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Yang B.,Shanghai JiaoTong University | Xu Q.,Shanghai Electrical Power Generation R and nter | He L.,Shanghai Electrical Power Generation R and nter | Zhao L.H.,Shanghai Electrical Power Generation R and nter | And 2 more authors.
Journal of Turbomachinery | Year: 2015

In this paper, a novel global optimization algorithm has been developed, which is named as particle swarm optimization combined with particle generator (PSO-PG). In PSO-PG, a PG was introduced to iteratively generate the initial particles for PSO. Based on a series of comparable numerical experiments, it was convinced that the calculation accuracy of the new algorithm as well as its optimization efficiency was greatly improved in comparison with those of the standard PSO. It was also observed that the optimization results obtained from PSO-PG were almost independent of some critical coefficients employed in the algorithm. Additionally, the novel optimization algorithm was adopted in the airfoil optimization. A special fitness function was designed and its elements were carefully selected for the low-velocity airfoil. To testify the accuracy of the optimization method, the comparative experiments were also carried out to illustrate the difference of the aerodynamic performance between the optimized and its initial airfoil. © 2015 by ASME.

Liu L.,CAS Institute of Engineering Thermophysics | Liu L.,University of Chinese Academy of Sciences | Zhang H.,CAS Institute of Engineering Thermophysics | Zhang H.,Shanghai Electrical Power Generation R and nter | And 6 more authors.
Proceedings of the ASME Turbo Expo | Year: 2013

In this paper, experiments are performed to measure and demonstrate the whole throttling process from the steady operating state to stall inception with water ingestion in a low speed axial compressor. A transparent casing is used to visualize the water distribution on the casing. Two types of nozzles are used, giving the average droplets diameters of 35 μm and 90 μm, respectively. Six different water mass flow rates are tested, ranging from 0.064% to 2.05% compared to the reference airflow rate. The compressor performance curves change significantly as the ingested water flow rate. Small water flow rates even improve the performance while the middle water flow rates decrease it. For large water flow rates, the pressure rise coefficient drops rapidly and becomes "flat" at low airflow rate but the stall margin is extended much further into the low airflow rate region. To visualize the whole stall evolution process, photos and digital videos are both taken through transparent casing and record the patterns of the water distribution on the casing. Dynamic casing static pressure is also measured at the same time. Due to the centrifugal force acting on the water droplets, the water film on the casing along the tangential direction is observed in photos and videos. The edges of water film can be identified, and the back edge is believed to separate the incoming flow and the tip leakage flow. As the compressor is throttled to smaller flow rates yet still away from the stall limit, this interface moves forwards and becomes fluctuating which can be visualized with bare eyes. The fluctuation becomes more and more violent until the water film suddenly spills out of the leading edge, and thus the stall happens. As the water ingestion rate increases, the film gets wider and thicker, and even exceeds the leading edge before stall inception. Unsteady casing static pressure is also measured. The increased power spectrum density of pressure signals in frequency domain is found and believed to might be related with the water film fluctuation observed on the compressor casing. The phenomena observed in photos and videos provide interesting information of the flow in the compressor and deserve further research. Copyright © 2013 by ASME.

Li L.,Xi'an Jiaotong University | Yang J.-D.,Xi'an Jiaotong University | Yang J.-D.,Shanghai Electrical Power Generation R and nter | You W.,Xi'an Jiaotong University | And 2 more authors.
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy | Year: 2014

The vapour-liquid two-phase flow in the low-pressure cylinder of a 1000 MW nuclear steam turbine has been investigated. Firstly, a comparative study of the flows with equilibrium and non-equilibrium condensation is described. The vapour extraction and moisture removal processes are included in the calculations to simulate the actual operating conditions in the low-pressure cylinder. Differences in the thermodynamic expansion lines, and in the distributions of wetness and degree of reaction, for equilibrium and non-equilibrium flow calculations are discussed. Secondly, the deposition of the fog and coarse water droplets in the last stage stator is investigated computationally. An empirical approach, together with the predictions of the non-equilibrium flow calculation, is used to redistribute the spanwise profile of the wetness at inlet to the last stage of the turbine. The movement and deposition of the water droplets are tracked in a Lagrangian frame. The variations of the fog and coarse water deposition rates are obtained in both the spanwise and axial-chordwise directions. © IMechE 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Qihe H.,Shanghai Electrical Power Generation R and nter | Jiao W.,Shanghai Electrical Power Generation R and nter | Lei H.,Shanghai Electrical Power Generation R and nter | Qiang X.,Shanghai Electrical Power Generation R and nter
ASME 2013 Turbine Blade Tip Symposium, TBTS 2013 | Year: 2013

