Nowadays total inlet temperature of gas turbine is far above the permissible metal temperature;as a consequence,advanced cooling techniques must be applied to protect from thermal stresses,oxidation and corrosion the ...Nowadays total inlet temperature of gas turbine is far above the permissible metal temperature;as a consequence,advanced cooling techniques must be applied to protect from thermal stresses,oxidation and corrosion the components located in the high pressure stages,such as the blade trailing edge.A suitable design of the cooling system for the trailing edge has to cope with geometric constraints and aerodynamic demands;state-of-the-art of cooling concepts often use film cooling on blade pressure side:the air taken from last compressor stages is ejected through discrete holes or slots to provide a cold layer between hot mainstream and the blade surface.With the goal of ensuring a satisfactory lifetime of blades,the design of efficient trailing edge film cooling schemes and,moreover,the possibility to check carefully their behavior,are hence necessary to guarantee an appropriate metal temperature distribution.For this purpose an experimental survey was carried out to investigate the film covering performance of different pressure side trailing edge cooling systems for turbine blades.The experimental test section consists of a scaled-up trailing edge model installed in an open loop suction type test rig.Measurements of adiabatic effectiveness distributions were carried out on three trailing edge cooling system configurations.The baseline geometry is composed by inclined slots separated by elongated pedestals;the second geometry shares the same cutback configuration,with an additional row of circular film cooling holes located upstream;the third model is equipped with three rows of in-line film cooling holes.Experiments have been performed at nearly ambient conditions imposing several blowing ratio values and using carbon dioxide as coolant in order to reproduce a density ratio close to the engine conditions(DR¼1.52).To extend the validity of the survey a comparison between adiabatic effectiveness measurements and a prediction by correlative approach was performed to compare the experimental results with 1D methodologies.展开更多
Nanocrystalline TiO2 thin film electrodes have been prepared from mixed pastes of tetrabutyl titanate and nanocrystalline TiO2 particles by common pressure hydro- thermal method at low temperature. The tetrabutyl tita...Nanocrystalline TiO2 thin film electrodes have been prepared from mixed pastes of tetrabutyl titanate and nanocrystalline TiO2 particles by common pressure hydro- thermal method at low temperature. The tetrabutyl titanate was hydrolyzed and crystallized into anatase TiO2 to inter- connect nanocrystalline TiO2 particles and adhere them to conductive substrates, obtaining highly porous and me- chanically stable TiO2 nanocrystalline film. The conversion efficiencies of the dye-sensitized solar cells based on prepared electrodes on conductive glass substrates and flexible sub- strates were 4.8% and 1.9% under illumination of 100 mW/cm2, respectively.展开更多
目的研究膝关节置换术中髌股关节压力对术后膝关节功能的影响。方法本文随机选取2016年4月至2016年12月间接受膝关节置换术患者共24例,男8例,女16例,年龄在58~69岁,平均年龄为63.4岁,使用压敏片测量假体置换前后不同屈曲角度(30°、...目的研究膝关节置换术中髌股关节压力对术后膝关节功能的影响。方法本文随机选取2016年4月至2016年12月间接受膝关节置换术患者共24例,男8例,女16例,年龄在58~69岁,平均年龄为63.4岁,使用压敏片测量假体置换前后不同屈曲角度(30°、60°、90°及120°)时髌股关节生物应力情况。术后根据测得的压迹形状分为哑铃组和彗星组,对两组患者手术前后膝关节美国特种外科医院(the hospital special surgery,HSS)评分、关节活动度(range of motion,ROM)、膝前痛及髌骨评分等情况随访1~1.5年,平均13.4个月,并将结果进行统计学分析。结果患者一般情况、术前HSS、ROM及假体置换前髌股关节应力情况差异均无统计学意义。根据压迹形状分组,14例患者纳入哑铃组,髌股关节压力分布正常,影像学显示髌骨无明显倾斜;10例患者纳入彗星组,其中7例患者髌股压力分布过于趋于外侧接触面,余3例压力分布主要趋于内侧接触面。术后影像学显示:10例彗星组患者髌骨有不同程度倾斜,随访结果显示两组患者术后HSS评分、ROM及膝前痛等情况均优于术前,差异有统计学意义(P<0.05);哑铃组kujala评分、ROM优于彗星组,差异有统计学意义(P<0.05);而组间HSS评分对比差异无统计学意义(P>0.05)。结论髌股关节压力对TKA术后膝关节功能恢复情况有一定的影响,术中应注意髌股关节生物力学的调整。展开更多
