The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken a...The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design. The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and the seismic force, and that the optimum excavation slope angle is 60°.展开更多
In this paper, in order to design a fast steering mirror(FSM) with large deflection angle and high linearity, a deflection angle detecting system(DADS) using quadrant detector(QD) is developed. And the mathematical mo...In this paper, in order to design a fast steering mirror(FSM) with large deflection angle and high linearity, a deflection angle detecting system(DADS) using quadrant detector(QD) is developed. And the mathematical model describing DADS is established by analyzing the principle of position detecting and error characteristics of QD. Based on this mathematical model, the variation tendencies of deflection angle and linearity of FSM are simulated. Then, by changing the parameters of the DADS, the optimization of deflection angle and linearity of FSM is demonstrated. Finally, a QD-based FSM is designed based on this method, which achieves ±2° deflection angle and 0.72% and 0.68% linearity along x and y axis, respectively. Moreover, this method will be beneficial to the design of large deflection angle and high linearity FSM.展开更多
The embankment and the hill cut are conventional infrastructure scenarios along the railway line in windy regions.The windbreak walls with the same height are separately installed on them to guarantee the safety of tr...The embankment and the hill cut are conventional infrastructure scenarios along the railway line in windy regions.The windbreak walls with the same height are separately installed on them to guarantee the safety of train operation.However,due to the realistic terrain,the distances of windbreak walls on the embankment and hill cut from the railway centreline are not the same,generating a windbreak wall transition and causing a sudden change of the windproof performance,which contributes to the so-called'yawingphenomenon when the train passes through the windbreak transition.The current study aims to predict the flow characteristics around the existing right-angled windbreak wall,with three preliminary designs and four local improvement designs at the transition connecting the embankment and the hill cut along the high-speed railway.The detached-eddy simulation method with the realizable k-ε turbulence model was used,while the contour lines were applied to generate the realistic terrain.The velocity distributions in the existing windbreak wall transition present a fast change from the large negative value(i.e.-0.16U on windward line(WWL)and-0.20U on leeward line(LWL))to the positive value(i.e.0.47U on WWL and 0.42U on LWL)within the distance of 10h.The different locations of windbreak walls on the embankment and hill cut create a rectangular discontinuous transition.The consistency of the windproof performance is destroyed at the windbreak wall transition,resulting in a sudden gust on the railway lines.A preliminary design idea coming from the hypotenuse on a right triangle was proposed to smooth the transition from the windbreak on the cut to that on the embankment.Three included angles were discussed,and the 30ºscheme shows the best shielding performance,achieving about 46%reduction on the peak-to-peak value on the WWL and 32% on the LWL at the middle height of the train.However,the positive peaks are stil observed.On this 30ºscheme,four local improvement designs are attempted to further smooth the velocity distributions.The best design that meets three wind directions can achieve about 80% reduction of peak-to-peak values.All achievements can provide a reference for the design of windbreak walls at different transition s and improve the safety of train operation under strong winds.展开更多
In this paper, a novel engineering platform for throughflow analysis based on streamline curvature approach is developed for the research of a 5-stage compressor. The method includes several types of improved loss and...In this paper, a novel engineering platform for throughflow analysis based on streamline curvature approach is developed for the research of a 5-stage compressor. The method includes several types of improved loss and deviation angle models, which are combined with the authors' adjustments for the purpose of reflecting the influences of three-dimensional internal flow in high-loaded multistage compressors with higher accuracy. In order to validate the reliability and robustness of the method, a series of test cases, including a subsonic compressor P&W 3S1, a transonic rotor NASA Rotor 1B and especially an advanced high pressure core compressor GE E^3 HPC, are conducted. Then the computation procedure is applied to the research of a 5-stage compressor which is designed for developing an industrial gas turbine. The overall performance and aerodynamic configuration predicted by the procedure, both at design- and part-speed conditions, are analyzed and compared with experimental results, which show a good agreement. Further discussion regarding the universality of the method compared with CFD is made afterwards. The throughflow method is verified as a reliable and convenient tool for aerodynamic design and performance prediction of modern high-loaded compressors. This method is also qualified for use in the further optimization of the 5-stage compressor.展开更多
基金theNationalNaturalScienceFoundationofChina (No .40 0 72 0 85 )
文摘The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design. The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and the seismic force, and that the optimum excavation slope angle is 60°.
