The flow in the positive displacement blower is very complex.The existing two-dimensional numerical simulation cannot provide the detailed flow information,especially flow characteristics along the axial direction,whi...The flow in the positive displacement blower is very complex.The existing two-dimensional numerical simulation cannot provide the detailed flow information,especially flow characteristics along the axial direction,which is unfavorable to improve the performance of positive displacement blower.To investigate the effects of spiral inlet and outlet on the aerodynamic performance of positive displacement blower,three-dimensional unsteady flow characteristics in a three-lobe positive displacement blower with and without the spiral inlet and outlet are simulated by solving Navier-Stokes equations coupled with RNG k-ε turbulent model.In the numerical simulation,the dynamic mesh technique and overset mesh updating method are used.The computational results are compared with the experimental measurements on the variation of flow rate with the outlet pressure to verify the validity of the numerical method presented.The results show that the mass flow rate with the change of pressure is slightly affected by the application of spiral inlet and outlet,but the internal flow state is largely affected.In the exhaust region,the fluctuations of pressure,velocity and temperature as well as the average values of velocity are significantly reduced.This illustrates that the spiral outlet can effectively suppress the fluctuations of pressure,thus reducing reflux shock and energy dissipation.In the intake area,the average value of pressure,velocity and temperature are slightly declined,but the fluctuations of them are significantly reduced,indicating that the spiral inlet plays the role in making the flow more stable.The numerical results obtained reveal the three-dimensional flow characteristics of the positive displacement blower with spiral inlet and outlet,and provide useful reference to improve performance and empirical correction in the noise-reduction design of the positive displacement blowers.展开更多
The operating performance of positive discharge blower is markedly influenced by the pulsation of the discharge flow, but difficult to be measured with experimental methods. The internal and discharge flow of positive...The operating performance of positive discharge blower is markedly influenced by the pulsation of the discharge flow, but difficult to be measured with experimental methods. The internal and discharge flow of positive discharge blower with involute type three-lobe are numerically investigated, both in air cooling and countercurrent cooling conditions by means of computational fluid dynamics （CFD）. The unsteady compressible flow equations are solved using RNG x-ε turbulent model. The finite difference method and the second order upwind difference scheme are applied into discrete equations. In the numerical simulation, the dynamic mesh techniques are used to approach the rotating displacement of cell cubage and the alterability of inlet, outlet flow area. The non-uniform mesh is applied to the rotor-stator coupled area. The reliability of the numerical method is verified by simulating the inner flow and comparing with the semi-empirical theory. The flow flux curves and the distributing of velocity vector showed obvious vortex motion in all the discharge process, both in air cooling and countercurrent cooling conditions. These vortexes with different positions, intension and numbers at different rotating angles have remarkable influences on the discharge flux. For air cooling, the vortex produced a second pulsation with big-amplitude in a cycle, and led to the early appearance of maximum of backflow. For countercurrent cooling, the frequency of pulsation increased due to the pre-inflow, but the backflow at the outlet is prevented, also the pulsation strength has greatly decreased.展开更多
Regenerative machines allow high heads at small flow rates and present performance curves with very stable features. This research includes a study of the effect of four inlet flow angles (90°, 115°, 125...Regenerative machines allow high heads at small flow rates and present performance curves with very stable features. This research includes a study of the effect of four inlet flow angles (90°, 115°, 125° and 135°) of the blade at outlet flow angle of 90° on the performance of regenerative blower at rotation speed of 3000 rpm and at different flow rates. Investigation and comparison of the experimental results with both one-dimensional theoretical model and numerical CFD technique using CFX-ANSYS 16.1 are done. The numerical CFD analysis show that the flow enters the impeller from the blade side (about 65% of the blade side area) and leaves from the blade tip and blade side (the remaining 35% from the blade side area). According to this observation, a mathematical model that is based on momentum exchange theory to handle one inlet angle and two exit angles for the regenerative blower impeller blades is proposed. Consequently, the experimental work is carried out by two steps. The first step is