共查询到19条相似文献,搜索用时 86 毫秒
1.
PerformanceofWellsTurbinewithGuideVanesforWaveEnergyConversionManabuTakao;ToshiakiSetoguchi;KenjiKaneko(DepartmentofMechanica... 相似文献
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ExperimentalStudiesonHeatTransferintheTipGapofaSectorialTurbineCascadeExperimentalStudiesonHeatTransferintheTipGapofaSectoria... 相似文献
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This paper presents the work carried out to predict the behavior of a 0.6 m Impulse turbine with fixed guide vanes with 0.6 hub-to-tip (H/T) ratio under real sea conditions. In order to predict the true performance of the actual Oscillating Water Column (OWC), the numerical technique has been fine tuned by incorporating the compressibility effect. Water surface elevation verses time history based on Pierson Moskowitz Spectra was used as the input data. Standard numerical techniques were employed to solve the non-linear behavior of the sea waves. The effect due to compressibility inside the air chamber and turbine performance under unsteady and irregular flow condition has been analyzed numerically. Considering the quasi-steady assumptions, unidirectional steady flow experimental data was used to simulate the turbine characteristics under irregular unsteady flow conditions. The results show that the performance of this type of turbine is quite stable and efficiency of air chamber and the mean conversion 相似文献
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IntroductionA ttirbomachinery rotor must have a slhall hilt finite clearance relative to its surrounding casing. Theflow, which leaks thlough this fililte gap, has a surprisingly large effect on the aerodynamics of the flow.The loss produced due to the tip clearance is an.unavoidable loss. The presence of tip clearance ajtersthe endwall flow siglilflcaotly. The normal secondaryflow interacts with the leakage fluid ajs it easts fromthe suction surface. The leakage fluid rolls into whatis known… 相似文献
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Catalytic combustion of propane-air mixture was investigated.Platinum catalysts over a flat stainless steel with γ-alumina washcoat were employed.The employed burner has three catalysts set parallel to the mixture flow,spaced at an interval of 5,10 and 15 mm.Both experiment and numerical simulation were made at inlet temperature of 553 K,inlet velocity of 3 to 7 m/s and equivalence ratio of 0.3 to 0.5.In the numerical simulation,two-dimensional,steady state model was developed to calculate the temperature and species concentration in gas-phase.In this model.chemical reaction on the catalyst surface and that in the gas phase were assumed to occur in three-steps.The numerical results show good agreement with experimental results.It was found that the properties of the catalyst strongly affect the catalyst surface temperature.Especially,the thermal conductivity of catalyst has a great effect,while the emissivity of catalyst has less effect. 相似文献
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The objective of this paper is to present the performance comparison of 2D Computational Fluid Dynamics (CFD) analysis with experimental analysis of 0.6 m impulse turbine with fixed guide vanes for both 0.6 and 0.7 hub to tip ratio (H/T). Also the comparison of 2D CFD analysis of the said turbine with different values of H/T ranging from 0.5 to 0.7. A 2D-cascade model was used for CFD analysis while uni-directional steady flow was used for experimental analysis. The blade and guide vane geometries are based on 0.6 m rotor diameter, with optimum profile, and different H/T of 0.5, 0.6 and 0.7. It was concluded from 2D CFD analysis that 0.5 H/T ratio performances was higher than that of 0.6 and 0.7 H/T at peak efficiency and the operational flow range for 0.5 H/T was found to be wider than that of 0.6 and 0.7 H/T ratio. 相似文献
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INTRODUCTIONMapstudies[1-13lonthecondensationshockwaveoccurringinthecaseoftherapidexpansionofmoistairorsteaminasupersonicnozzlehavebeenper-formed,andthecharacteristicsofcondensationshockwavhavenearlybeenclarified.Acondensationshockwavalsooccursinthebladepassageinasteamturbinel14'15].Suchacondensationshockwavethatinteractswiththeboundary1ayeronthesurfaceofthettirbineblade,affectsthellowinthebladepas-sageinasteamturbine.However,thefiowinthebladepaJssagewiththecondensationshockwaveisnotyetun… 相似文献
