Nitrogen and helium was injected from various geometry injectors to a Mach 2.5 airstream to simulate ethylene fuel and hydrogen fuel injection in a supersonic combustor. Penetration height and mass fraction of nitrogen and helium were compared after normalizing for fair comparison. Penetration height was normalized with a length scale, which took the difference in mass flow rate at equivalence ratio of unity for different gases into account. On the other hand, mass fraction was converted into local equivalence ratio. When a circular injector was used, penetration height of nitrogen plume decreased by 40% in comparison with that of helium. So-called stinger shaped injector had high penetration than the circular injector in the condition of low dynamic pressure ratio for both gases. Penetration height of nitrogen plume from the stinger shaped injector was lower than that of helium plume and the maximum value of local equivalence ratio in case with nitrogen injection was higher than that in case with helium injection. And there was not much different in growth of penetration height and attenuation of maximum equivalence ratio between the case of nitrogen injection and helium injection.
Flight control of quad rotor UAVs has been studied by a number of research groups. However, a reason for the stable flight of quad rotor UAVs has not been revealed yet. In the present paper, advantages of quad rotor UAVs against a single rotor helicopter are discussed. In the analysis, their weights are assumed to be same. When they encounter a side wind gust, the effect of the gust on the motion of the quad rotor UAVs is smaller than that on the single rotor helicopter. This is a big advantage of the quad rotor UAVs against the single rotor helicopters.
About half of airliner accidents in Japan occurred in the decade between 2003 and 2012 is related to air turbulence. To contribute flight safety, JAXA proceeds with development of an airborne Doppler LIDAR (Light Detection and Ranging) that can detect air turbulence in clear weather condition. Even if the Doppler LIDAR has an enough observation range on the ground, its observation range comes to be shortened at high altitude, because the intensity of scattered laser light is low due to the low density of aerosol particles. The JAXA's newest model of LIDAR has a capability to observe air turbulence at a distance of more than 30km on the ground. The LIDAR was installed on a jet aircraft and the observation capability was evaluated at high altitude. Consequently, the observation range of more than 9km was verified. Development of the LIDAR and the test result are explained.
This paper presents development of a simulator for orbital missions to transfer unmanned orbital cargo to the International Space Station (ISS). In the missions, capture in enclosed region is adopted as grasping mechanism. Since this capturing method is safer and more reliable in space, future orbital missions will adopt this method. However, it is still necessary to analyze and ensure the safe capturing operation in advance. Therefore, the simulation on ground is definitely required for not only behavior analysis of the capturing of the orbital target but also verification of contingencies and their avoidance methods. In this paper, we construct a hybrid motion simulator for the mission to capture the H-II Transfer Vehicle (HTV). Then we simulate several cases of accidental capturing at the HTV mission and analyze the results.
The microwave ion thruster μ10's ion beam current saturated at a large mass flow rate when propellant gas was injected from a waveguide inlet and it was improved by additional propellant inlets to a discharge chamber. In order to understand the mechanism of these phenomena, it is important to measure distributions of the microwave electric field inside the discharge chamber, which is directly related to plasma production. In this study, we applied an electro-optic (EO) probe to measuring the microwave electric field. The probe contains no metal and can be accessed in the discharge chamber with less disruption to the microwave distribution. We measured electric-field profiles along the centerline and in the ECR area of μ10 with the EO probe. Consequently, this paper revealed that when the propellant was injected from the waveguide inlet, microwave was reflected in the waveguide at large mass flow rate, which disturbed a propagation of microwave to the ECR area. It also revealed that when the propellant was injected from the discharge chamber inlet, the mass flow rate where the microwave reflection occurred shifted to larger rate, which resulted in the increase of the beam current．