Heat Release Rate and Sprinkler Response Characterization in Large-Scale Fires

2011 ◽  
Author(s):  
Tamanini F.
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale

Flame Area Fluctuation Measurements in Velocity-Forced Premixed Gas Turbine Flames

2015 ◽  
Author(s):  
Alexander J. De Rosa ◽  
Janith Samarasinghe ◽  
Stephen J. Peluso ◽  
Bryan D. Quay ◽  
Domenic A. Santavicca
Keyword(s):  
Heat Release ◽  
Gas Turbine ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Small Scale ◽  
Flame Velocity ◽  
Unstable Combustion

Fluctuations in the heat release rate that occur during unstable combustion in lean premixed gas turbine combustors can be attributed to velocity and equivalence ratio fluctuations. For a fully premixed flame, velocity fluctuations affect the heat release rate primarily by inducing changes in the flame area. In this paper, a technique to analyze changes in flame area using chemiluminescence-based flame images is presented. The technique decomposes the flame area into separate components which characterize the relative contributions of area fluctuations in the large scale structure and the small scale wrinkling of the flame. The fluctuation in the wrinkled area of the flame which forms the flame brush is seen to dominate its response in the majority of cases tested. Analysis of the flame area associated with the large scale structure of the flame resolves convective perturbations that move along the mean flame position. Results are presented that demonstrate the application of this technique to both single-nozzle and multi-nozzle flames.

Fire Growth in Standard Tests and Railcars

2018 ◽  
Author(s):  
Charles Luo ◽  
Soroush Yazdani ◽  
Brian Y. Lattimer
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Growth Conditions ◽  
Standard Test ◽  
Fire Growth ◽  
Gas Temperature ◽  
Fire Dynamics ◽  
Room Corner Test

Large scale flammability performance of interior finish used on railcars has been evaluated in previous studies using the NFPA 286 room corner fire test, which has a cross-section similar to a railcar. In some studies, the wall containing the door was removed to account for the shorter length of the room compared to the railcar length. The focus of this study is to assess whether the NFPA 286 standard room-corner test with a door represents conditions that developed inside a railcar during a fire. Fire Dynamics Simulator (FDS) was used to model the fire growth in a NFPA 286 standard room-corner test with a door, NFPA 286 room without the wall containing the door, and railcar geometry with a single door open. All three cases had the same exposure fire in a corner and the same lining material. In predictions of the NFPA 286 room-corner test with a door, gas temperature, heat release rate, and time to flashover agreed well with available NFPA 286 standard test data. The simulation results of fire growth inside a railcar with one side door open produced similar conditions and fire growth compared with the standard NFPA 286 room with a door. For simulations on the NFPA 286 room with the wall containing the door removed, it was found that removal of the wall with the door resulted in non-conservative fire growth conditions with the gas temperature and heat release rate under-estimated compared to the standard NFPA 286 room with a door. These simulations indicate that the standard NFPA 286 room-corner test with a door is representative of conditions that would develop inside of a railcar.

scholarly journals Experimental Study on Occurrence Limit Heat Release Rate of Flashover in a Building Fire

2021 ◽  
Vol 21 (2) ◽  
pp. 65-71
Author(s):  
Seunggoo Kang ◽  
Yi Chul Shin
Keyword(s):  
Experimental Study ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Fire Behavior ◽  
Design Calculation ◽  
Building Fire ◽  
Fire Source ◽  
Combustion Tests

In this study, to allow the flashover to occur, combustion tests were conducted by setting the conditions of a fire source using a large-scale compartment and changing the opening condition. As a result, the inside temperature of the compartment was measured under the fire source conditions. Moreover, according to the “Handbook on Design Calculation &#x0004d;ethods of Fire Behavior” by the Architectural Institute of Japan, the validity of the heat release rate required for the flashover to occur was verified through the correlation between <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Q</mi><mrow><mi>F</mi><mi>O</mi></mrow></msub><mo>/</mo><msub><mi>Q</mi><mrow><mi>v</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>A</mi><mi>T</mi></msub><msup><mrow><mo>(</mo><mi>k</mi><mi>p</mi><mi>c</mi><mo>)</mo></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup><mo>/</mo><msub><mi>c</mi><mrow><mi>P</mi></mrow></msub><mn>0</mn><mo>.</mo><mn>5</mn><mi>A</mi><msup><mi>H</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math>.

Numerical and Experimental Study of Merging Fires in Square Arrays

2007 ◽  
Author(s):  
Kohyu Satoh ◽  
Liu Naian ◽  
Liu Qiong ◽  
K. T. Yang
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Forest Fires ◽  
Large Scale ◽  
Gas Flow ◽  
Fire Spread ◽  
Total Heat ◽  
Total Heat Release ◽  
Convective Gas Flow

In large-scale forest fires and city fires, merging fires and fire whirls have often been observed, which cause substantial casualties and property damages. It is important to know particularly where and under what conditions of weather such merging fires and fire whirls appear in cities or forests. However, there have been no adequate answers, since the detailed physical characteristics about them are not fully clarified yet, although previous studies have examined the phenomena of merging flames. Therefore, we have carried out preliminary studies and found that the merged tall fires can enhance the fire spread, and developed a method to analyze burn-out data of fire arrays. If sufficient knowledge can be obtained by relevant experiments and numerical computations, it may be possible to mitigate the damages due to merged fires and fire whirls. The objective of this study is to investigate the merging conditions of fires in square arrays in laboratory experiments and also by CFD numerical simulations, varying the size of square array, inter-fire distance and heat release rate, to judge ‘unmerged’ or ‘merged’ conditions in the fire array. It has been found that the fire merging is dependent on the inter-fire distance in the array and also on the total heat release rate of all fires surrounding the center region of the array. Also found that the experimental and simulated results on the merged and unmerged cases in the fire array, as affected by the total heat release rate and the inter-fire distance, which control the convective gas flow into the array, behave very similarly. Therefore, it can be concluded that the fire merging in array fires are highly based on the convection in the flow field due to fires and can be predicted by simple CFD simulations.

