CFD Modelling of Cabin Air Ventilation in the International Space Station: A Comparison of RANS and LES Data with Test Measurements for the Columbus Module

Abstract

Ventilation characteristics of the Columbus module are numerically predicted on the basis of the ReynoldsAveraged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The steady-state RANS computations were performed using the high-Reynolds-number k-ε turbulence model, and the SmagorinskyLilly subgrid-scale model was used for LES. The computed results were compared with experimental data available for spatial distributions of the time-averaged absolute velocity magnitude. On the basis of LES data, distinctions in the fields of this quantity and the whole mean velocity were analysed. A procedure for evaluation of the time-averaged absolute velocity spatial distributions using RANS data on the mean velocity and the turbulent kinetic energy is suggested and examined.

CFD Evaluation of Directional Variation Effects of the Air Supply Diffuser for the International Space Station Cabin Atmosphere

“…The RANS-based modeling approach greatly reduces the required computational effort and resources, and it is widely adopted for practical engineering applications. For the ISS ventilation case, a comparison of the Columbus experimental data with the results of 3D RANS computations as well as with the accurate Large Eddy Simulation computations prove that RANS modeling is quite accurate regarding the air ventilation velocity field [10,11].…”

“…As discussed in [11], CFD solutions based on the RANS approach produce a distribution of the absolute magnitude of the local mean velocity, or simply "velocity", abs<V> = (<Vx> 2 +<Vy> 2 +<Vz> 2 ) 0.5 { Vm, < > denotes time averaging. However, to assess thermal comfort and draught risk indexes, the mean speed values, <abs V> = <(Vx 2 +Vy 2 +Vz 2 ) 0.5 > { Va, are required.…”

“…Contrary to RANS, Large Eddy Simulation (LES) computations give both the velocity and the speed data directly, and it is possible to use the LES data for Vm data processing procedure development and testing. It has been done already in [10,11] where a theoreticallydeveloped procedure of Vm processing has been examined using both the LES and the cabin ventilation qualification test data for the ISS pressurized module Columbus. The accuracy of the velocity-to-speed conversion procedures developed for the RANS data processing was evaluated in [16,17] where LES data on mixing ventilation in a test isothermal room with a sidewall jet were compared with the experimental data [18], namely, the LDA measurement data in the highvelocity jet zone and omnidirectional low velocity thermal anemometer data in the occupied zone.…”

CFD Modeling of Water Droplet Transport for ISS Hygiene Activity Application

“…For the ISS ventilation case, a comparison of the Columbus experimental data with the results of 3D steady-state RANS computations as well as with the accurate Large Eddy Simulation computations prove that RANS modeling is quite accurate regarding to air ventilation velocity field. 6 The standard k-ε model, with the standard wall functions, was used for computations. 7 For all the cases computed, the wall distance of a cell centre adjacent to a solid wall measured in wall units, y p + , ranged from 10 to 50 over the majority of the solid walls.…”

Evaluation of mean velocity and mean speed for test ventilated room from RANS and LES CFD modeling

“…Therefore, LES computations provide both Vm and Va fields that could be used for Vm data processing procedures development and testing. In [9,10] a theoretically developed procedure of Vm processing has been proposed and examined using both the LES and the cabin ventilation qualification test data for the International Space Station pressurized module Columbus.…”