The parachute container cover ejection separation is the first and foremost motion for the return capsule recovery system,which is related to the success of a recovery system.Adopting the computational fluid dynamics(...The parachute container cover ejection separation is the first and foremost motion for the return capsule recovery system,which is related to the success of a recovery system.Adopting the computational fluid dynamics(CFD)simulation and flight dynamics coupling method,the parachute container cover ejection separation is simulated.The rationality of the ejection separation speed and dynamic characteristics of the separation process is analyzed.Meanwhile,the influences of angle of attack,Mach number and ejection separation speed on the parachute container cover ejection are also investigated.Results show that the ejection separation speed design is reasonable.It has a certain design margin for parachute container cover to escape from the wake region,and to pull out the drag parachute completely.The results may provide a theoretical basis for recovery system engineering design of the lunar exploration project.展开更多
The objective of present work is to find out the sources of fluid-borne noise in vertical inline pump for various flow rates. The three-dimensional unsteady Reynolds Average Navier Stokes equation was solved using com...The objective of present work is to find out the sources of fluid-borne noise in vertical inline pump for various flow rates. The three-dimensional unsteady Reynolds Average Navier Stokes equation was solved using computational fluid dynamics code to predict the acoustic distribution. The pump chosen for study was of low specific speed and the experimental performance characteristic was very well matched with computational head developed. PROUDMAN sound power contour analysis showed the critical zone of noise in inlet pipe,impeller,and volute. Based on this,the variations of acoustic power were depicted over the cross section of inlet pipe,along the mean streamline of inlet pipe,as well along the volute circumference. The result concludes that the predominant flow noise is at tongue region and followed by noise generated due to turbulence in inlet pipe which occurs by the sudden variation in flow passage as well it depends on the operating condition of pump. The frequency analysis gives a glimpse of understanding about the broadband noise distribution due to flow phenomenon over a frequency range.展开更多
基金Supported by the Aeronautical Science Foundation of China(2012ZC52035)
文摘The parachute container cover ejection separation is the first and foremost motion for the return capsule recovery system,which is related to the success of a recovery system.Adopting the computational fluid dynamics(CFD)simulation and flight dynamics coupling method,the parachute container cover ejection separation is simulated.The rationality of the ejection separation speed and dynamic characteristics of the separation process is analyzed.Meanwhile,the influences of angle of attack,Mach number and ejection separation speed on the parachute container cover ejection are also investigated.Results show that the ejection separation speed design is reasonable.It has a certain design margin for parachute container cover to escape from the wake region,and to pull out the drag parachute completely.The results may provide a theoretical basis for recovery system engineering design of the lunar exploration project.
基金State Key Program of National Natural Science Foundation of China(51239005)
文摘The objective of present work is to find out the sources of fluid-borne noise in vertical inline pump for various flow rates. The three-dimensional unsteady Reynolds Average Navier Stokes equation was solved using computational fluid dynamics code to predict the acoustic distribution. The pump chosen for study was of low specific speed and the experimental performance characteristic was very well matched with computational head developed. PROUDMAN sound power contour analysis showed the critical zone of noise in inlet pipe,impeller,and volute. Based on this,the variations of acoustic power were depicted over the cross section of inlet pipe,along the mean streamline of inlet pipe,as well along the volute circumference. The result concludes that the predominant flow noise is at tongue region and followed by noise generated due to turbulence in inlet pipe which occurs by the sudden variation in flow passage as well it depends on the operating condition of pump. The frequency analysis gives a glimpse of understanding about the broadband noise distribution due to flow phenomenon over a frequency range.
