Talk:Relative pressure
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[edit]The comment(s) below were originally left at Talk:Relative pressure/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.
| Relative Pressure is not the same as Gage Pressure Italic textat allItalic text
Relative Pressure, or Pr, is a property of gasses and is defined as the quantity: exp[s^o(T)/R] where s^o(T) is the specific entropy at temperature T and Italic texta pressure of 1 atmItalic text. Therefore, s^o(T) is solely dependent on temperature. R is the ideal gas constant for the gas being analyzed. R can also be found be dividing the universal gas constant, Ru, by the molar mass, M, of the gas being analyzed. This quantity is useful in analyzing isentropic terbines and compressors because: P2/P1 = Pr2/Pr1 So if all you are given is the inlet and outlet temperature and the pressure at the inlet, you can find the pressure at the outlet using Pr values from a thermodynamic property table. Gage Pressure is the pressure observed minus the atmospheric pressure as stated in the article. |
Last edited at 20:05, 27 February 2007 (UTC). Substituted at 04:08, 30 April 2016 (UTC)