Three-Dimensional Pressure Controlled Vortex Design of a Turbine Stage
A three-dimensional (3D) Pressure Controlled Vortex Design (PCVD) method for turbine stage design is proposed and discussed in this paper. The concept is developed from conventional Controlled Vortex Design (CVD) via pressure control approach and CVD technology. By specifying the static pressure and axial velocity distributions, the spanwise pressure gradient incorporated with pressure gradient in streamwise and azimuthal directions is moderated. Not only can profile loss profit from pressure control approach, but also secondary flow can be managed. The reasons for CVD are derived from stream surface thickness and stream surface twist. Through modifying stream surface thickness and inducing large stream surface twist, the secondary flow migrations are controlled properly and orderly. The relations of pressure control approach and CVD technology complement one another and finally lead to a well-posed flow pattern in turbine stage. The first stage redesign of a well-designed low pressure turbine demonstrates this technique application. A significant reduction of secondary flow losses and a corresponding increase of stage efficiency have achieved.