Study of methods for measuring thin water films for use in steam turbines

CTU in Prague, Energy Engineering Department, Technická 4, Prague 6, 166 07, Czechia

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Published online: 12 March 2026

Abstract

This article focuses on the experimental investigation of thin liquid films, with relevance to their behaviour and measurement in steam turbine applications. The main motivation comes from the fact that the formation, atomization, and subsequent droplet distribution of these films play a critical role in the erosion of turbine blades during non-structural operation, a phenomenon that can significantly impact blade efficiency and operational reliability. Understanding the properties of thin liquid films is essential not only for analysing the dynamics of droplet impact and resulting erosion but also for improving maintenance strategies and the longevity of energy systems. The research introduces a novel interferometric measurement device designed to precisely gauge thin film thickness in varying experimental conditions. The development of this instrument draws upon earlier work in optical measurement methods, aiming for high accuracy, non-invasiveness, and rapid responsiveness suited to tracking dynamic processes. The measurement method employs a rotating cylinder, partially submerged in liquid, to create a controlled film, with experimental variables including the rotational velocity and surface treatment (e.g., sandblasted versus polished). The study also highlights the importance of surface quality, since surface roughness and texture directly influence film formation and thickness, which in turn affect the atomization process and the likelihood of erosion events.