Experimental and Numerical Investigation on Flow Characteristics of a Vaneless Counter-Rotating Turbine at Off-Design Conditions

Abstract

In this paper, a lot of experimental and numerical investigations are performed to explore the flow characteristics of a vaneless counter-rotating turbine at off-design conditions. The experimental investigations were carried out on a blow-down short duration turbine test facility, and the numerical simulations were performed by means of a three-dimensional multiblade row steady Navier-Stokes code. Depending on the experimental and numerical investigations, the operating characteristics of the vanless counter-rotating turbine are obtained. The investigation results indicate that the ratio of specific work of the high-pressure turbine to that of the low-pressure turbine and the efficiency of the vaneless counter-rotating turbine are increased as the rotation speed of the rotor increases under the same expansion ratio. And the research results show that when the rotation speed of the rotor increases, the specific work of the low pressure turbine is decreased, and the effective operation range of the vaneless counter-rotating turbine is reduced. The investigation results also indicate that the numerical code in this paper can qualitatively predict the flow characteristics of the vaneless counter-rotating turbine at off-design conditions. The prediction ability of the numerical code is credible.