In order to investigate the self-priming process of the self-priming pump,an unsteady simulation was conducted where the Navier-Stokes equations were used with the Lagrangian-Eularian mo-del.In course of this investig...In order to investigate the self-priming process of the self-priming pump,an unsteady simulation was conducted where the Navier-Stokes equations were used with the Lagrangian-Eularian mo-del.In course of this investigation,the volume fractions,pressure distribution and self-priming time were carried out.By analyzing the volume,velocity and pressure distribution of the gas-liquid two-phase flow at different time,the two-phase content via the variation law of the two-phase flow in the pump was carried out.By monitoring and analyzing the gas-liquid flow at the outlet of the pump,the self-priming time and crucial periods were given.Two phenomena were mainly characterized by the self-priming process such as the gas-liquid mixing and separation,which occur in the early stage of self-priming process.During that period the gas-liquid mixing clouds appear on the outer edge of the impeller,and the instantaneous void fraction at the inlet and outlet of the impeller decreases obviously.It was also established from the transient study that the gas has a major influence on the hydraulic performance of the pump at the early stage of operation.To increase the usage of self-priming pump and to also understand the energy conversion of the pump,it is very essential to investigate and establish the basic working principle of the self-priming pump.展开更多
The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure gen...The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure generator and heat exchanger are analyzed in detail. The proper shut-down mode of the heat pump is presented,which, in consideration of solution parameters, has a great effect on the possibility of crystallization of some components.展开更多
The coolant pump impeller casting is the only rotating component in the nuclear island of an AP1000 nuclear power station, and is required to have a 60-year service time, which requires advanced materials and processi...The coolant pump impeller casting is the only rotating component in the nuclear island of an AP1000 nuclear power station, and is required to have a 60-year service time, which requires advanced materials and processing technologies to guarantee. In this paper, the casting process was studied, designed and modified by means of numerical simulation. The gating system was distributed symmetrically and the runner diameter was a little bigger for avoiding sand wash and turbulence;the feeding system focused on the solution of blades feeding, as some parts of which should reach Severity Level 1 radioactive testing standard. Therefore, upper and lower plates cooperating with chillers acted as feeding method besides additional 2-3 times thickness;in addition, lowering sand core strength, decreasing pouring temperature and increasing dimension allowance would be adopted to avoid crack defects. Finally, the pilot impeller was cast. The results show that the casting process design is reasonable, as the liquid rises very smoothly when pouring, and no volume defects are found by means of 100% radioactive testing. Based on this casting process, 16 coolant pump impellers have been successfully produced and delivered to customers.展开更多
The using situation at present is summarized about the scal for process thick liquid pump. It is reasonable that sealing scheme is composed of secondary impeller and centrifugal block stop seal. Main formulas are dedu...The using situation at present is summarized about the scal for process thick liquid pump. It is reasonable that sealing scheme is composed of secondary impeller and centrifugal block stop seal. Main formulas are deduced and some problems are pointed out on design and calculation of centrifugal block stop seal.展开更多
