Abstract
Healthy, comfortable and intelligent indoor environment is a key objective in comprehensive well-being. This is also a main target of advanced HVAC-technology. In indoor environments, air distribution plays a major role while providing clean air to occupants. Therefore, investigating ventilation jets is an essential matter. In this study, the main objective was to improve knowledge on numerical modeling and airflow characteristics. In addition, the reliability of modeling methods were investigated. The experiments were carried out in a test room by using omnidirectional anemometers. The planar air jets were supplied below the ceiling from the opposite long-side walls. The exhaust openings were correspondingly near the floor. Isothermal and incompressible viscous airflow was simulated by using RANS, URANS, DES (SST-k-ω - LES) and SBES (SST-k-ω - LES) methods. The results show that modeling method has considerable effects on the predicted airflow field. However, the study indicates that correctly implemented numerical modeling may predict well the averaged airflow characteristics. Furthermore, the unsteady simulation allows airflows to fluctuate reasonably. In addition, SBES and DES methods were more sensitive in generating the airflow fluctuations than URANS. A recommendation is to carefully test and choose a modeling method for indoor airflows.
Highlights
Air distribution is one of the major factors for health, comfort and performance [1]
Stress-Blended Eddy Simulation (SBES) (Fig. 4b) and Detached Eddy Simulation (DES) (Fig. 4c) provided more airflow structures than Unsteady Reynolds-averaged Navier–Stokes (URANS) (Fig. 4a) that can be obtained as a diversity in the airflow field
More reliable indoor airflow simulations can be made by using an unsteady CFD simulation method than by a steady CFD simulation methods, because the turbulent flow is time-dependent and the unsteady simulation allows airflows to fluctuate
Summary
Air distribution is one of the major factors for health, comfort and performance [1]. The main purpose of air distribution is to provide clean air for individuals, maintaining thermal conditions, and reducing pollutants from breathing zone. Airflow interaction is an important matter to investigate. Numerical modeling is a common method while investigating indoor airflows. The simplified mathematical model is discretized, in which the partial differential equations are approximated by a system of linear algebraic equations at discrete locations in space and time [2]. A numerical solution of linear algebraic equations is mainly obtained by using iterative methods. Experimental methods are necessary for validating numerical modeling. The standards EN ISO 7726 and EN 13182 provide a basis for measuring instruments of indoor climate
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