Experimental investigation on flow approach profile for comparison of surface velocity at the inlet of the vertical ultra-low head hydro turbine using a non-rotating model

This article reports the need for an inlet approach profile in front of the turbine system for the newly developed vertical ultra-low head turbine applicable on channel flow section without dropped bed level. The fixed wall available in the conceptualization stage was found to act as a barrier to a certain level dis-turbing the flow towards the turbine that need to rectify with the addition of a suitable profile. The four -simple geometry for inlet approach profiles as vertical, inclined, curved, and a combination of inclined and curved profiles were selected for testing in pair with the alternation of a two-dimensional non -rotating model of the turbine having 150, 180, and 22.50 orifice opening on it. With the review of the lit-erature, a different experimental methodology has been explained. The tests were conducted on an experimental setup tank of the length of 10 m developed for the vertical ultra-low head hydro turbine with input variables such as flow rate, inlet profile, and non-rotating models. The experimental analysis is presented about the vertical profile with the concern of flow surface velocity and upstream height pos-sessed by different combinations. The comparisons made for upstream height and surface velocity with different flow rates, upstream height with surface velocity, maximum surface velocity, and upstream height with orifice opening of non-rotating models are discussed and selected the most suitable one among the tested. The conclusion is made for the necessity of an inlet approach profile with suitable geometry to minimize the loss at turbine inlet mentioning the future task is desired for optimization.(c) 2023 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).