done by studying the effect of inlet blade angle of 90° and analyzing the results by using the CFD analysis. The CFD results show shock losses and vortices behind each blade at the inlet flow regions. To reduce these losses, an increase of the inlet blade angle in a range between 25° to 45° is proposed. The second step is the splitting of this angle range to three inlet blade angles of 115°, 125° and 135° in order to study and analyze the CFD results for these angels. The CFD analysis shows the disappearance of the shock losses and vortices that are formed behind the blade of angle 90°. The experimental results show that the pressure head and the efficiency depend strongly on the blade inlet and outlet flow angles as well as on the blade geometry. The results also show that the best blower performance can be obtained at an inlet flow angle of 125°, and this is confirmed by CFD simulation analysis. Finally, it is shown that the proposed one-dimensional model yield results that are in a good agreement with the experimental results.展开更多
To improve the performance of the positive displacement blower, it is imperative to understand the detailed internal flow characteristics or enable a visualization of flow status. However, the existing two-dimensional...To improve the performance of the positive displacement blower, it is imperative to understand the detailed internal flow characteristics or enable a visualization of flow status. However, the existing two-dimensional unsteady, three-dimensional steady or quasi-unsteady numerical simulation and theoretical analysis cannot provide the detailed flow information, which is unfavorable to improve the performance of positive displacement blower. Therefore, the unsteady flow characteristics in a three-lobe positive displacement blower are numerically investigated by solving the three-dimensional, unsteady, compressible Navier-Stokes equations coupled with RNG k-e turbulent model. In the numerical simulation, the dynamic mesh technique and overset mesh updating method are adopted. Due to the air being compressed in the process of the rotors rotating, the variation of the temperature field in the positive displacement blower is considered. By comparing the experimental measurements and the numerical results on the variation of flow rate with the outlet pressure, the maximum relative error of the flow rate is less than 2.15% even at the maximum outlet pressure condition, which means that the calculation model and numerical computational method used are effective. The numerical results show that in the intake region, the fluctuations of the inlet flow are greatly affected by the direction of the velocity vectors. In the exhaust region, the temperature changes significantly, which leads to the increase of the airflow pulsation. Through analysis on the velocity, pressure and temperature fields obtained from the numerical simulations, three-dimensional unsteady flow characteristics in the positive displacement blower are revealed. The studied results will provide useful reference for improving the performance and empirical correction in the design of the positive displacement blower.展开更多
The rotor of a Roots blower is the key component relating to its capability, so the profile design of the rotor in a Roots blower is extremely important. We focused on the modelling and verification for a novel Roots ...The rotor of a Roots blower is the key component relating to its capability, so the profile design of the rotor in a Roots blower is extremely important. We focused on the modelling and verification for a novel Roots blower tooth profile based on the performance analysis. By comparing the area utilization coefficient and the ratio of several traditional rotor profiles, we proposed a new rotor profile. Then, we further accomplished the mathematical modelling of the proposed rotor profile and the computational fluid dynamics(CFD) simulation, and obtained the Roots blower outlet flow monitoring curves. Finally, we verified the characteristics by a physical experiment.展开更多
This paper describes the optimal design of a Cathode blower used for a building fuel cell system. The Cathode air blower has a regenerative blower type. Two design variables, extension angle and number of impeller bla...This paper describes the optimal design of a Cathode blower used for a building fuel cell system. The Cathode air blower has a regenerative blower type. Two design variables, extension angle and number of impeller blade are introduced to enhance the blower performance. Pressure and efficiency of the blower are selected as an object function, and the optimal design is performed by a response surface method. Three-dimensional Navier-Stokes equations are introduced to analyze the performance and internal flow of the blower and to find the value of object function for the training data. Throughout the design optimization, it is found that an extension angle is effective to increase blower efficiency in the blower. The pressure rise for the optimal blower is successfully increased up to 3.17% compared with that of reference one at the design flow rate. It is noted that low velocity region disturbs to make strong recirculation flow in the each blade passage, thus increases local pressure loss. Detailed flow field inside a regenerative blower is also analyzed and compared.展开更多
