Control of ThermoAcoustic Phenomena with Applications to Novel Energy Conversion Devices

热声能量转换装置是一种发动机和冰箱，其中的机械工作是通过强烈的、封闭的压力波来完成的，而不是传统发动机和冰箱中存在的传统活塞、曲柄或涡轮机构。这些设备几乎没有活动部件，因此最大限度地减少了机械摩擦损失，并可能比传统设备具有更高的效率。该奖项支持研究导致新型热声设备，其中主动控制能够优化热力学循环并适应快速变化的负载和操作条件。这些智能热声设备与控制电子设备集成在一起，从而将复杂的机械设计转移到控制算法的设计中，在那里它可以更容易地实现。它们特别适合于不可预测和时变的环境，例如利用废热或小型太阳能热发电的环境。本项目研究的控制设计技术包括(a)利用最优周期控制（OPC）技术和频域方法对热声系统的周期性运行轨迹进行优化设计，(b)围绕时空极限环对周期性分布式系统进行反馈调节的设计，以及(c)点与分布式传感控制热声系统性能极限的研究。除了与热声系统直接相关外，这些研究课题在流动和气体动力学、柔性结构和其他领域的广泛空间分布动力系统中也很重要。在拟议的研究计划中，另一个重要组成部分是对几种热声设备的控制设计概念的实验研究，包括新品种的Rijke和Sondhauss管，以及热声发动机和热泵。

Thermoacoustic energy conversion devices are engines and refrigerators in which mechanical work is done by intense, contained pressure waves rather than the traditional pistons, cranks or turbine mechanisms present in traditional engines and refrigerators. These devices have almost no moving parts, thus minimizing mechanical friction losses and leading to potentially higher efficiencies than traditional ones. This award supports research leading to new types of thermoacoustic devices in which active control enables the optimization of thermodynamic cycles and adaptation to rapidly varying loading and operating conditions. These smart thermoacoustic devices are integrated with control electronics, thus transferring complexity from mechanical design into the design of the control algorithm, where it can be much more easily implemented. They are particularly suited to unpredictable and time-varying settings such as those that harness waste heat or small-scale solar-thermal power. The control design techniques investigated in this project include (a) optimal design of periodic operating trajectories of thermoacoustic systems using the techniques of Optimal Periodic Control (OPC) as well as frequency domain methods, (b) the design of feedback for regulation of periodic distributed systems around spatio-temporal limit cycles, and (c) the investigation of the limits of performance in the control of thermoacoustic systems with point versus distributed sensing. Aside from their direct relevance to thermoacoutic systems, these research topics are important in a wide class of spatially distributed dynamical systems that occur in flow and gas dynamics, flexible structures and other domains. Another significant component in the proposed research program is the experimental investigation of control design concepts in several thermoacoustic devices including new varieties of Rijke and Sondhauss tubes, as well as thermoacoustic engines and heat pumps.