池火特性参数计算及其热辐射危害评价

可燃性油品池火的火焰及其产生的热辐射 ,可能导致周围人员伤亡或设备设施损坏。笔者介绍了油品池火的质量燃烧速率、火焰长度、火焰倾角及火焰后拖量等特性参数的计算方法 ,提出了池火热辐射强度的预测模型 ,给出了热辐射伤害 /破坏准则 ,并进行了模拟计算和评价。     

黄磷燃烧特性的试验研究

研究了不同试验条件下,黄磷的燃烧速率、火焰高度、温度、热辐射通量等特性,并对采集的试验数据进行整理.结果表明:黄磷燃烧速率与容器面积正相关,面积越大,燃烧速率越大;黄磷燃烧的火焰脉动现象很明显,不同的试验条件,脉动程度存在差异,并对此给出了理论阐述;黄磷燃烧时90％以上的热量以对流的形式向外传递,热辐射只占很小一部分.     

航空煤油薄油层燃烧特性实验研究

为研究薄油层燃烧特性,开展航空煤油薄层油池火实验,分析油品燃烧的整个过程、燃烧速率、火焰高度和辐射反馈等参数随时间的变化规律。结果表明:整个薄层燃烧过程除发展、稳定和熄灭阶段外,还存在薄层燃烧衰减阶段。稳定阶段的燃烧速率与初始油层厚度相关,但随着厚度的增加其逐渐趋于稳定;薄层燃烧衰减阶段,燃烧速率会随着实时油层厚度的下降逐渐降低。对比火焰高度的实测值和模型预测值发现,Heskestad模型的预测更接近实际结果;燃烧发展阶段后,火焰辐射反馈基本维持稳定,受初始厚度的影响较小,但辐射透射强度会随着油层厚度的降低而增加,且增速逐渐加快,表明辐射透射在薄层燃烧衰退阶段中起到关键作用。结合辐射透射的变化规律,将辐射反馈分为可吸收和不可吸收2部分,并提出用于预测辐射透射大小的经验模型。     

3m直径煤油池火灾火焰特性的数值研究

为了预测油池火灾的火焰特性,采用CFD模拟技术开展静风状态下3 m直径煤油液池的火灾场景模拟,探讨火焰温度、火焰羽流速度、辐射热通量、燃烧产物质量分数等油池火焰特性参数随高度的变化关系;并结合火焰形态分布,提出一种4区域模型,即将湍流扩散火焰划分为油气混合燃烧区、燃烧火焰区、烟尘区和热烟气区来分析燃烧气流在不同高度的实际物理化学特性。此外,通过经验公式和CFD模拟2种方法分别计算出3 m直径煤油池火灾的火焰高度、火焰表面的辐射通量及热辐射破坏半径,并对计算结果进行比较分析,结果表明:2种方法可互相补充完善,有助于池火灾的热辐射危害性评估。     

火焰沿层状疏松燃料的定常蔓延

本文从燃料预热角度出发，建立了一个无风状态下火焰沿层状疏松燃料水平定常蔓延的物理模型。在该模型中，假设环境无风，从热学角度考虑燃料很薄。燃料加热机制包括火焰辐射，燃料中的热辐射和热传导以及火焰通过扩散对流对其附近燃料的加热，散热机制包括燃料上表面辐射散热和对流散热。计算得到了火焰蔓延速度同几个主要影响因素之间的关系，并用曲线拟合技术得到了一个简单的函数表达式。该模型用实验进行了检验，由于对燃料中的热辐射采用了辐射向量的处理方法，同时，考虑了火焰卷吸引起的强迫对流对散热的影响，从而使计算结果同实验取得了较好的一致。     

闪火灾害的后果分析

闪火是可燃性气体或蒸气泄漏到空气中并与之混合被点燃而发生的一种非爆炸性的蒸气云燃烧,其主要危害是热辐射和火焰直接灼烧。闪火的热辐射计算包括闪火动力特性及热通量计算。热辐射的大小由火焰的辐射能,视角系数和大气传输率所决定。运用Pietersen(1990)热辐射的伤害－破坏理论,分析计算了一起闪火灾害热辐射造成人的伤害后果和对建筑物的破坏后果。     

航空煤油小尺度池火燃烧规律及火焰结构研究

为分析油池火灾发展的一般规律,利用小尺度池火燃烧特性试验系统,对航空煤油池火的宏观和微观特性进行试验研究,重点分析质量燃烧速率、火焰涡流结构和火焰温度的变化规律。结果表明:燃烧速率方面,油品质量随时间近似呈线性变化,瞬时燃烧速率作为时间的函数分为5个阶段,火灾的有效防控必须放在初期;涡流结构方面,不同燃烧阶段火焰涡流结构的明显程度不同,与燃烧剧烈程度成反比关系,计算出涡流结构产生频率为4~5 Hz,其产生的原因是油品蒸发、燃烧流动与火焰浮力耦合作用的影响;火焰温度方面,就整个燃烧过程而言,竖直方向轴线上火焰下部温度明显高于上部,水平方向上火焰中心与火焰边缘未燃区之间温差随高度不同而差别较大。     

