卧轴混流式水轮机前盖板(顶板)、与转轮上冠、下环的迷宫配合部位在运行中受泥沙磨损,使间隙增大。漏水量增加,造成效率下降;使较大颗粒的泥沙将进入前盖板内腔,加速其内表面的磨损;转轮背部水压上升,轴向水推力势必加大;瓦温升高,加速主轴密封的磨损。前盖板间隙的漏水量随 Horizontal axis Francis turbine front cover (roof), and the crown on the runner, the lower part of the labyrinth maze with the site by the sediment wear and tear, so that the gap increases. Leakage increases, resulting in decreased efficiency; make larger particles of sediment will enter the inner cavity of the front cover to accelerate the wear and tear of its inner surface; runner back pressure increases, the axial thrust is bound to increase water; Accelerate spindle seal wear. Leakage of the front cover gap with