#### The flow of gas in a cylindrical channel at a subsonic speed

Abstract
The article gives the account of steady flow of a perfect gas in a vertical channel having some other parameters set. The flow is supposed to be highspeed, subsonic and design, that is the gas pressure at the outlet equal to the pressure (back pressure), while the forces of gravity can be neglected. The boundary value problem is solves with the standard numerical method, the Mathcad in particular. The least squares method was used to find the empirical dependence of the heat nitrogen on the temperature. Third order polynomial approximation gives the average deviation from experimental data of less than 0.5 %. The paper also shows that with increase of the wall temperature of channel increases the required pressure at the inlet of the lance and the speed of the output. The latter fact is important in the process to increase the influence of the purge. The developed method allows applying the Mathcad to solve the boundary problem of gas dynamics of a perfect gas in the channel with heat supply. The authors also show the dependence of the viscosity and heat capacity on the gas temperature.