Combustion of ammonia under application-relevant conditions: a case study to improve thermal radiation models and reactivity prediction

该项目的主要目标有两个：第一，将提供在高压和高温下测量的氨火焰的新实验数据;第二，将开发一种稳健的方法，使用光学和压力上升方法准确测量层流火焰速度，特别强调辐射和浮力效应。为了实现这一目标，将在两个互补的实验装置中测量氨混合物的层流火焰速度，其条件与应用最相关，包括以前从未探索过的高温和高压。将在ITV-RWTH亚琛在正常重力下使用光学成像方法（纹影和粒子图像测速-PIV技术）对球形燃烧容器进行代表性测量，以评估辐射效应。使用新开发的实验装置进行补充层流火焰速度测量，以记录由于封闭腔室中火焰传播引起的压力增加以及整个腔室中火焰半径的演变，将在法国奥尔良的ICARE-CNRS合作进行。该技术最近被成功地用于获得甲烷/空气混合物在高压和高温下的层流火焰速度。该方法具有不受辐射热损失影响的优点。众所周知，氨具有低火焰速度，因此受到浮力效应的影响。还计划在不莱梅的落塔设施ZARM中利用ITV、RWTH亚琛室进行微重力实验，以抑制浮力的影响，同时获得受辐射强烈影响的缓慢氨/空气火焰的测量值。在正常重力下测量的火焰速度，使用这两种设置，以及在微重力下测量的火焰速度，然后将用于提供一种方法，以更好地解释极慢燃烧火焰辐射造成的热损失。

The main objective of this project is two-fold: First, new experimental data of ammonia flames measured at high pressures and temperatures will be provided; second, a robust methodology to accurately measure laminar flame speeds using the optical and the pressure rise methods with special emphasis on radiation and buoyancy effects will be developed. To achieve this goal, laminar flame speeds of ammonia mixtures will be measured in two complementary experimental setups at conditions most relevant to applications, including high temperatures and pressures never explored before. Representative measurements in a spherical combustion vessel using optical imaging methods (Schlieren and Particle Image Velocimetry-PIV techniques) under normal gravity will be performed at ITV-RWTH Aachen to assess radiation effects. Complementary laminar flame speed measurements using a newly developed experimental setup allowing to record the pressure increase due to the flame propagation in the closed chamber and the evolution of the flame radius throughout the entire chamber will be conducted in a collaborative approach at ICARE-CNRS in Orléans, France. This technique was recently successfully used to obtain laminar flame speeds of methane/air mixtures at high-pressure and temperature. The method has the advantage of not being affected by radiation heat losses. Ammonia is well known for having low flame speeds and being thus subject to buoyancy effects. It is also planned to perform experiments under microgravity in the drop tower facility ZARM in Bremen with the ITV, RWTH Aachen chamber to suppress the influence of buoyancy while obtaining measurements for slow ammonia/air flames strongly impacted by radiation. The flame speeds measured under normal gravity, using both setups, and those measured under microgravity will then be used to provide a methodology to better account for heat losses by radiation of extremely slow burning flames.