摘要：The three-dimensional internal flow field of centrifugal pump is complex and variable with design parameters and operation conditions. The post-processing technique named differential amplification method was proposed for the comparison study of different flow structures. The full steady flow fields of an industrial centrifugal pump working on-design and off-design points were numerically investigated by solving Reynolds average Navier-Stokes equations together with a shear-stress transport(SST) k-? turbulence model. And the numerically predicted performance curves of the studied pump agree well with test measurement results. Compared with the flow flied on design point under the help of differential amplification method, the disturbance caused by interaction between blade and volute tongue is very obvious and it extends to the diffuser pipe on the working point with 0.8 times rated flux. While on the point with 1.2 times rated flux, the flow distribution in impeller region is roughly even and it flows more to the bottom section of the diffuser pipe. The above method was proved to be good at displaying the subtle secondary flow structure changes with a higher resolution effect relative to single isolated case observation, which helps the optimization decision-making from multiple design cases.

摘要：A novel method was proposed to design the structure of a bone tissue engineering scafold based on triply periodic minimal *** this method,reverse engineering software was used to reconstruct the surface from point cloud *** method overcomes the limitations of commercially available software packages that prevent them from generating models with complex surfaces used for bone tissue engineering ***,the fluid feld of the scafolds was simulated through a numerical method based on fnite volume and the cell proliferation performance was evaluated via an in vitro *** cell proliferation and the mass flow evaluated in a bioreactor further verifed the flow feld simulated using computational fluid *** result of this study illustrates that the pressure value drops rapidly from 0.103 Pa to 0.011 Pa in the y-axis direction and the mass flow is unevenly distributed in the *** mass flow in the side outlets is observed to be approximately 24.3 times higher thanthe ***,although the mean value of wall shear stress is signifcantly more than 0.05 Pa,there is stil a large area with a suitable shear stress below 0.05 Pa where most cells can proliferate *** result shows that th inlet velocity 0.0075 m/s is suitable for cell proliferation in the *** study provides an insight into the design analysis,and in vitro experiment of a bone tissue engineering scafold.

摘要：Curved blade and end-bend blade are considered as effective passive control methods for improving the aerodynamic performance of a compressor cascade,and their applicability also needs to be further studied.A highly-loaded compressor linear cascade in the design condition was taken as the research objective in this *** simulation was used to study the positive and negative effects of these methods on the flow loss of the cascade by redistributing the vortex *** show that:the curved blade could reduce the flow loss to 2.55%,while the end-bend blade and the end-bend+curved blade increase it to 10.58%and 2.19%,*** positive effect of the curved blade weakens the strength and scale of Concentrated Shedding Vortex(CSV),which accounts for 59.2%of the total flow *** negative effect of the end-bend blade exacerbates the low-energy fluid clusters from the end wall and wake into ***,the end-bend+curved blade can take their own strengths,but it enhances the twisting motion of Passage Vortex(PV)and CSV,which makes it fail to reduce the flow ***,the positive and negative effects of these methods on the flow loss of a compressor cascade are much *** addition,we also predict the potential danger of the end-bend blade in the negative incidence conditions and provides some suggestion for future study.

摘要：Laminar flow design is one of the most effective ways to reduce the drag of a commercial aircraft by expanding the laminar flow region on the surface of the aircraft. As material science develops, the emergence of new materials such as low surface energy materials has offered new choices for laminar flow design of commercial aircraft. Different types of low surface energy micro-nano coatings are prepared to verify the effects on the boundary layer transition position and the drag of the airfoil through wind tunnel tests. The infrared thermal imaging technology is adopted for measuring the boundary layer transition, while the momentum integral approach is employed to measure the drag coefficient through a wake rake. Infrared thermal imaging results indicate that the coatings are capable of moving backward the boundary layer transition position at both a low velocity of Mach number 0.15 and a high velocity of Mach number 0.785. Results of the momentum integral approach demonstrate that the drag coefficients are reduced obviously within the cruising angle of attack range from 1° and 5° by introducing the low surface energy micro-nano coating technology.

