Dynamic wind tunnel testing is an important method to obtain aerodynamic characteristics of an aircraft. In this study, an experimental system for longitudinal dynamic force measurement is designed. A set of static and dynamic force measurement of a model aircraft is conducted using this system. Aerodynamic characteristics of the test model including dynamic stability coefficients were obtained from the results. Finally, dynamic wind tunnel system was coupled with 1DoF flight simulator. The amplitude and the frequency of the dynamic motion of the model aircraft was simulated successfully by the current system.
For the improvement of the performance of a miniature microwave discharge neutralizer, the dependencies of the performance of a neutralizer on the microwave frequency, magnetic field strength, antenna length among other factors were investigated. Extracted electron current strongly depends on magnetic field strength and microwave frequency, and the optimal magnetic field depends on the operational condition. Overall, extracted electron current was achieved 19mA at xenon mass flow rate of 5μg/s, incident microwave power of 2W and collector applied voltage of 30V. The demonstrated performance is enough for practical use as a 30W class microwave discharge ion engine for 50kg class satellites.
In this study, we aim to enhance the deflagration-to-detonation transition (DDT) using a newly developed matrix hole (MH)--type device that provides intermittent flame jets. The MH-type device consists of two parts: a guide section for accelerating flame propagation and an effective section with multiple orifices for projecting intermittent flame jets. The effects of the lengths of the guide- and effective sections, and the orifice diameter on DDT were studied experimentally using a stoichiometric hydrogen--air mixture as a test gas. The results show that varying the orifice diameter while maintaining a constant blockage ratio has no significant influence on DDT. Among the various MH-type device construction parameters, the optimum guide section length leads to the minimum DDT distance. For the condition considered herein, the DDT time achieved with the developed device is 16% lower than that achieved with the optimized Shchelkin spiral, but the DDT distance is 22% more. Visualization of the DDT process using the MH-type device reveals that detonation first occurs inside the device, followed by the initiation of detonation outside the device.
Humidity in working fluid affects on supersonic flow properties. The paper is to evaluate the flow quality of the indraft supersonic wind tunnel of Muroran Institute of Technology against moisture. The static pressure fluctuation is measured by means of an unsteady pressure sensor buried in the model of 10 degree aperture cone model installed in the test section. Results show that supersonic flow at Mach 2 is contaminated by self-sustained oscillation of condensation shock wave in case of relative humidity more than approximately 50%. It is also shown that static-pressure fluctuation to the dynamic pressure below a critical point with an absolute humidity 2[g/cm3] is attained below 0.1% in Mach 2 flow. Under atmospheric conditions between absolute humidity 2[g/cm3] and 6[g/cm3], static-pressure fluctuations may increase in the frequency range of 1--30[kHz] due to phase change of minute ice particles generated in the supersonic nozzle. Experimental observations on three-dimensional boundary-layer transition hypersensitive to free-stream humidity are exemplified.
The space elevator construction begins with its initial cable deployment. In this paper, the feasibility of the space elevator initial cable deployment system is investigated through numerical system analysis. During the initial cable deployment, the orbit of the space elevator must be controlled to be geostationary to avoid any conflict with other GEO satellites. This orbital control becomes the constraint to determine the total mass of the initial cable deployment system and the required time to complete the full cable deployment. Through the system analysis assuming the use of the ion thruster or bipropellant thruster, it is found that the total fuel for the orbital control decreases as the main satellite mass increases. It is also found that the main satellite mass has the optimum value to minimize the total mass in the case of the bipropellant thruster. As the initial cable does not have sufficient strength and survivability against debris, its deployment time should be minimized. The deployment time analysis has clarified it is possible to complete the full deployment of the initial cable in about 5 days in both the ion and bipropellant thruster cases. The feasible configuration of the initial cable deployment system is clearly presented.