MHD 추진에 관한 모델실험 = Model Experiment for MHD Propulsion

국문 초록 (Abstract)

영구자석(Nd\(_2\)Fe\(_{14}\)B)을 사용한 MHD 추진(Magnetohydrodynamic propulsion) 장치의 모델을 개발\(\cdot\)제작하여 전류와
염화나트륨 수용액의 농도변화에 따른 MHD 추진력을 조사하였다.
MHD 추진력을 조사하기 위하여 다양한 조건변화로 추진용 duct 내의 극판의 크기,
극판 사이의 거리, duct 양쪽의 자기장의 세기를 측정하여 최적의
MHD 추진장치인 소형 모형 선박의 구조를 결정하였다. 염화나트륨 수용액의 농도 및 극판 사이의
전류의 세기를 변화시키면서 모형선박의 이동거리와 시간을 측정하여 공급전압과 전류와의 관계,
추진력에 대한 이론값과 실험값의 비교, 평균속력도 조사하였다. 그 결과 전류세기 변화에 따라
MHD 추진력이 선형적으로 비례하여 변화하고, 염화나트륨 수용액 농도(농도변화 범위
3.5 \% $\sim$ 25 \%)가
증가함에 따라서 MHD 추진력은 차츰 감소하는 경향을 확인하였다.

다국어 초록 (Multilingual Abstract)

In this study, we made a small-scale magnetohydrodynamic
(MHD) thruster to investigate the characteristics of MHD propulsion in sodium chloride solution.
This thruster was made with a rare--earth permanent magnet Nd$_2$Fe$_{14}$B and platinum (Pt) electrodes in a sodium
chloride solution filled with dust. In order to investigate how the critical factors, $i.e$., the size of the electrodes,
the distance between electrodes, the magnetic fields of the rare-earth permanent magnet, the NaCl concentration,
and the electric current, affect the MHD propulsive force in the duct, we carried out extensive experiments for various
values for each factor. Using those results, we designed a MHD thruster and estimated the MHD propulsive force by
using a magnetic field of 4100 Gauss supplied by a rare-earth permanent magnet Nd$_2$ Fe$_{14}$ B and an electric field of 5200
V/m supplied by a DC power supply through the platinum(Pt) electrodes NaCl concentrations ranging from 10% to 25\%
and electric currents ranging from 1 A to 9 A in the duct. The strongest MHD propulsive force was found to be at a NaCl concentration of
25\%, an electric current of 9 A, when the mean velocity of the thruster ranged from to. Also, we discovered that the
MHD propulsive force increased as the applied electric-currents increased at each NaCl concentrations, and that there
was a greater difference between the experimental values and the theoretical values at high NaCl concentrations.
The mean value of the propulsive force we measured was smaller than the corresponding theoretical value by about 73.1\%.
The results obtained in this study can be provide useful data for a practical study of a large--scale MHD propulsive force.