• International Journal of Fluid Machinery and Systems
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• v.6 no.1
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• pp.11-17
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• 2013

Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Blade-to-blade low velocity regions are suppressed in the case with the splitter blades and total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

• International Journal of Fluid Machinery and Systems
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• v.5 no.4
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• pp.168-173
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• 2012

This paper presents a numerical investigation on the aerodynamic performance according to the application of splitter blades in an impeller of a centrifugal fan used for a refuse collection system. Numerical analysis of a centrifugal fan was carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. A validation of numerical results was conducted by comparison with experimental data for the pressure and efficiency. From analyses of the internal flow field of the reference fan, the losses by the reverse-flows were observed in the region of the blade passage. In order to reduce these losses and enhance fan performance, two splitter blades were applied evenly between the main blades, and centrifugal impellers having the different numbers of the main blades were tested with their application. Throughout the numerical analyses of the centrifugal fan with splitter blades, it was found that the reverse-flow regions in the blade passage can be reduced by controlling the main blade numbers with splitter blades. The application of splitter blades in a centrifugal fan leads to significant improvement in the overall fan performance.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.129-136
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• 2000

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed Information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan, and to calculate the effects of small vanes that are attached in original impeller - Splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller and splitter impeller which splitter locates in jet region are good for acoustic characteristics.

• The KSFM Journal of Fluid Machinery
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• v.4 no.1 s.10
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• pp.22-29
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• 2001

Centrifugal fans are widely used in industrial practices but the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the easing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan, and to calculate the effects of small vanes that are attached in original impeller - Splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller and splitter impeller which splitter locates in jet region are good for acoustic characteristics.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.152-155
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• 2008

In this paper, the effect of modification of geometric variables on the performance of a centrifugal compressor blade has been studied numerically. The compressor contains six main blades and six splitter blades. Reynolds averaged Navier-Stokes (RANS) equations with shear stress turbulence (SST) model are discretized by finite volume approximations and solved on hexahedral grids for flow analysis. The design variables from blade lean angle at tip and middle of the blade have been modified. The isentropic blade efficiency and pressure have been predicted with the variation of the variables. Frozen rotor simulation is performed and adiabatic wall condition has been used. One of the six blades of compressor has been used for simulation to reduce the computational load. Optimum number of meshes has been selected by grid-dependency test, and this is used for all the simulations with changing geometric variables. The detailed flow analysis results have been reported as well as the effects of the variables.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.113-118
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• 2000

Centrifugal pump are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal pump noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal pump, and to calculate the effects of small vanes that are attached in original impeller-splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method(DVM) is used to model the centrifugal pump and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller is good for acoustic characteristics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.168-172
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• 2008

Three different geometry shapes of the blade leading edge in a centrifugal compressor were investigated in this paper. Numerical simulation was done to analyze the effect of the leading edge shape on the performance of the centrifugal compressor. The result shows that compared to the blunt leading edge, the circular leading edge will raise the chocking mass flow. The pressure ratio and efficiency will increase obviously. Using elliptical leading edge will get a further improvement on the performance than circular leading edge. The analysis of the flow field shows that the leading edge often causes flow separation near the inlet; using circular leading edge and elliptical leading edge will reduce the separation. What's more, using circular and elliptical leading edge will also reduce the wake loss near the outlet of the impeller. In a centrifugal compressor, using circular or elliptical leading edge on the splitter will improve the pressure loading distribution of main blade near the position of the splitter leading, which will increase the pressure ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1067-1073
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• 2011

This paper describes the performance of a centrifugal fan used for refuse collection systems according to the chord length of the splitters installed near the blade suction and pressure surface sides. The fan performance is analyzed by three-dimensional Navier.Stokes analysis and is compared to the results obtained experimentally. Throughout the numerical simulation of the fan with splitters, it is found that the reverse-flow region observed near the suction side of the blade can be reduced by installing a splitter. The fan performance is successfully improved by controlling the chord length of the splitter installed near the blade suction side. Under the designed flow condition, the efficiency and pressure of a fan with splitters increase by up to 4% and 18%, respectively, compared to the reference fan.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1065-1072
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• 2014

The shape of an impeller splitter for a dual-inlet centrifugal blower was optimized to enhance the blower performance. Two design variable, the normalized chord and pitch of a splitter, were used to evaluate the blower performance and internal flow fields based on the three-dimensional flow analysis. The blower performance obtained using this numerical simulation had a maximum error of 4 percent compared to that in an experiment at the design flow condition. The shape optimization of the splitter successfully increased the blower efficiency and pressure by 3.65 and 1.14 percent compared to the reference values. The blower performance was increased by reducing the flow separation near the blade suction surface by optimizing the shape of the splitter, which produced a pressure increase at the outlet of the volute casing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1419-1424
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• 2007

Centrifugal turbo blower is requested highly efficiency and low noise in FCEV, but the noise generated by this machine causes of the most serious problems in the NVH performance. In general, centrifugal turbo blower is dominated by mechanical noise and aerodynamic noise. Mechanical noise is generated by rotation of the bearing, misalignment and unbalance. And aerodynamic noise is generated by the strong intersection between the flow discharged from the impeller and the cut-off in the casing. The first object of this study is to comprehend a noise property of the blower through the noise test. And, second object is to bring up the method that can reduce blower noise.