透平叶片尾切对叶型损失和流量系数影响的实验研究

通过对运行透平机组叶栅的模型实验数据的分析，探讨了采用叶片轴向尾切在提高机组出力时最佳尾切尺寸的问题，实验表明，叶片尾切在增加叶栅喉宽提高流量的同时，增大了叶型损失并降低了流量系数，得出尾切尺寸的大小取决于流量系数与喉宽的乘积的结论，同时还应考虑尾流宽度对下流叶栅的非定常影响。     

尾切叶片全叶栅气动特性的实验研究

在不同节距和冲角下，对具有尾切叶片的透平高压级转子全叶栅进行了静吹风。实验结果表明，无论在设计和变工况下，由于二次流损失的影响端壁附近的流量系数最小，这是实际最佳尾切尺寸小于理想最佳尾切尺寸的原因之一，但不是主要原因。主要原因是前列静子叶栅叶片尾切使尾流区加宽，这样的尾流进入转子流道引起流动严重恶化。     

尾切叶片全叶栅气动特性的实验研究

在不同节距和冲角下，对具有尾切叶片的透平高压级转子全叶栅进行了静吹风。实验结果表明，无论在设计和变工况下，由于二次流损失的影响端壁附近的流量系数最小，这产实际最佳尾切尺寸小于理想最佳尾切尺寸的原因之一，但不是主要原因。主要原因是前列静子叶栅叶片尾切使尾流区加宽，这样的尾流进入转子流道引起流动严重恶化。     

损失模型在透平尾切叶片栅损失计算中的应用

应和强国芳等四种损失模型，计算了尾切叶片栅的流动损失，并将计算结果与实验值进行了比较，以期找到适于计算尾切叶片栅流动损失的损失模型。     

损失模型在透平尾切叶片栅损失计算中的应用

应用强国芳等四种损失模型，计算了尾切叶片栅的流动损失，并将计算结果与实验值进行了比较，以期找到适于计算尾切叶片概流动损失的损失模型。     

粒子尺寸和速度对喷嘴叶栅磨蚀特性的影响

应用PIV激光测速仪对某调节级喷嘴叶栅(73A)进行了气固两相流场测量,以研究粒子的尺寸和速度对喷嘴叶栅内粒子运动轨迹及磨蚀特性的影响。实验结果表明:随着固粒尺寸的增加,撞击速度减小,撞击角度和撞击次数增大,叶栅磨蚀大都是大、中粒子造成。粒子的撞击速度与气流速度成正比,气流速度越高,粒子对喷嘴壁面的磨蚀越严重。     

某重型燃气轮机压气机顶切方法的数值模拟

为了满足某型压气机改型设计的需求,提出并推导了基于位置修正的等流管顶切方法,应用此方法对该压气机进口导叶至第2级静叶的5列叶栅进行了顶切设计,通过三维数值计算验证了该方法的可行性,在此基础上进一步分析了顶切对压气机气动性能的影响。结果表明,应用此方法可以根据不同的目标流量实现快速准确的顶切设计,顶切后的压气机在满足流量要求并保持压比基本不变的条件下,在不进行任何优化设计时仍然能够具有较高的气动性能,应用此方法进行顶切设计不会导致严重的流场匹配问题。     

汽轮机低压级叶栅尾缘波系与蒸汽自发凝结的交互作用

采用数值模拟的方法研究了渐缩叶栅及缩放叶栅在变工况跨音速状态下尾缘波系的演变规律及其与湿蒸汽非平衡自发凝结相变间的内在联系。研究发现两类叶栅尾缘在跨音速工况下放射出的膨胀波系对于蒸汽自发凝结过程有显著影响。对于渐缩叶栅,随背压降低,渐强的尾缘膨胀波促进了成核过程,凝结产生的液态水质量分数升高;对于缩放叶栅,发生在喉部下游的蒸汽自发凝结显著的削弱了尾缘再附激波强度,当背压降低,膨胀波系强度增强,使得液滴生长速率加快,导致液相质量分数的升高。     

