Correct Answer - Option 4 : compression ratio
Compression ratio can be defined in three terms i.e. pressure, volume and temperature.
\(r = \frac{{{V_1}}}{{{V_2}}}\) (In terms of volume)
\({r_P} = \frac{{{P_2}}}{{{P_1}}}\) (In terms of pressure)
\({r_T} = \frac{{{T_2}}}{{{T_1}}}\) (In terms of temperature)
Relation between these three:
\(\frac{{{T_2}}}{{{T_1}}} = {\left( {\frac{{{P_2}}}{{{P_1}}}} \right)^{\frac{{\gamma - 1}}{\gamma }}} = {\left( {\frac{{{V_1}}}{{{V_2}}}} \right)^{\gamma - 1}}\)
\({r_T} = r_P^{\frac{{\gamma - 1}}{\gamma }} = {r^{\gamma - 1}}\)
So we can conclude that the ratio of delivery pressure (P2) to suction pressure (P1) is called compression ratio.
