Investigation On Scraping Heat Transfer In Turbine Blade

The scraping between turbine blade tip and the casing has a serious impact on the whole performance and durability of the engine. In order to improve the efficiency and reliability of the engine, further research on the scraping of turbine blade needs to be carried out. In this paper, both numerical and experimental study has been performed to investigate the influence of the heat transfer characteristics resulting from the scraping. Specific contents are as follows:First of all, the emission rate of the experimental blade is obtained by the energy method. After this, experimental study of the scraping between the blade tip and casing is carried out to investigate the effect on the temperature and scraping force with different wheel velocity, scraping depth and scraping rate. Experimental results showed that: the scraping occurred in a short moment, with the temperature increasing rapidly. At this time, the tip temperature gradient is great; keeping the other two parameters constant, the scraping temperature increased when the scraping depth and wheel velocity increased, while the scraping temperature showed a trend of rise first then fall when the scraping rate increased; the scraping force increased as the scraping depth and scraping rate are added, but decreased as the wheel velocity increase.Finally, according to the experimental results, some heat transfer characteristics were studied by numerical simulation. The results showed that: by the means of controlling the heat flux, the scraping temperature can be effectively simulated and predicted. Keeping the other two parameters constant, the scraping temperature also increased when the scraping depth and tip linear velocity increased, but decreased when the scraping rate increased, and the blade tip temperature increased when the scraping depth increased, and decreased when the rotational speed and scraping rate increased. The scraping temperature can reach the extreme that the blade can support, which can cause the blade ablation and damaged. The effect of the scraping hot in the cascade is limited. Meanwhile the flow and heat transfer of blade tip radial elongation process is in the tip region because of the tip leakage flow. With the increase of radial elongation, the influence range of leakage flow and the heat transfer coefficient decreases. The rotational speed has little effect on the turbine tip clearance flow. With the increasing of rotational speed, heat transfer coefficient increased.