# Comparison of Dual-Combustion Ramjet and Scramjet Performances Considering Combustion Efficiency
## 4 Conclusions
\begin{tabular}{l l} \(\bar{n}\) & Mass of flow per unit time, kg/s. \\ \(M\) & Molar mass, kg/mol. \\ \(\overline{h}_{j}^{0}\) & Formation enthalpy, J/mol. \\ \(T\) & Temperature, K. \\ \(P\) & Pressure, kPa. \\ \(Ma\) & Mach number. \\ \(\eta_{c}\) & Combustion efficiency. \\ \(K_{p}\) & Total pressure recovery coefficient. \\ \(F\) & Thrust, which is the thrust gain in the paper, N. \\ \(I\) & Specific impulse, m/s. \\ \(Sp\) & Specific thrust, m/s. \\ \(S_{a}\) & Stream thrust function, m/s. \\ \(u\) & Axial velocity of air flow, m/s. \\ \(R\) & The average gas constant of the flow, J/(kg\(\cdot\)k). \\ \(h_{burn}\) & Heat released per unit mass of complete combustion, J/kg. \\ Subscripts & A\(\_\)tot & Sum of the air mass of the subsonic combustor and supersonic combustor. \\ fuel & Fuel, i.e., kerosene. \\ hot & Operating conditions when the fuel is burned. \\ cold & Operating conditions when the fuel is not burned. \\ net & Net increase value. \\ c\(\_\)in & Inlet of combustor. \\ 0 & The state of a stagnant air flow. \\ 1 & Operating condition 1, which is 30 km flight altitude and Mach 6. \\ 2 & Operating condition 2, which is 30 km flight altitude and Mach 7. \\ \end{tabular}   
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