Joule heating flow control methods for high-speed flows

Joule heating is the generation of heat by the passage of current through a conductor. This is a review of a group of flow control methods that employ Joule heating to do so and can collectively be called energy deposition flow control methods. The energy deposition flow control methods discussed are surface plasma actuators, laser energy deposition and microwave generated plasma. These type of actuation methods are of particular interest for applications to high-speed flows. Conventional, mechanical actuation methods can be problematic in supersonic/hypersonic use as they require large forces to move and do not have fast enough response times depending on the application. Energy depositing actuators overcome these two problems as they have no moving parts and the response times can be in nanoseconds. This promising application to high-speed flows is one of the main driving factors behind the research in energy deposition flow control technologies. This review brings together the fundamental physics behind the operation of such methods. Both the fundamental characteristics of the flow control methods as well as the experience of their applications in high-speed flows is covered. A brief discussion of potential areas that require further study for each type of actuator/technique is also provided. Finally, a discussion of the possible future applications of energy deposition flow control methods is presented. [Display omitted] •This paper examines various Joule-heating based flow-control methods.•Benefits and drawback of each technique is discussed relating to high-speed flows.•Areas for further optimisation are highlighted for each technology.