Most forest chips are delivered to large-sized, combined heat and power plants in Finland. In this study, we introduce and demonstrate the small-scale delivery of forest wood chips to potential clients, with the wood ...Most forest chips are delivered to large-sized, combined heat and power plants in Finland. In this study, we introduce and demonstrate the small-scale delivery of forest wood chips to potential clients, with the wood chips being delivered in a container truck and pneumatically blown into a storage facility. This arrangement of wood chips being blown through a pipe into a storage eliminates the ground handling while requiring a relatively small space. In the demonstration tests, we tested the volumetric flow of biomass in the hose and its noise level while the blower was blowing the material and the flow speed of the material in the hose. This study discusses the test conditions in which the compatibility and suitability of the truck and its hydraulic system were used in conventional chip delivery in Finland and the selected blower type was investigated. According to the results, the biomass volume flow was higher (~0.46 m3/min) when the blower revolution was lower (2392 - 2566 RPM). However, when the RPM was increased to ~3000, the volumetric flow decreased to ~0.24 m3/min. Similarly, the speed of the chips was higher with a lower RPM;29.9 m/s at an RPM of 2400 and 25 m/s at an RPM of 2700. This is potentially due to both the blower and screw conveyer using the same power source. Additional optimization research would be needed to conclusively state the root cause of this phenomenon. On the other hand, chips from pruned stems had better flow than the chips from whole trees, since chips from whole tree have a wider range of chips sizes, including 1.3% of chips being in the range of 31.5 - 40 mm. The larger chips clogged the hose, which hindered the flow. Finally, the noise tests showed that it was louder at 0 degrees, which contrasted with the situation for the blower, with an aside at 90 degrees.展开更多
The 2015 elections and swearing of new leadership in Nigeria brought about new promises as well as new policies and strategies. The president elect, Muhammadu Buhari, was quick to indicate his intentions to fight corr...The 2015 elections and swearing of new leadership in Nigeria brought about new promises as well as new policies and strategies. The president elect, Muhammadu Buhari, was quick to indicate his intentions to fight corruption as one of the means through which the government intends to achieve good governance in Nigeria. This intention and follow-up action is like the biblical two-edged sword, cutting off sadness from the lower class while at the same time cutting off happiness from some corrupt people in government. The recent announcement of the whistle blower policy by the Federal Government as another means of fighting corruption in Nigeria brought about an increase in the discovery of hidden/looted money. Relying on primary and secondary findings, based on qualitative and quantitative data the paper examines the potency of the whistle blower policy on corruption. The puzzle： is the policy yielding positive result？ The case provides a strong case to the methodological analysis for both institutional norms to fight corruption and good governance in Nigeria. The thrust of this paper is that, the fight against corruption is a national issue that can be successfully tackled by the citizens. The paper therefore recommends that government and its citizenry come together to fight this malice called corruption.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
The ultra-low specific speed centrifugal blower is widely used in energy industries due to its features such as low flow rate,high pressure and low manufacturing cost. However,the width-to-diameter ratio of the above ...The ultra-low specific speed centrifugal blower is widely used in energy industries due to its features such as low flow rate,high pressure and low manufacturing cost. However,the width-to-diameter ratio of the above blower becomes relatively small to satisfy the needed operation condition and its performances are considerably degraded as a result of relatively high leakage,disc friction and passage friction loss consequently. The purpose of this paper is to improve its performance through the optimization design of the blade’s profile properly. Based on artificial neural networks (ANN) and hierarchical fair competition genetic algorithms with dynamic niche (HFCDN-GAs),the optimization design approach is established. By conjoining Bezier parameterization and FINE/TURBO solver,the optimized blade is designed by adjusting the profile gradually. An industrial ultra-low specific speed centrifugal blower with parallel hub and shroud has been selected as a reference case for optimization design. The performance investigations of the centrifugal blowers with different types of blades are conducted. The conclusions of the performance improvement of the optimized blade provide positive evidences in the application of the optimization design of the above blower blade.展开更多
