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Old 02-21-2012, 06:21 AM
evolvingape evolvingape is offline
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Join Date: Dec 2011
Posts: 164
Turgo Turbine

The Turgo turbine is an impulse water turbine designed for medium head applications. Operational Turgo Turbines achieve efficiencies of about 87%. In factory and lab tests Turgo Turbines perform with efficiencies of up to 90%.

Developed in 1919 by Gilkes as a modification of the Pelton wheel, the Turgo has some advantages over Francis and Pelton designs for certain applications.
First, the runner is less expensive to make than a Pelton wheel. Second, it doesn't need an airtight housing like the Francis. Third, it has higher specific speed and can handle a greater flow than the same diameter Pelton wheel, leading to reduced generator and installation cost.

Turgos operate in a head range where the Francis and Pelton overlap. While many large Turgo installations exist, they are also popular for small hydro where low cost is very important. Like all turbines with nozzles, blockage by debris must be prevented for effective operation.

Theory of operation

The Turgo turbine is an impulse type turbine; water does not change pressure as it moves through the turbine blades. The water's potential energy is converted to kinetic energy with a nozzle. The high speed water jet is then directed on the turbine blades which deflect and reverse the flow. The resulting impulse spins the turbine runner, imparting energy to the turbine shaft. Water exits with very little energy. Turgo runners may have an efficiency of over 90%.

A Turgo runner looks like a Pelton runner split in half. For the same power, the Turgo runner is one half the diameter of the Pelton runner, and so twice the specific speed. The Turgo can handle a greater water flow than the Pelton because exiting water doesn't interfere with adjacent buckets.

The specific speed of Turgo runners is between the Francis and Pelton. Single or multiple nozzles can be used. Increasing the number of jets increases the specific speed of the runner by the square root of the number of jets (four jets yield twice the specific speed of one jet on the same turbine ).

Renewable Components - Manufacturers of MiniWind Downwind Domestic Turbines

These Turgo Cups are moulded in very durable Polycarbonate plastic, and are easily replaceable if they become worn or damaged.* Their design allows the user to create a wide range of wheel diameters, but we can supply a moulded plastic turgo disc of 260mm diameter (giving a jet PCD of 330mm) to match the performance of our 2200W PMG range of generators.

The design of our turgo discs gives a very robust mounting of the cups, allowing the completed turgo wheel to be used with up to 4 jets of 30mm diameter, giving powers from a few hundred watts to over 2200W.* The flexibility of this design allows the user to match the turgo turbine's performance to the available water head and flow rate.* Each plastic turgo disc takes 24 turgo cups.

Turgo turbines are generally more suited to lower head, higher flow rate applications than the pelton turbines, and typically your site will require a minimum head height of 10-15m to be effective.

Custom Turgo Turbines - better than a pelton.

3 Phase Brushless generators for MicroHydro

EcoInnovation - Pelton Spoons and Fixings

The Turgo Turbine, quite an interesting device. Let's see what we can learn from the available information...

The efficiency is good with operational turbines producing up to 87%, and controlled lab tests under optimum conditions producing 90%, and very similar to the Pelton Turbine. When you factor in the added simplicity of the spoon design, and the suitability of the Turgo to lower head (pressure) and higher mass flow rate (larger volume of water), this is the design that ticks more boxes.

“Increasing the number of jets increases the specific speed of the runner by the square root of the number of jets ( four jets yield twice the specific speed of one jet on the same turbine )”. This shows us that adding more jets is not necessarily a good idea, with diminishing returns, so a 2 jet per rotor design will stabilise and produce more torque per rotor at a slower speed, and we can compensate by adding more rotors and the extra jets can power them more efficiently, with a cost in specific speed of the drive shaft.

Minimum head height for effective operation of a Turgo is 10 – 15m, 10m of head = 1 Bar, 1 Bar = 14 psi, So a Turgo will need between 14 and 21 psi minimum to operate, which is well within the range of tap water, and you can increase the mass flow by turning on a second tap. The water company will sense a loss of pressure, and boost the pressure to your ring main to compensate, after a few weeks they will figure they have a leak and send someone to check it out, who will promptly go away scratching his head finding no leak anywhere!

260mm diameter is a large wheel according to this information, with a jet PCD (Pitch Centre Diameter) of 330mm. Ok, so now we know that, let's look at how we could build one of these as cheap as possible...
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