Проблема использования энергии ветра. Ч. 4 : Теория и аэродинамический расчет ветряных двигателей

— 68 — 1. е. Solution of Ше two last equation gives the relation (11) l + y From the equation of discharge and expression (11) there is obtained = • (14) The mass of fluid carried away is found to be mi +/«2 = does not depend on the working regime of the windmill. The load on the disc area of the windmill B' b. V Efficiency For there is obtained 4 =/ 2 - 1 ^ „ „ - 2 ( 2 - K 2 > = 0,687. (20) ) In Fig. 5 are plotted t h e values of B ' and ^ of . In the same figure b y short dashes is shown t he value of B' calculated on the old theories which ignored the attached mass. The dotted lines whose experimental values of t he function taken from the paper of H. Glauert (R & M N o 1067), In chapter II is given tlie theory of real windmill. The relation between the forces acting on blade elements (Fig. 6) and t he Increase in t he momentum of an elementary annular current is given b y two equations of continuity (21) and (<40) the projections of t he forces of t he axis of t he windmill give Inrdr^Vv^ = i[bdr C^pW^ cos ^ + bdrC j s i n P) ( 24 and the moment of the forces about t he axis of t he windmill 2r:rdr^V • 2Uxr ~i(bdrC,jpW^ ?>h\^ — bdr (40a) From (24) and (40a) is found the width of the blade ih ' ^ C y ' ( 1 - 1 - e ) ( - • ( ^ 2 ) The torque- developed by an elementary windmill . (35) Efficiency 1 (J' 1 — e •'