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Air Grilles Designed to Prevent Backflows in Natural Ventilation Stacks – Experimental Investigation Cover

Air Grilles Designed to Prevent Backflows in Natural Ventilation Stacks – Experimental Investigation

Architecture, Civil Engineering, Environment
Volume 16 (2023): Issue 2 (June 2023)
By: Piotr Koper and  Dominik Szpank  
Open Access
|Jul 2023

Figures & Tables

Figure 1.

Examples of shapes of air channels where pressure loss strongly depends on flow direction a) Tesla valve [13, 14], b) diffuser, pressure loss coefficient × from [15]
Examples of shapes of air channels where pressure loss strongly depends on flow direction a) Tesla valve [13, 14], b) diffuser, pressure loss coefficient × from [15]

Figure 2.

Cross-section of the test setup: 1 – chamber representing a fragment of the room, 2 – chamber representing ventilation stack, 3 – thermoanemometers, 4 – fan (can be placed at another outlet), 5 – channel for tested air grill, 6 – pressure difference measurement ports, connected to micromanometer
Cross-section of the test setup: 1 – chamber representing a fragment of the room, 2 – chamber representing ventilation stack, 3 – thermoanemometers, 4 – fan (can be placed at another outlet), 5 – channel for tested air grill, 6 – pressure difference measurement ports, connected to micromanometer

Figure 3.

Photos of the test setup: a) overall view, b) air grill installed for testing, c) air speed measurement, d) pressure difference measurement
Photos of the test setup: a) overall view, b) air grill installed for testing, c) air speed measurement, d) pressure difference measurement

Figure 4.

Ordinary air grill tested for comparison
Ordinary air grill tested for comparison

Figure 5.

Air grill with moving flaps
Air grill with moving flaps

Figure 6.

Air grill shaped to prevent backflow
Air grill shaped to prevent backflow

Figure 7.

CFD simulation of the air inlet a) geometry with boundary conditions: blue – opening, green – outlet with defined mass flow, red cross – location of the thermoanemometer sensor, b) example of results of the simulation – velocity profile in cross-section for mass flow 35 kg/h
CFD simulation of the air inlet a) geometry with boundary conditions: blue – opening, green – outlet with defined mass flow, red cross – location of the thermoanemometer sensor, b) example of results of the simulation – velocity profile in cross-section for mass flow 35 kg/h

Figure 8.

Results of the pressure drop measurements for all three air grilles
Results of the pressure drop measurements for all three air grilles

Figure 9.

Mass flow for all the air grilles with a pressure difference of 15 Pa
Mass flow for all the air grilles with a pressure difference of 15 Pa

Figure 10.

Hydraulic losses at both ends of the diffuser-shaped air grill
Hydraulic losses at both ends of the diffuser-shaped air grill

Hydraulic loss coefficient (x) for the tested air grills

DiffuserForward flowReverse flow
99
19616
270260

Characteristics of measuring devices used in the experiments

DeviceTypeMeasurement rangeaccuracy
ThermoanemometerAirDistSys 50000.05 to 5 m/s±0.02 m/s ±1% of readings
Difference micromanometerCMR-100 to 1500 Pa±0.1Pa
DOI: https://doi.org/10.2478/acee-2023-0025 | Journal eISSN: 2720-6947 | Journal ISSN: 1899-0142
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Language: English
Page range: 161 - 169
Submitted on: Feb 3, 2023
|
Accepted on: May 12, 2023
|
Published on: Jul 20, 2023
Published by: Silesian University of Technology
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
Natural ventilation,
Backflow,
Hydraulic losses,
Air grill,
Air diode
Related subjects:
Architecture and design,
Architecture,
Architects, buildings

© 2023 Piotr Koper, Dominik Szpank, published by Silesian University of Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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