GOALI: Transient Jets and Re-Ignition for Energy Efficiency Gains from Confined Combustion

智力优势：可燃的燃料-空气混合物可以有意或无意地被来自相邻燃烧事件的热反应性气体的瞬时射流（喷流）点燃。这种再点火现象与常见的电火花或压缩点火事件有很大不同。是否以及多快发生重新点燃取决于以不同速率发生的物理和化学过程的复杂相互作用：烟团涡流旋转，混合和燃料分子氧化。初步的实验表明，与气体运动的预测很好的协议，但也表明，再点火延迟时间取决于燃料-空气比的方式，是尚未解释。该项目将使用计算，实验和分析方法来研究混合残余或再注入燃烧气体和新鲜混合物的瞬态射流的再点火，建立常见气体燃料的再点火延迟时间，并确定其对关键参数的敏感性。计算模型将用于预测稳定和横向射流中的喷烟涡流动力学和反应混合物温度。实验将验证涡流动力学和测量重燃延迟时间，通过使用压力传感器，可视化和光学诊断的横向和固定射流。然后将开发一个简化的数学模型，以仔细地解开气体混合和化学过程，并更准确地预测再点火。在其他类型的燃烧中验证的燃料氧化理论将被测试是否适用于喷气再点火。参与该项目的公司的科学家不仅将指导项目本身，还将指导一名博士生在该公司应用研究成果。广泛影响：该项目将使喷气点火燃烧方法成为可能，旨在大幅度减少燃料消耗和温室气体排放，适用于各种发电厂。该项目的成功有可能改变自工业革命以来燃料消耗的许多方式。它直接导致了新的燃烧方法，在飞机和发电发动机中产生增压。通过改造或重新设计带有增压燃烧室的发电燃气轮机和飞机喷气发动机，美国每年可以节省约100亿美元的燃料和100兆吨的二氧化碳排放。该项目将有助于开发使用称为波转子燃烧器的装置的增压燃烧技术。这种颠覆性的技术还可以使创新的中小型发电机以及更高效的混合动力汽车和便携式动力装置成为可能。此外，该项目使使用内燃机的卡车和机车能够更可靠地点火，从而可以用更便宜的国产气体燃料替代从进口石油中提炼的柴油。来自小型预燃室的瞬态射流可以实现天然气的一致点火，同时减少氮氧化物排放并避免柴油烟雾。这项研究的结果将立即用于同时进行的但单独的波转子燃烧室实验，简化模型将被纳入工业可用的设计代码中。博士生将协助行业合作伙伴开发波转子燃烧室原型，其初步目标是将燃料消耗，碳排放和燃气轮机重量分别减少约20%。

Intellectual Merit: Combustible fuel-air mixtures can be ignited, intentionally or not, by a transient jet, a puff, of hot reactive gas from an adjacent combustion event. This re-ignition phenomenon differs greatly from common electric spark or compression ignition events. Whether or not, and how quickly, re-ignition occurs depends on a complex interaction of physical and chemical processes occurring at different rates: puff vortex spinning, mixing and fuel molecule oxidation. Preliminary experiments show good agreement with gas motion predictions, but also indicate that re-ignition delay time depends on the fuel-air ratio in a way that is as yet unexplained. This project will use computational, experimental, and analytical approaches to investigate re-ignition by transient jets that mix residual or re-injected combustion gases and fresh mixtures, establish the re-ignition delay time for common gaseous fuels, and determine their sensitivities to key parameters. Computational models will be used to predict puff vortex dynamics and reacting mixture temperature in stationary and traversing jets. Experiments will verify vortex dynamics and measure re-ignition delay times for traversing and stationary jets through the use of pressure sensors, visualization, and optical diagnostics. A simplified mathematical model will then be developed to carefully disentangle the gas mixing and chemical processes, and more accurately predict re-ignition. Fuel oxidation theory validated in other types of combustion will be tested for applicability to jet re-ignition. Scientists at a company partnering in this project will not only guide the project itself, but also mentor a doctoral candidate in applying the research findings at the company.Broad Impacts: This project will enable jet-ignited combustion approaches aimed at dramatic reductions in fuel consumption and greenhouse gas emissions in a wide range of power plants. The success of this project has the potential to transform many of the ways in which fuel has been consumed since the Industrial Revolution. It leads directly to novel combustion methods that create a pressure boost in aircraft and electric power generation engines. By retrofitting or redesigning power generation gas turbines and aircraft jet engines with pressure-boost combustors, the United States can save an estimated $10 billion dollars in fuel and 100 megatons of CO2 emissions each year. The project will help develop pressure-boost combustion technology using a device called a wave rotor combustor. This disruptive technology can also enable innovative medium- and small-scale power generators as well as more efficient hybrid vehicles and portable power units. Additionally, the project enables more reliable ignition in trucks and locomotives using internal combustion engines, allowing the substitution of less expensive, domestic gas fuels for diesel refined from imported petroleum. Transient jets from small pre-chambers can accomplish consistent ignition of natural gas while reducing nitrogen oxide emissions and avoiding diesel smoke. The results of this research will be immediately utilized in concurrent but separate wave rotor combustor experiments, with simplified models being incorporated into design codes usable by industry. The doctoral candidate will assist the industry partner in the development of a wave rotor combustor prototype, the initial goal of which is reducing fuel consumption, carbon emissions, and the weight of gas turbines by about 20% each.