fluid mechanic interface in a francis runner turbine · fluid mechanic interface in a francis...
TRANSCRIPT
Fluid Mechanic Interface
in a Francis Runner Turbine
A Case Study
Michelle de Abreu
Andritz Hydro Inepar
Araraquara – SP
PRESENTATION TOPICS
• Company Overview;
• Problem Description
• Hydraulic design on the Blade Runner Turbine
• Structural and Modal Analysis
• Methodology;
• Goals;
• Conclusion and next steps.
Andritz Hydro Overview
• Global supplier for
hydropower plants:
– Hydraulic systems
– Mechanical systems
– Services and
– Electrical systems
“From water to wire”
• Areas of Competence:
– Large new installations
– Compact hydropower
– Modernization and rehab
• A leader in world market
hydro power generation
Geometry and Meshing
• Runner - Total Blades: 13
• 1 Blade modeled
• ASTM A 743 CA6NM
(12%Chromium 4%Nickel)
Sy = 550 MPa; Su = 755 MPa
Crown
Band
Blades
Load Cases and Boundary Conditions
• Runaway Speed
n = 26,7 rad/s
No pressure
• Normal Operation (Hmax – Pmax)
n = 14,5 rad/s
Hydraulic Load Pressure
Radial Gap – Crown and Band
Crown – radial gap = 3,7 / 2 = 1,85 mm – máx.
3,1 / 2 = 1,55 mm – mín
Band – radial gap = 3,28 / 2 = 1,64 mm – máx.
2,68 / 2 = 1,34 mm – mín.
Crown
Band
Von Mises Stress – Normal Operation
Normal Operation (Hmax-Pmax)
• Maximum Von Mises Stress:
81,14 MPa
• Allowable Stress:
150 MPa
Von Mises Stress – Normal Operation
Maximum Von Mises
Stress: 53 MPa
All. Stress - Crown: 175 MPa
All. Stress - Band: 125 MPa
Normal Operation
(Hmax-Pmax)
Von Mises Stress - Runaway
Runaway • Maximum Von Mises Stress: 174,4 MPa
• Allowable Stress: Sm/2 = 755/2 = 377 MPa
Modal Analysis in Water
Natural frequencies and the corresponding mode
shapes (nodal diameter modes ND)
ND is a line on a structure that does not move while the rest
of the structure is vibrating.
ND= i.z2 - z0 = 2
NDmax = (z2 - 1) / 2 = 6,
the maximum number
of ND-modes.
ND<=NDmax
z2= number of runner blade = 13
z0= number of guide vane = 24
Coarse mesh without fillets
Cilinder – Element Fluid (Fluid 221)
Runner – Element Solid
Modal Analysis in Water
Excitation Frequency (fe)
fe = fn / 60 x z0 = 55,44 Hz
n =138.46 rpm;
f = 138.46 / 60 = 2.31 Hz
SF = +/- 15%
The natural frequency does
not be included between:
47.07 and 63.69 Hz.
The result ND=2 is the Mode 4
Natural Frequency = 18,8Hz