One of the most critical challenges for turbine-based combined cycle propulsion systems utilized in hypersonic civil aircrafts (Mach 0 to Mach 5) lies in guaranteeing the propulsion system to operate efficiently and stably along a very wide operating range. This has resulted in a need to investigate the matching restraints between the inlet and turbine-based combined cycle engine and nozzle from the integration point of view at the early stage of design. To get a good understanding of this integration concept design process, in this article, several basic design principles were first put forward. Next, a fast, versatile and trusted modular analysis tool for this concept design was developed and implemented. Third, several issues on this concept were analyzed including the design issues, the mechanisms of the variable geometries as well as the control schedules. Finally, a solution for the turbine-based combined cycle propulsion system was carried out and discussed. The results show that at least 11 total variables were required to be adopted in the variable cycle propulsion system to meet the basic mission requirements for Mach 5 civil airplane. How to guarantee these variable geometries function efficiently and reliably along the wide flight regime is one of the most critical technology challenges to make this concept feasible. The uniqueness of the developed analysis tool lies in that it affords a platform capable of investigating the design constraints and the matching relationships between the various propulsion components along a wide operating range, which is beneficial to predict the potential critical technological barriers at the early design stage.

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Plasma-activated water (PAW) with reactive species produced by plasma in water can efficiently inactivate bacteria and has potential biomedical applications. Surface dielectric barrier discharge (SDBD) is extensively used for the preparation of PAW, and the bactericidal effects of PAW are highly related to the discharge mode. In previous studies, saline was directly placed under surface plasma within a short distance, and the gaseous reactive species diffused into the saline. In this study, the gaseous reactive species flowed into the saline by airflow, which was outside the treatment distance and accelerated the diffusion rate. The gaseous reactive species were compared at different power levels and flow rates, and three discharge modes were classified, namely, ozone, transition, and nitrogen oxides modes, based on the characteristic peaks in the spectra. Long-lived and short-lived species were detected in the saline, and short-lived species were more associated with the bactericidal effect. The results suggest that the bactericidal effect of the transition mode is the most prominent and the scavenger results show that nitric oxide (•NO), singlet oxygen, and peroxynitrite play a more crucial role in bacterial inactivation. This study provides a potential strategy for modulating the discharge mode to generate selective reactive species in plasma-activated saline to promote bactericidal application.

The model of a gasoline engines cylinder head with 4 cylinders was reconstructed by CAD through slicing method and using Imageware and UG. The reverse design methods used for complex interior structure surface were explored based on slicing method through remodeling the cylinder head. The technologies of reverse design such as the measure method of points cloud, points cloud data treatment, and curve modeling were studied. The methods can be referenced for reverse designing the similar parts.

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