🌊 Francis & Kaplan Turbine Cavitation Sizer
Calculate Francis and Kaplan reaction turbine cavitation limits: Thoma critical cavitation coefficient sigma, metric specific speed nq, and maximum setting height above tailwater.
⚡ Fortran 90 Engine
Double Precision (IEEE 754)
✓ ISO / ASME Validated
📊 Solver Telemetry
● ACTIVE
👁️ Consultations
36
⚡ Calculs faits
32
💾 Téléchargements
354
📦 Code Fortran
5.2 KB
📅 Mise en service
Jun 2026
⏱️ Latence
< 1 ms
🌊 Reaction Turbine Runner, Draft Tube & Tailwater Elevation
Real-time visual simulation: Runner elevation setting zs relative to tailwater level to avoid cavitation📝 Configuration & Presets
🏔️ Medium-Head Francis (85m)
⚡ Pumped-Storage (220m)
🏞️ River Kaplan (18m)
🌊 Bulb Tidal Turbine (6.5m)
Thoma Cavitation & Setting Height Formulation:
• Metric Specific Speed: nq = N · √Q / Hnet0.75 [rpm]
• Thoma Critical Coeff: σc = 0.0437·(nq/100)1.64 + 0.015 (Francis)
• Permissible Setting Height: zs = (Hatm − Hvap) − σc·Hnet − 0.50 [m]
• If zs < 0: Powerhouse runner must be submerged below tailwater.
• Metric Specific Speed: nq = N · √Q / Hnet0.75 [rpm]
• Thoma Critical Coeff: σc = 0.0437·(nq/100)1.64 + 0.015 (Francis)
• Permissible Setting Height: zs = (Hatm − Hvap) − σc·Hnet − 0.50 [m]
• If zs < 0: Powerhouse runner must be submerged below tailwater.
📊 Performance Results
Configure inputs and click Compute to view results.
📘 Calculation Methodology & Hydro Cavitation Standards
Thoma Cavitation Parameter ($\sigma$)
Cavitation occurs when local pressure on the suction side of runner blades drops below vapor pressure $P_v$. The Thoma parameter $\sigma_c$ links dynamic pressure depressions to the net head $H_{net}$.
Setting Height ($z_s$) & Submergence
If $z_s < 0$, the runner must be excavated and placed below the downstream tailwater canal level to provide positive static suction head against cavitation pitting and vibrations.
Key Engineering Assumptions
- IEC 60193 / USBR Monograph empirical cavitation coefficients.
- Atmospheric barometric pressure correction for powerhouse altitude.
- Widely used in hydroelectric dam powerhouse design and pumped storage plants.