Integrated control of an air-breathing hypersonic vehicle considering the safety of propulsion system

Chengkun, Lv,Juntao, Chang,Lei, Dai Techno-Press 2023 Advances in aircraft and spacecraft science Vol.10 No.1

This paper investigates the integrated control of an air-breathing hypersonic vehicle considering the safety of propulsion system under acceleration. First, the vehicle/engine coupling model that contains a control-oriented vehicle model and a quasi-one-dimensional dual-mode scramjet model is established. Next, the coupling process of the integrated control system is introduced in detail. Based on the coupling model, the integrated control framework is studied and an integrated control system including acceleration command generator, vehicle attitude control loop and engine multivariable control loop is discussed. Then, the effectiveness and superiority of the integrated control system are verified through the comparison of normal case and limiting case of an air-breathing hypersonic scramjet coupling model. Finally, the main results show that under normal acceleration case and limiting acceleration case, the integrated control system can track the altitude and speed of the vehicle extremely well and adjust the angle deflection of elevator to offset the thrust moment to maintain the attitude stability of the vehicle, while assigning the two-stage fuel equivalent ratio to meet the thrust performance and safety margin of the engine. Meanwhile, the high-acceleration requirement of the air-breathing hypersonic vehicle makes the propulsion system operating closer to the extreme dangerous conditions. The above contents demonstrate that considering the propulsion system safety will make integrated control system more real and meaningful.

Modeling and coupling characteristics for an airframe-propulsion-integrated hypersonic vehicle

Lv, Chengkun,Chang, Juntao,Dong, Yilei,Ma, Jicheng,Xu, Cheng Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.6

To address the problems caused by the strong coupling of an airbreathing hypersonic vehicle's airframe and propulsion to the integrated control system design, an integrated airframe-propulsion model is established, and the coupling characteristics between the aircraft and engine are analyzed. First, the airframe-propulsion integration model is established based on the typical nonlinear longitudinal dynamical model of an air-breathing hypersonic vehicle and the one-dimensional dual-mode scramjet model. Thrust, moment, angle of attack, altitude, and velocity are used as transfer variables between the aircraft model and the engine model. The one-dimensional scramjet model can accurately reflect the working state of the engine and provide data to support the coupling analysis. Second, owing to the static instability of the aircraft model, the linear quadratic regulator (LQR) controller of the aircraft is designed to ensure attitude stability and height tracking. Finally, the coupling relationship between the aircraft and the engine is revealed through simulation examples. The interaction between vehicle attitude and engine working condition is analyzed, and the influence of vehicle attitude on engine safety is considered. When the engine is in a critical working state, the attitude change of the aircraft will not affect the engine safety without considering coupling, whereas when coupling is considered, the attitude change of the aircraft may cause the engine unstart, which demonstrates the significance of considering coupling characteristics.

Study on micro-scale 3D numerical modeling and droplet deposition of plain weave fabric

Yuan Xiao,Chengkun Zhang,Qian LI,Pengcheng Yang,Dan He 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

To define the deposition and morphology changes of the droplets on fabric medium clearly in spraying printing the electrical circuits on fabric surface. The Navier-Stokes (NS) equation and volume of fluid (VOF) boundary tracking model are adopted to set up a microscale three-dimensional (3D) numerical model for plain weave fabric. Simulation focused on the evolution process of phase field, pressure field and speed field during the droplets deposition. The results show that axial momentum controls the droplets outward spread quickly and synchronously with a ring shape at early stage. The control of unbalanced-Young driving force causes the three-phase contact line fixes on fiber cylinder, droplets are in an instantaneous stable state. Capillary pressure gradient controls the three-phase contact line pinning and slippage forward lead to differences in spreading direction. The rebound effect of droplets promotes further penetration of droplets into fabric. Experiment analysis displays the well match with the simulation results, indicating the rationality of the proposed micro-scale 3D plain weave fabric modeling method. The findings of this paper would contribute to the future works for flexible electronic devices on fabric surface research studies.

