环周进汽型两相流升压装置的实验研究

对环周进汽型变截面通道内超音速汽液两相流升压装置进行了系统的实验研究,实验中进汽压力为0.15～0.4MPa,进水压力为0.2～0.6 MPa,汽水面积比为0.5～9.0.实验结果分析表明,装置的升压性能随汽水面积比的增加先上升后降低.最佳而积比随进汽压力的增加而减小,随进水压力的增加而增加.同时对装置的耗汽性能进行了...     

环周进汽型超声速汽液两相流升压装置性能计算分析

对环周进汽型的变截面通道内超声速汽液两相流升压装置进行了实验及理论研究,实验中进汽压力为0.15～0.4MPa,进水压力为0.2～0.6 MPa。实验结果表明在不同的汽水参数条件下,混合腔内压力与温度分布呈现出相似的规律。在同一工况下,激波前混合腔内各点的压力基本保持不变,随着凝结激波的产生,压力突然增大。激波过程中蒸汽几乎全部凝结,激波过后温度分布趋于平缓。并在实验结果的基础上分别建立了水喷嘴、蒸汽喷嘴、混合腔内两相区和扩散段的数学模型,其预测的装置出口压与实验值之间的误差小于15%。     

超音速两相流极限升压能力的理论与试验研究

采用理论和实验的方法研究了一定汽水参数下的超音速汽液两相流升压装置的极限升压能力以及主要结构参数对其的影响规律。计算与实验的结果表明:超音速汽液两相流升压装置的极限升压能力计算值可达进汽压力的14倍左右,实验值可到进汽压力的2.6倍左右;混合腔和水喷嘴的几何尺寸是影响极限升压能力的最主要的结构参数;极限升压能力随混合腔收缩比增大而增大,随水喷嘴出口与混合腔喉部截面积比增大而减小,随蒸汽喷嘴喉部与出口截面积之比变化不大。计算和实验得到的结构参数对极限升压能力的影响规律是基本一致的。     

低进汽压力下超音速两相流升压特性实验研究

本文采用实验方法研究了进汽压力为0.2 MPa以下时,由蒸汽喷嘴、混合腔及相应的阀门和管道组成超音速汽液两相流升压加热装置的运行特性。实验表明在进汽压力为0.1 MPa-0.2 MPa时,超音速汽液两相流升压加热装置都可稳定可靠地运行,且升压效果明显,可满足电力、供暖、轻工等许多行业蒸汽加热的要求。     

旋流喷射乏汽回收装置性能的实验研究

针对采用旋流喷射式进水的低温乏汽回收装置的性能进行了实验研究.实验结果表明,引射系数随进水压力和进水温度的升高而降低,随进汽压力的升高而升高,基本不受出水压力的影响;阻力系数随进水压力和进水温度的升高而升高,随着进汽压力的升高而降低.采用旋流喷射进水方式使得装置的加热、引射性能有很大提高,同时使流动的阻力系数增大.     

参数对变截面内超音速两相流极限升压能力的影响

在建立变截面通道内超音速汽液两相流升压装置的极限升压能力计算模型的基础上,对极限升压能力的影响因素进行了分析,定量计算了各影响因素对极限升压能力的影响,计算结果表明:极限升压能力随混合腔进出口截面积比增大而增大;随蒸汽压力升高而下降;随引流系数变化存在最小值;随进口低压水温的升高略有升高。这些对变截面通道内超音速汽液两相流升压装置的设计和应用具有重要意义。     

变截面超音速汽液两相流升压过程的研究

本文针对超音速汽液两相流在变截面通道中的升压过程进行了实验研究,得到了变截面混合腔中超音速汽液两相流的压力变化规律,通过实验结果的分析得出了变截面混合腔中的渐缩部分的压力分布与出口压力无关、变截面通道的渐扩部分为一个单相流体扩压管、压力突变发生在变截面混合腔喉部和随着出口压力升高而激波强度增大、变截面超音速汽液两相流升压技术具有定流量特征等结论。     

冷源冷量对压缩/喷射制冷系统性能影响的实验研究

实验研究了喷射器的最优喷嘴距及在此条件下,冷凝器进水冷量对喷射器及双蒸发压缩/喷射制冷系统性能的影响,同时对双蒸发压缩/喷射制冷系统与蒸汽压缩制冷系统进行了对比研究。结果表明:喷射器引射系数随冷凝器进水冷量的增大而减小,喷射器升压比随冷凝器进水冷量的增大而增大;双蒸发压缩/喷射制冷系统COP_P随冷凝器进水冷量的增加先快速增加后缓慢减小,冷凝器进水冷量存在一个合理值,当冷凝器进水冷量控制在17.81 kW时,系统性能最好;高温蒸发器的制冷量约占系统总制冷量的88%,低温蒸发器的制冷量约占系统总制冷量的12%;在不同的冷凝器进水冷量下,双蒸发压缩/喷射制冷系统比蒸汽压缩制冷系统COP提高约36%左右。     

单纤光纤探针测量空泡份额的实验研究

1前言气（汽）液两相流广泛应用于工业过程中。空泡份额是气（汽）液两相流的重要参数，它与流场、压力、热流密度和流型等密切相关。由于目前的理论计算模型还有较大的局限性，因此实验测量是研究气（汽）液两相流空泡份额的最主要的研究手段。经过近几十年的研究，各国学者开发出了许多有价值的空泡份额测量方法，其中包括平均空泡份额测量方法和局部空泡份额测量方法，这些测量方法本身各有各的局限性和一定的针对性。本文研究水平管束间汽液两相流流动和沸腾传热特性，流道中加热管柬的存在对流体流动产生强烈的影响，使管束间汽液两相…     

