Numerical simulations of natural convection of an air filled open-top cavity with some of the cavity surfaces heated are performed by using Fire Dynamics Simulator (FDS). The impact of the cavity geometry with a heated floor is examined when the cavity is examined, and a stable vortex is observed under certain conditions. It is found that when the aspect ratio (height to width ratio) is below 0.6 (approximately), the cavity behavior is unstable, but when the aspect ratio is above this value, a stable vortex forms in the cavity. Increase the aspect ratio further leads to multiple vertically aligned vortices. It is found that when the aspect ratio is at the critical values (≈0.6), a strong, horizontal mass flow is observed over the cavity and the strength of the top vortex, measured in terms of its circulation, is maximized. Then the ability of this partially heated cavity to induce a horizontal flow in a duct is examined through two dimensional and three-dimensional modelling. The results show that it is possible to create a net horizontal flow in the duct-cavity system and the device operation is steady. For the 2-D open-top cavity in a duct, when the temperature of hot surface smaller than 100℃, induced air mass flux reaches the peak value when size of duct is 2cm, further increase size of duct cannot increase air mass flux. For the 3-D open-top cavity in a duct, as the cavity depth increases from 4 to 7cm, the induced air mass flux relatively stable, the induced air mass flux independent of depth.

Creator

• Wei, Chuming

Contributors

• Urban, James
• Rangwala, Ali S.
• Simeoni, Albert

Degree

• MS

Unit

• Fire Protection Engineering

Publisher

• Worcester Polytechnic Institute

Identifier

• etd-22931

Keyword

• Vortex
• Air entrainment
• Cavity
• Heat Transfer

Advisor

• Rangwala, Ali S.
• Urban, James

Committee

• Simeoni, Albert

Defense date

• 2021-05-06

Year

• 2021

Date created

• 2021-05-06

Resource type

• Thesis

Rights statement

• In Copyright

License

• Creative Commons BY Attribution 4.0 International

Last modified

• 2023-12-05