Electronic edition ISSN 1574-0579

Numerical results of calculations for a number of variants of conductive MHD pumps

Yu. A. Birzvalk - I. N. Mikryukova

Institute of Physics, Latvian Academy of Sciences, Salaspils-1, LV-2169, Latvia

Abstract
It is shown by results of a number of numerical calculations that a pump, optimized with respect to efficiency, does not, in the general case, have a maximum in efficiency at the rated point p=p_n, Q=Q_n of the pQ plane. Conventionally we call a pump for which η = η_max in the m-dimensional space of variable parameters (independent variables) α₁α₂,... ,α_m for a given p = p_n, Q = Q_n a pump of type A, and a pump for which, besides this requirement, we have in addition ∂η/∂|_p=pn=0, ∂η/∂Q|_Q=Qn=O a pump of type B. Then in general η_max A > η_{max B}, but with an increase in the rated current supply this difference diminishes. However, in terms of other characteristics - current supply and weight - a pump of type A can be superior to one of type B by 10-40%. Theoretically η_{max A} ≥ η_{max B}, but in the power range under consideration and under the assumed conditions (I = const, G = const) the equality sign practically never occurs. Limitations on I and G do not preclude the design of a pump with acceptable efficiency, but a pump of type B cannot be constructed.