Stereo particle image velocimetry system for combustion and turbulence studies

湍流预混燃烧是许多实际燃烧系统的工作模式，如燃气轮机燃烧室和直喷式火花点火发动机。目前和未来对低排放的要求预计将推动未来燃气轮机系统开发的几乎所有问题。燃气轮机发动机的稀薄预混燃烧室概念似乎最有希望实现极低的氮氧化物排放。稀薄预混燃烧系统具有控制燃烧过程的内在吸引力，是控制燃烧过程的首选方法。完全预混燃烧系统提供对燃烧化学、反应动力学、火焰温度和污染物排放的控制。然而，为了充分利用这些优势，湍流与火焰的相互作用应该得到澄清。试图量化湍流对预混湍流燃烧速度的影响在理论和实验上都遇到了一些挑战。在开发数值程序来模拟燃烧装置中的三维非定常流动结构方面取得了实质性的进展。然而，由于缺乏一个稳健的、计算上有效的湍流预混火焰传播预测模型，在模拟燃烧过程方面进展缓慢。为了解决这个问题，应该更好地了解湍流火焰锋面的结构。为了破译湍流燃烧中火焰前锋的结构，三维流场信息以及具有足够空间分辨率的瞬时标量梯度是必不可少的。目前测量湍流预混火焰火焰前锋温度和OH自由基浓度的瞬时测量方法是瑞利散射和平面激光诱导荧光。所要求的仪器是一个立体粒子图像测速系统，将提供同时测量三维速度场和标量梯度的能力。

Turbulent premixed combustion is the mode of operation in many practical combustion systems such as gas turbine combustors and direct injection spark ignition engines. Current and future requirements for low emissions are expected to drive virtually all issues in the development of future gas turbine systems.  Lean premixed combustor concept for gas turbine engines appears to have the most promise for very low oxides of nitrogen emissions. Lean premixed combustion systems have an intrinsic attraction for controlling the combustion process and are the method of choice.  Fully premixed systems provide control over combustion chemistry, reaction kinetics, flame temperatures, and pollutant emissions. However, to fully benefit from these advantages, the turbulence-flame interactions should be clarified.The attempts to quantify the effects of turbulence on premixed turbulent burning velocity have encountered several challenges, both theoretically and experimentally.  Substantial progress has been made in the development of numerical codes to simulate the 3D unsteady flow structures in combustion devices. However, progress has been slower in simulating the combustion process due to a lack of a robust and computationally effective prediction model for turbulent premixed flame propagation. To overcome this problem, the structure of the turbulent flame front should be better understood. To decipher the structure of the flame fronts in turbulent combustion, three dimensional flow field information along with instantaneous scalar gradients with sufficient spatial-resolution are essential.  Instantaneous measurements of temperature and OH radical concentrations at the flame front of turbulent premixed flames are currently being measured by Rayleigh scattering and planar laser-induced fluorescence. The requested instrument, a stereo particle image velocimetry system, will provide the capability to make simultaneous measurements of three dimensional velocity field along with scalar gradients.