Abstract: Guiding vertical axis wind turbine (Guiding VAWT) is named after a guiding impeller surrounding a vertical axis wind impeller，which has higher aerodynamic performance than the traditional VAWTs. The flow field inside the Guiding VAWT is a multi-scale, unsteady, three- dimensional vortex one with the combined characteristics of both the internal flow and external flow. The unsteady, three-dimensional simulation of this complex flow field needs large amount of calculation not only far beyond the ability of current personal computer, but also hardly acceptable for the design period of enterprise’s product. By discussing two aspects of the numerical simulation for the flow field inside the Guiding VAWT, efforts are put on finding a simplified model for the numerical simulation of the Guiding VAWT, which needs only moderate computing capability and time but can obtain enough precision. Two aspects are discussed in detail: One is the feasibility of the Multiple Reference Frame Approach needing less computing capability in place of the Sliding Mesh Approach needing larger computing capability during the delivery of the unsteady calculation information between the rotating wind impeller and the stationary guiding impeller; the other is the feasibility of the simplified two-dimensional model in place of the actual three-dimensional model. Results indicate that the total performance of Guiding VAWT simulated respectively by the Multiple Reference Frame Approach and Sliding Mesh Approach are almost identical but the flow field details are somewhat different, which appears obvious in the windward area of the wind impeller. Obtained respectively by the simplified two-dimensional model and the actual three- dimensional model, the total performance curves of the Guiding VAWT are similar with the same optimal tip speed ratio. But the total performance obtained by two-dimensional model is always lower in quantity than that obtained by three-dimensional model. As far as the tentative simulation of the flow field inside the Guiding VAWT is concerned, the simplified two-dimensional model with Multiple Reference Frame Approach can be adopted, which needs moderate calculating capability and time to obtain computation results with due precision to satisfy the requirement of industrial design.

Key words: Flow field simulation, Guiding VAWT, Multiple reference frame approach, Sliding mesh approach, Two dimensional and three dimensional model