小型涡轮平面叶栅试验段设计

Performance improvement of the high-load transonic turbine is the key method of improving the thrustto-weight ratio or the power density of gas turbine engines. In order to investigate the flow behaviors inside the high load turbine cascades, a linear turbine cascade test section is designed, which enables the Schlieren photography and static pressure measurement along the cascade profile can be conducted. Variable pitch is realized in the test section to achieve different Zweifel coefficients. Due to the capability limitation of the air supplier, the test section is designed to have only5 blade channels with shortened blade height to achieve high Mach number flow conditions. Numerical investigations were carried out to investigate the wall effect and its in fluences on the flow fields inside the test section. The result indicates that the shape of the connecting part of the test section has a significant influence on the flow similarity among different blade passages. With the proper design, a good repetition flow is achieved between neighbored blade passages.

Heat Transfer in Horizontal Copper Tube Heated by Electric Heating Process

Heat transfer from electrical and electronics component is essential for better performance of that electrical system,The maximum heat transfer from that system results long period durability.In most of the system base provided for equipments are very small and placed in a very complicated position.so heat transfer by forced convection is not easy for that purpose.The heat transfer by natural convection is the familiar technique used in electronics cooling;there is huge group of apparatus that lends itself to natural convection.This category consist of stand-alone correspondence such as modems and small computers having an array of printed circuit boards(PCB)accumulate within an area.Natural convection heat transfer in heated horizontal duct drive away heat from the interior surface is offered.The duct is open-ended and round in cross section.The test section is heated by provision of heating coils,where constant wall heat flux mentioned.Heat transfer experiment is carried out for channel of 50 mm.internal diameter and 4 mm thickness with length 600 mm.Ratios of length to diameter of the channel are taken as L/D=12.Wall heat fluxes maintained at q//=300 W/m2 to 3150 W/m2.A methodical investigational record for the local steady state natural convection heat transfer activities is obtained.The wall heating condition on local steady-state heat transfer phenomena are studied.The present experimental data is compared with the existing theoretical and experimental results for the cases of vertical smooth tubes.

Effects of copper, lead and zinc in soil on egg development and hatching of Folsomia candida

Effects of CaCl2, CuCl2, ZnCl2 and PbCl2 on development and hatching success of eggs of Folsomia candida （Collembola） were studied under laboratory conditions. Thousands of healthy eggs from synchronized cultures were incubated in soils treated with different concentrations of the metals. Compared with the water control, egg hatch significantly decreased when concentrations of Cu, Pb and Zn reached 400, 1 600 and 800 mg/kg dry soil, respectively. Values of EC50（hatching）, calculated according to the exponential model （with 95% confidence limits in brackets）, were 625 （407-875）, 2 361 （2 064-2 687） and 1 763 （1 548-2 000） mg/kg dry soils for Cu, Pb and Zn, respectively. When Cu concentration reached 1 600 mg/kg dry soil, eggs became green and the percentage of green eggs changed from 5%-20% after incubation for 2 days to 15%- 30% after incubation for 4 days. At 3 200 mg Cu/kg dry soil, tissues inside eggs were black and shrunken.

Recent investigations of shock wave effects and interactions

Despite over fifty years of research on shock wave boundary layer effects and interactions,many related technical issues continue to be controversial and debated.The present survey provides an overview of the present state of knowledge on such effects and interactions,including discussions of:(i)general features of shock wave interactions,(ii)test section configurations for investigation of shock wave boundary layer interactions,(iii)origins and sources of unsteadiness associated with the interaction region,(iv)interactions which included thermal transport and convective heat transfer,and(v)shock wave interaction control investigations.Of particular interest are origins and sources of low-frequency,large-scale shock wave unsteadiness,flow physics of shock wave boundary layer interactions,and overall structure of different types of interactions.Information is also provided in regard to shock wave investigations,where heat transfer and thermal transport were important.Also considered are investigations of shock wave interaction control strategies,which overall,indicate that no single shock wave control strategy is available,which may be successfully applied to different shock wave arrangements,over a wide range of Mach numbers.Overall,the survey highlights the need for additional understanding of fundamental transport mechanisms,as related to shock waves,which are applicable to turbomachinery,aerospace,and aeronautical academic disciplines.