Validation of simulated velocity distribution in isothermal mixing ventilation cases with particle streak tracking

Abstract

This is a validation study for the velocity distribution in mixing ventilation. Two different supply air diffusers a slot and a swirl diffuser form two different room airflows. For the swirl diffuser two different and for the slot diffuser five different exhaust positioning are tested numerically and experimentally. A comparison of the flow structure shows good agreement between simulation and experiment for six air changes per hour, but not for the lower air change rate of 1.5 per hour. The velocity deviations between experiment and simulation are higher for the swirl diffuser. These exist partly due to the experimental methodology, but also due to an overestimation of the supply air momentum. Thus, further sensitivity investigations are carried out for the swirl diffuser. The overestimation of the supply air momentum depends mainly on a geometric model error in the computational fluid dynamics simulation. A comparison of different turbulence models confirms the advantages of the RST elliptic blending turbulence model over the k-epsilon realizable model for the swirl diffuser case.

Highlights

• Comparison between experimental and numerical velocity determination

• Full-scale experimental data with PST-technology

• Two different supply air diffusers: slot and swirl

• Validation of different turbulence models including RST

• Cosine theorem-based method for comparison of the flow characteristic

Keywords:

• Airflow characteristic
• airflow structure
• turbulence models
• computational fluid dynamics
• experimental fluid dynamics

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are openly available in DepositOnce of the Technische Univeristät Berlin at https://doi.org/10.14279/depositonce-18189.

Notes

1 Trox GmbH, LVS/125/G1/P1-RAL9005-70%.

2 Trox GmbH, VDW-Q-Z-V/500x24/P1-RAL9005-70%.

3 Trox GmbH, VSD35-1-AK-M-L/600x98/C1/P1-RAL9005-70%.

4 The photo is taken from a nonisothermal setup. The cylindrical heat dummies are not part of the isothermal measurements.

5 Developed and manufactured by the Hermann-Rietschel-Institut, Technische Universität Berlin.

6 CANON EOS 5D.

7 National Institutes of Health.

8 Dantec Dynamics, accuracy: $\pm 2\hspace{0.33em}\mathrm{\%}$ for 0–1 m s⁻¹, $\pm 5\hspace{0.33em}\mathrm{\%}$ for 1–5 m s⁻¹.

9 Siemens Digital Industries Software.

10 The subsequent aim of the research project is to evaluate the ventilation effectiveness, therefore, the age of the air is considered as a quality characteristic in the grid independency study.

11 Python Software Foundation.

12 Pillow is a PIL fork by Alex Clark and Contributors.

Additional information

Funding

This work was funded by the German Federal Ministry for Economic Affairs and Climate Protection (BMWK) under the IGF funding code 20440 N. The authors assume responsibility for the content of this publication.

Notes on contributors

Gerrid Brockmann

Gerrid Brockmann is an engineering scientist at the Hermann-Rietschel-Institut of the Technische Universität Berlin and is working in the field of indoor air flow characteristics and ventilation effectiveness since 2015. He graduated in mechanical engineering at the RWTH Aachen University with a focus in thermodynamics and energy technologies in 2013. With first steps in the thermal storage and gas turbine research, he collects over twelve years’ experience in computational fluid dynamics and experimental validation processes.

Anne Hartmann

Anne Hartmann was a research associate at the Hermann-Rietschel-Institut of the Technische Universität Berlin from 2016 to 2022, where she focused on ventilation, indoor air hygiene, air purification, airborne spread of pathogens, thermal comfort and air conditioning. Since 2020 she took over the lead of the contamination control research group and lead though the COVID-19 pandemic research topics and publicated several papers about indoor infection risk. 2023 she moved with her expertise to IT G Institute for Building Systems Engineering Research and Application.

Martin Kriegel

Martin Kriegel finished his PhD about experimental investigations and numerical simulations of displacement ventilation in 2005 at the Technische Universität Berlin. Afterwards he worked as a project manager and deputy managing director in an engineering office for energy systems in buildings. Since 2011, Prof. Dr.-Ing. Martin Kriegel has been head of the Hermann Rietschel Institut at the Technische Universität Berlin with the focus on contamination control, indoor environmental quality and energy systems for buildings and districts.