风电机舱内典型混合液态油品热诱导燃烧特性

为探究不同尺寸方形油盘对双馈异步风力发电机组机舱中典型混合油品燃烧特性的影响,自主设计和搭建了热平板诱导油品加热燃烧测定实验系统。将液压油(CALTEXRANDO HDZ32)和齿轮箱油(CALTEXMEROPA320)按1∶1质量(各40.0g)比例均匀混合后,盛装于横截面尺寸分别为6.5cm×6.5cm、10.0cm×10.0cm、13.5cm×13.5cm 的钢制油盘中,利用热平板加热和诱导盘内同样质量混合油品燃烧,利用摄像机记录其燃烧行为和阶段节点时间,利用热电偶树、温度采集模块对油品燃烧对应阶段节点液内和上方火焰中心轴温度分布进行测定。观察发现,液/齿混合油品在加热后出现液内流动、蒸发、冒泡、气化、燃烧、发烟、火焰蹿高等典型传热传质和液相燃烧现象。实验结果表明,随油盘横截面尺寸递增,混合油品着火时间依次缩短(最高1048.0s),燃烧持续时间依次递减(最高1980.0s),燃烧液内最高温度依次升高(最高564.3 ℃),中心轴第一层火焰熄灭温度依次升高(最高489.2 ℃)。小尺寸油盘内油品交流换热过程缓慢,质量损失速率较低,着火前阶段出现最大质量损失速率(0.041g/s);中大尺寸油盘内对流、传质和传热过程明显增强,质量损失速率较高,火焰蹿高节点时出现最大质量损失速率(0.25g/s和0.29g/s)     

障碍物对甲烷水平喷射火燃烧特性的影响

为了对比不同障碍物对甲烷水平喷射火几何特征和燃烧特性的影响,分别采用高度为120,180和240 mm的障碍物进行室内实验,分析了在3种不同流量工况下火焰的轴向温度及热辐射的分布规律。研究结果表明:障碍物能有效阻挡火焰在水平方向的传播;在相同流量下障碍物越高,对控制火焰传播的效果越好;当障碍高度h=240 mm时,火焰几何尺寸下降最大,障碍物后方的温度和热辐射分别下降了88.5%和64.1%;随着障碍物与泄漏孔间距的增加,障碍物前后两侧温差逐渐减小,对火焰传播控制效果减弱,因此障碍物布置在持续燃烧区域之前对火焰的控制效果最好。研究结果可为管道和储罐发生泄漏事故的应急处置和防护设施的设计提供参考。     

细水雾阻隔火焰热辐射的模拟研究

从热辐射传递方程出发，根据Mie散射理论,考虑雾滴对热辐射的散射和吸收特性，建立细水雾阻隔火焰热辐射的两通量模型，并给出简化算法；同时建立小尺度模拟实验系统，对理论模型进行验证。结果表明，两通量模型较为合理地预测了细水雾对火焰热辐射的衰减作用。在此基础上，应用上述理论模型进一步探讨火焰温度、细水雾特性参数、雾场厚度对阻隔热辐射效率的影响，为细水雾系统的实际工程应用提供了理论和依据。     

飞火和热辐射耦合作用点燃松针的实验研究

飞火颗粒点燃和火焰辐射引燃是森林-城镇交界域火灾两种主要引燃方式。已有很多研究关注单种引燃方式,但缺乏二者耦合作用下的引燃机理研究。实验研究了热颗粒与热辐射耦合作用下松针燃料床的点燃行为,分析了热颗粒尺寸、温度及辐射热通量对点燃特性的影响。实验结果表明:热颗粒和热辐射耦合作用的点燃危险性远远高于热颗粒或者热辐射单独作用下的点燃危险性。耦合作用时,点燃概率随颗粒尺寸、温度和辐射热通量增大而增大,热颗粒临界点燃温度以及临界辐射热通量均随热颗粒尺寸增大而降低;阴燃向明火转变的点燃时间随辐射热通量增大而降低,但与颗粒状态呈现出较为复杂的关系。     

Analytical Study of the Heat Loss Attenuation by Clothing on Thermal Manikins Under Radiative Heat Loads

For wearers of protective clothing in radiation environments there are no quantitative guidelines available for the effect of a radiative heat load on heat exchange. Under the European Union funded project ThermProtect an analytical effort was defined to address the issue of radiative heat load while wearing protective clothing. As within the ThermProtect project much information has become available from thermal manikin experiments in thermal radiation environments, these sets of experimental data are used to verify the analytical approach. The analytical approach provided a good prediction of the heat loss in the manikin experiments, 95% of the variance was explained by the model. The model has not yet been validated at high radiative heat loads and neglects some physical properties of the radiation emissivity. Still, the analytical approach provides a pragmatic approach and may be useful for practical implementation in protective clothing standards for moderate thermal radiation environments.     

