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RISS 인기검색어
- 검색키워드
- 저자 : Fenghui Han (검색결과 3 건)
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Fenghui Han,Zhe Wang,Yijun Mao,Yiyun Zhang,Jiajian Tan 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.1
Multi-hole probe (MHP), as a classical measuring instrument, continues to play an important role in the pressure and velocity measurements for industrial applications by virtue of its robust and reliable performance as well as the simple structure and low cost. But the flow directionality limitations and the low efficiency of traditional operations become obstacles to the large-scale measurements of MHPs. In this paper, an improved operating method is adopted for conventional MHPs to extend their measuring range of incidence angles, and a corresponding auto-measuring system has been developed to realize automatic calibration and measurement of MHPs for industrial large-scale flow measurements. Measurement uncertainties of the system have been experimentally analyzed, verifying a good accuracy: errors of 0.36° in pitch angle, 0.40° in yaw angle and 0.83% in velocity magnitude (95% CI). Furthermore, this auto-measuring system has been applied in the large-scale measurements on different radial inlets for industrial centrifugal compressors, which provide valuable flow information that was not previously available for industrial productions and assist with the improvement study. Analysis and applications in this paper prove that the developed system not only reduces the flow directionality limitations of conventional MHPs, but also significantly improves the experimental efficiency and the control-precision of the probe, achieves a good repeatability and ensures the reliability of the experimental data, which satisfies the requirements of large-scale measurements in industrial applications. Meanwhile, the portability of the system makes it more convenient and flexible to be applied in various industrial productions.
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Fenghui Han,Yijun Mao,Jiajian Tan 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10
Radial inlets are typical upstream components of multistage centrifugal compressors. Unlike axial inlets, radial inlets generate additional flow loss and introduce flow distortions at impeller inlets. Such distortions negatively affect the aerodynamic performance of compressor stages. In this study, industrial centrifugal compressor stages with different radial inlets are investigated via numerical simulations. Two reference models were built, simulated, and compared with each original compressor stage to analyze the respective and coupling influences of flow loss and inlet distortions caused by radial inlets on the performances of the compressor stage and downstream components. Flow loss and inlet distortions are validated as the main factors through which radial inlets negatively affect compressor performance. Results indicate that flow loss inside radial inlets decreases the performance of the whole compressor stage but exerts minimal effect on downstream components. By contrast, inlet distortions induced by radial inlets negatively influence the performance of the whole compressor stage and exert significant effects on downstream components. Therefore, when optimizing radial inlets, the reduction of inlet distortions might be more effective than the reduction of flow loss. This research provides references and suggestions for the design and improvement of radial inlets.
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A thermal design method for the performance optimization of multi-stream plate-fin heat exchangers
Zhe Wang,Fenghui Han,Bengt Sundén,Yanzhong Li 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6
An optimization design method based on field synergy principle is developed for Multi-stream plate-fin heat exchangers (MPHEs)with a segmented differential model. The heat exchanger is divided into a number of sub-exchangers along the main stream, and eachsub-exchanger consists of N passages along the height of the exchanger. Compared with the traditional heat exchanger design, this methodallows temperature and pressure fields to be obtained via coupling calculation with consideration of variable physical properties andthe axial heat loss of the heat exchanger. Finally, the heat exchanger is optimally designed using a temperature-difference uniformityoptimization factor based on field synergy principle. This design model can provide an accurate temperature field and pressure field,because the stream properties are determined by the mean temperature and pressure of each local sub-exchanger. Optimum results indicatethat the temperature distribution on the cross section of the heat exchanger is relatively uniform and that the temperature differenceof heat transfer for each stream is always a small value. These characteristics prove the feasibility and effectiveness of this design model. In this paper, a case of five stream plate-fin heat exchangers for an ethylene plant is designed under a practical cold box operating conditionwith the proposed model, the structure and heat transfer of which are optimally determined. The design model and optimizationmethod proposed in this work can provide theoretical and technical support to the optimization design of MPHEs.
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