| 1. |
|
|
| 2. |
- Fan, Chuan Gang, et al.
(author)
-
Effect of tunnel cross section on gas temperatures and heat fluxes in case of large heat release rate
- 2016
-
In: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 93, s. 405-415
-
Journal article (peer-reviewed)abstract
- Tests with liquid and solid fuels in model tunnels (1:20) were performed and analysed in order to study the effect of tunnel cross section (width and height) together with ventilation velocity on ceiling gas temperatures and heat fluxes. The model tunnel was 10m long with varying width (0.3m, 0.45m and 0.6m) and height (0.25m and 0.4m). Test results show that the maximum temperature under the ceiling is a weak function of heat release rate (HRR) and ventilation velocity for cases with HRR more than 100MW at full scale. It clearly varies with the tunnel height and is a weak function of the tunnel width. With a lower tunnel height, the ceiling is closer to the base of continuous flame zone and the temperatures become higher. Overall, the gas temperature beneath the ceiling decreases with the increasing tunnel dimensions, and increases with the increasing longitudinal ventilation velocity. The HRR is also an important factor that influences the decay rate of excess gas temperature, and a dimensionless HRR integrating HRR and other two key parameters, tunnel cross-sectional area and distance between fuel centre and tunnel ceiling, was introduced to account for the effect. An equation for the decay rate of excess gas temperature, considering both the tunnel dimensions and HRR, was developed. Moreover, a larger tunnel cross-sectional area will lead to a smaller heat flux.
|
|
| 3. |
- Fan, Chuan Gang, et al.
(author)
-
Experimental study of sidewall effect on flame characteristics of heptane pool fires with different aspect ratios and orientations in a channel
- 2017
-
In: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489 .- 1873-2704. ; 36:2, s. 3121-3129
-
Journal article (peer-reviewed)abstract
- A series of small scale tests was conducted to investigate the influence of sidewall on flame characteristics of heptane pool fires in a channel, considering pool shape (aspect ratio: 1, 2, 4 and 8) and pool orientation relative to sidewall. Distance between fire and sidewall was changed systematically. Both transverse flame development (along the direction of channel width) and longitudinal flame development (along the direction of channel length) were recorded by digital video. Results show that for a fixed fire location, the heat release rate increases with the increasing pool aspect ratio (namely a larger pool perimeter), which indicates more air entrainment and more intense combustion. In wall fire cases, when the long pool rim is perpendicular with channel sidewall, the flame can obtain more air entrainment with a weaker boundary restriction from the sidewall, compared to the case with the long pool rim being parallel with sidewall. Comparison of some previously established correlations based on various experimental conditions with our test results is made. Due to the fact without considering sidewall effect and fuel shape on the air entrainment of fire plume, the classic correlations need to be further improved. Therefore, an integral flame length model considering both sidewall effect and fuel shape is developed, which correlates well with all the data from cases with various pool positions, orientations and aspect ratios. © 2016 The Combustion Institute. Published by Elsevier Inc.
|
|
| 4. |
- Ji, Jie, et al.
(author)
-
Experimental study of non-monotonous sidewall effect on flame characteristics and burning rate of n-heptane pool fires
- 2015
-
In: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 145, s. 228-233
-
Journal article (peer-reviewed)abstract
- To study the influence of sidewall effect on flame characteristics and burning rate, a series of experiments with heptane pools was conducted. The results showed that as the fires were placed close to the sidewall, the flames inclined to the sidewall due to the restriction on air entrainment, and the burning rate increased on the whole, which could be mainly due to the enhanced radiation from the heated sidewall and ceiling flame. However, regardless of fuel pool shape, the burning rate obtained the peak value when the fire was near the sidewall, rather than attached to the sidewall, resulting from less flame radiation from the vertical flame part to the fuel in the latter case. The ratio of longitudinal ceiling flame length to transverse length tended to decrease with the fire moving close to the sidewall. For cases with the largest length and wall fires, the ratio was nearly 0.5, which could be explained according to the theory of mirror effect. Also, due to the non-monotonous sidewall effect, a higher burning rate did not necessarily lead to a larger ceiling flame length.
|
|
| 5. |
- Li, Ying Zhen, et al.
(author)
-
Effect of cross section and ventilation on heat release rates in tunnel fires
- 2016
-
In: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798 .- 1878-4364. ; 51, s. 414-423
-
Journal article (peer-reviewed)abstract
- Model scale fire tests were performed in tunnels with varying tunnel widths and heights in order to study the effect of tunnel cross-section and ventilation velocity on the heat release rate (HRR) for both liquid pool fires and solid fuel fires. The results showed that for well ventilated heptane pool fires, the tunnel width nearly has no influence on the HRR whilst a lower tunnel height clearly increases the HRR. For well ventilated solid fuel fires, the HRR increases by approximately 25% relative to a free burn test but the HRR is not sensitive to either tunnel width, tunnel height or ventilation velocity. For solid fuel fires that were not well ventilated, the HRRs could be less than those in free burn laboratory tests. In the case of ventilation controlled fires the HRRs approximately lie at the same level as for cases with natural ventilation.
|
|
| 6. |
|
|
