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There are fewer reports on the impinging shock/boundary layer interaction in the high Mach number and high-temperature flow than that in the supersonic flow. High-temperature flow characteristics of the impinging shock/flat-plate turbulent boundary layer interaction (IS/FTBLI) at Mach 8.42 are numerically investigated by solving two-dimensional Reynolds averaged Navier–Stokes equations coupling with the thermal–chemical non-equilibrium model. An impinging shock is formed by the wedge with a 10° deflection angle. The inviscid flow parameters ahead of the cowl of a Mach 12 inlet are selected as the free-stream condition of this study. The primary emphasis of this study lies in understanding the thermal–chemical non-equilibrium effects in the IS/FTBLI. Moreover, the chemical non-equilibrium effects similar to previous reports from others are utilized for the comparative analysis. Our findings reveal that the vibrational or thermal non-equilibrium effects exhibit maximum prominence subsequent to the intersection of the impinging shock with separation shock, as well as in the convergence area of compression waves during the flow reattachment. On the other hand, the chemical non-equilibrium effects predominantly result from oxygen dissociation and atomic nitrogen production within the boundary layer; the chemical reactions are most intense within the separation zone. By comparing with a thermally perfect gas, a reduction in the flow separation is observed in the chemical non-equilibrium effects, but the flow separation is enhanced in the thermal–chemical non-equilibrium effects. The insights gained from our research are expected to contribute to the development of flow control technology in hypersonic IS/FTBLI scenarios and aid in configuring wave structures in the inner compression section of high Mach number scramjet inlets. [ABSTRACT FROM AUTHOR]

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By introducing an open stub loaded resonator (OSLR) and a uniform impedance resonator (UIR) into balanced stepped-impedance microstrip-slotline transition structures, a balanced dual-band bandpass filter (BPF) with high selectivity and low insertion loss performance is presented in this paper. The balanced microstrip-slotline transition structures can achieve a wideband common-mode (CM) suppression. Meanwhile, the differential-mode (DM) passbands are independent from the CM responses, which greatly simplifies the design procedure. In addition, four varactors are loaded into OSLR and UIR to achieve the electrical reconfiguration. The proposed balanced dual-band BPF can realize quasi-independently tunable center frequencies and bandwidths. In order to verify the feasibility of the proposed design method, a prototype circuit of the proposed reconfigurable balanced dual-band BPF is simulated, fabricated and measured. A good agreement between the simulation and measurement results is observed. [ABSTRACT FROM AUTHOR]

A novel jet-edge structure for flexible piezoelectric harvester is proposed in this paper which converts wind energy into electrical energy by fluid-induced vibrations. This type of the piezoelectric harvester can be applied to self-powered and auxiliary power supplies for aircraft electronic systems. Here, the operational principle for jet-edge flow oscillations is introduced and a specific example of its application is given in this paper. To study the influence of jet, jet outlet with different sizes and the distance between the cantilever beam and the jet outlet were designed and the operating characteristics were investigated by experiments. Results show that, (1) when the aspect ratio of the jet outlet is less than 8.3, the peak voltage increases with the aspect ratio. (2) With the aspect ratio of 8.3, and the distance between the cantilever beam and jet outlet of 80 mm, the piezoelectric device beam vibrates periodically over the wind speed range of 6 to 14 m/s. (3) The piezoelectric energy harvester (with an optimal load of 2.55 M Ω) could generate a maximum power output of ∼83 μW with a resonant frequency of ∼48 Hz at the wind speed of 14 m/s. These results will be helpful to engineering design for energy harvesting devices. [ABSTRACT FROM AUTHOR]