Vol.2,
No 7/2, 1997 pp. 341 - 352
UDC: 532: 62-828;
532.51: 532.513
A NEW
APPROACH TO THE EVALUATION OF FRICTION AND SEPARATION LOSSES IN DUCTS
Vladan D. Đorđević*, Vladimir
Raičević**, Milorad Tankosić***
*Faculty of Mechanical Engineering,
University of Belgrade
**Faculty of Mechanical Engineering,
University of Priština
***Higher School of Mechanical Engineering,
Zemun
Abstract. Extended Bernoulli
equation and energy equation for a finite fluid volume are derived in the
paper and applied for fluid flow in ducts. It is shown that both friction
and separation losses can be uniquely expressed in terms of the dissipation
function. Consequently, they can be exactly evaluated in all cases in which
the dissipation function is known, like in laminar and turbulent flow in
pipes. In complicated 3-D flows, usually present in most of separation
losses, method presented accurately predicts the structure of losses and
enables a relatively simple fitting with experiments, as it is shown in
the paper on the example of flow through branched ducts.
JEDAN
NOVI PRISTUP IZRAČUNAVANJU GUBITAKA ENERGIJE
U CEVIMA
U ovom radu su izvedene proširena Bernulijeva
jednačina i jednačina energije za konačnu zapreminu fluida i primenjene
su za strujanje fluida u cevima. Pokazano je da su gubici kako usled trenja
tako i usled odvajanja mogu se jedinstveno izraziti u obliku funkcije disipacije.
Shodno tome, oni se mogu tačno oceniti u svim slučajevima u kojima je funkcija
disipacija poznata, slično laminarnim i turbulentnim strujanjima u cevima.
U složenim trodimenzionalnim strujanjima, koji se javljaju kod većine gubitaka
usled odvajanja, metod koji je predstavljen, tačno predviđa strukturu gubitaka
i omogućava relativno jednostavno poklapanje sa eksperimentalnim rezultatima,
kako je prikazano u radu na primeru strujanja kroz cevi koje se granaju.
