12:15
277 6.6.5 1), 2), 3), 4) ονομαστικά
277 6.6.6 1), 2), 3)
ΣΕΛ 89 3.4.1 1), 2), 3), 4)
ΘΕΜΑ Γ
Γ1
ΣΕΛ 153 5.3.4 Η ελλειπτική
Γ2
z=8
VH=12,56m³
D=100cm=1m
ω=9,42 rps
s, ce
α)
A = πD²/4 = 3,14·1²/4 = 3,14/4 = 314/400 = 0,785m²
VH = z·Vh → 12,56 = 8·Vh → Vh = 12,56/8 = 1256/800 = 1,57m³
Vh = A·s → 1,57 = 0,785·s → s = 1,57/0,785 = 1570/785 = 2m
β)
ω=π·n/30 → 9,42=3,14·n/30 → 9,42·30=3,14·n→ n = 9,42·30/3,14 = 3·30 = 90rpm
ce=s*n/30=2*90/30=180/30=6m/s
ΘΕΜΑ Δ
κ=2
Ni=75000KW
Nr=15000KW
pi=25bar
m’ B=3kg/s
ηe=0,5
ω=10rps
α) Ne σε KW
β) pe σε bar
γ) Θu σε KJ/kg
δ) Md σε KWm
ε) VH σε m³
α) Ne = Ni - Nr → Ne = 75000 - 15000 = 60000KW
β) ηm = Ne/Ni = 60000/75000 = 60/75 = 0,8 = 80%
ηm = Pe/Pi → 0,8 = Pe/25 → Pe = 0,8·25 → Pe = 20bar
γ) ηe = Ne/(m’ B·Θu) → 0,5 = 60000/(3· Θu) → 0,5 = 20000/Θu→ Θu·0,5 = 20000
→ Θu = 20000/0,5 = 200000/5 = 40000 KJ/kg
δ) Md = Ne/ω = 60000/10 = 6000KNm
ε) Pe = (π·k·Md)/VH → 20·10⁵ = (3,14·2·6000·10³)/VH → 20·10⁵ VH = 3,14·2·6000·10³
→ VH = (3,14·2·6000·10³)/(20·10⁵) = (3,14·2·6000)/(20·102)=(3,14·2·6000)/(20·100) = =3,14·2·3= 18,84m³