Deep microhole machining is currently a prominent research area within the aerospace field,encompassing blade film cooling and fuel injection control technologies.However,taper defects in metal materials may lead to p...Deep microhole machining is currently a prominent research area within the aerospace field,encompassing blade film cooling and fuel injection control technologies.However,taper defects in metal materials may lead to performance degradation or even structural damage over a component’s lifetime.Trepanning and helical drilling,facilitated by ultrashort pulse lasers,have proven more suitable for achieving high-precision,deep holes in metal materials.Nonetheless,excessive repetition rates can also result in severe thermal damage.Various methods are commonly employed for controlling taper,including parameter optimization,assistance,and secondary modification.Tilted laser beam drilling is widely utilized and has been integrated into relevant machining systems for commercial applications.Typical deep microholes include film cooling holes and injection microholes.Laser drilling is a potential machining method for new materials in the aerospace field.Although laser drilling processing has been studied,numerous related scientific challenges and technical difficulties must be addressed before practical implementation.展开更多
In this study, an effective method is proposed for controlling a titanium foil surface's wettability. A microholes array series is fabricated on the surface of titanium foil by a femtosecond laser under different ...In this study, an effective method is proposed for controlling a titanium foil surface's wettability. A microholes array series is fabricated on the surface of titanium foil by a femtosecond laser under different laser energy and pulse number. The changes of the titanium surface's morphology are characterized. When placed in a darkroom with high-temperature treatment and immersed in alcohol under UV irradiation, respectively, the femtosecond laser treated surfaces display switchable wettability. It is demonstrated that the changing between Ti-OH and Ti-O prompts the transformation between superhydrophilic and superhydrophobic. Compared with existing reports, the switchable wetting cycle is shortened to 1.5 h. The functional surfaces with switchable wettability have potential applications in oil–water separation and water mist collection.展开更多
Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three-dimensional discrete hole film cooling RSM-AKN turbulent heat transfer models based on variable turbulent P...Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three-dimensional discrete hole film cooling RSM-AKN turbulent heat transfer models based on variable turbulent Prandtl number approaches were considered. Obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two-equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models. The RSM-AKN turbulent model was used in micoholes case too. The main target of simulations was maintain the same level of cooling efficiency ratio in both cases and confirm that is possible significantly reduce mass flows of the coolant in microholes case.展开更多
The growth and coalescence of two microholes in copper foil were studied experimental ly by in situ tensile tests under a,scanning electronic microscope.Two microholes of 15-35μm in di- ameter were arranged in differ...The growth and coalescence of two microholes in copper foil were studied experimental ly by in situ tensile tests under a,scanning electronic microscope.Two microholes of 15-35μm in di- ameter were arranged in different distances and orientations.It was found that the mechanisms of mi crohole evolution were represented by slipping band creation,and then crack initiation and propagation along the slipping bands,in ligament.The process of microhole growth and coalescence was influenced by the inter-center distance and orientation of microholes.The critical surface of microholes at coales- cence is about 2—2.5 times that of the initial one.The variation of both the inter center distance and orientation depends on the initial angle.展开更多
The machine is a third generation high-speed EDM microhole drilling machinedeveloped and produced by the SuzhouElectromachining Tool Research Institute.It is used in cutting wire-guiding holes,jetholes for fuel pumps,...The machine is a third generation high-speed EDM microhole drilling machinedeveloped and produced by the SuzhouElectromachining Tool Research Institute.It is used in cutting wire-guiding holes,jetholes for fuel pumps,holes for jet plates展开更多
基金This work was supported by the Science Center for Gas Turbine Project(Grant No.P2022-A-IV-002-003)the National Natural Science Foundation of China(Grant No.52022078)+1 种基金Shaanxi Provincial Key Research and Development Program(Grant No.2021ZDLGY10-02)the fund of the State Key Laboratory of Solidification Processing in NPU(Grant No.SKLSP202203).
文摘Deep microhole machining is currently a prominent research area within the aerospace field,encompassing blade film cooling and fuel injection control technologies.However,taper defects in metal materials may lead to performance degradation or even structural damage over a component’s lifetime.Trepanning and helical drilling,facilitated by ultrashort pulse lasers,have proven more suitable for achieving high-precision,deep holes in metal materials.Nonetheless,excessive repetition rates can also result in severe thermal damage.Various methods are commonly employed for controlling taper,including parameter optimization,assistance,and secondary modification.Tilted laser beam drilling is widely utilized and has been integrated into relevant machining systems for commercial applications.Typical deep microholes include film cooling holes and injection microholes.Laser drilling is a potential machining method for new materials in the aerospace field.Although laser drilling processing has been studied,numerous related scientific challenges and technical difficulties must be addressed before practical implementation.
基金supported by the National Key R&D Program of China (No.2017YFB1104300)the National Natural Science Foundation of China (No.51975595)+1 种基金the Natural Science Foundation of Hunan Province (No.2020JJ5738)the Project of State Key Laboratory of High Performance Complex Manufacturing (No.ZZYJKT2020-10)。
文摘In this study, an effective method is proposed for controlling a titanium foil surface's wettability. A microholes array series is fabricated on the surface of titanium foil by a femtosecond laser under different laser energy and pulse number. The changes of the titanium surface's morphology are characterized. When placed in a darkroom with high-temperature treatment and immersed in alcohol under UV irradiation, respectively, the femtosecond laser treated surfaces display switchable wettability. It is demonstrated that the changing between Ti-OH and Ti-O prompts the transformation between superhydrophilic and superhydrophobic. Compared with existing reports, the switchable wetting cycle is shortened to 1.5 h. The functional surfaces with switchable wettability have potential applications in oil–water separation and water mist collection.
文摘Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three-dimensional discrete hole film cooling RSM-AKN turbulent heat transfer models based on variable turbulent Prandtl number approaches were considered. Obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two-equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models. The RSM-AKN turbulent model was used in micoholes case too. The main target of simulations was maintain the same level of cooling efficiency ratio in both cases and confirm that is possible significantly reduce mass flows of the coolant in microholes case.
文摘The growth and coalescence of two microholes in copper foil were studied experimental ly by in situ tensile tests under a,scanning electronic microscope.Two microholes of 15-35μm in di- ameter were arranged in different distances and orientations.It was found that the mechanisms of mi crohole evolution were represented by slipping band creation,and then crack initiation and propagation along the slipping bands,in ligament.The process of microhole growth and coalescence was influenced by the inter-center distance and orientation of microholes.The critical surface of microholes at coales- cence is about 2—2.5 times that of the initial one.The variation of both the inter center distance and orientation depends on the initial angle.
文摘The machine is a third generation high-speed EDM microhole drilling machinedeveloped and produced by the SuzhouElectromachining Tool Research Institute.It is used in cutting wire-guiding holes,jetholes for fuel pumps,holes for jet plates