基金supported by the National Natural Science Foundation of China(No.51605465)
文摘In this paper, in order to design a fast steering mirror(FSM) with large deflection angle and high linearity, a deflection angle detecting system(DADS) using quadrant detector(QD) is developed. And the mathematical model describing DADS is established by analyzing the principle of position detecting and error characteristics of QD. Based on this mathematical model, the variation tendencies of deflection angle and linearity of FSM are simulated. Then, by changing the parameters of the DADS, the optimization of deflection angle and linearity of FSM is demonstrated. Finally, a QD-based FSM is designed based on this method, which achieves ±2° deflection angle and 0.72% and 0.68% linearity along x and y axis, respectively. Moreover, this method will be beneficial to the design of large deflection angle and high linearity FSM.
基金supported by the Science and Technology Innovation Program of Hunan Province,China(Grant No.2022RC3040)the Science and Technology Research Program of China State Railway Group Co.,Ltd.(Grant No.Q2023T002)+1 种基金the Technology Research and Development Program of China Rail-way Urumqi Group Co.,Ltd.(Grant No.2023-kj-91)the Nat-ural Science Foundation of Hunan Province,China(Grant Nos.2022JJ40064 and 2022JJ30727).
文摘The embankment and the hill cut are conventional infrastructure scenarios along the railway line in windy regions.The windbreak walls with the same height are separately installed on them to guarantee the safety of train operation.However,due to the realistic terrain,the distances of windbreak walls on the embankment and hill cut from the railway centreline are not the same,generating a windbreak wall transition and causing a sudden change of the windproof performance,which contributes to the so-called'yawingphenomenon when the train passes through the windbreak transition.The current study aims to predict the flow characteristics around the existing right-angled windbreak wall,with three preliminary designs and four local improvement designs at the transition connecting the embankment and the hill cut along the high-speed railway.The detached-eddy simulation method with the realizable k-ε turbulence model was used,while the contour lines were applied to generate the realistic terrain.The velocity distributions in the existing windbreak wall transition present a fast change from the large negative value(i.e.-0.16U on windward line(WWL)and-0.20U on leeward line(LWL))to the positive value(i.e.0.47U on WWL and 0.42U on LWL)within the distance of 10h.The different locations of windbreak walls on the embankment and hill cut create a rectangular discontinuous transition.The consistency of the windproof performance is destroyed at the windbreak wall transition,resulting in a sudden gust on the railway lines.A preliminary design idea coming from the hypotenuse on a right triangle was proposed to smooth the transition from the windbreak on the cut to that on the embankment.Three included angles were discussed,and the 30ºscheme shows the best shielding performance,achieving about 46%reduction on the peak-to-peak value on the WWL and 32% on the LWL at the middle height of the train.However,the positive peaks are stil observed.On this 30ºscheme,four local improvement designs are attempted to further smooth the velocity distributions.The best design that meets three wind directions can achieve about 80% reduction of peak-to-peak values.All achievements can provide a reference for the design of windbreak walls at different transition s and improve the safety of train operation under strong winds.
基金supported by SEDRIand the National Natural Science Foundation of China(Grant No.51136003)
文摘In this paper, a novel engineering platform for throughflow analysis based on streamline curvature approach is developed for the research of a 5-stage compressor. The method includes several types of improved loss and deviation angle models, which are combined with the authors' adjustments for the purpose of reflecting the influences of three-dimensional internal flow in high-loaded multistage compressors with higher accuracy. In order to validate the reliability and robustness of the method, a series of test cases, including a subsonic compressor P&W 3S1, a transonic rotor NASA Rotor 1B and especially an advanced high pressure core compressor GE E^3 HPC, are conducted. Then the computation procedure is applied to the research of a 5-stage compressor which is designed for developing an industrial gas turbine. The overall performance and aerodynamic configuration predicted by the procedure, both at design- and part-speed conditions, are analyzed and compared with experimental results, which show a good agreement. Further discussion regarding the universality of the method compared with CFD is made afterwards. The throughflow method is verified as a reliable and convenient tool for aerodynamic design and performance prediction of modern high-loaded compressors. This method is also qualified for use in the further optimization of the 5-stage compressor.
