Flame Manikin Research Articles

Development and application of numerical model of thermal sensors for thermal protective clothing evaluation based on CFD simulation

PurposeThe purpose of this paper is to study the heat transfer effect of copper sensor and skin simulant on skin.Design/methodology/approachFor the sensor, the physical and mathematical models of the thermal sensors were used to obtain the definite conditions in the heat transfer process of the sensor, and the heat transfer models of the two sensors were developed and solved respectively by using ANSYS WORKBENCH 19.0 software. The simulation results were compared with the experimental test results. For the skin, the numerical model of the skin model was developed and calculated. Finally, the heat transfer simulation performance of the two sensors was analyzed.FindingsIt is concluded that the copper sensor is more stable than the skin simulant, but the material and structure of the skin simulant is more suitable for skin simulation. The skin simulant better simulates the skin heat transfer. For all the factors in the model, the thermal properties of the material and the heat flux level are the key factors. The convective heat transfer coefficient, radiation heat transfer rate and the initial temperature have little influence on the results, which can be ignored.Research limitations/implicationsThe results show that there are still some differences between the experimental and numerical simulation values of the skin simulant. In the future, the thermal parameters of skin simulant and the influence of the thermocouple adhesion should be further examined during the calibration process.Practical implicationsThe results suggest that the skin simulant needs to be further calibrated, especially for the thermal properties. The copper sensor on the flame manikin can be replaced by the skin simulant with higher accuracy, which will be helpful to improve the accuracy of performance evaluation of thermal protective clothing.Social implicationsThe application of computational fluid dynamics (CFD) technology can help to analyze the heat transfer simulation mechanism of thermal sensor, explore the influence of thermal performance of thermal sensor on skin simulation, provide basis for the development of thermal sensor and improve the application system of thermal sensor. Based on the current research status, this paper studies the internal heat transfer of the sensor through the numerical modeling of the copper sensor and skin simulant, so as to analyze the effect of the sensor simulating skin and the reasons for the difference.Originality/valueIn this paper, the sensor itself is numerically modeled and the heat transfer inside the sensor is studied.

Functional Development and Evaluation of Residential Fire-Resistant Clothing

Residential fires are a significant risk factor threatening the health and security of occupants. The purpose of this study was to develop a novel fire-safety product to help occupants safely and quickly evacuate from fire. Residential fire-resistant clothing with an alterable robe-coverall structure was developed according to a functional design procedure. The protection and ergonomic performance of the new fire-resistant clothing were verified by material selection and testing, flame manikin testing, and a simulated evacuation test. The results demonstrated that the fire-resistant clothing could provide essential thermal protection, inhalation protection, tear resistant, and visibility. Moreover, compared to current fire blankets, this fire-resistant clothing integrated the robe and coverall together, providing improved thermal protection and ergonomics, while decreasing skin burn percentage by 30.04% and allowing flexible leg movement.

A prediction method to evaluate thermal performance of protective clothing based on the correlation analysis of the bench scale and flame manikin tests

PurposeBench scale and flame manikin tests are two typical methods to evaluate thermal protective performance (TPP) of fire protective clothing. However, flame manikin test is limited to be widely used for its complication and high cost. The purpose of this paper is to develop a method to evaluate the thermal performance of protective clothing from the bench scale test results and garment parameters, which predicts the body burn injuries without conducting flame manikin tests.Design/methodology/approachBench scale and flame manikin tests’ data were collected from the previous research literature and then statistical analysis was performed to quantitatively investigate the correlations between the two test methods. Equations were established to predict the TPP values accounting for the effects of entrapped air gap and thermal shrinkage. Fitting analysis was conducted to analyze the relationship between the predicted TPP values and total burn injury. Finally, a method to predict total burn injury from the TPP values was proposed and validated.FindingsThe results showed that when the TPP value was predicted with the effects of air gap and thermal shrinkage considered, there was an approximate linear relationship between the predicted TPP values and total burn injury from the manikin test. Therefore, the prediction model of burn injury was developed based on the correlation analysis and verified with a generally good accuracy.Originality/valueThis paper presented a new prediction method to evaluate the thermal performance of protective clothing, which saved significant time and cost compared to the conventional methods. It can provide useful information for burn injury prediction of protective clothing.

