Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet ...Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD (X-ray diffraction) are formed based on mechanics effects of laser thermal stress. The mechanisms of sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD are analyzed, and the theory of photo-mechanics manufacturing and detecting technologies based on laser thermal stress is originally put forward, whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.展开更多
This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of thi...This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of this phenomenon were used: the pressure profile using the Kiel total pressure probe, the velocity profile using the CTA (constant temperature anemometry) probe and the visualization of the flow field using the hot film and the thermo camera, The experimental results with and without the influence of the synthetic jet were compared, as well the impact of the phase shift of the neighbouring synthetic jets. As a reference case, the flow around the hump without the influence of the synthetic jet was selected. The results of the measurement are presented in figures and compared.展开更多
Different methods to detect boundary layer transition are investigated within the scope of this paper. Laminar and turbulent boundary layers exhibit a significantly different behavior, not only regarding skin friction...Different methods to detect boundary layer transition are investigated within the scope of this paper. Laminar and turbulent boundary layers exhibit a significantly different behavior, not only regarding skin friction but also for heat-transfer which affects the blade cooling design. The present work presents a novel and non-intrusive measurement technique to detect the transition, based on acoustic concepts. The reliability of the technique was investigated by means of boundary layer measurements over a fiat plate in subsonic flow conditions. After a preliminary assessment with a conventional Preston tube, a row of microphones were installed along the plate to correlate transition pressure fluctuations. To provide a comprehensive representation of the experiment, dedicated measurements with a fast response aerodynamic pressure probe were performed to determine the turbulence intensity and the dissipation rate upstream of the flat plate. The experimental results were systematically compared with calculations performed with three different computational fluid dynamics solvers (ANSYS-Fluent, ANSYS-CFX, OpenFOAM) and using both the k-k1-ω and the γ-Reθ transition models. Results show a fair agreement between CFD (computational fluid dynamics) predictions and the acoustic technique, suggesting that this latter might represent an interesting alternative option for transition measurements.展开更多
基金this research from the Scientific Research Fund of Jiangsu Polytechnic University(GrantNo.ZMF07020042)Fund of Jiangsu ProvincialKey Laboratory for Science and Technology of Photo-manufacroring (Grant No.GZ-1-02)the NaturalScience Foundation of the Jiangsu Higher EducationInstitutions of China( Grant No. 08KJB430002 ) is gratefully acknowledged.
文摘Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD (X-ray diffraction) are formed based on mechanics effects of laser thermal stress. The mechanisms of sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD are analyzed, and the theory of photo-mechanics manufacturing and detecting technologies based on laser thermal stress is originally put forward, whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.
文摘This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of this phenomenon were used: the pressure profile using the Kiel total pressure probe, the velocity profile using the CTA (constant temperature anemometry) probe and the visualization of the flow field using the hot film and the thermo camera, The experimental results with and without the influence of the synthetic jet were compared, as well the impact of the phase shift of the neighbouring synthetic jets. As a reference case, the flow around the hump without the influence of the synthetic jet was selected. The results of the measurement are presented in figures and compared.
文摘Different methods to detect boundary layer transition are investigated within the scope of this paper. Laminar and turbulent boundary layers exhibit a significantly different behavior, not only regarding skin friction but also for heat-transfer which affects the blade cooling design. The present work presents a novel and non-intrusive measurement technique to detect the transition, based on acoustic concepts. The reliability of the technique was investigated by means of boundary layer measurements over a fiat plate in subsonic flow conditions. After a preliminary assessment with a conventional Preston tube, a row of microphones were installed along the plate to correlate transition pressure fluctuations. To provide a comprehensive representation of the experiment, dedicated measurements with a fast response aerodynamic pressure probe were performed to determine the turbulence intensity and the dissipation rate upstream of the flat plate. The experimental results were systematically compared with calculations performed with three different computational fluid dynamics solvers (ANSYS-Fluent, ANSYS-CFX, OpenFOAM) and using both the k-k1-ω and the γ-Reθ transition models. Results show a fair agreement between CFD (computational fluid dynamics) predictions and the acoustic technique, suggesting that this latter might represent an interesting alternative option for transition measurements.