This paper describes the optimization of the impeller having splitters for a turbo blower.Two design variables,chord of splitter and pitch of splitter,are introduced to enhance the blower performance.Blower pressure a...This paper describes the optimization of the impeller having splitters for a turbo blower.Two design variables,chord of splitter and pitch of splitter,are introduced to enhance the blower performance.Blower pressure and ef-ficiency are selected as an object function,and the optimization of the blower impeller is performed by a response surface method (RSM).Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of the object function for each case.Throughout the shape optimization of the splitters attached to the impeller in the turbo blower,pressure and efficiency at the design flow condition are suc-cessively increased by 5.9 percent and 17.9 percent respectively based on the reference blower.The higher blower efficiency obtained by optimization of impeller having splitters is mainly caused by reducing the number of im-peller blades and optimal design of splitters in the blade passage while pressure increase keeps almost the same with the reference blower.For the object function of pressure,pressure increase is obtained at the design and off-design conditions while efficiency keeps higher compared to the reference blower.The enhancement of blow-er performance is due to the reduction of reverse and circulation flows in the blade passage.展开更多
This paper deals with the effect of the blade tip-groove of the low solidity cascade diffuser (LSD) on the blowercharacteristic and the noise generated by the LSD. The small grooves were set up at the root and/or tip ...This paper deals with the effect of the blade tip-groove of the low solidity cascade diffuser (LSD) on the blowercharacteristic and the noise generated by the LSD. The small grooves were set up at the root and/or tip near theleading edge of the LSD blade. In order to clarify the mechanism of noise increase due to LSD and also to reducethe noise, the relationships between the noise increase based on the LSD, the LSD performance and the secondaryflow formed additionally by the tip-groove were investigated experimentally as well as numerically, especiallyanalyzing flow behaviors in the LSD in view points of flow separation on the suction surface of the LSD bladeand the secondary flow on the side walls. By reducing the stagnation region smaller near the root and/or tip of theLSD blade leading edge, the secondary flow behavior changes remarkably around the LSD blade, as a result, thenoise level and the blower characteristics vary. It can be concluded that, by means of a small tip-groove locatedonly at the shroud side near the LSD blade leading edge, the noise generated by the LSD can be reduced withoutdeteriorations of the LSD performance and the blower characteristics as well.展开更多
基金supported by Fundamental Research Funds for the Central UniversitiesChina(Grant No.xjj20100073)Science and Technology Innovation Project of Shaanxi Province of China(Grant No.2011KTCL01-04)
文摘The flow in the positive displacement blower is very complex.The existing two-dimensional numerical simulation cannot provide the detailed flow information,especially flow characteristics along the axial direction,which is unfavorable to improve the performance of positive displacement blower.To investigate the effects of spiral inlet and outlet on the aerodynamic performance of positive displacement blower,three-dimensional unsteady flow characteristics in a three-lobe positive displacement blower with and without the spiral inlet and outlet are simulated by solving Navier-Stokes equations coupled with RNG k-ε turbulent model.In the numerical simulation,the dynamic mesh technique and overset mesh updating method are used.The computational results are compared with the experimental measurements on the variation of flow rate with the outlet pressure to verify the validity of the numerical method presented.The results show that the mass flow rate with the change of pressure is slightly affected by the application of spiral inlet and outlet,but the internal flow state is largely affected.In the exhaust region,the fluctuations of pressure,velocity and temperature as well as the average values of velocity are significantly reduced.This illustrates that the spiral outlet can effectively suppress the fluctuations of pressure,thus reducing reflux shock and energy dissipation.In the intake area,the average value of pressure,velocity and temperature are slightly declined,but the fluctuations of them are significantly reduced,indicating that the spiral inlet plays the role in making the flow more stable.The numerical results obtained reveal the three-dimensional flow characteristics of the positive displacement blower with spiral inlet and outlet,and provide useful reference to improve performance and empirical correction in the noise-reduction design of the positive displacement blowers.