Quantitatively evaluating the effects of flash fire exposure on the mechanical performance of thermal protective clothing

PurposeThe purpose of this paper is to determine the effect of flash fire exposure on the mechanical properties of single-layer thermal protective clothing.Design/methodology/approachThe full-scale flame manikin tests were performed to simulate flash fire exposure. Two typical fire-resistant fabrics were investigated. The manikin was divided into seven body parts and the specimens meeting the requirements of tensile and tear strength standards were sampled. Fabric thickness, mass per unit area, tensile strength and tear strength were measured and analyzed.FindingsThe results revealed the significant influence of heat flux on both of tensile and tear strength. However, the regression analysis indicated the low R2 of the liner models. When the tensile and tear strength retention were reorganized based on the body parts, both of the multiple linear regression models for tensile and tear strength showed higher R2 than the one-variable linear regressions. Furthermore, the R2 of the multiple linear regression model for tear strength retention was remarkably higher than that of the tensile strength.Practical implicationsThe findings suggested that greater attention should be paid to the local part of human body and more factors such as the air gap should be considered in the future thermal aging of firefighters’ clothing studies.Originality/valueThe outcomes provided useful information to evaluate the mechanical properties of thermal protective clothing and predict its service life.

소방공무원 대상 국내 소방용 개인보호구 성능 평가법 개선에 대한 설문조사

This study investigated Korean firefighters’ requirements for newly-added test methods of personal protective equipment(PPE) through questionnaire. One hundred forty four firefighters were participated in two different surveys(38 at the 1SUPst/SUP and 106 at the 2SUPnd/SUP questionnaire). The results showed that 1) 97% of the firefighters replied that a test method using the newly-developed hand flame manikin needs to be added to the current test methods; 2) a protective item most needing improvements was protective gloves(32%). followed by self-contained breathing apparatus(13%) and bunker jacket and pants(13%); 3) Over 86% of firefighters agreed that human wear trials to evaluate thermal strain, metabolic burden and mobility in dry, wet, or smoky conditions need to be added to the current test methods. 4) Firefighters dissatisfied with comfort functions(80.2%) more than protective functions (54.7%) of PPE in current use. 5) Firefighters who dissatisfied more with comfort functions expressed more requirements for the adding of human wear trials to the current test methods. In conclusion, the current test methods, which consist of mostly material tests, need to be improved in terms of human wear trials to test comfort functions.

소방관 안전장갑의 열 보호성능 평가를 위한 손 화상예측 화염마네킹 개발

소방관 안전장갑의 열 보호성능 평가를 위한 손 화상예측 화염마네킹 개발

Relationship between Total Heat Loss and Thermal Protective Performance of Firefighter Protective Clothing and Consequent Influence on Burn Injury Prediction via Flame-Engulfment Manikin Test

Firefighter protective clothing (FPC) provides barrier protection from hazardous materials. Two of the important performance factors tested for FPC are total heat loss (THL) and thermal protective performance (TPP). The present study evaluated the relationship between THL and TPP, and tested its subsequent influence on burn injury prediction via the flame-engulfment manikin test, using three FPC samples from the United States, Europe, and South Korea. The study results showed an inverse relationship between THL and TPP (r=-.949, p<.001). Predicted total area of second and third degree burn injury was 7.2±1.6, 19.7±4.1, and 5.0±1.0% for the United States, European, and South Korean FPC, respectively, which was significantly explained by both THL and TPP (F=34.630, p=0.001, R2=.920). The flame manikin test results showed that affected burn injury areas are not uniform over the body, but more frequent on the head and limbs.

