Tarek ElGammal Tomoki Sakamoto Prof. Ryoichi Amano Exploring the Cavitation Sensitivity in New Designs of Micro-Kaplan Hydro-Turbines Tarek ElGammal Tomoki Sakamoto Prof. Ryoichi Amano Mechanical Engineering, CEAS 2018

Introduction Hydroelectricity started in WI during the 19th century. Most efficient electricity-generation system (90-95%). Accounts for 16.4% of the World’s electric power capacity, but leads the renewable energy systems by 71%. Paper mill in Appleton Statistics: https://www.worldenergy.org/data/resources/resource/hydropower/

Introduction Most of the generated hydroelectricity is based on small-to-large scale turbines (10-100 MW) with storage in dams. Lately, DOE stated that 200,000 GWh/year is a potential in rivers. Run-of-river and pumped storage technologies are paid attention nowadays through the micro Kaplan hydro-turbines (5-100 kW). Voith reached 100 MW turbine Kaplan is efficient at low-head stream of water (i.e. run-of-river and small pumped storage)

Technology Challenges Multiple designs variables for an efficient system Cavitation: bubble implosion (1 GPa) and micro-jets (100 m/s). Dramatic low performance and turbine damage. Diseconomies of small scale

Objectives Designing efficient regular micro-turbines (RT) to suit the new expansive market. Propose and build novel hydroelectric systems (e.g. Rim-Drive or RDT). Investigating the cavitation sensitivity in the new models and submitting ideas to control it.

Results The two turbines follow the same efficiency trend. The optimum run occurs at N= 3000 rpm and Pout,gage= -24 kPa (the closest negative equivalent to Pin, gage= 27 kPa).

Results TLV is missed in RDT because of the rim integration RDT cavitation avoids the adjacent area to the blade tip RDT cavitation skips the intersection locus of blades/rim leading to a reduction in the cavitation area. Cavitation startup coverage on the RT blades suction side is nearly 200% more than RDT. Hub cavitation has a faster tendency in RDT than RT. Diseconomies of small scale

Results 3000 rpm Diseconomies of small scale 4000 rpm

Results The RDT efficiency bests that of RT at the same operating conditions by 15.1% (non-cavitating flow) and 16.5% (cavitating). Diseconomies of small scale

Conclusions RDT is more efficient by ~15% because of saving the energy losses at power. transmission. RDT design induces less cavitation at the beginning. Despite the efficiency drop at extreme cavitation conditions, RDT maintains higher levels of performance than RT.