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A 2 MW gas turbine engine has been developed for the distributed power market.This engine features a 7:1 pressure ratio radial inflow turbine.In this paper,influences of various geometry features are investigated including turbine tip and backface clearances.In addition to the clearances,the effects of the inducer deep scallop and exducer rounded trailing edge are investigated.Finally,geometric features associated with a split rotor(separate inducer and exducer)are studied.These geometry features are investigated numerically using CFD.Part of the numerical results is also compared to experimental data acquired during engine test to validate the CFD results. 相似文献
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INTroDUCTIONThe Horizontal Bias Combustioll Pulverized Coal(HBC) burner for tangential firing system has advantages of improving flame stabilization, slaggingresistance, pollution control and high combustionefficiency[']. However, in the thin and tall furnace firedwith coal with strong slagging telldency) it is possiblethat slagging occurred on water-cooled wall, especiallywhen the cross-sectional and volumetric heat releaserate are very high in the burner domain.The HBC burner with Si… 相似文献
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Effect of Nonequilibrium Homogenous Condensation on Flow Fields in a Supersonic Nozzle 总被引:1,自引:0,他引:1
INTRODUCTIONManystudies[1-131onthecondensationshockwaveoccurringinthecaseoftheraPidexPansionofmoistairorsteaminasupersonicnozzlehavebeenper-formed,andthecharacteristicsofcondensationshock'wavehavenearlybeenclarilied.Acondensationshockwavealsooccursinthebladepassageinasteamturbinel14,15]andsuchacondensationshockwavinteractswiththeboundarylayeronthesurfaceoftheblade.Thus,thefiowinthebladepassageofthesteamturbinewiththecondensationshockwavehasnotyetbeenclariliedl16'17].InthepreseDtstudythee… 相似文献
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A Wells turbine is a self-rectifying air flow turbine capable of converting pneumatic power of the periodically reversing air stream in Oscillating Water Column into mechanical energy. The Wells turbine has inherent disadvantages; lower efficiency, poorer starting characteristics, higher axial force and low tangential force in comparison with conventional turbines. Guide vanes before and after the rotor suggest a means to improve the tangential force, hence its efficiency. Experimental investigations are carried out on a Wells turbine with the constant chord and variable chord blade rotors fitted with inlet and outlet guide vanes to understand the aerodynamics. Experiments were also conducted for the above said rotors with various stagger angles to validate the design stagger angle. In addition, the starting and running characteristics of the rotors have been studied and compared with the case without guide vanes. Studies were done at various flow coefficients covering the entire range of flow coefficients over which the turbine is operable. The efficiency, starting characteristics of the turbines with guide vanes have improved when compared with the respective turbines without guide vanes. 相似文献
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Xiao Jun Gu Chuangang Shu Xinwei Gao Chuang 《Frontiers of Energy and Power Engineering in China》2007,1(4):473-476
The flow in a centrifugal compressor stage with variable inlet guide vanes (VIGVs) is investigated by numerical simulation
in this paper. Analysis of the performance curves and relative velocity vectograms indicates that performance curves shift
toward small flow domain when VIGVs turn positively, and toward large flow domain when VIGVs turn negatively. Stage efficiency
drops quickly after work condition enters a small flow domain through the peak efficiency point. Under the circumstance of
large setting angles of the guide vanes, there exist obvious flow separations in guide vane passages within wide flow ranges,
and back flow regions can be located at the front of splitter suction surfaces under large flow conditions, while under the
condition of small flow, flow separations occur on suction surfaces of long blades.
