Application of the Parametric Method for Profiling the Interblade Channels in the Nozzle Cascades of Axial-Flow Turbine Machines

Examples of successful application of the technique for parametrically profiling the blades of axial-flow turbine machines are given. The interconnection between the cascade parameters and the profile parameters that are used for representing the blade profile's shape is described. The influence of each of the considered parameters on the flow characteristics downstream of the cascade, in particular, on the kinetic energy losses and working fluid outlet angle, is analyzed. The initial cascade is optimized for enhancing its aerodynamic efficiency by improving the streamlining of the blade suction side and trailing edge. The optimization results were confirmed by calculation and experimental investigations. By using the developed method, the problem of designing the turbine nozzle cascade for its operation under wet steam conditions with high-efficient removal of moisture from the steam turbine flow path has been solved. Based on the elaborated recommendations for controlling droplet flows through modifying the blade profile's shape, the profile and cascade have been designed that make it possible to obtain highly intensive growth of liquid film thickness and flowrate on the interblade channel surfaces in the places from which it can be removed through the interchannel separation slots. The accomplished set of calculation and experimental investigations has confirmed the effectiveness of the selected approach.