The Text Mining Analysis of Macau’s Participation in International Organizations

Wu Shianghau,Liu Chengkun,Shi Haoyu,Pang Chuan 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.11

In recent years, Macau has actively participated in international organizations according to the Macau Basic Law. After fifteen years of regaining sovereignty by China, Macau has faced some internal and external challenges. In order to comprehend the new policy directions regarding Macau’s participation in international organizations, this paper made the depth interviews and applied the text mining analysis to the interviews responses. Through applying the random forests model and fruit fly optimization algorithm to keywords classification, the study concluded several points related to Macau’s participation in international organizations.

High Temperature Plastic Deformation Constitutive Equation of a New Alloy for Piston Ring

Dejin Wei,Ruirui Liu,Chengkun Zuo,Haitao Zhou 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.6

Hot compression tests of a new CrMoV alloy for piston ring are conducted by Gleeble-3800 thermal mechanical simulationtester at the temperature of 950, 1000, 1050, 1100 and 1150 °C and strain rate of 0.01, 0.1, 1, 10 s−1. The results show thatthe true stress strain curves first go up to peak, and then go down to steady state in accord with characteristics of dynamicrecrystallization, indicating that the main softening mechanism of this alloy during hot deformation is dynamic recrystallization. The hot deformation behavior of this alloy is characterized by Arrhenius hyperbolic sine relationship with theactivation energy and stress index. On the basis of the true stress strain curves, the constitutive equation of the peak flowstress of this alloy is established. With the equation, the flow stress of this alloy can be predicated by numerical simulationfor a new type piston ring.

Research on the Recovery and Reuse Method of Train Regenerative Braking Energy Based on the Decommissioned Equipment of EMU Trains

Lu Jingtao,Zhu Chengkun,Li Xin 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

With the continuous increase of electric multiple unit (EMU) train service life, the train will be out of operation, but there are still some parts on the train can work normally. When EMU trains operate in regenerative braking state, a large amount of energy will be returned to the traction grid. In this paper, the decommissioned train equipment is selected, and the energy conversion method is considered, and a new regenerative braking energy recovery and utilization method is proposed, which is composed of decommissioned power converters, traction motors and vortex spring energy storage devices using mechanical elastic energy storage. And the energy storage system is constructed by feasibility analysis. This method provides a new idea for the reuse of retired equipment.

Analysis on the influence of sports equipment of fiber reinforced composite material on social sports development

Jian Li,Ningjiang Bin,Fuqiang Guo,Xiang Gao,Renguo Chen,Hongbin Yao,Chengkun Zhou Techno-Press 2023 Advances in nano research Vol.15 No.1

As composite materials are used in many applications, the modern world looks forward to significant progress. An overview of the application of composite fiber materials in sports equipment is provided in this article, focusing primarily on the advantages of these materials when applied to sports equipment, as well as an Analysis of the influence of sports equipment of fiber-reinforced composite material on social sports development. The present study investigated surface morphology and physical and mechanical properties of S-glass fiber epoxy composites containing Al₂O₃ nanofillers (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%). A mechanical stirrer and ultrasonication combined the Al₂O₃ nanofiller with the matrix in varying amounts. A compression molding method was used to produce sheet composites. A first physical observation is well done, which confirms that nanoparticles are deposited on the fiber, and adhesive bonds are formed. Al₂O₃ nanofiller crystalline structure was investigated by X-ray diffraction, and its surface morphology was examined by scanning electron microscope (SEM). In the experimental test, nanofiller content was added at a rate of 1, 2, and 3% by weight, which caused a gradual decrease in void fraction by 2.851, 2.533, and 1.724%, respectively, an increase from 2.7%. The atomic bonding mechanism shows molecular bonding between nanoparticles and fibers. At temperatures between 60 ℃ and 380 ℃, Thermogravimetric Analysis (TGA) analysis shows that NPs deposition improves the thermal properties of the fibers and causes negligible weight reduction (percentage). Thermal stability of the composites was therefore presented up to 380 ℃. The Fourier Transform Infrared Spectrometer (FTIR) spectrum confirms that nanoparticles have been deposited successfully on the fiber.