摘要：The chief aim of the present work was to achieve drag reduction in stator blades with liquid using boundary layer control. A stator blade of hydraulic torque converter with bionic grooves in suction side and hydrophobic surface in pressure side was designed. The hydrophobic surface was created using anodic oxidation method and irregular A1203 thin films were found on the surface. They formed hierarchical structure consisting of mini porous structures and microscopic pore spaces, resulting in the hydrophobicity. The bionic groove was designed by Computational Fluids Dynamics （CFD） method. Multi-Island Genetic Algorithm （MIGA） was adopted for groove multi-objective optimization. Through optimization, the maximum drag reduction was close to 12% in oil. In addition, the drag reduction calculation was verified by closed channel experiment and ＂Tire Vortex＂ was proposed to explain the drag reduction mechanism. The bionic Janus blade could maintain its initial profile without any additional device, which had lower risk and less cost. The results are encouraging and show great potential to apply in other flow machineries.

摘要：The complex structure of the bottom of a high-speed train is an important source of train aerodynamic ***,improving the bottom structure is of great significance to reduce the aerodynamic drag of the *** this study,computational fluid dynamics(CFD)based on three-dimensional steady incompressible Reynolds-average Naiver-Stokes(RANS)equations and Realizable k-ε turbulence model were utilized for numerical *** by the concept of streamlined design and the idea of bottom flow field control,this study iteratively designed the bogies in a streamlined shape and combined them with the bottom deflectors to investigate the joint drag reduction *** models,i.e.,single-bogie model,simplified train model,and eight-car high-speed train model,were created and their aerodynamic characteristics were *** results show that the single-bogie model with streamlined design shows a noticeable drag reduction,whose power bogie and trailer bogie experience 13.92%and 7.63%drag reduction,*** range of positive pressure area on the bogie is *** aerodynamic drag can be further reduced to 15.01%by installing both the streamlined bogie and the deflector on the simplified train *** the streamlined bogies and deflectors are used on the eight-car model together,the total drag reduction rate reaches 2.90%.Therefore,the proposed aerodynamic kit for the high-speed train bottom is capable to improve the flow structure around the bogie regions,reduce the bottom flow velocity,and narrow the scope of the train’s influence on the surrounding environment,achieving the appreciable reduction of aerodynamic *** paper can provide a new idea for the drag reduction of high-speed trains.

摘要：Two-dimensional and three-dimensional shock control contour bumps are designed for a supercritical wing section with the aim of transonic wave drag reduction. The supercritical airfoil （NASA SC （02）-0714） is selected considering the fact that most modern jet transport aircrafts that operate in the transonic flow regime （cruise at transonic speeds） employ supercritical airfoil sections. Here it is to be noted that a decrease in the transonic wave drag without loss in lift would result in an increased lift to drag ratio, which is a key range parameter that can potentially increase both the range and endurance of the aircraft. The major geometric bump parameters such as length, height and span are altered for both the two-dimensional and three-dimensional bumps in order to obtain the optimum location and shape of the bump. Once an optimum standalone three-dimensional bump is acquired, an array of bumps is manually placed spanwise of an unswept supercritical wing and analyzed under fully turbulent flow conditions. Different configurations are tested with varying three-dimensional bump spacing in order to determine the contribution of bump spacing on overall performance. The results show a 14% drag reduction and a consequent 16% lift to drag ratio rise at the design Mach number for the optimum arrangement of bumps along the wing span.

摘要：In the present study, a high Reynolds number version of a turbulence model was proposed by using drag reduction to analyze the turbulent flows of power-law fluid for engineering applications. In order to determine the model constants in the constitutive equation, numerical simulation was conducted under the same conditions that were applied to obtain the experiment re- suits and previous turbulence models. For validation of the modified turbulence model, numerical simulations were performed for power-law fluids of different viscosities. The results of the modified k-ε turbulence model showed better agreement with the experimental results than those of the standard k-ε turbulence model. In addition, computation time and computer resource of the modified k-ε turbulence model were reduced by about one third as compared to the low Reynolds number model for power-law fluids.

摘要：Both the academic society and the industry are hunting for new energy forms for the ***,the world should not forget the conventional technologies that contribute to the sustainable society by technical *** them,lubrication plays a significant role in energy saving and in low CO2emission by increasing the fuel efficiency and by prolonging the service life of *** the advance of novel synthetic approaches,and nanoscience and technologies,novel lubrication oils and additives and their formulations are being developed to reduce friction and wear,and novel surface treatment routes and surface coatings are invented and provide more efficient *** technologies create tremendous chances for machines to work more efficiently with low energy *** we review the recent progresses and challenges associated with some novel lubrication techniques that include novel surface treatment(such as texturing,high-performance nanocomposite coatings,adapting coating),tribology design(solid and liquid lubrication),energy-conserving engine oil and novel lubricants and formula(such as ionic liquids,low S,P content additives)which are to be adopted to enhance the fuel efficiency to achieve energy saving and low carbon *** is increased demand to replace fossil lubricants by degradable green *** designed coatings can reduce drag significantly during navigation of both airplanes and *** these aspects will be also reviewed in the paper.