energies Article Numerical Investigations of the Effects of the Rotating Shaft and Optimization of Urban Vertical Axis Wind Turbines Lidong Zhang 1, Kaiqi Zhu 1, Junwei Zhong 2,*, Ling Zhang 1, Tieliu Jiang 1, Shaohua Li 1 and Zhongbin Zhang 1 1 Energy and Power Engineering, Northeast ...