The theoretical foundation for the modelling of the turbulent pressure\|strain correlations in rotating reference frame is presented. Based on the recently developed materially\|frame indifference principle it is obse...The theoretical foundation for the modelling of the turbulent pressure\|strain correlations in rotating reference frame is presented. Based on the recently developed materially\|frame indifference principle it is observed that most of the existing second\|moment closures violate the Taylor\|Proudman theorem in the limit of rapid rotation. It is shown that the application of the materially\|frame indifference principle gives rise to the formation of a new pressure\|strain correlation model which satisfies the Taylor\|Proudman theorem.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
文摘The theoretical foundation for the modelling of the turbulent pressure\|strain correlations in rotating reference frame is presented. Based on the recently developed materially\|frame indifference principle it is observed that most of the existing second\|moment closures violate the Taylor\|Proudman theorem in the limit of rapid rotation. It is shown that the application of the materially\|frame indifference principle gives rise to the formation of a new pressure\|strain correlation model which satisfies the Taylor\|Proudman theorem.
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.
