Question

6.39 Design a rotating lawn sprinkler to deliver 0.25 in. of water per hour over a circle of 50 ft radius. Make the simplifying assumptions that the pressure to the sprinkler is 50 psig and that frictional effects involving the flow of water through the sprinkler flow passages are negligible (the Bernoulli equation is applicable). However, do not neglect the friction between the rotating element and the fixed base of the sprinkler.

Answer 1

Solution Determine the area of the CİYcleYonhng awin SPrinkler using the Pormola 너 Hene d s the dmte the cirele Substi tute 5oft ey d 116 3.5o t 关Convent inch opeet Ceent the dischange rate Prom heur to Conven e con the dischange using the formula schanje ㅊ DetW mine Hene h is the ate of deliven and A is of the ciycle

2. Substitve 463 5oftt Por A. and u inch 2. * There enovgh Preu avai ble for the desi , but thenewill Some lesse fo aflet the design the g i Prakicle will Frodc dag lets when the waten Cmenege Pom the head he dvep lets yedeced «diJtance thajey and the size of drop lets Course) the Smallen Size dxeplets tyave smaldiyance and agen size dvop lets avel lange distanie Considen ho lose and the Sprinklen head, wovld give and exit velocity at he a Convet the pressure yom si -Jape Pound Pen Svulk betuween the sopply Preuve

Determine he velocity vsing the Pamta Here preure o the SPrinklen ond p is the density f water Sebstitote So Psi-gape The wate wee o extthe Sprinkler head at the angle Por distonte laveledt or the oftimom yae the waten can be caed vSing the Pormula Hene.5 s the ditane lyoveked by the wate is the Vdoci ty。RExit. and g is the accelanation due o gavity

The Velecity is heceny fav a distanie2s Peet diskance Cius he yoluting ciyde Detemine the veloity Exit using the abave oclty is hece al ad egn Ve 295 610 4oft/s 2 *The Sprinklen headcn be set in motien dve ot Yepect othe Tadius the ciydle ed C he Wate exit at ca anle with NC *Consde the asm of the Sprinkle iswinchg an d the ane Tf dePlechion at the ond s l degree Detomine the tovgve usin the yelution emin e USing 2 latio Heepis the density the wahe , dischange and V.. s the Velecity f exie e, s the

Sobst ote44su r , o.ol P+/s Jo ve' and x Dete mine the dohwand eod acking onhis head due to the dischang the haten s Cealculated vsing the Parmula V.sin : Ι.qu Xo.01' Χ4c x take ya ding the pipe is%ỉnch ohvent inch to Pect The mmen vevvired to overcome the fricon on a lat Plate yotating on another i S

Detmine the coefficent of Prichion using the ahve e lation HueCeeficent ichon is a Yadies the plate and downisald Pore is n Substitute ¼nch.eov' Vo. O.lu,FYnf.A 6oft 사 to get o -143 1 2 0.444 0、050 Thus the Coefficent icon lve is 3.83