Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/20388

Title

The effect of jet velocity ratio on aerodynamics of a rectangular slot-burner in the presence of cross-flow

Author(s)

Ahmed, Shakhil;  Hart, James T.;  Nikolov, Jonian;  Solnordal, Chris B.;  Yang, William;  Naser, Jamal A.

Abstract

In a typical coal-fired power station boiler the ignition and the combustion of the fuel is largely controlled by burner aerodynamics. An experimental and numerical study of the rectangular slot-burners widely used on power stations in Victoria, Australia has been conducted to improve understanding of jet development within the boiler. The 1:15 scale model burner consisted of a central (primary) rectangular fuel nozzle with two (secondary) rectangular air jets positioned above and below it. The burner jets entered the measurement vessel at an angle of 60° to the wall. A cross-flow jet was attached to the wall of the vessel to simulate the recirculation prevalent in power station boilers. Experiments were conducted using a primary to cross-flow jet velocity ratio (φ) of 1.0 and secondary to primary jet velocity ratios (φ) of 1.0 and 3.0. Laser Doppler Anemometry (LDA) was used to measure mean and turbulent velocity components in the near field and downstream regions of the jets. Cross-flow significantly influenced the near field flow development from the slot-burner by deviating both primary and secondary jets from their geometric axes towards the wall. The degree of deviation was greater for φ = 1.0 since the higher velocity secondary jets increased the overall momentum of the primary jet for φ = 3.0. A numerical investigation of the rectangular slot-burner was also performed. First, the numerical results were validated against the experimental results and then visualization of the developing flow field was used to reveal the finer details of the cross-flow/burner jet interaction. Agreement between numerical and experimental jet features was good, although the numerical results predicted a primary jet that was marginally too narrow. Also the predicted downstream behaviour for φ = 3.0 deviated more significantly from experimental observation. Using the SST turbulence model, the numerical results suggested that a twin vortex was generated behind the initial region of the primary jet and this would aid in mixing of gas and fuel between primary and secondary jets.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Engineering and Industrial Sciences

Source

Experimental Thermal and Fluid Science, Vol. 32, no. 2 (2007), p. 362-374

Publication year

2007

Keyword(s)

Jet velocity ratio;  Rectangular slot-burner;  Tangentially fired furnace;  Cross-flow;  LDA;  CFD

Publisher

Elsevier

ISSN

0894-1777

Publisher URL

http://dx.doi.org/10.1016/j.expthermflusci.2007.04.011

Copyright

Copyright © 2007. Published by Elsevier Inc.

Peer reviewed