Research And Application Of Pedestrian-level Wind Comfort Criteria And Wind Chill Index In Severe Cold Areas

Wind is one of the main factors affecting the urban environment.The design and distribution of buildings in the city will change the local wind-field structure,causing strong winds around the building that affect pedestrian comfort,that is,the problem of pedestrian wind environment.For the cities in cold areas,the synergistic effect of lower air temperature and wind speed in the cold winter environment will accelerate the heat loss from outdoor skin exposure,namely wind chill effect,which will cause pedestrians to feel uncomfortable and even frostbite.A good pedestrian-level wind environment and a suitable atmospheric thermal environment are prerequisites to ensure the safety and comfort of urban residents.Some problems in the pedestrian wind comfort criteria and wind chill evaluation standard are firstly studied,which established a comparison method between different wind comfort criteria,and established a local wind chill evaluation index through a questionnaire survey.Then,starting from the university campus that can reflect the characteristics of the urban area,based on the statistical data of local meteorological data and wind farm information from CFD numerical simulation,the pedestrian wind environment and wind chill were evaluated on the university campus in a winter city.The specific research content is as follows:(1)8 kinds of wind comfort criteria were selected and the pedestrian activity categories and wind speed thresholds were uniformly processed.Based on the Weibull distribution theory,a comparative method and mathematical model for the relative rigor of the criteria were established.The analysis results showed that the relative stringency between the criteria is related to the prescribed wind speed threshold,the exceeding probability threshold and the shape parameter.(2)In the university campus area,a questionnaire survey was conducted on pedestrian wind chill in winter.Microclimate measurements were performed while surveying pedestrians’ feelings.Based on the correlation analysis and statistical analysis of the results of the questionnaire,the relationship between the cold temperature and facial tingling votes was established,which was used as the basis for wind chill assessment.(3)Wind environment and wind chill assessment methods and assessment processes were established,which divided the pedestrian wind environment and wind chill assessment on campus into three aspects: “indicator establishment”,“meteorological data arrangement and statistical analysis” and “CFD numerical simulation”.Based on the preparation work,the statistics and analysis of localmeteorological data,the establishment of the campus model,the CFD grid division of the campus model,and the calculation parameter settings were carried out.(4)Based on the statistical data of meteorological data and the results of CFD numerical simulations,the pedestrian wind environment on campus was evaluated and analyzed in combination with 8 kinds of wind comfort criteria.The pedestrian wind chill on campus in winter was evaluated in combination with the wind cold evaluation index.The analysis results showed that the wind environment assessment results basically meet the comfortable interval;the wind chill assessment results meet the facial painful sensation weaker than the “moderate” grade.