查看更多>>摘要：With the expansion of tunnel construction scale,accurate modeling of 3D unsteady flow fields in ultra-long tunnels requires high computational resources.In this study,a resistance compensation method based on the St and Eu similarity criterion is proposed to construct the simplified model to rapidly and precisely replicate the train-driven unstable airflow.A 6000 m ultra-long tunnel is utilized as a reference model and simplified models with the scale ratio varying from 80％to 10％are developed to assess the method performance.The multi-region dynamic mesh model is employed to simulate train tracking motion.After weighing the computational accuracy and efficiency,the results show that 20％is the optimal scale ratio.The unsteady wind speed of the simplified model deviates 6.96％from the reference model,while the simulation computation time is reduced by 85.01％.On this basis,the simplified model is applied to analyze the impacts of tunnel friction coefficients,blockage rates,train lengths and speeds,and departure intervals.The mean bias error(MBE)and Pearson correlation coefficient(PCC)are within 10％and over 0.8 respectively,confirming the reliability of the simplified model.The resistance compensation method is a crucial technique to improve the accuracy and efficiency of the unsteady flow field in ultra-long tunnels.
查看更多>>摘要：Design parameters at different scales in the pre-design phase could significantly impact both building energy consumption and photovoltaic(PV)power generation potential.However,existing studies often overlook the synergistic effects of design parameters across multiple scales(block-building-facade scales)when evaluating these aspects.This paper aims to propose a workflow for the assessing building energy consumption and PV power generation potential of office blocks applicable in the pre-schematic design phase considering the synergistic influence of multi-scale design parameters,using building typology and parametric modelling approach.The study proposed a multi-scale design parameter classification system combined with parametric modelling.The study investigated 80 office blocks in Wuhan as the study case,which were classified into array type and enclosed type.Correlation analysis and multiple regression equations were used to quantify the single versus synergistic effects of different scale design parameters.Results suggest that focusing solely on a single scale during the pre-design stage is typically inadequate for understanding building energy potential.In contrast,multi-scale synergistic analysis boosts energy use intensity(EUI)by 7.56％and net energy use intensity(NEUI)by 33.96％.Under multi-scale synergistic conditions,the EUI of array type is more influenced by the building design parameters,while the NEUI is effected by the balance of multi-scales design parameters.While the EUI of enclosed types exhibit balanced effects across multi-scale design parameters,with NEUI results aligning closely with PV power generation potential.Multiple regression equations highlight building density and shape factor as key influencers for both array and enclosure layouts.This study offers designers a flexible and scalable workflow for evaluating building energy consumption and PV power generation potential in the pre-design phase.The findings can guide nearly-zero energy urban block planning to achieve a balance between energy supply and demand.
查看更多>>摘要：Energy simulation is a valuable tool for evaluating and improving the thermal performance and energy efficiency of buildings during the design phase.Common evaluation methods are thermal load(TL),degree-hour(DH),and design days(DD).The choice of method and its settings may vary depending on regional factors and researchers'preferences,leading to diverse and often incompatible metrics and results.Therefore,this study aims to investigate the influence of these evaluation methods on the assessment of buildings'performance and,consequently,on design choices.For this purpose,this study compared the results of the 3 evaluation methods and different settings for 3 different wall systems,4 ranges of comfort temperature,and 2 residential models located in the 8 Brazilian bioclimatic zones.As result,the best and worst wall systems varied depending on the evaluation method and the threshold/setpoint temperature range considered.Warmer regions showed greater variability in the results.We noticed that it is not possible to compare and interpret results from different evaluation methods,and that the variation of only 1 ℃ in the setpoint temperatures can lead to entirely different practices being considered the best for a given building model.In conclusion,the most suitable evaluation method is the one that best portrays the operation and dynamic reality of the building to be designed,and building regulations and standards can occasionally lead to unrealistic assessments.
NETL
NSTL
万方数据
维普