Design and development of non-recirculating type erosion test setup for hydraulic turbines

Abstract

Slurry erosion phenomena are inevitable and commonly occurring processes in all types of hydro turbines and components that are exposed to sediment particles. The design of these components and the choice of the materials to resist erosion require laboratory testing using various erosion testing apparatus. These test apparatuses are designed specifically to meet the particular study requirements and to simulate the actual flow conditions in turbines. However, the design of these test apparatus must be flexible and versatile to assess erosion resistance under different combinations of operating conditions. The existing test rigs mostly comprise of rotary type with re-circulation of the slurry. This study proposes a new type of test setup that describes the sediment particles injection method into the system as well as immediate rejection of those particles striking the test specimen. The components of test rig and the test methodology are described. An accelerated tests have been performed on Cross-flow turbine to verify the suitability of the rig for erosion testing in laboratory environment. The design principle of this setup is to eliminate the limitations of the existing test rigs such as slurry ageing problem, use of acceleration tube to maintain the particle velocity and constant operating parameters (discharge velocity and pressure head). The non-recirculation of the slurry is maintained by the use of hydro cyclone as the particle separation device, which is found to have an efficiency of 97%. This test facility provides flexibility in the performance testing of miniature model of different types of hydro turbines with limited adjustments.