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The objective of this study is to improve the performance of the sensitivity-adjustable three component force balance developed in the previous study for the usage of various experimental conditions. In the present study, balance shape is modified from the previous oval-shape to hexagonal-shape. First, the strain distribution for three kinds of balance shapes is deduced by FEM analysis to decide the strain gauge paste positions and the validity is confirmed by force balance calibration. Then, the characteristics of the sensitivity adjustability are investigated by FEM analysis and force balance calibration for various kinds of balance shapes. Finally, a hexagonal force balance is designed and applied to the wind tunnel experiment in a supersonic flow condition which is one of the severe experimental conditions. As a result, the use of hexagonal-shape enables us to improve the measurement accuracy because to paste strain gauges on appropriate positions is much easier for hexagonal-shape than for oval-shape. In addition, we can adjust the sensitivity ratio more extensively for hexagonal-shape than for oval-shape. The designed hexagonal force balance can measure aerodynamic forces in a supersonic flow condition. In conclusion, we can improve the performance of the sensitivity-adjustable three component force balance by the use of hexagonal-shape and apply to a supersonic wind tunnel experiment. In future, force balance calibration to investigate dynamic characteristics is required for a supersonic wind tunnel experiment.

The objectives of the present study are to obtain unsteady pressure distributions on a freely oscillating body and to examine its relation with the body motion. In the present experiment, a low speed wind tunnel was used, where the exit was directed in a vertical direction. The shape of the model is similar to a Chinese pan with a diameter of 480mm. This experiment was performed at two flow velocities: 10m/s and 20m/s, and the model was suspended from a bar above the wind tunnel exit. The model was freely oscillated in the wind tunnel flow under the gravity and aerodynamic forces. The amplitude of this oscillation was damped due to the aerodynamic forces. The pressure distributions on the body were successfully measured, which clarified the damping mechanism of the body motion. To compare with the experimental result, the unsteady numerical calculations were also performed with the boundary element method.

Numerical prediction of a steady intake airflow was performed with an unstructured grid. Changing surface rougheness and configuration of an intakeport, airflow rate and velocity vectors were calculated. Comparing the calculated results with the experimental ones by LDV measurements, the accuracy was evaluated. It was found that airflow rate can be predicted with the accuracy of 5 percent, and the predicted velocities, especially in the intakeport, agreed with the measured ones. The predicted airjets at the valve annular passage were slower than the experimental ones. The application of the standard k-e turbulence model to the airjet at the valve passage was found to be an essential factor for the discrepancy.

The purpose of the research is to clarify the generation mechanism of precursor electrons ahead of a hypersonic shock wave in argon. The triple-probe measurements and radiation measurements are carried out using a hypersonic shock tube. Theoretical analysis is also carried out using a one-dimensional photoionization model. The triple-probe measurements show that the electron temperature is almost uniform ahead of the shock wave and ranges from 5000 to 11000 K. In contrast to the electron temperature, the electron density increases exponentially as approaching the shock wave and lies between 1015 and 1017 m-3. These results show that considerable electrons exist in the region ahead of the shock wave. From the radiation measurements, argon ions are found to emit radiation in the region ahead of the shock wave, showing that argon ions are generated from argon atoms by photoionization. The behavior of electron temperature and density is well accounted for by the one-dimensional photoionization model with an assumption of photoionization as the primary ionization process ahead of the shock wave. In conclusion, precursor electrons are mainly generated by photoionization, making use of the radiation energy behind the shock wave.

A method of motion reconstruction from a image streak taken by a single video camera, and a procedure to calculate aerodynamic force and moment from the motion are proposed. In this method the motion of an object is separately measured with translational and rotational motion. For the translational motion, the size and its location of a moving object is used to get the instantaneous position of the object. For the rotational motion, the attitude of the object is calculated by tracking featured points on the object. In addition to accomplish the aerodynamic measurement by this method, an evaluation was done for the measurement errors in the aerodynamic force, which are caused from image distortion by aberration of a lens. A series of the experiments for the flying ball showed the validity of the proposed method and the aerodynamic characteristics of the flying ball were analyzed using this method.