Abstract: A Couette rheometer with flow visualization and pressure control is made boy using the techniques of high-precision machining and dynamic sealing. With the rotating outer cylin-der and static inner cylinder, the rheometer can realize stable and uniform simple shear flow of the shear rate up to 105/s. Utilizing the well-known viscosity-temperature formula, the viscosities of water and silicone oils at high shear rates meas-ured by this rheometer agree well with that obtained by the commercial rotational rheometer at low shear rates and various temperatures. At a certain shear stress, cavitation occurred for fresh water and two silicone oils with low and medium viscosities. Strong dependence of the onset of shear cavitation on the amount of dissolved gas is observed.

Key words: Rheometer, Cavitation, Couette flow, High shearing