INFLUENCE OF CAVITATION ON BLADE CHARACTERISTICS

An experimental study of flow around a blade with a modified NACA 4418 profile was conducted in a water tunnel that also enables control of the cavitation conditions within it. Pressure, lift force, drag force and pitching moment acting on the blade were measured for different bl ade angles and cavitation numbers, respectively. Relationships between these parameters were elaborated and some of them are presented here in dimensionless form. The analysis of results confirmed that cavitati on changes the pressure distribution significantly. As a consequence, lift force and pitching moment are reduced, and the drag force is incr eased. When the cavitation cloud covers one side of the blade and the flow becomes more and more vaporous, the drag force also begins to dec rease. The cavity length is increased by increasing the blade angle an d by decreasing the cavitation number.