3D Euler flow simulation in hydro turbines: unsteady analysis and automatic design. Two hydro turbine fluid flow problems are solved numerically in the paper. Both problems are solved in frames of Euler model using CFD code developed by the authors. The code is based on finite volume artificial compressibility approach. The accuracy of numerical scheme is second order in time and third order in space. For the solution of unsteady problems dual-time-stepping algorithm is used. Complex geometry of a turbine passage is handled using domain decomposition. The first problem considered is a simulation of precessing vortex rope downstream the turbine runner. Numerical results showed that this phenomenon can be captured by Euler model. The second problem is an automatic design (optimization) of runner blade shape with help of Breeder genetic algorithm. Different formulations of the objective function are considered and their influence on the blade shape is demonstrated.