A numerical study is performed to simulate the tip leakage flow and heat transfer on the first stage rotor blade tip of GE-E3 turbine, which represents a modern gas turbine blade geometry. Calculations consist of the flat blade tip without and with film cooling. For the flat tip without film cooling case, in order to investigate the effect of tip gap clearance on the leakage flow and heat transfer on the blade tip, three different tip gap clearances of 1.0%, 1.5% and 2.5% of the blade span are considered. And to assess the performance of the turbulence models in correctly predicting the blade tip heat transfer, the simulations have been performed by using four different models (the standard k-ε, the RNG k-ε, the standard k-ω and the SST models), and the comparison shows that the standard k-ω model provides the best results. All the calculations of the flat tip without film cooling have been compared and validated with the experimental data of Azad[1] and the predictions of Yang[2]. For the flat tip with film cooling case, three different blowing ratio (M=0.5, 1.0, and 1.5) have been studied to the influence on the leakage flow in tip gap and the cooling effectiveness on the blade tip. Tip film cooling can largely reduce the overall heat transfer on the tip. And the blowing ratio M=1.0, the cooling effect for the blade tip is the best. Copyright © 2013 by ASME.

Sun B.,Shanghai Electrical Power Generation R and nter | Wu K.,Shanghai Electrical Power Generation R and nter | Peng S.,Shanghai Electrical Power Generation R and nter | Ji J.,Shanghai Electrical Power Generation R and nter | He L.,Shanghai Electrical Power Generation R and nter
International Conference on Power Engineering 2013, ICOPE 2013 | Year: 2013

According to the packed saturator in humid air turbine (HAT) cycle, the heat-transfer, mass-transfer and air-water flow characteristics are discussed and analyzed. Control equations are established based on physical principles. A dynamic model of the packed saturator consists of several sectional models along with air flow direction is developed by using explicit Runge-Kutta method in Simulink environment focusing on the time-dependent accumulation and flow in the structured packing. Based on this saturator model, numerical simulations are carried out to explore the system dynamic performance with respect to step changes in the inlet water flow, inlet air flow, inlet water temperature and inlet air temperature. The dynamic responses of key outlet variables, including the outlet humid air temperature, outlet water temperature, outlet air humidity, pressure drop and liquid holdup in the packing etc., are obtained. Different steady-state and dynamic operation conditions are analyzed in this paper, for the step changes occur on the inlet variables, the outlet variables take certain inertia time constant to arrive at new steady-state. The response time of outlet temperature variables is about 50s long, which is longer than pressure drop and liquid holdup. The simulation results agree well with experimental data. The model and simulation method may be useful for providing insights to the design, operation and control of the HAT cycle process with respect to complex varying working conditions.

Ying Y.,Shanghai Electrical Power Generation R and nter | Sun B.,Shanghai Electrical Power Generation R and nter | Peng S.,Shanghai Electrical Power Generation R and nter | Wu K.,Shanghai Electrical Power Generation R and nter | And 2 more authors.
Proceedings of the ASME Turbo Expo | Year: 2014

One of the most troublesome problems in the development of a component-based engine model is the compressor modeling because of the strong dependence of its performance on rotational speed and the treatment of compressor characteristic curves plays a significant role in modeling and simulation of gas turbine for the analysis of its off-design performance and thus it is crucial to describe compressor map exactly. Usually part of rotational speed characteristic curves of compressor including on-design operating point are known during actual modeling and simulation, and reasonable interpolation and extrapolation have to be done in order to make good use of flow characteristics and efficiency characteristics under more constant rotational speed lines during off-design performance simulation. Due to that the accuracy of traditional approaches for component characteristic treatment is not satisfactory, and the performance of interpolation and extrapolation of artificial neural network is poor, a linear multiple regression method, i.e., partial least-squares regression method was proposed in this paper. Partial least-squares regression modeling method was used to reproduce the compressor maps. Different polynomial functions of various powers were used to obtain respectively expressions of compressor maps. Fitting accuracy and performance of interpolation and extrapolation of this method were analyzed, and the simulating experimental results show that partial least-squares regression method can ensure good fitting accuracy and good performance of interpolation and extrapolation for compressor thermodynamic modeling with both maximum RMS errors less than 0.5%. It can be expected that the application of partial leastsquares regression modeling has a certain reference value to improve the solution accuracy for thermodynamic model of industrial gas turbine. Copyright © 2014 by ASME.

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