This paper investigates the relations between the fluctuating pressure and velocity of the source by means of nu- merical method and sound pressure in the far field obtained with an noise experiment for a novel cross ...This paper investigates the relations between the fluctuating pressure and velocity of the source by means of nu- merical method and sound pressure in the far field obtained with an noise experiment for a novel cross flow fan. The frequency characteristics of the fluctuating pressure and velocity in a cross flow fan are analyzed by means of spectral analysis and wavelet transform. The fluctuating pressures obtained by large eddy simulation on the casing wall are compared with that of experiments and show good agreement. From the spectral analysis of sound source, it is found that the pressure fluctuating peak is correspond with the sound pressure in the far field.展开更多
According to the previous experimental works on the low solidity circular cascade diffuser (LSD), a pressure recovery of a centrifugal blower was improved by the LSD significantly in a wide range of flow rate, and the...According to the previous experimental works on the low solidity circular cascade diffuser (LSD), a pressure recovery of a centrifugal blower was improved by the LSD significantly in a wide range of flow rate, and the pres-sure recovery was improved further by the LSD with a tandem cascade in comparison with the LSD with a sin-gle-row cascade. In the present study, the flow behavior in the LSD with the tandem cascade has been analyzed numerically by using the commercial CFD code of ANSYS-CFX12. It was shown clearly that the higher pressure recovery was achieved by applying the LSD with the tandem cascade, and the high pressure recovery is based on the high pressure rise in the vaneless space upstream of the LSD and the high blade loading of the front blade of the LSD. The high pressure recovery in the LSD could be achieved by controlling the flow separation on the suc-tion surface of the front blade and also on that of the rear blade due to formation of the favorable secondary flow and due to increase in mass flow passing through the slit section between the front and rear blades.展开更多
This paper describes the shape optimization of an impeller used for two-stage high pressure ring blower.Two shape variables,which are used to define an impeller shape,are introduced to increase the blower performance....This paper describes the shape optimization of an impeller used for two-stage high pressure ring blower.Two shape variables,which are used to define an impeller shape,are introduced to increase the blower performance.The pressure of a blower is selected as an object function,and the blade optimization is performed by a response surface method.Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of object function for the training data.Relatively good agreement between experimental measurements and numerical simulation is obtained in the present study.Throughout the shape optimization,it is found that a hub height is effective to increase pressure in the ring blower.The pressure rise for the optimal two-stage ring blower is successfully increased up to 1.86% compared with that of reference at the design flow rate.Local recirculation flow having low velocity is formed in both sides of the impeller outlet by different flow direction of the inlet and outlet of the impeller.Detailed flow field inside the ring blower is also analyzed and discussed.展开更多
基金a Grant-in-Aid for Scientific Research through grant number 50676035 from National Natural Science Foundation of China
文摘This paper investigates the relations between the fluctuating pressure and velocity of the source by means of nu- merical method and sound pressure in the far field obtained with an noise experiment for a novel cross flow fan. The frequency characteristics of the fluctuating pressure and velocity in a cross flow fan are analyzed by means of spectral analysis and wavelet transform. The fluctuating pressures obtained by large eddy simulation on the casing wall are compared with that of experiments and show good agreement. From the spectral analysis of sound source, it is found that the pressure fluctuating peak is correspond with the sound pressure in the far field.
文摘According to the previous experimental works on the low solidity circular cascade diffuser (LSD), a pressure recovery of a centrifugal blower was improved by the LSD significantly in a wide range of flow rate, and the pres-sure recovery was improved further by the LSD with a tandem cascade in comparison with the LSD with a sin-gle-row cascade. In the present study, the flow behavior in the LSD with the tandem cascade has been analyzed numerically by using the commercial CFD code of ANSYS-CFX12. It was shown clearly that the higher pressure recovery was achieved by applying the LSD with the tandem cascade, and the high pressure recovery is based on the high pressure rise in the vaneless space upstream of the LSD and the high blade loading of the front blade of the LSD. The high pressure recovery in the LSD could be achieved by controlling the flow separation on the suc-tion surface of the front blade and also on that of the rear blade due to formation of the favorable secondary flow and due to increase in mass flow passing through the slit section between the front and rear blades.
文摘This paper describes the shape optimization of an impeller used for two-stage high pressure ring blower.Two shape variables,which are used to define an impeller shape,are introduced to increase the blower performance.The pressure of a blower is selected as an object function,and the blade optimization is performed by a response surface method.Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of object function for the training data.Relatively good agreement between experimental measurements and numerical simulation is obtained in the present study.Throughout the shape optimization,it is found that a hub height is effective to increase pressure in the ring blower.The pressure rise for the optimal two-stage ring blower is successfully increased up to 1.86% compared with that of reference at the design flow rate.Local recirculation flow having low velocity is formed in both sides of the impeller outlet by different flow direction of the inlet and outlet of the impeller.Detailed flow field inside the ring blower is also analyzed and discussed.