An improved model for estimating heat release rate in horizontal cable tray fires in open space

2018 ◽  
Vol 36 (3) ◽  
pp. 275-290 ◽  
Author(s):  
Xianjia Huang ◽  
He Zhu ◽  
Lan Peng ◽  
Zihui Zheng ◽  
Wuyong Zeng ◽  
...  
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Open Space ◽  
Local Error ◽  
Bench Scale ◽  
Improved Model ◽  
Cable Fire ◽  
Fire Experiments

Electric cable fires in nuclear power plants could be disastrous and have to be studied carefully for safety and economic considerations. Based on the results of previous work on large-scale and bench-scale cable fire testing, the Flame Spread over Horizontal Cable Trays model was modified and improved to estimate the heat release rate of large-scale cable fires using bench-scale measured data. The heat release rate per unit area measured in the cone calorimeter experiment is taken as the input, to avoid introducing any prediction uncertainties caused by inconsistent values of the heat of combustion and char yield of the cable. Cable fire experiments with vertical stacks of trays with one to three layers of cables were conducted in open space to assess the accuracy of the improved model. In comparing with the experimental results, predictions using the improved model are encouraging. The local error of prediction is less than 15% and the global error lies between 19.2% and 35.7%. In addition, three cable tray fire experiments with data available in the literature were used to validate the improved model. It is shown that the improved model had good predictions for these cable tray fires.

Effects of Ambient Pressure on the Mass Burning Rate and Heat Release Rate of n-Heptane Pool Fire

2016 ◽  
Author(s):  
Qiuju Ma ◽  
Quanyi Liu ◽  
Runhe Tian ◽  
Junjian Ye ◽  
Rui Yang ◽  
...  
Keyword(s):  
Heat Release ◽  
Burning Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Ambient Pressure ◽  
Pool Fire ◽  
Pure Liquid ◽  
Mass Burning Rate ◽  
The Mean

This research aims to investigate the effect of ambient pressure on the burning rate and heat release rate (HRR) of n-heptane pool fire. The experiments were performed in a large-scale altitude chamber of size 2 m×3 m×4.65 m under series of pressure, 24kpa, 38 kPa, 64 kPa and 75 kPa to 90 kPa. A round steel fuel pans of 34 cm in diameter and 15 cm in height was chosen for the pool fire tests. The fuel pan was filled with 99% pure liquid n-Heptane. Experimental results show that the burning rate increases rapidly after ignition until it reaches to the peak, and then maintains at a relatively stable stage. It decreases gradually until the flame extinguishes. The burning time is longer at lower pressure. The mean mass burning rate at the steady burning stage increases exponentially with pressure as ṁ ∼ Pα, with α = 0.68. HRR curve has a similar trend with the burning rate. The maximum HRR increases from 27kW to 62kW as the pressure rises from 24kPa to 90kPa. It is concluded that the ambient pressure has a significant effect on the fire heat release rate, and will further influent on other fire parameters.

Transient Plume Influence in Measurement of Convective Heat Release Rates of Fast-Growing Fires Using a Large-Scale Fire Products Collector

1990 ◽  
Vol 112 (1) ◽  
pp. 186-191 ◽  
Author(s):  
Hong-Zeng Yu
Keyword(s):  
Heat Flow ◽  
Heat Release ◽  
Convective Heat ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Release Rates ◽  
Fast Growing ◽  
Fire Source ◽  
Rack Storage

A theory for strongly buoyant transient plumes was used to determine whether the convective heat flow measured by a large-scale Fire Products Collector (FPC) could approximate the instantaneous convective heat release rate generated by fast-growing fires. The theory was confirmed by the plume data of rack storage fires obtained in this study. The theory provides a scheme for deriving the convective heat release rate generated at the fire source from the convective heat flow measured by the FPC.

scholarly journals G-equation modelling of thermoacoustic oscillations of partially premixed flames

2017 ◽  
Vol 9 (4) ◽  
pp. 260-276 ◽  
Author(s):  
Bernhard Semlitsch ◽  
Alessandro Orchini ◽  
Ann P Dowling ◽  
Matthew P Juniper
Keyword(s):  
Heat Release ◽  
Limit Cycle ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Describing Function ◽  
Describing Functions ◽  
Wide Range ◽  
Flame Describing Function ◽  
Thermoacoustic Oscillations

Numerical simulations aid combustor design to avoid and reduce thermoacoustic oscillations. Non-linear heat release rate estimation and its modelling are essential for the prediction of saturation amplitudes of limit cycles. The heat release dynamics of flames can be approximated by a flame describing function. To calculate a flame describing function, a wide range of forcing amplitudes and frequencies needs to be considered. For this reason, we present a computationally inexpensive level-set approach, which accounts for equivalence ratio perturbations on flames with arbitrarily complex shapes. The influence of flame parameters and modelling approaches on flame describing functions and time delay coefficient distributions are discussed in detail. The numerically obtained flame describing functions are compared with experimental data and used in an acoustic network model for limit cycle prediction. A reasonable agreement of the heat release gain and limit cycle frequency is achieved even with a simplistic, analytical velocity fluctuation model. However, the phase decay is over-predicted. For sophisticated flame shapes, only the realistic modelling of large-scale flow structures allows the correct phase decay predictions of the heat release rate response.

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