气液两相流压力波色散特性实验研究

设计了可调频式压力扰动源的气液两相流压力波实验装置,实验研究了垂直上升管内气液两相流泡状流、弹状流压力波的色散规律。实验结果表明,对泡状流,在实验范围内,压力波的传播速度及其衰减跟扰动频率有关,随着扰动频率的增加,波速及其衰减都增加;工质的流速对压力波的色散特性没有影响。结合数值模拟结果,验证了泡状流压力波色散特性的临界频率现象,即高于临界频率,压力波色散特性消失,本文分析了相应的物理机制。对弹状流,压力波同样具有典型的色散特性,已有研究结果还不能预测其色散规律。     

并联管两相流不稳定性的研究

在高压汽水回路上对垂直并联管中汽液两相流不稳定性进行了试验研究．确定了压力、质量流速、入口过冷度、热负荷及热负荷不对称分布、进口及出口节流、可压缩容积等对不稳定性的影响．得出了压力降型和密度波型不稳定性的界限，给出了并联管中计算不稳定性起始条件的无因次方程，为大型直流锅炉和蒸汽发生器的设计提供依据．     

卧式螺旋管内汽液两相流不稳定性试验研究

本文在中、低压汽水试验台上对卧式螺旋管内汽液两相流动不稳定性进行了详细的试验研究，获得了各类脉动发生的界限及各主要参数对脉动的影响规律，并在无固次分析的基础上，给出了密度波脉动起始边界的预报关系式。     

压水堆冷凝回流特性的研究

利用高压汽水两相流试验系统模拟压水堆小破口失水事故中冷凝回流传热模式,进行了传热、流动及不凝结气影响的试验。实验表明：冷凝回流传热是一种十分有效的传热模式,它在很小的一、二次侧温差时就能排放大量堆芯余热。冷凝回流系统在正常情况下流动阻力很小且稳定,但在达到回流流动极限后出现不稳定。不凝结气的存在将大大降低蒸汽发生器的传热能力,但一般情况下,系统能自动增加一次侧压力而达到排除余热的目的。     

A Novel Dehumidification Strategy to Reduce Liquid Fraction and Condensation Loss in Steam Turbines

Massive droplets can be generated to form two-phase flow in steam turbines, leading to erosion issues to the blades and reduces the reliability of the components. A condensing two-phase flow model was developed to assess the flow structure and loss considering the nonequilibrium condensation phenomenon due to the high expansion behaviour in the transonic flow in linear blade cascades. A novel dehumidification strategy was proposed by introducing turbulent disturbances on the suction side. The results show that the Wilson point of the nonequilibrium condensation process was delayed by increasing the inlet superheated level at the entrance of the blade cascade. With an increase in the inlet superheated level of 25 K, the liquid fraction and condensation loss significantly reduced by 79% and 73%, respectively. The newly designed turbine blades not only remarkably kept the liquid phase region away from the blade walls but also significantly reduced 28.1% averaged liquid fraction and 47.5% condensation loss compared to the original geometry. The results provide an insight to understand the formation and evaporation of the condensed droplets inside steam turbines.     

Prediction of soot and thermal radiation in a model gas turbine combustor burning kerosene fuel spray at different swirl levels

Combustion of kerosene fuel spray has been numerically simulated in a laboratory scale combustor geometry to predict soot and the effects of thermal radiation at different swirl levels of primary air flow. The two-phase motion in the combustor is simulated using an Eulerian–Lagragian formulation considering the stochastic separated flow model. The Favre-averaged governing equations are solved for the gas phase with the turbulent quantities simulated by realisable k–? model. The injection of the fuel is considered through a pressure swirl atomiser and the combustion is simulated by a laminar flamelet model with detailed kinetics of kerosene combustion. Soot formation in the flame is predicted using an empirical model with the model parameters adjusted for kerosene fuel. Contributions of gas phase and soot towards thermal radiation have been considered to predict the incident heat flux on the combustor wall and fuel injector. Swirl in the primary flow significantly influences the flow and flame structures in the combustor. The stronger recirculation at high swirl draws more air into the flame region, reduces the flame length and peak flame temperature and also brings the soot laden zone closer to the inlet plane. As a result, the radiative heat flux on the peripheral wall decreases at high swirl and also shifts closer to the inlet plane. However, increased swirl increases the combustor wall temperature due to radial spreading of the flame. The high incident radiative heat flux and the high surface temperature make the fuel injector a critical item in the combustor. The injector peak temperature increases with the increase in swirl flow mainly because the flame is located closer to the inlet plane. On the other hand, a more uniform temperature distribution in the exhaust gas can be attained at the combustor exit at high swirl condition.     

Characteristics of cavitation onset and development in a self-excited fluidic oscillator

Hydrodynamic cavitation has been widely employed in modern chemical technology. A high-speed camera experiment is conducted to reveal the characteristics of hydrodynamic cavitation generated in one self-excited fluidic oscillator. The images obtained from the high-speed camera system are employed to describe several development stages of the hydrodynamic cavitation. The gray intensity of the images which is the volume of bubbles formed is extracted to distinguish the cavitation bubbles from the water. It is found that three regions in the fluidic oscillator could be divided according to the distance from the entrance. The inception of cavitation occurs in the region nearest the entrance. For a relatively low inlet flow rate, the whole process of cavitation could complete within the region that is the second nearest the entrance as a low pressure area appears periodically in this region. For a high inlet flow rate, the vortexes in the region farthest from the entrance are able to generate sufficient low pressures to induce the generation of cavitation. In addition, the intensity of cavitation could be reflected by the cavitation number in a self-excited fluidic oscillator.