Evaluation for characteristics of wet snow accretion on transmission lines - Establishment of an experimental method using a vertical plate

Abstract

It is of primary importance to decrease risks of snow damages on electric transmission lines to ensure a stable supply of electricity. For the acquisition of reliable data to clarify characteristics of snow accreted on a transmission line, it is effective to conduct an indoor experiment. The present report describes an experimental method for snow accretion on a vertical plate by using a wind tunnel including measurements of snow properties such as snow density and liquid water content, which can be extended to measure a shear adhesive stress of accreted snow. These measurements are systematically applied to different conditions of the wind speed, the air temperature, as well as the snow flux particularly focusing on wet snow accretion. Based on measurement data, the influence of the wind speed, the air temperature, and the snow flux on the snow density and the liquid water content is investigated. The analysis is further extended to include a parametric evaluation of the snow density and the liquid water content to examine their dependency on atmospheric parameters. As a result of analytical considerations of the consolidation effect by wind and melting of snow by heat exchanges, equations to estimate the snow density and the liquid water content by the wind speed, the air temperature, as well as the accreted snow mass are derived. The experimental results validate these equations, which enable the acquisition of desired snow properties by adjusting experimental parameters. The successful evaluation of snow properties in the presented experiments can substantially contribute to the establishment of practical data-set for further investigations to characterize wet snow accretion.