In high-pressure dynamic thermodynamic processes, the pressure is much higher than the air critical pressure, and the temperature can deviate significantly from the Boyle temperature. In such situations, the thermo-physical properties and pneumatic performance can’t be described accurately by the ideal gas law. This paper proposes an approach to evaluate the pneumatic performance of a high-pressure air catapult launch system, in which esidual functions are used to compensate the thermal physical property uncertainties of caused by real gas effects. Compared with the Nelson-Obert generalized compressibility charts, the precision of the improved virial equation of state is better than Soave-Redlich-Kwong (S-R-K) and Peng-Robinson (P-R) equations for high pressure air. In this paper, the improved virial equation of state is further used to establish a compressibility factor database which is applied to evaluate real gas effects. The specific residual thermodynamic energy and specific residual enthalpy of the high-pressure air are also derived using the modified corresponding state equation and improved virial equation of state which are truncated to the third virial coefficient. The pneumatic equations are established on the basis of the derived residual functions. The comparison of the numerical results shows that the real gas effects are strong, and the pneumatic performance analysis indicates that the real dynamic thermodynamic process is obviously different from the ideal one.

In view of the poor thermodynamic environment problem of the self-powered launch of land-based concentric canister launcher (CCL), the launching scheme of injecting water at the bottom of launching tube is adopted to improve the thermodynamic environment of the launching system fundamentally. The solution program for liquid water vaporization is compiled and embedded into the homogeneous gas–liquid two-phase flow model, the source phase corrections of the momentum equation and the energy equation are also performed, and then the three-dimensional gas–liquid two-phase fluid dynamics model is established for the land-based CCL; analysis shows that the improvement of the thermal environment of the 35° and 45° water injection schemes is more better among these schemes. So coupling the mixture model, vaporization program and FW–H (Ffowcs Williams Hawkings) noise model, the noise distribution law in the bottom of the launcher cube for 35 and 45 water injection angles is discussed; in the intermediate frequency range, the −45° water injection scheme is about 2–10 dB higher than the noise signal of the −30° water injection scheme. Finally, it is recommended to optimize the overall thermal environment of the CCL by using the −30° preferred water injection scheme with both cooling effect and noise control.