Turbine blade runner

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Professor Li He on understanding better how turbines function at high temperatures: making jet engines greener, and turbines cheaper to run

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Professor Li He, Rolls-Royce / Royal Academy of Engineering Professor in Computational Aerothermal Engineering

What we found as part of this research project seemed to show something we didn’t expect. We were a little bit puzzled. So what was that?

We couldn’t quite figure out what is going on. Mostly aeroplane propellers are powered by the jet engine which makes quite a considerable impact into environmental change and global warming. We are mainly looking at the blade and input blade of high pressure turbine; how to make it better, more efficient and less polluting. This is a very challenging part because this is right behind the combustion chamber where you have the moving blade and you have to have a small gap relative to the stationary component. You have very high speed, very high pressure as well as, of course, after combustion you have very high temperature. So therefore the heat transfer and cooling is an important part. That is one of the major challenges in the engine department.

The conventional wisdom was that designers could probably scale up some of the low speed test results for heat transfer, in particular for the blade tip, but what we found is that actually the tip flow is far more complex than we had originally thought.

We tried to replicate a consistent picture and it turned out that there is a strong shock waves structure which we didn’t expect and that really made a difference. It really changed our way of what extent we could actually make use of this flow state and to what extent we can actually make use of this flow state to modify or control the tip shape, because if we can manage to reduce the great load on the blade tip, then the life can be increased tremendously. Also the cooling required will be much different than otherwise so it’s quite relevant not only in terms of the fundamental understanding, but also in terms of the real design implications.

We hope we can help the designers to reduce the fuel burn as well as to have a longer life engine and all of this will help, of course, economically as well as environmentally. Being an engineer, that is the sort of thing that you want to really make a difference with and to be involved with this kind of activity. The potential to make that kind of difference is a privilege.