基金supported by National Natural Science Foundation of China (Grant No. 10802058)
文摘The operating performance of positive discharge blower is markedly influenced by the pulsation of the discharge flow, but difficult to be measured with experimental methods. The internal and discharge flow of positive discharge blower with involute type three-lobe are numerically investigated, both in air cooling and countercurrent cooling conditions by means of computational fluid dynamics （CFD）. The unsteady compressible flow equations are solved using RNG x-ε turbulent model. The finite difference method and the second order upwind difference scheme are applied into discrete equations. In the numerical simulation, the dynamic mesh techniques are used to approach the rotating displacement of cell cubage and the alterability of inlet, outlet flow area. The non-uniform mesh is applied to the rotor-stator coupled area. The reliability of the numerical method is verified by simulating the inner flow and comparing with the semi-empirical theory. The flow flux curves and the distributing of velocity vector showed obvious vortex motion in all the discharge process, both in air cooling and countercurrent cooling conditions. These vortexes with different positions, intension and numbers at different rotating angles have remarkable influences on the discharge flux. For air cooling, the vortex produced a second pulsation with big-amplitude in a cycle, and led to the early appearance of maximum of backflow. For countercurrent cooling, the frequency of pulsation increased due to the pre-inflow, but the backflow at the outlet is prevented, also the pulsation strength has greatly decreased.
文摘Regenerative machines allow high heads at small flow rates and present performance curves with very stable features. This research includes a study of the effect of four inlet flow angles (90°, 115°, 125° and 135°) of the blade at outlet flow angle of 90° on the performance of regenerative blower at rotation speed of 3000 rpm and at different flow rates. Investigation and comparison of the experimental results with both one-dimensional theoretical model and numerical CFD technique using CFX-ANSYS 16.1 are done. The numerical CFD analysis show that the flow enters the impeller from the blade side (about 65% of the blade side area) and leaves from the blade tip and blade side (the remaining 35% from the blade side area). According to this observation, a mathematical model that is based on momentum exchange theory to handle one inlet angle and two exit angles for the regenerative blower impeller blades is proposed. Consequently, the experimental work is carried out by two steps. The first step is done by studying the effect of inlet blade angle of 90° and analyzing the results by using the CFD analysis. The CFD results show shock losses and vortices behind each blade at the inlet flow regions. To reduce these losses, an increase of the inlet blade angle in a range between 25° to 45° is proposed. The second step is the splitting of this angle range to three inlet blade angles of 115°, 125° and 135° in order to study and analyze the CFD results for these angels. The CFD analysis shows the disappearance of the shock losses and vortices that are formed behind the blade of angle 90°. The experimental results show that the pressure head and the efficiency depend strongly on the blade inlet and outlet flow angles as well as on the blade geometry. The results also show that the best blower performance can be obtained at an inlet flow angle of 125°, and this is confirmed by CFD simulation analysis. Finally, it is shown that the proposed one-dimensional model yield results that are in a good agreement with the experimental results.
基金Supported by Fundamental Research Funds for the Central Universities,China(Grant No.xjj20100073)Science and Technology Innovation Project of Shaanxi Province of China(Grant No.2011KTCL01-04)
文摘To improve the performance of the positive displacement blower, it is imperative to understand the detailed internal flow characteristics or enable a visualization of flow status. However, the existing two-dimensional unsteady, three-dimensional steady or quasi-unsteady numerical simulation and theoretical analysis cannot provide the detailed flow information, which is unfavorable to improve the performance of positive displacement blower. Therefore, the unsteady flow characteristics in a three-lobe positive displacement blower are numerically investigated by solving the three-dimensional, unsteady, compressible Navier-Stokes equations coupled with RNG k-e turbulent model. In the numerical simulation, the dynamic mesh technique and overset mesh updating method are adopted. Due to the air being compressed in the process of the rotors rotating, the variation of the temperature field in the positive displacement blower is considered. By comparing the experimental measurements and the numerical results on the variation of flow rate with the outlet pressure, the maximum relative error of the flow rate is less than 2.15% even at the maximum outlet pressure condition, which means that the calculation model and numerical computational method used are effective. The numerical results show that in the intake region, the fluctuations of the inlet flow are greatly affected by the direction of the velocity vectors. In the exhaust region, the temperature changes significantly, which leads to the increase of the airflow pulsation. Through analysis on the velocity, pressure and temperature fields obtained from the numerical simulations, three-dimensional unsteady flow characteristics in the positive displacement blower are revealed. The studied results will provide useful reference for improving the performance and empirical correction in the design of the positive displacement blower.
