Tri-electrode plasma actuators (TED-PAs) can induce a stronger jet than that of conventional two-electrode plasma actuators (DBDPAs). For practical application of a TED-PA, it is significant to develop a TED-PA engineering model for implementing CFD simulations. In this study, we model the body force distribution generated by a TED-PA utilizing the Suzen model, which is one of engineering models used for DBDPAs. First, we define a function to describe the charge distribution profile on the dielectric surface with two half-Gaussian distributions. Second, we define the maximum values of surface charge as functions of the voltage applied based on the plasma simulation results. Finally, the flow fields numerically obtained using the model developed are compared with the experimental results from our previous study. Although there are some discrepancies mainly due to the two-dimensional laminar flow simulation, the model developed can quantitatively reproduce the voltage characteristics of thrust force and the jet structure induced. Therefore, the model developed is expected to evaluate the flow control effect precisely.
This paper reports the Smart Call from the Sky (SCSky) Can Satellite (CanSat) platform developed by Chosun University, South Korea, with a focus on a smart material of shape memory alloy actuator applications. The primary objective of this study is to verify the effectiveness of a remote screen touch system using shape memory alloy wires. The system is currently being utilized to operate the on-board smartphone of a CanSat by telecommands from a ground station. It provides real-time streaming video showing the internal and external states of CanSat through video calls during actual flight. The secondary objective of the mission is to acquire a wide-scan image from the on-board USB cameras, whose elevation angles are actuated using shape memory alloy springs. The effectiveness of the design proposed was validated experimentally through actual flight tests using model rockets.
A full-sky autonomous star identification algorithm aimed at solving the “lost-in-space” problem is presented in this paper. It mainly consists of two steps: an initial match step and a reliability evaluation step. Oriented singular value feature matching is adopted to search for corresponding candidates of the stars detected in the initial match. After obtaining the stars' initial match results, an evaluation method is applied to estimate the reliability of candidates from the star voting results, acquiring the final unique matching of stars in the image. Experiments show that our algorithm is more robust to star position noise and magnitude noise than the two conventional algorithms. In the simulations, our algorithm achieves an identification rate of 97.0% with 2-pixel star position noise and 0.3 Mv star magnitude noise, and also performs well with false stars in the field of view. In addition, the memory requirement and identification time of our method are acceptable for actual engineering projects.
Carbon fiber reinforced plastic (CFRP) exhibits high specific elasticity and a low coefficient of thermal expansion. Therefore, CFRP is considered to be a suitable material for fabricating reflectors for high-precision, space-based astronomical observation systems. However, non-negligible out-of-plane thermal deformation on CFRP reflectors may occur due to errors in the fiber orientation of each layer. In addition, out-of-plane thermal deformation can be generated because of non-uniform temperature conditions even when no fiber orientation error exists. In this study, the out-of-plane thermal deformation of a CFRP reflector model due to normally distributed fiber orientation errors was probabilistically examined, and methods to mitigate the effect of fiber orientation errors were investigated. The Monte Carlo method was used for analysis. The results demonstrated that increasing the number of layers using thin prepregs was found to be an effective method to mitigate not only the effect of fiber orientation errors, but also out-of-plane thermal deformation modes caused by non-uniform temperature distributions. Furthermore, it was found that the stacking sequence should be appropriately determined to reduce the effect of fiber orientation errors.
In this study we report an experimental research on the characteristics of combustion chamber in a solid propellant ducted rocket (SPDR) with a chin type inlet. Two kinds of propellants are tested, including boron-based solid propellant and hydrocarbon solid propellant. A new configuration of the SPDR with swirling flow is proposed. Effects on combustion characteristic of swirling flow, chamber length, propellant type and equivalence ratio are conducted. Results show that combustion efficiency based on temperature rise of the SPDR with swirling flow can reach 95%, which is 7% higher than the one without swirling flow. Furthermore, the swirler used in this study offers a significant effect on thermal protection. The combustion efficiency of hydrocarbon fuel-rich propellant is lower than that of boron-based fuel-rich propellant, and the SPDR using hydrocarbon propellant suffers from an ignition delay problem. When equivalence ratio decreases, combustion efficiency of the SPDR without swirling flow remains the same, whereas combustion efficiency of the SPDR with swirling flow increases first and then decreases.