Thermal protection retention of fire protective clothing after repeated flash fire exposure

Fire protective clothing worn by the emergency responders may be exposed to intensive heat condition time and time again during a firefighting work. In this research, the level of thermal protection retained by the fire protective clothing after repeated exposures to flash fire was investigated from bench-scale test to full-scale test. A thermal protective performance tester and an instrumented manikin with a transverse motion system device which was capable of simulating the action of running across the flame were used for the exposure test. Physical properties (mass, thickness, thermal shrinkage, tear strength) and thermal protective property of the test specimens were examined after each exposure. The results showed that repeated heat exposures resulted in continuous decrease of mechanical performance of the fabrics. The thermal protective performance of fabrics with good thermal dimensional stability such as polybenzimidazole/Kevlar and flame resistant cotton decreased after exposure. For the fabrics with severe thermal shrinkage such as Nomex IIIA and polysulfonamide, the thermal protective performance was improved due to the increase of fabric thickness induced by thermal shrinkage. However, this positive effect of thermal shrinkage diminished in the manikin test as it decreased the air gap size between the garment and flame manikin. The thermal protective property of Nomex IIIA garment exhibited continuous decrease after repeated exposures. This study was expected to provide new sights for the performance evaluation and application of fire protective clothing.

Simulating the thermal response of the flame manikin with different materials exposed to flash fire by CFD

SummaryTo investigate the differences of thermal response between heat flux sensors and human skin on the flame manikin, a three‐dimensional heat transfer model was developed and validated by the flame manikin system. The initial temperature of the model with sensor material was set to 300 K, and the model with skin material was set as the real condition. Simulated results validated the effectiveness of heat flux measured by the sensor. The incident heat flux through the measured surface was influenced by the different emissivity of the human skin and experimental sensors. Significant difference was found for the temperature response of these two kinds of materials within 4‐s fire exposure. The heat flux measured by sensor or the simulated results with actual human skin parameters could be used as the input boundary condition of the skin heat transfer model for Henriques's skin burn prediction. It is necessary to study the actual skin thermal response by experiments, where the 3D model established in this study could be used as the supplementary means for skin simulant sensor development. These findings will also be adopted in our following study of skin burn prediction module in the 3D full‐scale simulation platform. Copyright © 2016 John Wiley & Sons, Ltd.

Personal thermal protection simulation under diverse wind speeds based on life-size manikin exposed to flash fire

A concept of personal thermal protection simulation was proposed to figure out the strategies of thermal protection when human body was in face of fire. A 3D unsteady Computational Fluid Dynamics model was established based on the flame manikin experiments. The model was then adopted as the fundamental model to investigate the influence of wind speed on the heat transfer in the combustion chamber. Simulated results indicated that the flame shape tended to be slender and the flame line was lengthened as wind speed increased. In order to investigate the heat flux density distribution, the manikin was divided into 24 regions, which were clustered by direction (front and back), side (left and right), and segment (chest/back, abdomen/hip, upperarm, forearm, upperleg and shank). Statistical analysis showed the significant direction and segment effects on the flux density of manikin surface. The decrease of heat flux with the increase of wind speed indicated the positive influence of wind when a person was entrapped in a fixed fire source with headwind. The increased proportion of radiant heat flux in the total heat flux as wind speed increased implied that strategies like lowing the fabric emissivity will be effective for thermal protection. The skin burn prediction and more characteristics of fire source will be investigated in future studies.

3D numerical simulation of heat transfer through simplified protective clothing during fire exposure by CFD

A three dimensional finite volume model was developed to simulate the transient heat transfer through a flame manikin located in a combustion chamber with the advanced technique of computational fluid dynamics. The model was validated by compared with physical experiments performed by Donghua flame manikin system point by point, and then applied as a fundamental model to investigate the heat transfer through a simplified protective clothing system. Both of single and multiply layers clothing with contact combination were simulated by taking fabric as a three dimensional media. The temporal heat flux and temperature distribution of each layer of the clothing and skin were predicted. Results indicated that the air gap of 6.35mm played a more critical role than the single-layer fire-proof clothing in deceasing heat transfer to the human skin. In the multi-layer garment system, the moisture barrier was the most effective layer on the thermal protection during the flash fire. The results of temporal heat flux and temperature could be used for further research of burn injury prediction and fabric parameters improvement.

