| On the basis of the research and analysis of comfortable hand washing by cold water tap,comfortable hand washing by cold and hot water mixed tap and the comfortable showering in winter,the comfortable showering research in summer and the fluid characteristic were studied.Combined with the research progress at home and abroad and the results of questionnaire,tests were carried out to find out the concentration range of cold water dynamic pressure,hot water dynamic pressure,comfortable flow rate,comfortable water temperature.And based on the typical three probabilities of standard normal distribution function,the evaluation method was obtained.The experimental showerhead was modeled in three dimensions and meshed,and the outflow characteristics including the distribution of pressure,flow rate,velocity and turbulence intensity were simulated,and the simulation results were compared with the experimental results to verify the rationality of the simulation.Before the start of the tests,this paper summarized the research progress of showerheads and showering systems at home and abroad,which found that many countries have regulations and standards on water-saving showerheads.And then it summarized the research progress of the simulation of the outflow characteristics of the nozzle at home and abroad,it is found that the simulation of the nozzle at home and abroad is mainly about the high pressure jet large flow nozzle and atomization nozzle in the fields of oil,cooling,irrigation and so on.The simulation of nozzle and sprinkler in the water supply and drainage system in the building can hardly be found,and the simulation software is basically ANSYS WORKBENCH,Gambit and Fluent.The residents’showering questionnaire survey in summer was carried out simultaneously with the comfortable showering tests in summer.A total of 106 subjects participated in the survey,and all the questionnaires were valid to obtaine 318 groups of valid data.The basic information of the subjects being tasted,shower habits and shower system of the subjects were sorted out.During the tests,each subject was required to perform a comfortable showering test under three static pressure of water supply,which were 0.15MPa,0.20MPa,and 0.25MPa.The seven parameters of hot water pressure,cold water pressure,effluent pressure,hot water temperature,cold water temperature,effluent temperature and effluent flow rate were measured.And through the centralized interval method,the most concentrated and the more concentrated comfortable outlet water temperature and outlet water flow range of the four types of population（young men,young women,middle ages and elderly men,middle ages and elderly women）under the three static pressure of water supply were obtained.The environmental temperature and humidity were measured by temperature and humidity meter.The body surface temperature of the subjects was measured by infrared thermal imager.The most concentrated temperature ranges of young men before and after the test were 34.6℃35.1℃and 34.9℃35.5℃,and the most concentrated temperature ranges before and after the test were 33.9℃34.8℃and33.8℃34.7℃for young women,and 30.6℃34.5℃and 34.7℃36.3℃for middle-aged and old men.The most concentrated temperature ranges of middle-aged and elderly women before and after the test were 34.2℃34.6℃and 34.9℃35.4℃.By comparing with the tests results in winter,it can be seen that 0.20MPa is the most suitable static pressure of water supply to meet the request of both comfortable showering and water saving.In the stage of statistical analysis,the software SPSS was used to analyze the effects of static pressure of water supply as systemetic factors,age,sex,body surface temperature of subjects as subjective factors,environmental temperature and humidity and season as objective factors on comfortable showering,comfortable water temperature and flow rate by two independent samples nonparametric test and the correlation analysis（Spearman rank correlation analysis）.Taking outdoor temperature,indoor humidity,shower temperature and body surface temperature after shower as independent variables and comfortable flow rate under water supply static pressure of 0.20MPa as dependent variable,multiple linear regression analysis was carried out,and it is difficult to obtain a specific mathematical model.It shows that there are still important independent variables,such as human metabolism and so on,were not in the calculation which need to be further studied.Up to now,there is no clear evaluation method of water comfort for all types of people at home and abroad.At present,there are three main methods to evaluate the comfort of human body:formula calculation,mathematical model,graph expression and graph analysis theory.The computation of the above methods is large and complex.For water comfort,the different feeling between different groups is the biggest difficulty in the unity of evaluation methods.Based on the three commonly used probabilities of the standard normal distribution function,this paper proposed reversely a water comfort evaluation method,which is called block diagram judgment method.Regarding comfortable water temperature and comfortable flow rate as the two key parameters,three commonly used probabilities of the standard normal distribution function,which are 68.27%,95.45%and 99.73%are used to judge the high concentration,middle concentration and low concentration range of water temperature and flow rate for various types of people when them take comfortable showering.The high concentration range of shower comfort of young men is that the comfortable water temperature is in the range of 35.1℃41.7℃,and the comfortable flow rate is in the range of 0.129L/s0.165L/s.The high concentration range of shower comfort of young women is that the comfortable water temperature is in the range of 36.4℃41.1℃and the comfortable flow rate is in the range of0.141L/s0.171L/s.The high concentration range of shower comfort in the middle and old age is that the comfortable water temperature is in the range of 34.9℃40.5℃and the comfortable flow rate is in the range of 0.119L/s0.169L/s.The method has less calculation and can directly represent the parameter interval that can meet the water comfort level of the vast majority of people.In order to improve the shower comfort of our country’s citizens,it is suggested that the static pressure of water supply should be controlled at about 0.20MPa,the water temperature range should be adjusted to 35.0℃40.5℃,and the discharge limit should be kept at 0.12L/s when building or rebuilding apartments for the elderly.In the simulation stage,based on the actual size and internal structure of the showerhead used in the experiment,the Geometry module in ANSYS WORKBENCH 15.0 was used to draw two-dimensional sketch and three-dimensional modeling,and then the Mesh module was used to mesh the model.Setting the physical property from Mechanical to CFD.The outlet,inlet and wall of the showerhead were named,and the outlet holes were numbered clockwise in the order of the circles from the inside to the out,reach to a total of 95 exits.The Skewness was almost within 0.63,which means that the grids quality is excellent.After the grid file was imported into the Fluent 15.0,the standard k-εmodel in the turbulence model was selected,and the fluid material was set to the liquid water(T=38.39℃,ρ=992.8kg/m3,μ=0.6739*10-3Pa*s).The outlet pressure was always 0MPa,and as for the velosity entrance,the three velocity were the maximum velosity under the water supply pressure of 0.20MPa,0.15MPa and0.25MPa respectively.It selected SIMPLE to calculate 400 steps to reach the convergence criterion of the residual 0.0001,and the calculated results were in accordance with the law of conservation of mass.After simulation,the distribution of pressure,velocity,turbulence intensity and flow under three static pressure of the water supply were compared.The flow error between the simulation results and the experimental results are all less than 7%,which is within the allowable range,and the parameters are in accordance with the theories of fluid mechanics,which shows that the simulation is reasonable. |
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