Numerical and experimental analysis of pressure fluctuation in axial flow turbine

Abstract

The operational stability of axial flow turbines (AFT) directly affects its safety and performance. Hence, dynamic analysis of its internal flow characteristics is essential, since its unsteady pressure characteristics are complicated. A reliable measurement approach becomes essential in order to analyze and understand the pressure fluctuation within the turbine. Dynamic pressure pulsation measurements were conducted by installing pressure sensors on the flow domain of the AFT under different operating conditions. Based on computational and experimental measurements, different unsteadiness in the flow structures resulted in various excitation signals. The excited frequencies of the stationary parts occurred at 72.50 Hz(3 × fn), 145.00 Hz (6 × fn),and 217.50 Hz (9 × fn), while for the impeller, excited frequencies of 217.50 Hz (9 × fn), 435.00 Hz (18 × fn), and 652.50 Hz (27 × fn) were recorded. The rotor-stator interaction with fluid flow from the guide vane to the impeller is culpable for strong pressure pulsations. The experimental measurement shows a comprehensive agreement with numerical results. This paper focused on the analysis of pressure fluctuation in AFT combining experimental and computational methods. Moreover, an exhaustive understanding of flow characteristics of the AFT is necessary for its optimization and operational reliability.