| The air environment in rooms depends to a large extent on indoor air distribution.For attachment ventilation,the indoor air distribution is affected by the interaction between the wall-attached air supply jet and the indoor thermal convection.The airflow movement characteristics in attached ventilated rooms vary with air supply modes（isothermal or non-isothermal ventilation）,air outlet forms,heat source characteristics,and room geometry and size,then affecting the vertical temperature distribution and cooling load in the room.The flow characteristics of the wall-attached jet,and the space heat distribution mechanism are the basis for calculating the cooling load of attached ventilated rooms.In this study,the airflow characteristics and room temperature distribution of the attachment ventilation were systematically investigated by theoretical analysis,experimental research,and numerical simulation.The methods for calculating the cooling load of the control zone of attachment ventilation were proposed.The specific contents and main conclusions are as follows.（1）The flow characteristics and velocity distribution of the vertical wall-attached air supply jet under isothermal conditions were studied in the vertical attachment region and horizontal air lake region.The transformation process from two-dimensional flow to three-dimensional flow after the wall-attached air supply jet impinges on the floor was analyzed.The results show that the mean velocity distribution of wall-attached jets in the spanwise direction of the air outlet has a Gaussian distribution in the horizontal air lake region.The velocity decay characteristics of vertical wall-attached jets were investigated under the influence of different air supply heights,air supply velocities,room cross-sectional areas,and exhaust air inlet locations.The dimensionless centerline velocity profiles can be expressed as u0/um（y*）～（y*/b）γand u0/um（x）～（x/b+Kh）γ,respectively,whereγis a constant related to the momentum decay rate.By fitting the numerical simulation data,γ=1.11 was obtained.Based on the theoretical derivation and numerical simulation,the correlation equations of the velocity distribution in the spanwise direction and the centerline velocity distribution along the flow direction were proposed.（2）Aiming at air supply uniformity,the optimized design of the internal structure of jet generators for attachment ventilation was proposed.The air supply uniformity is influenced by the internal structure and static pressure distribution of jet generators.The results shows that the air supply uniformity can be significantly improved by installing two orifice plates with variable aperture diameters and a vertical orifice plate near the air intake inside the jet generator,and the velocity non-uniformity coefficient is only6.8%.The dimensionless centerline velocity profiles are similar for wall-attached jets discharged from different air outlet forms of jet generators,but the velocity decay rates are different.The dimensionless centerline velocity decay rate of the annular grille outlet is greater than that of the 45°sector grille outlet in both the vertical attachment region and horizontal air lake region.A unified expression for the dimensionless centerline velocity was established for different air outlet forms.（3）Taking the warm wall-attached jets as the research object,the air distribution of attachment ventilation in heating mode was numerically studied.The similarities and differences between heating and cooling modes of attachment ventilation of the flow field and temperature field were compared and analyzed.On the premise that the warm wall-attached jet will not be separated from the wall due to the buoyancy force,the parameter correlation equation of the dimensionless centerline velocity distribution in the vertical attachment region was established.The key factors affecting the flow characteristics and horizontal attachment distance of the warm wall-attached jet were studied,and the correlation equation of horizontal attachment distance was proposed considering characteristic parameters of Ar,air supply height,and hydraulic diameter of air outlets.The effect of the horizontal attachment distance of the warm wall-attached jet on the heating performance and thermal comfort in the control zone was clarified.It can provide a reference for the design of attachment ventilation in heating mode.（4）For attachment ventilation in cooling mode,the horizontal and vertical temperature distribution in a ventilated room with a local heat source（point heat source,plane heat source,or volumetric heat source）was studied experimentally.Taking office rooms as the research object,the vertical temperature distribution characteristics of the room with decentralized heat sources were investigated by numerical simulation.The effects of the air supply parameters,heat source projection area,heat source intensity and location,and room height on indoor vertical temperature distribution were analyzed.The correlation equations of the vertical temperature difference within the occupied zone and between the head and the ankles were established,which laid the foundation for the calculation of the cooling load of the attachment ventilation.（5）The parameter correlation equations of the itemized correction method and the overall correction method for calculating the attachment ventilation cooling load were proposed.The itemized correction method is based on the proportion of different kinds of heat dissipation entering the control zone to correct the whole room cooling load,while the overall correction method is based on the heat distribution coefficient of the ventilated room.The influence of the main factors such as local and decentralized heat source types and air supply parameters on the heat distribution coefficients was studied,and the correlation equation of the heat distribution coefficient was established as the basis of cooling load calculation by the overall correction method.Through the verification of the accuracy of the two calculation methods,it is recommended to adopt the overall correction method for cooling load calculation.It provides a theoretical basis for determining the cooling load of attachment ventilation. |
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