Experimental investigation of a large-scale paste-cooled MHD channel

The results are given of experimental investigations of the continuous-elec trode channel of a pulsed Faraday MHD generator of the Pamir type [1-4]. In the channel, the most heat-stressed inlet section is paste-cooled. The cha nnel may be readily disassembled, which enables one to exchange the structu res of both electrode and insulating walls during the runs with a view to i nvestigating the effect of the structure on the power performance. The runs are performed with a solid-fuel plasma generator (with the pressure and te mperature in the combustor of similar to 4.5 MPa and 3750 K) in different m odes, namely, with applied electric field in order to determine the electri cal conductivity of the working medium and the effect of the injection of d ecomposition products on the electrical conductivity, and in modes with ind uced field (independent excitation and self-excitation with reaching the ex treme operating mode such as short-circuiting) in order to compare the powe r performance of the channel for different techniques of injection and remo val of the cooling agent decomposition products. A sublimating pastelike co oling agent on the basis of ammonium oxalate is used. It is demonstrated th at the injection of the products of decomposition of cooling agent on the i nsulating walls has no effect on the power performance of the channel. The experiments have revealed a high resistance and desired insulating properti es of paste-cooled structures under conditions of repeated operation, as we ll as the agreement in the power performance between paste-cooled and uncoo led channels. The obtained results point to the possibility of developing p aste-cooled channels of pulsed MHD generators.