The paper considers forming a LP running part of large power steam turbines allowing for the performance in the last stages of pulsating streams. The authors have obtained and generalized the results of researching LP running parts at experimental stands with wet steam. This paper discusses the physical model of a wet steam flow in LP last stages and the influence of various factors on the increase in flow pulsations and energy losses and on the reduction in the turbine stage efficiency. The research results of the experimental turbine are presented and analyzed. Important dependences have been obtained, including flow fluctuations and stability zones, as well as dynamic stresses while changing the operating mode.