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Lin Q.,Xiamen University | Huang Y.-Y.,Xiamen Airlines | Pan B.,CAS Institute of Engineering Thermophysics | Pan B.,Graduate University of Academy of science | Niu Z.-G.,Aerodynamics Research Institute
Kongqi Donglixue Xuebao/Acta Aerodynamica Sinica

The kinds of new-style plasma flow controllers have been designed to control flow actively according to the behavior of the directional air flow induced by DBD (Dielectric Barrier Discharge) plasma in still air. The desired flow structures have been obtained by organizing the directional flow induced by DBD plasma through arranging electrodes in the controllers purposefully. The flow fields induced by the new-style plasma active flow controllers have been investigated visibly and measured by PIV. The experiment shows that the required structure of the induced flow can be realized through designing new-style plasma flow controllers reasonably to control flow actively. The research results provide a novel flow controller without flow source for active flow control. Source

Chen Z.,Harbin Engineering University | Huang S.,Aerodynamics Research Institute | Han L.,Aerodynamics Research Institute
Key Engineering Materials

Model checking technique can give a specific counterexample which explains how the system violates some assertion when model does not satisfy the specification. However, it is a tedious work to understand the long counterexamples. We propose a genetic algorithm to enhance the efficiency of understanding long counterexample by computing the minimal unsatisfiable subformula. Besides, we also propose a Craig interpolation computation-based method to understand counterexample. The causes which are responsible for model failure are extracted by deriving interpolation from the proof of the nonsatisfiability of the initial state and the weakest precondition of counterexample. Experimental results show that our methods improve the efficiency of understanding counterexamples and debugging significantly. © 2014 Trans Tech Publications, Switzerland. Source

Ma W.,Harbin Engineering University | Sun H.,Aerodynamics Research Institute | Zou J.,Harbin Engineering University | Yang H.,Harbin Engineering University
Polish Maritime Research

In order to identify high-speed navigation ability of trimaran planing hull, as well as investigate the characteristics of its resistance and hull form, ship model tests were conducted to measure resistance, trim and heaving under different displacements and gravity centre locations. The test results were then used to study the influence of spray strips on resistance and sea-keeping qualities. Moreover, different planing surfaces were compared in the model tests which helped to look into influence of steps on hull resistance and its moving position. Also, the resistance features of monohull and trimaran planing hulls, both with and without steps, were compared to each other. From the tests it can be concluded that: the two auxiliary side hulls increase aerodynamic lift at high-speed motion, which improves the hydrodynamic performance; the trimaran planing hull has also excellent longitudinal stability and low wave-making action; when Fr∇ > 8, its motion is still stable and two distinct resistance peaks and two changes of sailing state (the second change is smaller) appear; spray strips are favourable for sea-keeping qualities at high speed. The change trends before the second resistance peak as to the resistance and sailing behaviour of trimaran planing hull without steps are the same as for monohull planing hull without steps. but when steps in both hulls exist the change trends are different; more specifically: trimaran planing hull with steps has only one resistance peak and its resistance increases along with its speed increasing, and the resistance is improved at the increasing speed as the number of steps increases. © Elsevier BV 2013. Source

Wei Q.,Peking University | Niu Z.,Aviation Industry Corporation of China | Niu Z.,Aerodynamics Research Institute | Chen B.,Aviation Industry Corporation of China | And 2 more authors.
Journal of Aircraft

A study was conducted to integrate flight control with active flow control using plasma actuators by investigating a control method specifically for plasma actuators in flight control. The bang-bang control method has been proposed for plasma actuators, taking account of practical issues such as limited actuation states with instantaneously varied aerodynamic control performance. Flow control effects have been examined in wind tunnel experiments, which show that the plasma authority for flow control is limited. However, flight-control simulations suggest that, using the proposed optimal control method, even those small plasma-induced roll moments can satisfactorily fulfill the maneuver tasks and meet flight quality specifications. In addition, the disturbance from volatile plasma-induced roll moments can be adequately rejected. Source

He W.,Xiamen University | He W.,Technical University of Madrid | Niu Z.-G.,Aerodynamics Research Institute | Pan B.,Army Aviation Research Institute | Lin Q.,Xiamen University
Gongcheng Lixue/Engineering Mechanics

The wind tunnel experiment on suppressing wingtip vortices (WTV) through adding energy with DBD plasma has been conducted in the paper. The WTV flow field of a swept wing has been visualized by PIV and the aerodynamic forces of a rectangular wing have been measured, in the condition of using three different kinds of plasma actuators respectively. The results show that the WTV may be suppressed and the separation on the upper wingtip surface may be delayed because the energy of the vortex induced by the plasma (VIP) is added into the flow field, which increases the lift and the ratio of lift to drag at a small angle of attack (AOA) effectively. Even at large AOA, the effect of plasma still appears. The effects are related to the structures of the plasma actuators. It can be obtain better results to suppress the WTV through optimizing the design of the plasma actuators and choosing the appropriate placement to install the actuators on wingtip surface. Source

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