I'd like to better understand though; what is an isoentrope? The slope is on which graph?
Hurricane6
The isoentrope is a region of constant entropy , this is an involved explanation dealing with the second law of thermodynamics I'm afraid the actual explanation is very involved I could explain.
but I'm not sure of your background, in order to pitch it to the correct level I don't mean in anyway to sound discouraging but if you haven't had calculus based physics or calculus.
it may be difficult to explain correctly as it doesn't really lend itself to a verbal analysis, the story is really best told mathematically.
I wrote that because I know there are many levels of understanding on pprune and I generally write on a few levels at once in light of this...are you an engineering student or science major? and what level of math and physics have you had?
Are P and V pressure and volume? If so of what? Can you give succinct reasoning for Sigma arriving in the developing expression?
P is pressure but the 'v' in that case represents 'velocity' those are Equations of the Bernoulli form in which the pressure is corrected adiabatic compression using the adiabatic gas laws in other word since P,T,Volume and density can all be related it is possible to have a function in which adiabatic gas laws can be substituted into Bernoulli equation in order to see how pressure varies with velocity changes giving the correction for adiabatic correction...thus you end up with Bernoulli's equation for compressible flow
The 'V' in the .5rhoV^2 equation is in terms of TAS--- TAS is the Equivalent Airspeed corrected for the altitude density ratio [not density altitude-that's different]...just as a very simple conceptual explan....in order to have the same number on the airspeed indicator...say 100 knots at 50' agl as at 10000 feet the speed would need to b increased because the distance between the molecules 'path length' is greater at high altitudes due to lower density that is the TRUE AIRSPEED... the correction factor sigma is Rho/Rho0 @ ISA...
I understood the speed of sound is faster in denser environments so it varies with pressure not temperature. But he formula is based purely on temperature not pressure.
Is the speed of sound the same if the temp is static ( eg 15c) and the pressure varies eg 990 mb vs 1013mb?
18greens:
The exact answer arises from '
kinetic molecular theory'- Mathytouches upon it nicely in his post
but in brief pressure and temperature are related to one another in a fixed relation however because there's a fixed relation between P and T every time one varies the 'P' there's a corresponding change in 'T' so the the temperature will not remain static [without an external heater] if the pressure changes...
It may be a while between responses,if there are further questions, up to a couple of weeks, I'm a little busy now...
in the mean time