叶栅稠密度对贯流式水轮机效率影响的研究

本文从理论上讨论了贯流式水轮机转轮叶栅稠密度对水轮机水力效率的影响,模型试验结果也说明了这一点。得出了应合理选择叶栅稠密度和叶片扭角,以提高大流量区的效率和机组比转速的结论,并提出了对多泥沙河流上的贯流式水轮机组应适当增大转轮叶栅稠密度,以减小叶片内的相对水力摩擦损失。     

涡轮叶栅流场的PIV测量实例

详细介绍了PIV的工作原理、数据处理流程和使用要点。针对涡轮内部复杂的流动特性,应用具有较高空间分辨率的非接触式瞬态速度的PIV测量技术,获得了较清晰完整的沿叶高平面和叶栅出口速度场的瞬时速度场信息,并据此分析了涡轮静叶出口二次流的流动特性。叶栅实验中将模拟动叶的圆柱列每次沿周向方向移动1/4节距,测量沿叶高平面的速度场。研究发现,前排圆柱尾迹进入叶栅流道不同,对叶栅内部流场气动效率影响巨大;同时由压力面向吸力面运动的二次涡(低能流体,耗能过程)逐渐向后传递、扩张,并在吸力面卷起、堆积,使吸力面附面层骤然增厚,并引起沿叶高总压损失系数和沿叶高出口气流角的剧烈变化。     

不同结构微小音速喷嘴的数值模拟与特性对比

为了降低加工水平对微小音速喷嘴性能的限制,提出了收缩喷嘴、扩散喷嘴和圆锥形文丘里喷嘴 3 种非标准音速喷嘴 结构,并分析形状结构对 3 种喷嘴流动特性的影响。 选取喷嘴喉径为 0. 03~ 0. 12 mm,分别对其内部流场进行数值仿真,并分析 收缩段、喉部和扩散段的几何结构对喷嘴流动特性的影响,最后对比了喷嘴的流动特性。 研究发现,扩散喷嘴的流出系数和临 界背压比较优,且该类喷嘴加工难度最小。 此外,喉径和喉部长度对喷嘴流动特性的影响最大,喉径越大,喉部长度越小,喷嘴 流动特性越好。 这为后续微小喷嘴的研制提供一定的借鉴。     

一种五电平航空有源电力滤波器

研究了一种应用于400Hz航空电网的并联型有源电力滤波器,其主电路采用了基于载波相移正弦脉宽调制技术(Carrier Phase Shift-Pulse Width Modulation,CPS-PWM)的H桥级联五电平变流器拓扑,适应了航空有源电力滤波器对容量和传输带宽的需求。在控制上,研究了一种基于直流侧电压反馈调节的电网电流直接控制策略。同时,为避免级联单元间直流侧电容电压不均衡,提出了一种新颖的均压控制方法。最后,在上述控制策略的基础上搭建了级联五电平航空有源电力滤波器系统的仿真和实验平台,结果表明该有源电力滤波器具有良好的补偿性能。     

太阳能辅助燃煤一体化热发电系统耦合机理

在系统中沿过程进行的方向火用具有不等价性。外部键系数作为一种结构系数,在用于揭示系统内在的热力学联系、分析不等价性时具有明显的优越性。利用信号流图理论,探讨了外部键系数的计算方法,得到不同容量燃煤机组不同流的外部键系数。揭示了太阳能辅助燃煤一体化热发电系统的耦合机理：不仅要遵循能量"品位对口、梯级利用"的原则,而且还需考虑外部键系数的大小;只有当太阳能热量用于取代燃煤机组中外部键系数高的火用流时,取得的效益才大。     