文摘Nowadays total inlet temperature of gas turbine is far above the permissible metal temperature;as a consequence,advanced cooling techniques must be applied to protect from thermal stresses,oxidation and corrosion the components located in the high pressure stages,such as the blade trailing edge.A suitable design of the cooling system for the trailing edge has to cope with geometric constraints and aerodynamic demands;state-of-the-art of cooling concepts often use film cooling on blade pressure side:the air taken from last compressor stages is ejected through discrete holes or slots to provide a cold layer between hot mainstream and the blade surface.With the goal of ensuring a satisfactory lifetime of blades,the design of efficient trailing edge film cooling schemes and,moreover,the possibility to check carefully their behavior,are hence necessary to guarantee an appropriate metal temperature distribution.For this purpose an experimental survey was carried out to investigate the film covering performance of different pressure side trailing edge cooling systems for turbine blades.The experimental test section consists of a scaled-up trailing edge model installed in an open loop suction type test rig.Measurements of adiabatic effectiveness distributions were carried out on three trailing edge cooling system configurations.The baseline geometry is composed by inclined slots separated by elongated pedestals;the second geometry shares the same cutback configuration,with an additional row of circular film cooling holes located upstream;the third model is equipped with three rows of in-line film cooling holes.Experiments have been performed at nearly ambient conditions imposing several blowing ratio values and using carbon dioxide as coolant in order to reproduce a density ratio close to the engine conditions(DR¼1.52).To extend the validity of the survey a comparison between adiabatic effectiveness measurements and a prediction by correlative approach was performed to compare the experimental results with 1D methodologies.
基金supported by the National Basic Research Development Program(973)(Grant No.G200028205)the High-Tech Research and Development(863)Program(Grant No.2002AA302403)the National Natural Science Foundation of China(Grant No.50221201).
文摘Nanocrystalline TiO2 thin film electrodes have been prepared from mixed pastes of tetrabutyl titanate and nanocrystalline TiO2 particles by common pressure hydro- thermal method at low temperature. The tetrabutyl titanate was hydrolyzed and crystallized into anatase TiO2 to inter- connect nanocrystalline TiO2 particles and adhere them to conductive substrates, obtaining highly porous and me- chanically stable TiO2 nanocrystalline film. The conversion efficiencies of the dye-sensitized solar cells based on prepared electrodes on conductive glass substrates and flexible sub- strates were 4.8% and 1.9% under illumination of 100 mW/cm2, respectively.
文摘目的研究膝关节置换术中髌股关节压力对术后膝关节功能的影响。方法本文随机选取2016年4月至2016年12月间接受膝关节置换术患者共24例,男8例,女16例,年龄在58~69岁,平均年龄为63.4岁,使用压敏片测量假体置换前后不同屈曲角度(30°、60°、90°及120°)时髌股关节生物应力情况。术后根据测得的压迹形状分为哑铃组和彗星组,对两组患者手术前后膝关节美国特种外科医院(the hospital special surgery,HSS)评分、关节活动度(range of motion,ROM)、膝前痛及髌骨评分等情况随访1~1.5年,平均13.4个月,并将结果进行统计学分析。结果患者一般情况、术前HSS、ROM及假体置换前髌股关节应力情况差异均无统计学意义。根据压迹形状分组,14例患者纳入哑铃组,髌股关节压力分布正常,影像学显示髌骨无明显倾斜;10例患者纳入彗星组,其中7例患者髌股压力分布过于趋于外侧接触面,余3例压力分布主要趋于内侧接触面。术后影像学显示:10例彗星组患者髌骨有不同程度倾斜,随访结果显示两组患者术后HSS评分、ROM及膝前痛等情况均优于术前,差异有统计学意义(P<0.05);哑铃组kujala评分、ROM优于彗星组,差异有统计学意义(P<0.05);而组间HSS评分对比差异无统计学意义(P>0.05)。结论髌股关节压力对TKA术后膝关节功能恢复情况有一定的影响,术中应注意髌股关节生物力学的调整。
