The static flow resistivity is a fundamental parameter for measuring and classifying the sound absorption behavior of various types of materials. Several methods have been developed for measuring the static flow resis...The static flow resistivity is a fundamental parameter for measuring and classifying the sound absorption behavior of various types of materials. Several methods have been developed for measuring the static flow resistivity acoustically. Most of these methods cannot be implemented directly in the standard tubes which are widely used for measurements of sound absorption coefficients and impedance as defined in ISO 10534.2. The accuracy of the proposed method and the tube is verified through finite element analysis and the feasibility to determine the static flow resistivity is validated through experiments. It is validated that the accuracy of the proposed method is highly dependent on the position of the acoustic center of the measurement microphones and the accuracy can be enhanced by increasing the back cavity depth and/or decreasing the measurement frequency.展开更多
This paper deal with the frictional resistance characteristics of gas liquid two phase flow in vertical upward helical coiled tubes under the system pressure 0.1 0.6MPa. By means of dimension analysis and π theo...This paper deal with the frictional resistance characteristics of gas liquid two phase flow in vertical upward helical coiled tubes under the system pressure 0.1 0.6MPa. By means of dimension analysis and π theorem, the correlation formulas were obtained for calculating the frictional resistance coefficients of gas liquid two phase flow in helical coiled tubes. The calculated results agree well with the experimental results.展开更多
Experimental investigation of heat transfer and flow resistance performance on heat exchanger with lozenge fin tubes supported by helical baffles was carried out. Under the experimental conditions,curves of relation b...Experimental investigation of heat transfer and flow resistance performance on heat exchanger with lozenge fin tubes supported by helical baffles was carried out. Under the experimental conditions,curves of relation between heat transfer film coefficient and flow velocity,relation between flow resistance coefficient and velocity were obtained,which provides references for industrial application of this type of heat exchanger. Experimental results indicated that within the range of diesel oil flow velocity 0.22-0.85 m·s -1,heat transfer film coefficient in shell side of heat exchanger with lozenge fin tubes supported by helical baffles was 512-1378?W·m -2·K -1,which was 54%-108% higher than that of heat exchanger with smooth tubes supported by helical baffles,while flow resistance coefficient was lower by 5%-30%,which showed that heat exchanger with lozenge fin tubes supported by helical baffles had favorable heat transfer and flow resistance performance.展开更多
文摘The static flow resistivity is a fundamental parameter for measuring and classifying the sound absorption behavior of various types of materials. Several methods have been developed for measuring the static flow resistivity acoustically. Most of these methods cannot be implemented directly in the standard tubes which are widely used for measurements of sound absorption coefficients and impedance as defined in ISO 10534.2. The accuracy of the proposed method and the tube is verified through finite element analysis and the feasibility to determine the static flow resistivity is validated through experiments. It is validated that the accuracy of the proposed method is highly dependent on the position of the acoustic center of the measurement microphones and the accuracy can be enhanced by increasing the back cavity depth and/or decreasing the measurement frequency.
文摘This paper deal with the frictional resistance characteristics of gas liquid two phase flow in vertical upward helical coiled tubes under the system pressure 0.1 0.6MPa. By means of dimension analysis and π theorem, the correlation formulas were obtained for calculating the frictional resistance coefficients of gas liquid two phase flow in helical coiled tubes. The calculated results agree well with the experimental results.
文摘Experimental investigation of heat transfer and flow resistance performance on heat exchanger with lozenge fin tubes supported by helical baffles was carried out. Under the experimental conditions,curves of relation between heat transfer film coefficient and flow velocity,relation between flow resistance coefficient and velocity were obtained,which provides references for industrial application of this type of heat exchanger. Experimental results indicated that within the range of diesel oil flow velocity 0.22-0.85 m·s -1,heat transfer film coefficient in shell side of heat exchanger with lozenge fin tubes supported by helical baffles was 512-1378?W·m -2·K -1,which was 54%-108% higher than that of heat exchanger with smooth tubes supported by helical baffles,while flow resistance coefficient was lower by 5%-30%,which showed that heat exchanger with lozenge fin tubes supported by helical baffles had favorable heat transfer and flow resistance performance.
