Bài giảng Thiết kế tuabin pelton

Design of Pelton turbines When to use a Pelton turbine Energy conversion in a Pelton turbine Outlet Outlet of the runner Inlet of the runner Outlet of the needle Inlet of the needle 2 2 c Main dimensions for the Pelton runner The ideal Pelton runner Absolute velocity from nozzle: n1 Hg2c ⋅⋅= 1 Hg2 c c n 1 1 = ⋅⋅ = Circumferential speed: n u1 1 Hg2 2 1 2 c u ⋅⋅⋅== 5.0u 1 = Euler`s turbine equation: )cucu(2 u22u11h ⋅−⋅=η 1)05,00.15,0(2)(2 2211 =⋅−⋅⋅=⋅−⋅⋅= uuh cucu η 1c u1 = 0c 2u = The real Pelton runner • For a real Pelton runner there will always be losses. We will therefore set the hydraulic efficiency to: 96.0 h =η The absolute velocity from the nozzle will be: 995.0c99.0 u1 <≤ C 1u can be set to 1,0 when dimensioning the turbine. This gives us: )cucu(2 u22u11h ⋅−⋅=η ⇓ 48,0 0,12 96,0 c2 u u1 n 1 = ⋅ = ⋅ η = From continuity equation: u1 2 s c 4 d zQ ⋅ ⋅π ⋅= ⇓ u1 s cz Q4 d ⋅π⋅ ⋅ = Where: Z = number of nozzles Q = flow rate C 1u = n Hg2 ⋅⋅ The size of the bucket and number of nozzles 4.3 d B 1.3 s ≥> Rules of thumb: B = 3,1 · d s 1 nozzle B = 3,2 · d s 2 nozzles B = 3,3 · d s 4-5 nozzles B > 3,3 · d s 6 nozzles Number of buckets 17 ≥ z empirical [...]... water will be lost is for very high head Pelton Speed number Ω = ω Q⋅z 2 2 π ⋅ ds π ⋅ ds Q= ⋅ c1u = 4 4 c1u = 1,0 u1 = 0,5 2 ⋅ g ⋅ Hn ω 2 ⋅ u1 1 ω= = = = 2 ⋅ g ⋅ Hn D ⋅ 2 ⋅ g ⋅ Hn D ⋅ 2 ⋅ g ⋅ Hn D 2 1 π ⋅ ds ⋅ z Ω = ω⋅ Q ⋅ z = ⋅ D 4 ds Ω= D π⋅z 4 For the diameter: and one nozzle: ds Ω= D D = 10 · ds z=1 π ⋅ z 1 π ⋅1 = = 0,09 4 10 4 The maximum speed number for a Pelton turbine with one nozzle is Ω = 0,09... speed number for a Pelton turbine with one nozzle is Ω = 0,09 For the diameter: and six nozzle: ds Ω= D D = 10 · ds z=6 π⋅z 1 π⋅6 = = 0,22 4 10 4 The maximum speed number for a Pelton turbine today is Ω = 0,22 Dimensioning of a Pelton turbine 1 The flow rate and head are given *H = 1130 m *Q = 28,5 m3/s *P = 288 MW 2 Choose reduced values c1u = 1 u1 = 0,48 3 ⇒ ⇒ c1u = 149 m/s u1 = 71 m/s Choose the number . Design of Pelton turbines When to use a Pelton turbine Energy conversion in a Pelton turbine Outlet Outlet of the runner. number for a Pelton turbine today is Ω = 0,22 The maximum speed number for a Pelton turbine with one nozzle is Ω = 0,09 Dimensioning of a Pelton turbine