Abstract: A series of experimental measurements are performed in details on three typical linear turbine cascades with turning angles of 68°, 113° and 160°. The effect of turning angle on outlet vorticity distribution, flow angle distribution and flow loss is discussed on the basis of detailed measurement and flow analysis of internal flow field. Then the vortex models of the three typical cascades are obtained. The experiment result shows that there exist complex vortex structures in linear turbine cascades. Moreover, for different turning angles, the vortex modes are also different. With the increase of turning angle, the intensity of passage vortex in flow field increases, and its position moves toward the middle of the blade, and affected by this, the position of trailing vortex in the whole flow field gradually lowers along with the increase of turning angle. The change of vortex structure will cause different distributions of flow angle and flow loss at the cascade outlet. The flow field can be re-organized by controlling the vortex structures. Therefore, understanding the basic characteristics of vortex structure in turbine cascade can provide the basis for the selection of aerodynamic optimization strategy.

Key words: Flow angle, Loss, Turning angle, Vortex structure