The pressure ratio known as critical pressure ratio for maximum discharge through the nozzle is given by:
1
\(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{{n + 1}}{2}} \right)^{n/n - 1}}\)
2
\(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{2}{{n + 1}}} \right)^{n - 1/n}}\;\)
3
\(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{2}{{n + 1}}} \right)^{n/n - 1}}\)
4
\(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{{n + 1}}{2}} \right)^{n - 1/n}}\)
5
\(\frac{{{p_2}}}{{{p_1}}} = {\left( {\frac{2}{{n + 1}}} \right)^{-\left(n/n - 1\right)}}\)