Maurer Matthew, Bojko Brian, Byrd Edward F C, Kalman Joseph
Appl Opt. 2019 Feb 20;58(6):1451-1459. doi: 10.1364/AO.58.001451.
Optical measurements in propellant flames are necessary to understand the combustion physics, yet these conditions provide challenges in probing the flame and may introduce uncertainty into the measurement. This work reports the use of simulations of an ammonium perchlorate propellant flame with finite rate chemistry to understand the role of ammonium perchlorate particle size and pressure on the uncertainty of imaging-based measurements on propellant flames. A two-dimensional ray tracing code was developed to incorporate the effects of the species concentration and temperature gradients on ray refraction within propellant flames. It was determined that the effects of the flame structure based upon pressure and oxidizer particle size increases the amount of ray deflection particularly at high pressures explaining a cause for challenges of aluminum agglomerate measurements at elevated pressure. This framework shows promise for understanding limitations and uncertainties of optical measurements for reacting and turbulent flows.
在推进剂火焰中进行光学测量对于理解燃烧物理过程是必要的，但这些条件在探测火焰时带来了挑战，并且可能给测量引入不确定性。这项工作报告了利用具有有限速率化学的高氯酸铵推进剂火焰模拟，来理解高氯酸铵颗粒尺寸和压力对基于成像的推进剂火焰测量不确定性的作用。开发了一个二维光线追踪代码，以纳入推进剂火焰内物种浓度和温度梯度对光线折射的影响。已确定基于压力和氧化剂颗粒尺寸的火焰结构效应会增加光线偏折量，特别是在高压下，这解释了在高压下测量铝团聚体时面临挑战的一个原因。该框架对于理解反应流和湍流的光学测量的局限性和不确定性显示出前景。
