LCE: Numerical Study of Turbulence-Radiation Interactions in Reactive Flows

摘要：项目负责人：M. Modest LCE：反应流动中湍流-辐射相互作用的数值研究辐射换热在大多数火灾以及商业燃烧应用中起着重要作用，其影响通常与对流换热具有相同的数量级，有时甚至占总换热率的主导地位。就像对流有湍流的帮助一样，辐射也是如此，在化学反应存在的情况下，由于湍流的相互作用，辐射可能会增加几倍。然而，这种湍流-辐射相互作用的计算是非常困难的，迄今为止，在所有流行的CFD求解器中都被忽略了，或者通过任意降低预测的火焰温度来处理湍流-辐射相互作用。概率密度函数（PDF）方法是解释这些相互作用的一种很有前途的方法。不幸的是，PDF方法在其目前的开发状态中有许多缺点，这妨碍了它在响应流中的使用。本研究的目的是进一步发展PDF方法来解决反应流动中存在的急剧梯度，并建立相互作用的标量方程。PDF方法的扩展将允许将其包含在已建立的CFD代码中。通过与DNS计算和实验数据的比较，验证了新方法的准确性。这项工作是NSF/Sandia生命周期工程联合倡议的一部分。

ABSTRACT Proposal Number: CTS 9732223 Principal Investigator: M. Modest LCE: Numerical Study of Turbulence-Radiation Interactions In Reactive Flows Radiative heat transfer plays an important role in most fires as well as in commercial combustion applications, with its effects usually being of the same order of magnitude as those of convective heat transfer, and sometimes dominating the overall heat transfer rates. In much the same way as convection is aided by turbulence, so is radiation, which in the presence of chemical reactions may increase several fold due to turbulence interactions. However, the calculation of such turbulence-radiation interactions is extremely difficult and has to date been neglected in all popular CFD solvers or is treated empirically by arbitrarily lowering the predicted flame temperatures to account for the turbulence-radiation interactions. A promising method for accounting for these interactions is the probability density function (PDF) approach. Unfortunately, the PDF method in its present state of development has a number of shortcomings, which preclude its use in reactive flows. The purpose of this research is to further develop the PDF method to resolve the sharp gradients, which exist in reacting flows, and to model the scalar equations for the interactions. The extension of the PDF method will permit it to be included in established CFD codes. The accuracy of the new method will be verified by comparison with DNS calculations and experimental data. This work is funded as part of the joint NSF/Sandia initiative in Life Cycle Engineering.