Improvement of disk MHD generator performance by inlet swirl

Yamasaki, Hiroyuki; Okuno, Yoshihiro; Torii, Syunsuke; Masuda, Junji; Tsutsumi, M.; Oda, Norihiko; Uchiyama, Kôhei; Kouka, H.; Fujimoto, Tetsuya; Suzuki, H.; e, al

doi:10.2514/6.1999-3658

Cited by 15 publications

(5 citation statements)

References 3 publications

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“…With the condition of SF =6.5×10 −4 and 9.5×10 −4 , the EE calculated here and the EE from Ref. [8] agree well. This suggests that the plasma is stable as discussed from the calculation in the case of T e implementing the seed complete ionization.…”

Section: Seed Fractionsupporting

confidence: 78%

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Analyses on the Ionization Instability of Non-Equilibrium Seeded Plasma in an MHD Generator

Kien

2016

Plasma Sci. Technol.

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Recently, closed cycle magnetohydrodynamic power generation system research has been focused on improving the isentropic efficiency and the enthalpy extraction ratio. By reducing the cross-section area ratio of the disk magnetohydrodynamic generator, it is believed that a high isentropic efficiency can be achieved with the same enthalpy extraction. In this study, the result relating to a plasma state which takes into account the ionization instability of non-equilibrium seeded plasma is added to the theoretical prediction of the relationship between enthalpy extraction and isentropic efficiency. As a result, the electron temperature which reaches the seed complete ionization state without the growth of ionization instability can be realized at a relatively high seed fraction condition. However, the upper limit of the power generation performance is suggested to remain lower than the value expected in the low seed fraction condition. It is also suggested that a higher power generation performance may be obtained by implementing the electron temperature range which reaches the seed complete ionization state at a low seed fraction.

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Section: Seed Fractionsupporting

confidence: 78%

“…3(a) are the experimental values refered to Ref. [8]. From the calculation results with the condition of SF =2×10 −4 shown in Fig.…”

Section: Seed Fractionmentioning

confidence: 98%

Analyses on the Ionization Instability of Non-Equilibrium Seeded Plasma in an MHD Generator

Kien

2016

Plasma Sci. Technol.

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“…Under such conditions, the electron density and electrical conductivity do not change abruptly with electron temperature, and the plasma is stable and homogeneous, as has been proven theoretically [1,2]. The effectiveness of such plasmas was also confirmed by experiments with strong MHD interaction; the enthalpy extraction ratio (ratio of electric output to thermal input) in shock-wave tube experiments has reached about 30%, while an isentropic (adiabatic) efficiency of about 55% was obtained despite a low magnetic flux density [3,4].…”

Section: Introductionmentioning

confidence: 48%

Numerical performance simulation of frozen helium plasma disk MHD generator

Kobayashi

Satou

Okuno

2002

Electrical Engineering Japan

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SUMMARYMHD electrical power generation with frozen helium plasma (FHP) is examined numerically. The FHP can be initiated by preionized helium without the alkali metal seed at the generator inlet. Since the three-body recombination coefficient of helium ions is low at electron temperatures above 5000 K, the ionization degree can be kept almost constant in the entire region of the generator channel. The r-θ two-dimensional numerical results show that the performance of the FHP MHD generator is comparable to that of the seeded plasma MHD generator, if the additional power consumed to preionization is ignored. In the FHP MHD generator, the ionization degree at the inlet should be controlled precisely, as well as the seed fraction in the seeded plasma MHD generator. Under an adequate inlet ionization degree for sustaining the FHP plasma, the plasma maintains the uniform structure. On the other hand, a slightly excess ionization degree causes a strong Lorentz force in the upstream region of the generator, deteriorating the generator performance.

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“…Enhanced mixing and flow recirculation were observed with the application of swirl, which was attributed to vortex breakdown. Yamasaki et al [7] experimentally studied the effects of inlet swirl on the performance of a disk magnetohydrodynamic (MHD) generator. Their experiments were carried out using a novel disk MHD generator with 24 swirl vanes installed in a large shock-tube-driven facility.…”

Section: Introductionmentioning

confidence: 99%

Effect of Swirl on Mixing in Underexpanded Supersonic Airflow

Abdelhafez

Gupta

2011

Journal of Propulsion and Power

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This study examines the effect of imparting swirl to underexpanded nozzle airflow on supersonic mixing under matched mass flow conditions. A convergent nozzle with swirling capabilities is used to generate the underexpanded airflow. Fuel is injected coaxially at the nozzle throat. Nonreacting conditions are considered, wherein fuel is simulated by mixtures of helium, argon, and krypton inert gases. It was found that the positive effect of swirl on supersonic mixing is noticeable, even at the low degree of swirl examined here. Better mixing was observed between the supersonic and subsonic parts of the diamond-shock air flowfield at no fuel injection as well as between the supersonic air and the subsonic injected fuel. The compressible mixing-layer thickness was found to increase slightly with swirl. However, when normalized to its incompressible counterpart, the compressible thickness was observed to decrease with swirl, because the former increases more with swirl than the latter. Decreasing the air-fuel relative Mach number and/or density ratio was found to deteriorate mixing. On the other hand, decreasing the compressibility of the injected fuel (i.e., injecting fuel at lower subsonic Mach numbers) improves mixing. Nomenclature a = speed of sound D = nozzle-exit diameter (11 mm) DR = air-fuel density ratio at injection plane M rel = air-fuel relative Mach number at injection plane S = swirl number v = velocity x = fuel-mixture fraction z = axial coordinate Subscripts a = axial t = tangential

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Improvement of disk MHD generator performance by inlet swirl

Cited by 15 publications

References 3 publications

Analyses on the Ionization Instability of Non-Equilibrium Seeded Plasma in an MHD Generator

Analyses on the Ionization Instability of Non-Equilibrium Seeded Plasma in an MHD Generator

Numerical performance simulation of frozen helium plasma disk MHD generator

Effect of Swirl on Mixing in Underexpanded Supersonic Airflow

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