Prediction of Transient Pressure Fluctuations within a Low-Pressure Turbine Cascade Using a Lanczos-Filtered Harmonic Balance Method

• Main Authors: Jan Philipp Heners, Stephan Stotz, Annette Krosse, Detlef Korte, Maximilian Beck, Damian Vogt
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: International Journal of Turbomachinery, Propulsion and Power
• Subjects: unsteady aerodynamics; harmonic balance; model order reduction; frequency domain methods
• Online Access: https://www.mdpi.com/2504-186X/6/3/25

Unsteady pressure fluctuations measured by fast-response pressure transducers mounted in a low-pressure turbine cascade are compared to unsteady simulation results. Three differing simulation approaches are considered, one time-integration method and two harmonic balance methods either resolving or averaging the time-dependent components within the turbulence model. The observations are used to evaluate the capability of the harmonic balance solver to predict the transient pressure fluctuations acting on the investigated stator surface. Wakes of an upstream rotor are generated by moving cylindrical bars at a prescribed rotational speed that refers to a frequency of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>∼</mo><mn>500</mn></mrow></semantics></math></inline-formula> Hz. The excitation at the rear part of the suction side is essentially driven by the presence of a separation bubble and is therefore highly dependent on the unsteady behavior of turbulence. In order to increase the stability of the investigated harmonic balance solver, a developed Lanczos-type filter method is applied if the turbulence model is considered in an unsteady fashion.