Thermal protective performance evaluation of fire proof garment eliminating air gaps effect based on computational fluid dynamics simulation

To evaluate thermal protective performance of fire proof garment under flash fire exposures, it is important to discuss garment heat transfer characteristics eliminating the effect of air gaps between garment and body. In this study, a test of flame manikin clothed with close-fitting garment was designed. And a three-dimensional transient heat transfer computational fluid dynamics simulation of the test was achieved to gain the garment surface temperature. By means of three-dimensional body scanner, Geomagic and Gambit software, we developed a method of three-dimensional geometrical modeling of the full-scale close-fitting clothed manikin. The accuracy of the computational fluid dynamics simulation was validated by actual experiments. It was found that the average incident heat flux to the exterior of the Nomex® IIIA garment is not 84 kW/m2, the value measured in nude manikin tests, but the value is 11% lower than it. This will help to set more accurate boundary conditions on garment surface in further simulations.

Correlation of bench scale and manikin testing of fire protective clothing with thermal shrinkage effect considered

Bench scale test and flame manikin test are two typical methods to evaluate the thermal protection provided by flame resistant fabrics or clothing. In this paper, the correlation between the test results of the two protocols was investigated. A group of fabrics commonly used in fire protective clothing were evaluated by a thermal protective performance (TPP) tester. Conditions with or without an air spacer were applied. Protective performance of the garments made of these fabrics with identical design feature was evaluated by a flame manikin testing system. Portable 3D body scanning technique was firstly used to characterize the air gap size change between the garment and manikin after flash fire exposure. The results showed that there was no significant correlation between the bench scale test and flame manikin test results in terms of TPP value and percent body burn. Thermal shrinkage which was not included in the bench scale test was demonstrated to be a key factor contributing to the weak correlation. It significantly decreased the air gap size between the garment and manikin and greatly affected the heat transfer after the flash fire exposure had ceased in the manikin test. Besides the TPP value, thermal shrinkage was suggested to be considered in the bench scale test as a parameter to predict the thermal protective property of flame resistant fabrics when made into garments.

CFD simulation of naked flame manikin tests of fire proof garments

The overall performance of the thermal protective clothing can only be evaluated using an assessment based on an instrumented manikin under defined, close to real-life conditions in a laboratory. However, the manikin tests can only give a few of pointwise information. This paper presents a three-dimensional transient CFD simulation of heat and mass transfer in the flame manikin test of thermal protective clothing. The used grid model, simulated from Donghua Flame Manikin, have real dimensions and accurate shape of a typical Chinese man. The solver and physical models are defined in FLUENT system and the CFD simulation of a naked flame manikin test is accomplished. By means of CFD simulation, temperature and velocity fields on the manikin surface and of the whole chamber during the process of 4-second flash fire combustion are obtained, which give well predictions to the heat flux distribution in an average sense. The cumulative curve of heat fluxes in the CFD simulation is close to the curve measured by 135 sensors in the real manikin experiment. The study could be a foundation for further study on modeling heat and mass transfer in the clothed manikin experiment and predicting skin damage accurately.

