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Turgo Turbine
Brief description
The Turgo turbine is an impulse water turbine designed for medium hydraulic heads (typically 15 to 300 meters). Modified from the Pelton wheel, the Turgo turbine directs a high-velocity jet of water at an angle (usually 20 degrees) into one side of the runner buckets, allowing the water to exit from the opposite side. This side-entry design enables a higher volume of water flow for a runner of the same diameter compared to a Pelton wheel, achieving higher rotational speeds for direct coupling to generators.
Use / Function
- Primary use: Generating medium-to-large-scale hydroelectric power in mountain streams and rivers with medium head and fluctuating water flow.
- Secondary uses: Direct mechanical power production for remote mechanical mills or water pumping stations.
- Scale: Small-to-medium installations (from low-kilowatt micro-hydro systems up to multi-megawatt regional power stations).
Operating principle
Angled Impulse Jet and Continuous Flow-Through:
- High-Velocity Nozzle: Water under high pressure from a penstock passes through one or more adjustable spear nozzles, converting hydraulic pressure into a high-speed free jet.
- Angled Side Impact: The jet strikes the curved runner blades at an oblique angle (typically 20°), transferring impulse energy to the runner shaft.
- Unobstructed Exit: Water flows across the single-curved bucket profile and exits on the opposite side without interfering with adjacent incoming water jets.
- Direct High-Speed Rotation: Because the runner can handle larger water flow volumes relative to its size, it rotates faster than a comparable Pelton wheel, often eliminating the need for step-up speed gearboxes.
How to create it
1. Runner and Bucket Fabrication
- Cast or machine individual runner buckets from corrosion-resistant Bronze or Steel using a asymmetrical curved profile with a single entry edge and an angled exit rim.
- Fabricate a central runner hub out of forged carbon Steel.
- Weld or bolt the buckets securely around the perimeter of the hub at the design angle.
2. Nozzle and Needle Mechanism
- Machine a tapered nozzle housing out of Cast Iron or steel.
- Craft an internal needle valve (spear) mounted on a threaded control rod to regulate nozzle aperture and water velocity.
3. Casing and Shaft Assembly
- Mount the runner on a heavy-duty Steel shaft supported by sealed bearings.
- Enclose the runner in a steel or cast-iron splash housing with a bottom discharge chute to guide spent water back into the tailrace.
Materials needed
- Runner Buckets & Hub: Bronze, stainless steel, or high-strength Steel.
- Housing & Nozzles: Cast Iron or structural steel plate.
- Shaft & Bearings: Forged steel shafting and heavy-duty roller bearings.
- Working Fluid: High-velocity Water delivered under medium head pressure.
Variants and improvements
- Multi-Nozzle Turgo: Utilizes two to four nozzles positioned around the runner perimeter to increase power output and flow capacity.
- Horizontal vs. Vertical Axis: Horizontal layout for simpler installation and maintenance; vertical shaft layout for multi-nozzle high-capacity plants.
- Micro-Hydro Turgo: Scaled-down simplified units with cast polyurethane or aluminum buckets for off-grid rural electrification.
Limits and risks
- Abrasion from Silt: High-velocity water jets carrying sand or silt cause accelerated erosion on the nozzle tip and bucket surfaces.
- Jet Alignment Criticality: Minor misalignments in the jet entrance angle significantly drop mechanical efficiency.
- Impulse Free-Discharge: Requires a atmospheric air cavity in the housing; cannot operate fully submerged under tailwater.