The effects of different yaw angles on the aerodynamic performance of city electric multiple units(EMUs)were investigated in a wind tunnel using a 1:16.8 scaled model.Pressure scanning valve and six-component box-type...The effects of different yaw angles on the aerodynamic performance of city electric multiple units(EMUs)were investigated in a wind tunnel using a 1:16.8 scaled model.Pressure scanning valve and six-component box-type aerodynamic balance were used to test the pressure distribution and aerodynamic force of the head car respectively from the 1.5-and 3-coach grouping city EMU models.Meanwhile,the effects of the yaw angles on the pressure distribution of the streamlined head as well as the aerodynamic forces of the train were analyzed.The experimental results showed that the pressure coefficient was the smallest at the maximum slope of the main shape-line.The side force coefficient and pressure coefficient along the head car cross-section were most affected by crosswind when the yaw angle was 55°,and replacing a 3-coach grouping with a 1.5-coach grouping had obvious advantages for wind tunnel testing when the yaw angle was within 24.2°.In addition,the relative errors of lift coefficient C_(L),roll moment coefficient C_(Mx),side force coefficient C_(S),and drag coefficient C_(D) between the 1.5-and 3-coach cases were below 5.95%,which all met the requirements of the experimental accuracy.展开更多
A rotary valve-controlled pitch system is proposed to regulate the generator power and smooth power fluctuationsfor a wind turbine. Design details and dynamic modeling of this pitch system are presented and analyzed. ...A rotary valve-controlled pitch system is proposed to regulate the generator power and smooth power fluctuationsfor a wind turbine. Design details and dynamic modeling of this pitch system are presented and analyzed. A practical loadingcompensation approach is synthesized and involved in the pitch system to compensate for the external uncertain pitch loads. Theproposed pitch system and loading compensation approach have been experimentally evaluated in terms of generator powersmoothing and control accuracy. As demonstrated by the comparative experimental results, the proposed pitch system can beused to significantly smooth the generator power fluctuations and hence to improve the power quality as compared with a servovalve-controlled pitch system under the same operating conditions. The loading compensation approach can also be used to sig-nificantly attenuate the effects of external pitch loads and improve the robustness and reliability of the pitch system. The pro-posed pitch system features good control accuracy and cost-efficiency and hence is attractive for applications in modem large-scale wind turbines.展开更多
基金Project(2020YFA0710903) supported by the National Key R&D Program of ChinaProjects(2020zzts111, 2020zzts117)supported by the Graduate Student Independent Innovation Project of Central South University,ChinaProject(202037)supported by Transport Department of Hunan Province Technology Innovation Project,China。
文摘The effects of different yaw angles on the aerodynamic performance of city electric multiple units(EMUs)were investigated in a wind tunnel using a 1:16.8 scaled model.Pressure scanning valve and six-component box-type aerodynamic balance were used to test the pressure distribution and aerodynamic force of the head car respectively from the 1.5-and 3-coach grouping city EMU models.Meanwhile,the effects of the yaw angles on the pressure distribution of the streamlined head as well as the aerodynamic forces of the train were analyzed.The experimental results showed that the pressure coefficient was the smallest at the maximum slope of the main shape-line.The side force coefficient and pressure coefficient along the head car cross-section were most affected by crosswind when the yaw angle was 55°,and replacing a 3-coach grouping with a 1.5-coach grouping had obvious advantages for wind tunnel testing when the yaw angle was within 24.2°.In addition,the relative errors of lift coefficient C_(L),roll moment coefficient C_(Mx),side force coefficient C_(S),and drag coefficient C_(D) between the 1.5-and 3-coach cases were below 5.95%,which all met the requirements of the experimental accuracy.
基金supported by the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.51221004)the National Natural Science Foundation of China(No.51275448)the Fundamental Research Funds for the Central Universities(No.2015QNA4005),China
文摘A rotary valve-controlled pitch system is proposed to regulate the generator power and smooth power fluctuationsfor a wind turbine. Design details and dynamic modeling of this pitch system are presented and analyzed. A practical loadingcompensation approach is synthesized and involved in the pitch system to compensate for the external uncertain pitch loads. Theproposed pitch system and loading compensation approach have been experimentally evaluated in terms of generator powersmoothing and control accuracy. As demonstrated by the comparative experimental results, the proposed pitch system can beused to significantly smooth the generator power fluctuations and hence to improve the power quality as compared with a servovalve-controlled pitch system under the same operating conditions. The loading compensation approach can also be used to sig-nificantly attenuate the effects of external pitch loads and improve the robustness and reliability of the pitch system. The pro-posed pitch system features good control accuracy and cost-efficiency and hence is attractive for applications in modem large-scale wind turbines.
