The paper was titled "Numerical Simulation on a Pump Operating in a Turbine Mode". It was presented in 2007. The authors were Sonia Rawal and J. T. Kshirsagar. I looked at the paper and I believe it would address your question. If you do not have access to the proceedings of this symposium, you can purchase copies from Texas A&M Turbomachinery Laboratory.
Johnny Pellin