Investigation of Nozzle Cascades of a Turbine Stage

Two different nozzle cascades designed for an LP aircraft turbine have been investigated. The cascade had large convergence, a moderate curvature of the airfoils, and it flowed over so that the outlet subsonic velocity was high. It was designed for a flow inlet angle of α₀ = 63.5°, an outlet angle of α₁ = 28.6°, and a reduced isoentropic outlet velocity of λ₁ = 0.93. Having the same width of 41 mm, the first cascade was made up of 5.9 mm thick profiles, while the second one from 4 mm thick profiles. To improve the efficiency of the second cascade, the suction side curvature near the trailing edge decreased more sharply, which yielded a smoother velocity distribution over the suction side according to the design calculation. However, calculations of a viscous flow in the second cascade revealed no tendency towards a decrease in the profile losses. The experiments demonstrated that both cascades featured a high efficiency on the ranges of λ₁ = 0.80–0.98 and α₀ = 52°–69°. It is important that the design mode with respect to λ₁ coincided with the mode giving the lowest energy losses. The first cascade from thicker profiles was more efficient than the second cascade where, with the same overexpansion of the flow on the suction side, the critical velocity was attained just downstream of the throat while it was shifted to the trailing edge in the first cascade. A slight flow deceleration on the suction side did not result in a local velocity equal to the velocity downstream of the cascade, and a flow separation occurred near the trailing edge at λ₁ ≥ 0.93. It is these features of the flow in the second cascade that are responsible for an increase in the profile loss coefficient by 0.26% under the design operating condition.     

弟级水电站发电能力评估的模型研究

建立了计及径流调节的梯级水电站最大出力模型和计及随机故障的水电机组可用容量概率模型,然后应用时历法进行梯级水电站发电能力的评估,并用一座简单二级水电站做算例分析。所用方法有效地解决了梯级水电站机组出力的水系相关性和随机故障的独立性问题。     

Achieving More Efficient and Reliable Operation of Geothermal Turbines by Using a Secondary Flash Steam Superheating System

Problems encountered in operation of saturated steam geothermal turbine units that stem from the specific features of a geothermal heat carrier are considered. A two-phase state, increased content of salts, and corrosiveness of geothermal working medium have a negative influence on the efficiency and reliability of the turbine’s first and last stages. Owing to high concentrations of impurities in the liquid phase, the first stages suffer from intense generation of deposits. The resulting decrease in the power output is due to both fouling of the flow path and significantly growing roughness of the turbine cascade blades. The flow of wet steam in the geothermal turbine flow path is accompanied by droplet impingement erosion of the last-stage blades and corrosion fatigue of the metal of rotor elements. In addition, the losses due to steam wetness in the flow path cause an essential decrease of the geothermal turbine efficiency. The article gives examples of erosioninduced damage inflicted to the last-stage rotor blades, corrosion fatigue of the metal of integrally-machined shroud elements, and deposits in the nozzle vane cascades of geothermal turbine stages. The article also presents the results from numerical investigations of the effect that the initial steam wetness has on the silicic acid concentration in the wet steam flow liquid phase in a 4.0 MW geothermal turbine’s stages. A method for achieving more efficient and reliable operation of the geothermal turbine low-pressure section by applying a secondary flash steam superheating system with the use of a hydrogen steam generator is proposed. The article presents a process arrangement for preparing secondary flash steam supplied to the geothermal turbine low-pressure section in which the flash steam is evaporated and superheated through the use of a hydrogen steam generator. The technical characteristics of the system for preparing secondary flash steam to be used in the intermediate inlet to the turbine were preliminarily assessed (taking the upgrading of the Mutnovsk geothermal power plant as an example), and it has been shown from this assessment that the wetness degree in the low-pressure section can be decreased down to its final value equal to 2.0%.     

汽水喷射器升压特性及输出量的调节方法

利用基于直接接触凝结的汽水喷射器一维理论模型对升压特性进行理论分析,并对求解该模型的一些关键问题进行了论述,如采用平均凝结换热系数计算相间质量传递及利用汽羽确定各相体积分数等。根据该理论模型给出了升压式汽水喷射器出口温度和流量的调节方案,理论分析表明出口温度及流量的调节是解耦的,调节进水的质量流量可控制出口温度;调节蒸汽喷嘴的喉部截面大小可控制出口质量流量。结合相关的实验结果表明输出压力具有定量特性,只须调节出口背压即可以实现对输出压力的调节且不影响进口状态。