Active flow and combustion control 2018. Papers contributed to the conference ``Active flow and combustion control 2018'', September 19--21, 2018, Berlin, Germany
The book is based on the papers presented in the conference ``Active flow and Combustion Control'', held in Berlin, Germany, in 2018. It covers the hitherto latest theoretical and experimental findings in the fields of active flow control, combustion control, related data assimilation and dynamic impingement cooling. The papers presented in the active control area include the development on the actuator technology, open and closed loop control. This control presents the lift gains and losses from superimposing a periodic actuation on a steady component for a high-lift Coanda flap, rolling maneuvers with a delta wing to attenuate the roll moment coefficients. Micro jet arrays-based flow control eliminates or significantly reduces rotating stall in the radial diffusers. Researches on the high frequency boundary layer actuation by fluid oscillators at high speed showed a significant reduction in the overall profile losses by 40\%. Other papers present the dielectric barrier discharge plasma actuators for the flow separation on an unmanned air vehicle. The development of passive flow control techniques is also required to keep the performance of the aircraft. A theoretical paper is devoted to an application of the linear Ginzburg-Landau equation to the vortex shedding instabilities of the wake of a bluff body. Shockless explosion combustion is a non-steady thermodynamic process which offers a solution for the problem of fuel efficiency. The principle is based on a quasi-homogeneous auto ignition process that leads to constant volume combustion. Three papers are presented in the combustion control area underlying the mechanisms, experiments and simulation for reducing the ignition delay time under the atmospheric condition. Another paper in this section deals with the modeling approach to the gasoline-controlled auto-ignition with the purpose of multi-scale control synthesis. There are also other ways of realizing approximate constant volume combustion, e.g., in the pulse detonation combustion, the detonation waves are created to combust the fuel and oxidizer. There are three papers on pulse detonation combustion. In one paper, a study is made to experimentally determine the detonation velocity and the detonation cell width with the varying initial mixing temperature in a valve-less pulse detonation combustor. Another paper deals with the identification and classification of three types of low-frequency instabilities in rotating detonation combustors, and the third paper presents a study on the directly injected liquid \(n\)-decane with a cyclic operation in a combustion chamber with pre-heated air. It is shown that the combustion characteristics are strongly dependent on the residual burnt gas properties. There are three papers on the computational fluid dynamics to simulate flows in rather complex geometries for data assimilation and model reduction. The first paper observes that an axisymmetric Euler code produces essentially the same results as a full 3D code in capturing shock in a combustion tube. Another paper presents the extension of the Loewner framework to compute reduced-order models which arise in semi-discretizations of fluid flow problems such as the Burgers equation or the Navier-Stokes equations. The method has been applied to the viscous Burger equation. The third paper proposes an optimization procedure to compute an optimal model decomposition of flows with multiple convection velocities. The method is tested for a pulsed detonation combustor with a shock focusing geometry. There are three other papers numerically studying the shock wave interaction with voids and explosive particles as well shockless explosion combustion tubes coupled to a turbine plenum. One of these papers studies the effect of air cavities and impurities on the performance of condensed phase explosives in a multi-physics computational framework. A numerical approach is presented in a paper for solving evolutionary partial differential equation in two and three dimensions on a block-based adaptive grid. Several shockless explosion combustion tubes firing into an annular intermediate plenum may be desirable for a gas turbine application. The paper presents a one-dimensional multi-tube code for simulating the coupled combustion tubes and the turbine plenum. There are also three papers on dynamic impingement cooling. In one paper, an experiment is performed on the investigation of the local heat transfer of an array of 7 by 7 dynamically forced impingement jets with superimposed cross-flow. An empirical correlation is used to compare the theoretical result. However, no error analysis is performed. In another paper, a round jet impinging on a curved concave surface has been investigated by means of a direct numerical simulation. The third paper attempts to develop an algorithm based on the extremum seeking controller to find a relationship between the actuation parameters of a pulsed jet and the realized heat transfer coefficients in an impingement cooling of a turbine blade. The book, altogether, presents state-of-art results on theoretical, numerical, and experimental treatment of active flow and combustion control for aerodynamics and propulsion and can be recommended to university libraries and research departments.
scientific article; zbMATH DE number 6946606