Electrical Characteristics of Magnetohydrodynamic-Generator Sidewalls with Segmented Z-Bar Design

The electrical characteristics of segmented Z-bar insulator walls for magnetohydrodynamic power generators havebeeninvestigated.Experimentswerecarriedout,usinga20-MW (thermalinput )powergenerator,tocompare the performance of the Z-bar sidewall design to that of the conventional straight-bar cone guration. Electrical properties were measured for clean-fuel (bare-wall) and simulated coal-e red (slagged-wall ) test conditions. The Z-bar sidewall design was found to be superior for its ability to adjust to varying generator load and operating conditions. Thewear-inducing electricalstressesweremuch lower and moreuniformly distributed in the Z-shaped cone guration than in the straight-bar design. The effects of bar segmentation on the interbar voltage and fault power distributions were also studied. The selection of sidewall design for several recent power generators was based in part on the results of this study. Nomenclature E = electric e eld intensity, V/m Ex = axial electric e eld intensity, V/m Ey = Faraday e eld intensity, V/m Eyc = value of Ey in the core e ow region, V/m Ie = electrode current, A Isc = interbar short-circuit current, A Novlp = number of overlapped electrodes VHall = Hall voltage of generator, V