Feedback acceptance in developmental assessment centers: the role of feedback message,participant personality,and affective response to the feedback session

We investigated feedback acceptance by participants (N = 141) in an operational developmental assessment center (AC). Consistent with predictions based on self‐enhancement theory and the Affective Infusion Model, results indicated that higher assessor ratings were associated with higher feedback acceptance, and this relationship was partially mediated by the participant's affective reaction to the feedback session. Participants' self‐ratings of their AC performance did not affect this relationship suggesting no support for our prediction based on self‐verification theory. We also investigated the role of participants' self‐ratings of agreeableness, extraversion, and emotional stability in feedback acceptance by testing specific moderated mediation hypotheses. Extraversion was related to feedback acceptance through the affective reaction to the feedback session. Agreeableness moderated the affective reaction to the feedback session and feedback acceptance relationship such that there was a strong relationship between affective reaction and feedback acceptance for highly agreeable participants, but no relationship for low agreeable individuals. For low agreeable individuals, there was a positive direct relationship between the assessor ratings and feedback acceptance which was not observed for highly agreeable individuals. The hypothesized role of emotional stability in predicting feedback acceptance was not supported. Implications for the delivery of feedback in developmental ACs are discussed in light of these findings. Copyright © 2008 John Wiley & Sons, Ltd.     

聚合物燃烧放热的通风

本文在小尺寸试件燃烧实验的基础上,着重研究了几种典型聚合物燃烧时放热参数的变化规律及其通风影响,通过实验数据的拟合和分析,揭示了燃烧放热、通风条件和燃料种类之间复杂的关系,给出了由放热参数决定的可燃性区域,得到了一些新的结论,有助于材料放热特性认识和室内火分析的进一步深入。     

细水雾幕衰减热辐射的数值模拟研究

针对现有防火分隔技术的不足,以细水雾幕作为新的防火分隔技术,开展了不同细水雾幕雾特性对衰减热辐射影响的数值模拟研究。通过建立长通道模型,在火源和被保护物体中间设置细水雾幕系统,测量有无细水雾幕及不同细水雾特性条件下被保护侧温度及热辐射强度值,来定性定量研究细水雾幕衰减热辐射的效率。模拟结果表明:细水雾幕可以很好的降低被保护侧空间的温度和热辐射强度;衰减热辐射效率随雾滴粒径的减小,喷雾流量的增大,喷头排数增加而增大;另外,其衰减热辐射效率与喷头布置方式有关,上喷方式明显优于下喷方式。研究结果将对现有防火分隔技术的改善提供帮助和技术支持。     

The impact of feedback and self-efficacy on performance in training

This field experiment examined the main and interactive effects of self-efficacy and feedback (i.e. the use of feedback versus no feedback) on performance in a speed reading class. Results showed that the provision of feedback was beneficial to the performance of all subjects, however as subject self-efficacy increased, the beneficial effects of feedback to the subject's performance also increased. Subjects who received feedback on their performance experienced significantly greater increases in self-efficacy than subjects who received no feedback. The more positive the performance feedback received, the greater the increase in individual self-efficacy. The implications of these results for training programs are discussed.     

Increasing industrial safety practices and conditions through posted feedback

This study examined the effects of posted feedback for improving safety in a paper mill. Data were taken once a week on 24 practices and 7 conditions. In addition, data on injuries with and without lost time were collected monthly. After posting feedback on safe and unsafe conditions for 6 months, more than half of the 17 divisions of the mill showed improvement. Similarly, safe practices increased after feedback was provided for them for 2 months. Most importantly, injuries were cut in half.     

The impact of self-appraisals on reactions to feedback from others: the role of self-enhancement and self-consistency concerns

This study examined the usefulness of self-appraisal (SA) as a technique designed to enhance the motivational and developmental impact of feedback from others. Drawing from research on self-enhancement and self-consistency motives, it was hypothesized that individuals would agree with and incorporate feedback that is consistent with their SA, whereas they would be more satisfied and perform better if feedback is more favorable than their SA. A field study was conducted with 122 MBA students as participants. On average, students were 25 years old and had 1.8 years of work experience. Seventy per cent of students were male and 82 per cent were white. The findings supported all of the hypotheses except the hypothesis concerning satisfaction. Implications for improving the impact of performance appraisal feedback are discussed.