涡轮机械转子在二氧化碳工质中风摩损耗的数值分析

在超临界二氧化碳布雷顿循环系统设计中，为提高系统能量转换效率，需要准确预测风摩损耗。风摩损耗大小与转子转速，转子几何结构，工质状态密切相关。本文针对2 MPa二氧化碳工质中，高转速（23 000 r/min）转子的风摩损耗特性进行数值计算分析。研究结果表明：转子粗糙高度对超临界二氧化碳布雷顿循环系统中高转速以及可能出现的较高压力工况下的风摩损耗具有显著影响。已有风摩损耗经验关系式未考虑粗糙度的影响，直接使用可能带来较大误差。风摩损耗随着转子粗糙高度的增加而增加，随转子转速的增加而增加，气腔间距的变化对风摩损耗不会造成明显影响。厦门大学能源学院发展基金(2018NYFZ01

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^