Uniformity Improvement on Back-Disk Impingement Cooling Preference of a Radical Turbine with Optimized Distribution Strategies of Jet-Holes

摘要

Adopting back-disk impingement cooling is an effective way to cool small radial turbines. The circumferential uneven flow field caused by the volute leads to an uneven distribution of cooling efficiency on the back disk. To improve the uneven distribution, the arrangement of impinging jet holes on the back disk was studied. The numerical simulation results for conjugated heat transfer (CHT) showed that impingement cooling can effectively cool the high-temperature region of the back disk. Due to the influence of the volute, there is a local low-efficiency cooling zone near the volute tongue of the volute. Changing the distribution of the jet holes can effectively reduce local high-temperature zones and improve uneven local cooling. Compared with other schemes, using a 40° phase angle for the seventh hole has the best cooling effect on the back disk, and the uniformity of the cooling efficiency is improved by 18.5 %. After the cooling fluid flows into the mainstream channel of the turbine, the turbine efficiency is reduced by the cooling fluid, and the effect of impingement cooling on the turbine expansion ratio is negligible.