Analyzing Thermal Shrinkage of Fire-Protective Clothing Exposed to Flash Fire

The thermal shrinkage of a fire-protective garment has significant influence on its thermal performance. However, there is a lack of systematic investigation on garment shrinkage under exposure to flash fire. Based on a posture-adjustable flame manikin, a new approach to characterize the thermal. The shrinkage during flash-fire exposure is proposed, and several factors were investigated shrinkage was measured in different test conditions by calculating the deformation of markers on the garment. Results showed that the shrinkage was affected by the exposure conditions, fabric properties, garment size, and body posture. The shrinkage showed different results in the four directions and was unevenly distributed over the manikin. The distribution of garment shrinkage was analyzed and correlated with the heat flux and air gap. The most severe shrinkage location was the arms and legs. The shrinkage at the rear was larger than at the front. There was significant difference between the chest and other parts such as the back, arms, and legs (P < 0.01). There was also significant difference between the back and the arms as well as legs (P < 0.01). This indicates that the correlation with shrinkage was weak for the air gap size but moderate for the heat flux. Design of fire-protective clothing should take the thermal shrinkage property into consideration, and this study provides a technical basis to engineer high-performance protective clothing.

Analyzing the Combustion Characters of Fire Protective Clothing Exposed to Flash Fire

Combustion characters such as afterflame, color fading, thermal shrinkage, carbonization, smoke production provide a comprehensive reflection of the garment performance as a whole. Based on the flame manikin testing system, six kinds of garments which can be divided into two groups (PSA clothing and aramid clothing) were used for combustion experiments, and the combustion characters were analyzed under the same exposure conditions. Results show that the after flame time of PSA clothing was longer than that of aramid clothing, showing poorer flame resistant performance. Large areas of color fading happened to most of the test samples. The average thermal shrinkage of the PSA clothing is greater than the aramid clothing with similar weight and weaving structure. Clothing with larger fabric gram weight and thickness tends to have smaller shrinkage degree. The carbonization degree of PSA clothing was more serious than that of aramid clothing. Smoke amount may relate to the dying and finfish of fabric.

Thermal Protection Evaluation of Fire Fighter Ensembles Using a Flame Manikin Test System

Objective and quantitative evaluation of garment thermal protective performance should be based on the simulation of human in actual thermal environments as realistic as possible. In this paper, by using a new type of flame manikin which can rotate and make different postures, the dynamic scene where a firefighter wearing fire protective ensembles rescue in the flash fire was simulated. The skin burn prediction result showed that the total burn percent suffered by the manikin was 7.76%, of which the 2nd degree burn and the 3rd degree burn was 5.12% and 2.64% respectively. This indicated that the firefighter ensembles exhibited relatively good thermal protective performance. It can provide enough protection for the firefighter in 8s dynamic exposure while more protection should be added to the head.

Effectiveness of Proban® flame retardant in used clothing

During conflict, Royal Navy personnel wear a two‐ply flame‐retardant (FR) “action coverall” (AC) and “anti‐flash” (AF) hood and gloves, made from Proban (Albright &amp; Wilson's registered trademark) treated cotton. It is a widely held belief that extended wear, and repeated washing damages the Proban® FR finish making the garments more susceptible to ignition if exposed to flame. To examine this, new and used AC and AF were exposed up to 10 s on a flame manikin. The examples of used AC and AF had been worn for approximately 56 days and washed 20 times over a 12 week period at sea. For flame challenges up to 10 s, much greater than expected in a fuel explosion, the protection afforded by the used clothing was as good as for the new clothing, with some evidence that protection had improved. It is concluded that the Proban® FR treatment was not damaged by wear or washing.

Fire hood retains fire protective qualities after wear and washing

Royal Navy (RN) fire fighters have recently been provided with a new two‐ply hood made from 20 per cent polybenzimidizole/80 per cent permanent flame retardant Rayon (fibre made from regenerated cellulose). After 15‐20 days of use during live‐fire training (and regular washing) the new type hood appeared to be suffering from excessive wear and there was concern that the level of protection might have decreased. To examine this, 25 new and 25 used hoods (worn and washed approximately 15‐20 times) were exposed to flame, five each at 2, 4, 6, 8 and 10 s using a flame manikin head to ascertain the predicted burn injuries. The new hood was shown to provide excellent protection against the most severe flame engulfment to which RN personnel might accidentally be exposed. There was no evidence that the protection afforded by the hoods was reduced by prolonged use and washing and therefore it was safe for the “new‐type” hood to remain in‐service.