Fluid connection for a hydromotive machine

A pump-turbine assembly comprising:

• a reversible pump-turbine having a pump inlet that is coaxial with a pump outlet, a direction of flow into the pump inlet being opposite a direction of flow out of the pump outlet;
• and
• a fluid connection comprising:
• a first duct extending from a first end of the first duct to a second end of the first duct, the first duct including a mid-portion between the first end of the first duct and the second end of the first duct that has a non-circular cross-section, the first duct having a substantially circular cross-section at the first end of the first duct and a substantially circular cross-section at the second end of the first duct, and
• a second duct extending from a first end of the second duct to a second end of the second duct, the second end of the first duct being wholly within the second end of the second duct, the first end of the second duct being wholly outside of the first duct, the second end of the second duct being coaxial with the second end of the first duct;
• in which the second end of the first duct is coupled to the pump inlet of the reversible pump-turbine and in which the second end of the second duct is coupled to the pump outlet of the reversible pump-turbine, thereby permitting fluid to flow from the first duct into the pump inlet and from the pump outlet into the second duct.