The flow characteristics and thermal effects in gas-flow medium where there is some deposited energy (such as electrical diseharge, absorption of laser radiation) have been analyzed on the basis of gasdynamic equations. When 0.05≤M≤0.2 which is a typical condition for gas-flow discharge lasers, the gasdynamie equations become the simplest ones. It is quite easy to get an analytical solution and it is possible to measure the distributions of the deposited energy, density, temperature and velocity in flow direction in the active medium by laser interferometry.