Abstract: While hydropower projects bring many positive benefits to people, they also produce some negative ecological effects like cutting off fish migration channels. To alleviate such side effects, fish-friendly turbines have attracted great research attention in recent years. This paper presents a new fish-friendly turbine for run-of-river hydropower plants. Aimed at reducing pressure gradients to obtain low fish casualties, this turbine has three major features: fewer spiral blades with long blade passages, better for lowering its fish hitting probability; two counter-rotating runners, better for lengthening its flow passage and improving its generating efficiency; all its blades satisfy the optimal conditions of velocity triangles at the blade inlet and outlet, better for even and smooth distributions of velocity and pressure. CFD simulations show that its generating efficiency can reach up to 80.4% and its pressure gradient is better than the existing fish-friendly standard recommended by international scholars.

Key words: water turbine, fish-friendly, CFD simulation, fish-passing characteristics, two runners, runner optimization