泵站机组运行受多种因素影响,导致泵站运行理论效率与实际效率误差较大。针对泵站机组运行效率精准模拟难题,运用基于高价多项式回归、回归树、多元线性回归、向量机回归、高斯过程回归、神经网络的10个回归算法,建立泵站机组效率模拟...泵站机组运行受多种因素影响,导致泵站运行理论效率与实际效率误差较大。针对泵站机组运行效率精准模拟难题,运用基于高价多项式回归、回归树、多元线性回归、向量机回归、高斯过程回归、神经网络的10个回归算法,建立泵站机组效率模拟模型并开展对比分析,优选出有效的泵站运行效率模拟建模方法。讨论分析采用“上下游水位+流量”代替传统“扬程+流量”开展泵站运行模拟的效果。以南水北调东线邳州站和遂宁二站共8台机组的历史数据开展实例分析,相关实验结果表明:在所有方法中,高斯过程回归(Gaussian process regression,GPR)模型在均方根误差(ERMS)、平均绝对误差(EMA)、均方误差(EMS)、决定系数(R2)和最大个体误差(EMI)指标上综合表现最佳,R2逼近0.95;使用站上、站下水位代替传统的扬程对模型进行训练,所有模型的综合评价指标整体有所改善。综合来看,使用GPR模型并使用上游、下游水位代替扬程进行模拟效率表现最好,以邳州站4号机为例,可将模拟效率的EMA和EMI分别从16.49%和20.40%减少至0.41%和2.30%,研究成果具有一定实际意义,可为我国调水工程泵站经济运行提供有力支撑。展开更多
基金supported by the National Natural Science Foundation of China (Grant No.51879120)。
文摘In order to investigate the self-priming process of the self-priming pump,an unsteady simulation was conducted where the Navier-Stokes equations were used with the Lagrangian-Eularian mo-del.In course of this investigation,the volume fractions,pressure distribution and self-priming time were carried out.By analyzing the volume,velocity and pressure distribution of the gas-liquid two-phase flow at different time,the two-phase content via the variation law of the two-phase flow in the pump was carried out.By monitoring and analyzing the gas-liquid flow at the outlet of the pump,the self-priming time and crucial periods were given.Two phenomena were mainly characterized by the self-priming process such as the gas-liquid mixing and separation,which occur in the early stage of self-priming process.During that period the gas-liquid mixing clouds appear on the outer edge of the impeller,and the instantaneous void fraction at the inlet and outlet of the impeller decreases obviously.It was also established from the transient study that the gas has a major influence on the hydraulic performance of the pump at the early stage of operation.To increase the usage of self-priming pump and to also understand the energy conversion of the pump,it is very essential to investigate and establish the basic working principle of the self-priming pump.
基金This paper is supported by thy UTC RongHong foundation
文摘The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure generator and heat exchanger are analyzed in detail. The proper shut-down mode of the heat pump is presented,which, in consideration of solution parameters, has a great effect on the possibility of crystallization of some components.
文摘The coolant pump impeller casting is the only rotating component in the nuclear island of an AP1000 nuclear power station, and is required to have a 60-year service time, which requires advanced materials and processing technologies to guarantee. In this paper, the casting process was studied, designed and modified by means of numerical simulation. The gating system was distributed symmetrically and the runner diameter was a little bigger for avoiding sand wash and turbulence;the feeding system focused on the solution of blades feeding, as some parts of which should reach Severity Level 1 radioactive testing standard. Therefore, upper and lower plates cooperating with chillers acted as feeding method besides additional 2-3 times thickness;in addition, lowering sand core strength, decreasing pouring temperature and increasing dimension allowance would be adopted to avoid crack defects. Finally, the pilot impeller was cast. The results show that the casting process design is reasonable, as the liquid rises very smoothly when pouring, and no volume defects are found by means of 100% radioactive testing. Based on this casting process, 16 coolant pump impellers have been successfully produced and delivered to customers.
文摘The using situation at present is summarized about the scal for process thick liquid pump. It is reasonable that sealing scheme is composed of secondary impeller and centrifugal block stop seal. Main formulas are deduced and some problems are pointed out on design and calculation of centrifugal block stop seal.
文摘泵站机组运行受多种因素影响,导致泵站运行理论效率与实际效率误差较大。针对泵站机组运行效率精准模拟难题,运用基于高价多项式回归、回归树、多元线性回归、向量机回归、高斯过程回归、神经网络的10个回归算法,建立泵站机组效率模拟模型并开展对比分析,优选出有效的泵站运行效率模拟建模方法。讨论分析采用“上下游水位+流量”代替传统“扬程+流量”开展泵站运行模拟的效果。以南水北调东线邳州站和遂宁二站共8台机组的历史数据开展实例分析,相关实验结果表明:在所有方法中,高斯过程回归(Gaussian process regression,GPR)模型在均方根误差(ERMS)、平均绝对误差(EMA)、均方误差(EMS)、决定系数(R2)和最大个体误差(EMI)指标上综合表现最佳,R2逼近0.95;使用站上、站下水位代替传统的扬程对模型进行训练,所有模型的综合评价指标整体有所改善。综合来看,使用GPR模型并使用上游、下游水位代替扬程进行模拟效率表现最好,以邳州站4号机为例,可将模拟效率的EMA和EMI分别从16.49%和20.40%减少至0.41%和2.30%,研究成果具有一定实际意义,可为我国调水工程泵站经济运行提供有力支撑。
