Unsteady RANS Simulation of Air Distribution in a Ventilated Classroom with Numerous Jets

Abstract

The study is devoted to the Unsteady Reynolds-Averaged Navies-Stokes (URANS) simulation of ventilation in an isothermal room with numerous jets supplied from ceiling diffusers. The computations of the airflow under the test conditions considered were carried out in the classroom of the Technical University of Sofia with no occupants. The room floor has a simple rectangular form, but several columns, beams, window sills, and four radiators are located inside the room that makes the geometry more complex. Air is supplied to the room through four ceiling fan coils, the Reynolds number is 2×104. Calculations were carried out using the ANSYS Fluent 18.2 software with the standard k-ε turbulence model chosen. Computational meshes of up to 33 million hexahedral cells clustered to the inlet and outlet sections were used. The main aim of the study presented is to analyze and discuss the complicated 3D flow structure in the room and to give foundation for future measurements of air velocity field in the room.

On the Procedure of Draught Rate Assessment in Indoor Spaces

“…The form of the room is a parallelepiped with the width of W = 5.4 m, the length of L = 11.8 m, and the height of H = 3.2 m. The floor area of the room is equal to W × L = 64 m 2 and the volume of the room is W × L × H = 204 m 3 . The detailed description of all room elements could be found in [37]. The air is supplied to the room by the four-way type MMU-AP0092H fan coils that could be used either in an isothermal regime or for cooling/heating purposes.…”

“…Depending on the local flow features, this height corresponds to the normalized distance from the center of the first near-wall cell to the wall, y + , in the range from the values less than one up to values exceeding 60. The sensitivity analyses of different computational parameters influence on the CFD results were performed previously and are discussed in [37]. In particular, the results of the mesh sensitivity analysis were presented in detail in [37].…”

“…The sensitivity analyses of different computational parameters influence on the CFD results were performed previously and are discussed in [37]. In particular, the results of the mesh sensitivity analysis were presented in detail in [37].…”

“…The second-order schemes for the spatial and time discretization were chosen. The value of the time step was 0.5 s. The time step value, ∆t, was varied in [37], from ∆t = 0.004 s to ∆t = 0.5 s, and it was found that the lower frequencies and the time-averaged flow patterns were the same in the ∆t range considered. The computations were performed using the resources of Peter the Great St.Petersburg Polytechnic University Supercomputer Center (scc.spbstu.ru).…”