摘要：For the hypersonic inlet and fore-body integrated design, the non-uniform incoming flow generated by the fore-body will bring a relatively big challenge to the inward-turning inlet design. To make the inlet match the non-uniform incoming flow, this paper, based on previous studies, develops a cross-stream marching plus(CSMP) method, by which an aerodynamic surface used to generate a given shock shape can be *** method can correct such solution points as may give rise to grid distortions or flow-field abnormity and overcome the shortcoming of the insufficient stability of previous methods. Numerical simulation results of the conical supersonic flowfield show that the error obtained from the proposed CSMP method drops with the reduction of the grid dimension and the marching step, being less than 0.05% for reducing the marching step to 10%; that with this method the maximum relative error of the pressure on the profile is less than 0.23%. In the design process of the inward-turning inlets that match the fuselage fore-body, it's found that in comparison with the results of the inviscid CFD results, the aerodynamic surface designed with the CSMP method can fully generate the given shock wave shape. Thus, the CSMP method provides a new direction for the inlet/fore-body integrated design.

摘要：As one of the core components of turbocharger or micro-turbine, radial turbine has the features of small size and high rotation speed. In order to explore the design method and flow mechanism of the turbine with a volute, a centimeter-scale radial turbine with a vaneless air-inlet volute was designed and simulated numerically to investigate the characteristics of the coupled flow field. The results show that the wheel efficiency of single passage computation without the volute is 80.1%. After accounting for the factors of the loss caused by the volute and the interaction between each passage, the performance is more accurate according to the whole flow passage computation with the volute. High load region gathers at the mid-span and the efficiency declines to 76.6%. The performance of the volute whose structure angle of the trapezoid section is equal to 70 degree is better. Unlike uniform inlet condition in single passage, more appropriate inlet flow for the impeller is provided by the rectification effect of the volute in full passage calculation. flow parameters are distributed more evenly along the blade span and are generally consistent between each passage at the outlet of the turbine.

摘要：The paper studies the methodologies of the cargo flow study and projections in Tumen River Economic Development Area(TREDA) that some governments and international scholars used. The authors consider that, in order topromote investment, facilitation of cross-border trade and infrastructure in the region, the basic methodology should bebased on the regional economic growth of pertinent Northeast Asian countries and regions to make projections of the situations of regional cargo flows, and then analyzing the cargo flow trend. Based on the above, the authors utilize the routescomparing model and gravity model to forecast the cargo flows through the ports and related routes in TREDA (2000 -2020). The authors also inquire into the main obstacles which affect the cargo flows of the region, analyze the influenceson cargo flows if the obstacles change with sensitivity analyses and try to find the way to sole the obstacles.

摘要：A polymethyl-methacrylate （PMMA） acrylic sample cell using flow injection is developed in this research for the determination of nitrite in an aqueous media. The research focuses on exhibiting direct absorbance spectrophotometry of nitrite using concentration of samples ranging from 0.1078 to 1.725 ppm. Nitrite determination is done colorimetrically using the Greiss reagent method. This method is based on the reaction of nitrite with sulphanilamide acid and N-l-napthylamine （NED） utilizing diazo coupling, and a syringe is used to administer the nitrite solution. The sample cell being used possesses a diameter of 1 mm with an overall size of 7.35×22 mm2. To gauge the direct absorbance, a wavelength range from 400 to 650 nm has been selected for the testing, and the maximum absorbance is found to be at 545 nm. The validity of the proposed cell is explained in this letter.

摘要：The present study focuses on the native readers’sense of flow,a construct frequently ignored in L2 writing *** on the author’s analysis of the communicative data in the web-based transnational peer editing activities named Cross-Pacific Exchange,an amendment is proposed for the currently well-accepted“input-output”models;that is,fluent output by classroom L2 learners may not always be accepted by native ***,L2 writing teachers should encourage their students to pay attention to their L1 readers’sense of flow,so as to enhance their own reader awareness,and improve the quality of their L2 composition through interaction with their L1 audience.

摘要：This paper reports the outcome of a study investigating four electrical heat-tracing strategies that can be employed to avoid wax deposition in subsea flowlines transporting untreated crude oil from subsea wells to a host installation. The strategies, described in the paper, are distinct by the configuration of deploying the heat tracing along the pipe and by the activation schedule (continuous or alternating heating cycles). The study demonstrates quantitatively that the electrical power required for maintaining wax-free flow depends strongly on the employed strategy. The complex thermo-hydraulic flow was modeled using a commercial Dynamic Multiphase flow Simulator with wax deposition option and thermal insulation as an input parameter. In conclusion, the paper ranks the strategies according to their computed energy efficiency, thus providing quantitative benchmarks for preliminary wax control assessment.