基金Funded by the National Natural Science Foundation of China(No.51375013)Fujian Provincial Research and Development Platform for Industrial Robotic Fundamental Components Technology(No.2014H2004)
文摘The rotor of a Roots blower is the key component relating to its capability, so the profile design of the rotor in a Roots blower is extremely important. We focused on the modelling and verification for a novel Roots blower tooth profile based on the performance analysis. By comparing the area utilization coefficient and the ratio of several traditional rotor profiles, we proposed a new rotor profile. Then, we further accomplished the mathematical modelling of the proposed rotor profile and the computational fluid dynamics(CFD) simulation, and obtained the Roots blower outlet flow monitoring curves. Finally, we verified the characteristics by a physical experiment.
文摘This paper describes the optimal design of a Cathode blower used for a building fuel cell system. The Cathode air blower has a regenerative blower type. Two design variables, extension angle and number of impeller blade are introduced to enhance the blower performance. Pressure and efficiency of the blower are selected as an object function, and the optimal design is performed by a response surface method. Three-dimensional Navier-Stokes equations are introduced to analyze the performance and internal flow of the blower and to find the value of object function for the training data. Throughout the design optimization, it is found that an extension angle is effective to increase blower efficiency in the blower. The pressure rise for the optimal blower is successfully increased up to 3.17% compared with that of reference one at the design flow rate. It is noted that low velocity region disturbs to make strong recirculation flow in the each blade passage, thus increases local pressure loss. Detailed flow field inside a regenerative blower is also analyzed and compared.
文摘Most forest chips are delivered to large-sized, combined heat and power plants in Finland. In this study, we introduce and demonstrate the small-scale delivery of forest wood chips to potential clients, with the wood chips being delivered in a container truck and pneumatically blown into a storage facility. This arrangement of wood chips being blown through a pipe into a storage eliminates the ground handling while requiring a relatively small space. In the demonstration tests, we tested the volumetric flow of biomass in the hose and its noise level while the blower was blowing the material and the flow speed of the material in the hose. This study discusses the test conditions in which the compatibility and suitability of the truck and its hydraulic system were used in conventional chip delivery in Finland and the selected blower type was investigated. According to the results, the biomass volume flow was higher (~0.46 m3/min) when the blower revolution was lower (2392 - 2566 RPM). However, when the RPM was increased to ~3000, the volumetric flow decreased to ~0.24 m3/min. Similarly, the speed of the chips was higher with a lower RPM;29.9 m/s at an RPM of 2400 and 25 m/s at an RPM of 2700. This is potentially due to both the blower and screw conveyer using the same power source. Additional optimization research would be needed to conclusively state the root cause of this phenomenon. On the other hand, chips from pruned stems had better flow than the chips from whole trees, since chips from whole tree have a wider range of chips sizes, including 1.3% of chips being in the range of 31.5 - 40 mm. The larger chips clogged the hose, which hindered the flow. Finally, the noise tests showed that it was louder at 0 degrees, which contrasted with the situation for the blower, with an aside at 90 degrees.
