Study on Accuracy of Heat Transfer Coefficient Determination in the Bearing Chamber for Gas Turbine Engine

Illia Petukhov^1^, Taras Mykhailenko^1^, Sergiy Yepifanov^1^, Oleg Shevchuk^2^

^1^ National Aerospace University “Kharkiv Aviation Institute” named by N Zukovskiy, Kharkiv, 61070, Ukraine

^2^ Zaporozhye Machine-Building Design Bureau Progress State Enterprise named after Academician A.G. Ivchenko, Zaporozhye, 69068, Ukraine

E-mail: t.mykhailenko@khai.edu, ShevchukOV@ivchenko-progress.com, mathieu.picard2@safrangroup.com

The development of gas turbine industry is guided by the instantly growing parameters of thermodynamic cycle as well as reduction of gas turbine engine overall size and in particular the size of bearing chambers. The above-mentioned trends lead to a heavier thermally stressed state of the engine, higher rotational speeds, higher temperatures, pressures and velocities of air flow moving through the gas path. Some challenges to be solved on the way to fuel efficient gas turbine engines are minimization of power consumptions for lubricating of the friction zones and minimization of air consumption to pressurize and protect the bearing chambers from the hot gases. One more challenge that designers of new engines must tackle is oil protection against the temperature impact.

Concluding all mentioned above, one of the cutting-edge problems addresses the safe temperature conditions for both the lubrication oil and compact bearing chambers of gas turbine engines. Only deep understanding of the thermal and hydraulic processes that related with complex behavior of oil-air mixture in the bearing chamber within the entire range of operating conditions can bring to the solution. One of the ways to achieve this is experimental investigation and heat transfer coefficient in the bearing chamber is a key parameter in this way. It depends on many factors, like flow structure, rotational speed of the shaft, amount of injected oil and airflow rate over the labyrinth seal, etc., and changes with changing of engine’s operating conditions.

Temperature gradient method is commonly used in experimental practice to determinate the heat transfer coefficient. The accuracy of heat transfer coefficient determination is sensitive to changing of bearing chamber operating conditions and should be analyzed on the preliminary stages of the experimental investigation planning. This paper presents the study on accuracy of heat transfer coefficient determination when the external cooling of bearing chamber is used to obtain temperature difference sufficient for measure. Three ways to reduce the relative error of heat transfer coefficient determination in the bearing chamber: i) decreasing of temperature measurement error; ii) decreasing the temperature of the external cooling media; ii) increasing of external heat transfer coefficient as well as the contribution of wall thermal resistance’s optimization were analyzed. For different operating modes of bearing chamber, the temperature of the outer wall that ensures the specified accuracy of the experimental heat transfer coefficient and the required parameters of the cooling medium were determined and recommended for practical implementation.

Key words: bearing chamber, heat transfer coefficient, accuracy, relative error, measurement, temperature gradient method, external cooling conditions.


Study on Accuracy of Heat Transfer Coefficient Determination in the Bearing Chamber for Gas Turbine Engine

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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