An experi ment was conducted to measure the breakup lengths of water jets with a high-speed video camera for Weber numbers from0 to about 1.1×103.The initial jet diameters are changed from0.3 mmto 1. 0 mm.The res...An experi ment was conducted to measure the breakup lengths of water jets with a high-speed video camera for Weber numbers from0 to about 1.1×103.The initial jet diameters are changed from0.3 mmto 1. 0 mm.The results indicate that at lowjet velocity the breakup lengths of the jets are increased linearly from 0 to a maxi mumvalue.At the Weber number about 20 the breakup length of the jet reaches its maxi mum value for different initial jet diameter.Acomputation based onthe dispersion equationis conducted to study the relationship between the growth rate of the jet surface wave and the maxi mumbreakup length.The computations showthat the maxi mumgrowth rate for the axisymmetric surface wave has a turning point at Weber number about 20,and that agrees well with the experi ments.展开更多
We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time- and spectrum- resolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond st...We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time- and spectrum- resolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond streak camera for providing time- and spectrum- resolved measurement and imaging in biomedicine. The performance of the system is tested and characterized by the fluorescence spectrum and lifetime analysis of several standard fluorescent dyes and their mixtures. Spectrum-resolved fluorescence lifetime images of fluorescence beads are obtained. Potential applications of the system include clinical diagnostics and cell biology etc.展开更多
In this study,an experiment was performed to clarify the flow field,in which the jets were normally injected into a main supersonic flow surrounded by a porous cavity,and this report figures out interaction between st...In this study,an experiment was performed to clarify the flow field,in which the jets were normally injected into a main supersonic flow surrounded by a porous cavity,and this report figures out interaction between starting shock wave and porous cavity.In the experiment,a porous cavity is attached to a main duct and jets and rods are inserted to the main duct on the porous cavity.To reveal this flow field,the thermal tuft probe was adopted to experimentally investigate the flow in the cavity.In the experiments,the effect of the porous cavity with jets or rods on the flow field is studied by means of visualization of schlieren method with a high speed camera and measurement of cavity flow with thermal tuft probe.As a results,frequency analysis of output of the thermal tuft probe revealed that some clear dominant frequencies were confirmed when the starting shock wave existed around the porous cavity in all cases of jets and rods arrangements.Moreover,visualization of schlieren method with a high speed camera clarified that a starting shock wave had the same dominant frequencies as that of the flow fluctuation in the cavity only around the cavity.展开更多
文摘An experi ment was conducted to measure the breakup lengths of water jets with a high-speed video camera for Weber numbers from0 to about 1.1×103.The initial jet diameters are changed from0.3 mmto 1. 0 mm.The results indicate that at lowjet velocity the breakup lengths of the jets are increased linearly from 0 to a maxi mumvalue.At the Weber number about 20 the breakup length of the jet reaches its maxi mum value for different initial jet diameter.Acomputation based onthe dispersion equationis conducted to study the relationship between the growth rate of the jet surface wave and the maxi mumbreakup length.The computations showthat the maxi mumgrowth rate for the axisymmetric surface wave has a turning point at Weber number about 20,and that agrees well with the experi ments.
基金This work was supported by the National Natural Science Foun-dation of China (60627003, 60408011)Guangdong Natural Science Foundation (5010500)was also supported in part by Shenzhen Sci & Tech Program (200516).
文摘We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time- and spectrum- resolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond streak camera for providing time- and spectrum- resolved measurement and imaging in biomedicine. The performance of the system is tested and characterized by the fluorescence spectrum and lifetime analysis of several standard fluorescent dyes and their mixtures. Spectrum-resolved fluorescence lifetime images of fluorescence beads are obtained. Potential applications of the system include clinical diagnostics and cell biology etc.
文摘In this study,an experiment was performed to clarify the flow field,in which the jets were normally injected into a main supersonic flow surrounded by a porous cavity,and this report figures out interaction between starting shock wave and porous cavity.In the experiment,a porous cavity is attached to a main duct and jets and rods are inserted to the main duct on the porous cavity.To reveal this flow field,the thermal tuft probe was adopted to experimentally investigate the flow in the cavity.In the experiments,the effect of the porous cavity with jets or rods on the flow field is studied by means of visualization of schlieren method with a high speed camera and measurement of cavity flow with thermal tuft probe.As a results,frequency analysis of output of the thermal tuft probe revealed that some clear dominant frequencies were confirmed when the starting shock wave existed around the porous cavity in all cases of jets and rods arrangements.Moreover,visualization of schlieren method with a high speed camera clarified that a starting shock wave had the same dominant frequencies as that of the flow fluctuation in the cavity only around the cavity.