文摘The 2015 elections and swearing of new leadership in Nigeria brought about new promises as well as new policies and strategies. The president elect, Muhammadu Buhari, was quick to indicate his intentions to fight corruption as one of the means through which the government intends to achieve good governance in Nigeria. This intention and follow-up action is like the biblical two-edged sword, cutting off sadness from the lower class while at the same time cutting off happiness from some corrupt people in government. The recent announcement of the whistle blower policy by the Federal Government as another means of fighting corruption in Nigeria brought about an increase in the discovery of hidden/looted money. Relying on primary and secondary findings, based on qualitative and quantitative data the paper examines the potency of the whistle blower policy on corruption. The puzzle： is the policy yielding positive result？ The case provides a strong case to the methodological analysis for both institutional norms to fight corruption and good governance in Nigeria. The thrust of this paper is that, the fight against corruption is a national issue that can be successfully tackled by the citizens. The paper therefore recommends that government and its citizenry come together to fight this malice called corruption.
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.
基金supported by the National Natural Science Foundation of China (Grant No.50776056)the National High Technology Research and Development Program of China ("863" Program) (Grant No.2009AA05Z201)
文摘The ultra-low specific speed centrifugal blower is widely used in energy industries due to its features such as low flow rate,high pressure and low manufacturing cost. However,the width-to-diameter ratio of the above blower becomes relatively small to satisfy the needed operation condition and its performances are considerably degraded as a result of relatively high leakage,disc friction and passage friction loss consequently. The purpose of this paper is to improve its performance through the optimization design of the blade’s profile properly. Based on artificial neural networks (ANN) and hierarchical fair competition genetic algorithms with dynamic niche (HFCDN-GAs),the optimization design approach is established. By conjoining Bezier parameterization and FINE/TURBO solver,the optimized blade is designed by adjusting the profile gradually. An industrial ultra-low specific speed centrifugal blower with parallel hub and shroud has been selected as a reference case for optimization design. The performance investigations of the centrifugal blowers with different types of blades are conducted. The conclusions of the performance improvement of the optimized blade provide positive evidences in the application of the optimization design of the above blower blade.
基金supported by the Korea Institute of Industrial Technology Evaluation and Planning (ITEP) grant funded by the Ministry of Knowledge Economy (No.10032063)
文摘This paper describes the optimization of the impeller having splitters for a turbo blower.Two design variables,chord of splitter and pitch of splitter,are introduced to enhance the blower performance.Blower pressure and ef-ficiency are selected as an object function,and the optimization of the blower impeller is performed by a response surface method (RSM).Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of the object function for each case.Throughout the shape optimization of the splitters attached to the impeller in the turbo blower,pressure and efficiency at the design flow condition are suc-cessively increased by 5.9 percent and 17.9 percent respectively based on the reference blower.The higher blower efficiency obtained by optimization of impeller having splitters is mainly caused by reducing the number of im-peller blades and optimal design of splitters in the blade passage while pressure increase keeps almost the same with the reference blower.For the object function of pressure,pressure increase is obtained at the design and off-design conditions while efficiency keeps higher compared to the reference blower.The enhancement of blow-er performance is due to the reduction of reverse and circulation flows in the blade passage.
文摘This paper deals with the effect of the blade tip-groove of the low solidity cascade diffuser (LSD) on the blowercharacteristic and the noise generated by the LSD. The small grooves were set up at the root and/or tip near theleading edge of the LSD blade. In order to clarify the mechanism of noise increase due to LSD and also to reducethe noise, the relationships between the noise increase based on the LSD, the LSD performance and the secondaryflow formed additionally by the tip-groove were investigated experimentally as well as numerically, especiallyanalyzing flow behaviors in the LSD in view points of flow separation on the suction surface of the LSD bladeand the secondary flow on the side walls. By reducing the stagnation region smaller near the root and/or tip of theLSD blade leading edge, the secondary flow behavior changes remarkably around the LSD blade, as a result, thenoise level and the blower characteristics vary. It can be concluded that, by means of a small tip-groove locatedonly at the shroud side near the LSD blade leading edge, the noise generated by the LSD can be reduced withoutdeteriorations of the LSD performance and the blower characteristics as well.
