthalpy] change
|Enthalpy change depending on entropy and pressure changes, equation created from the mix of the basic ones above.
|-
|-
|ΔS<sub>universe</sub> = ΔS<sub>surroundings</sub> + ΔS<sub>system</sub>
|ΔS<sub>universe</sub> = ΔS<sub>surroundings</sub> + ΔS<sub>system</sub>

Revision as of 19:43, 1 May 2012

Resources on physics related to aerodynamics

The List of elementary physics formulae on wikipedia is useful.

List of variables

Variable Meaning Unit (SI)
γ (gamma) Surface tension or Heat capacity ratio (adiabatic process in thermodynamics) N.m-1 (Newton per meter)
μ (mu) or η (eta) Viscosity Pa·s (Pascal second) or P (Poise, 1 Poise is 0.1 Pa.s)
ρ (rho) Density kg.m-3 (kg per cubic meter)
C, Cp, CV Heat capacity, general, at constant pressure, at constant volume. J.K-1 (Joule per Kelvin)
G Gibbs free energy J (Joule)
H Enthalpy: total energy of a thermodynamic system. J (Joule)
ΔHvap or L Vaporization heat or Latent heat of vaporization: energy required to vaporize a mole of liquid at a given temperature. J.mol-1 (Joule per mole)
M Mach number no unit
Q Amount of Heat J (Joule)
T Temperature. T0 or Tt is the stagnation temperature. K (Kelvin)
S Entropy J.K-1 (Joule per Kelvin)
U Internal energy of a system (see first law of Thermodynamics below) J (Joule)
V Volume m3 (cubic meter)
W Work: mechanical constraints on the system. J (Joule)
a Speed of sound in medium (used to calculate Mach number) m.s-1
c Velocity of a flow in thermodynamics, also noted V; generally noted u in fluid dynamics. m.s-1
n Quantity of matter mol (mole)
p Pressure. pt is the stagnation pressure. Pa (Pascal)

List of constants

Constant Meaning Value Unit (SI)
NA or N Avogadro constant, number of atoms or molecules in a mole. 6.02214129.1023 mol-1
R ideal gas constant 8.3144621 J.K−1.mol−1
kB or k Boltzmann constant, gas constant R divided by Avogadro number. 1.3806488.10-23 J.K-1

List of equations

Equation Name Meaning
pvnrtk.png Ideal gas equation Relation between properties of an ideal gas (state equation). k is kB.
clausius-clapeyron.png Clausius-Clapeyron relation Relation between the pressure, latent heat of vaporization and temperature of a vapour at two temperatures (approximation, at low temperatures).
QeqmL.png Heat at state change for an ideal gas. The heat required to change the state of a some matter, L being the latent heat. Delta H equals Q only when pressure is constant (isobaric).
dUeqdQmindW.png First law of thermodynamics Variations of internal energy of a system between two states is the sum of the received heat and work (minus the given work).
enthalpy.png Enthalpy Total amount of energy of a system, defined as the sum of the internal energy U of the system and pressure * volume at the boundary of the system and its environment.
workExpand.png Work of gas expansion. Work done by expanding an ideal gas.
entropy_dueqtdsmpdv.png Internal energy change related to entropy Internal energy related to entropy variation for a closed system in thermal equilibrium (fundamental thermodynamic relation).
dheqtds.png Enthalpy change Enthalpy change depending on entropy and pressure changes, equation created from the mix of the basic ones above.
ΔSuniverse = ΔSsurroundings + ΔSsystem Entropy variation as a whole. Entropy variation of a system is generally compensated by the inverse variation of the surroundings, not including losses.
dS.png Second law of thermodynamics A change in the entropy of a system is the infinitesimal transfer of heat to a closed system driving a reversible process, divided by the equilibrium temperature of the system.
gibbs.png Gibbs free energy / Free enthalpy Useful work obtainable from a system at isobaric and isothermal conditions. Since H is U + pV, it can be replaced in the equation, making G = H - TS.
deltaG.png Gibbs free energy variation. If ΔG < 0, the system's transformation can be spontaneous, if ΔG = 0 the transformation is inversible and the system is in an equilibrium state, if ΔG > 0 it can't be spontaneous.
density_ideal.png Density of an ideal gas. M is molar mass. This means that the density of an ideal gas can be doubled by doubling the pressure, or by halving the absolute temperature.