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Translated from Journal of Power Engineering, 2006, 26(6): 804–807 [译自: 动力工程] 相似文献
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In this study, in order to achieve further improvement of the performance of an impulse turbine with fixed guide vanes for wave energy conversion, the effect of guide vane shape on the performance was investigated by experiment. The investigation was performed by model testing under steady flow condition. As a result, it was found that the efficiency of the turbine with 3D guide vanes are slightly superior to that of the turbine with 2D guide vanes because of the increase of torque by means of 3D guide vane, though pressure drop across the turbine for the 3D case is slightly higher than that for the 2D case. 相似文献
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为探究单级变几何涡轮(VGT)在导叶转动过程中的过渡态性能,对某动力涡轮进行了非定常数值计算,应用动网格技术实现导叶转角的改变,并对导叶通道开大或关小过渡过程中涡轮性能进行了分析。结果表明:导叶转角从0°变化到-5°时,单级涡轮效率逐渐下降1.6%,从0°变化到6°时,效率逐渐提高0.5%;质量流量和导叶出口绝对气流角随转角改变接近线性变化,而动叶出口相对气流角、熵增、效率和导叶出口总压损失等随转角改变呈抛物线型变化;过渡态下导叶流场内损失变化主要受上、下端壁处间隙泄漏涡影响,动叶出口熵增变化规律主要受动叶吸力侧泄漏涡和下部通道涡影响,其中下部通道涡的改变是引起熵增变化的主要原因。 相似文献
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Hayati Olgun 《国际能源研究杂志》2000,24(11):953-964
The cross‐flow turbine has attracted much attention as a source of hydropower generation for small and micro‐systems, especially for low head establishments. Such turbines have a distinct advantage of lower initial and operating costs over other small scale turbines, but their efficiency is lower than others. Efficiency predictions of these turbines are generally based on the assumption that the entire flow crosses from the first stage to the second stage of the turbine runner. In this study, interior guide tubes were designed and used inside the runner of a cross‐flow turbine to collect and guide the crossing flow towards the second stage of the runner. The interior guide tubes were designed on the basis of observed flow patterns inside the runner. Experimentally, three different types of tubes were tested. The laboratory tests were conducted to calculate the turbine efficiency with different gate openings of nozzle and different positions of interior guide tubes. Results of this work with and without interior tubes have been presented in this paper. When the experiments were done with and without interior guide tubes, it has been found that turbine efficiency with the interior guide tube decreased about 5 per cent. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
17.
Forced responses on a radial turbine with nozzle guide vanes 总被引:1,自引:1,他引:0
Radial turbines with nozzle guide vanes are widely used in various size turbochargers. However, due to the inter- ferences with guide vanes, the blades of impellers are exposed to intense unsteady aerodynamic excitations, which cause blade vibrations and lead to high cycle failures (HCF).Moreover, the harmonic resonance in some frequency regions are unavoidable due to the wide operation conditions. Aiming to achieve a detail insight into vibration characteristics of radial flow turbine, a numerical method based on fluid .structure interaction (FSI) is presented. Firstly, the unsteady aerodynamic loads are determined by computational fluid dynamics (CFD).And the fluctuating pressures are transformed from time domain to frequency domain by fast Fourier-transform (FFT). Then, the entire rotor model is adopted to analyze frequencies and mode shapes considering mistuning in finite element (FE) method. Meanwhile, harmonic analyses, applying the pressure fluctuation from CFD, are conducted to investigate the impeller vibration behavior and blade forced response in frequency domain. The prediction of the vibration dynamic stress shows acceptable agreement to the blade actual damage in consistent tendency. 相似文献
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为提高垂直轴风力机气动性能,提出一种随相位角变化而改变相对夹角的分流导叶结构。以NACA0021为基础翼型,采用计算流体力学方法对分流导叶作用下垂直轴风力机风能利用系数、单叶片瞬时转矩、压力系数及速度场进行数值分析。结果表明:静态和动态分流导叶均可提高垂直轴风力机气动性能,且动态分流导叶提升效果更为显著;相较于静态分流导叶,动态分流导叶垂直轴风力机在尖速比为2.33时风能利用系数最高可提升23%,在尖速比为2.03时静态分流导叶垂直轴风力机较原始垂直轴风力机风能利用系数提高37%;分流导叶也可使最佳尖速比前移,稳定叶片转矩波动,提升垂直轴风力机的运行稳定性。 相似文献