Newsletter  2021.1  Index

Theme : "Mechanical Engineering Congress, 2020 Japan (MECJ-20)” Preface Masaaki MOTOZAWA, Hideo MORI Pending Issues in Large-Eddy Simulation of Turbulent Flows Takeo KAJISHIMA (Osaka University) Unsteady Flows in Turbomachines (What We Should Know and How We Can Apply to Designing) Ken-ichi FUNAZAKI (Iwate University) Modeling of a Two-Phase Flow Simulation with the Evaporation of the Gas Diffusion Layer in a Polymer Electrolyte Fuel Cell Ryuya NAGAYAMA, Satoshi SAKAIDA, Kotaro TANAKA, Mitsuru KONNO (Ibaraki University) Statistical Mechanical Analysis of Nanoparticle Behavior for Measurement of Flow Velocity Distribution in Nanochannels by Particle Tracking Velocimetry Minori TANAKA (Keio University), Itsuo HANASAKI (Tokyo University of Agriculture and Technology), Yutaka KAZOE (Keio University) Memorandum Record of the 2020 JSME Annual Meeting -as a committee member of the web conference- Yasumasa ITO (Nagoya University)

 

Unsteady Flows in Turbomachines (What We Should Know and How We Can Apply to Designing)

Ken-ichi FUNAZAKI Iwate University

Abstract

This article begins with a kind of prophecy given by Prof. Ohashi, well-known scholar in turbomachinery community, that turbomachines are immortal. In fact, this is true under the condition that designers will be updating their methodologies by taking the full advantage of the state-of-the-art advancements of science and technologies.

Although turbomachinery is regarded as one of the well-developed or matured technologies and some people might say that very few new developments can be achieved, there still remains enough space for innovation. Based on findings in a number of previous studies, it is highly possible that breakthrough in turbomachinery designing can arise from the design that considers unsteady flow effects upon the aerodynamic performance, along with the usage of Machine Learning, the latest data analysis technologies like POD or DMD. The research group in Iwate University have been working on the project to find out a new methodology for designing high-lifting Low-Pressure Turbine (LPT) cascade with high efficiency by taking incoming wake effects into account, and some of the results obtained through the project are described in this article.

Fig. 1 shows tested cascades with different loading levels and deceleration rate over the suction surfaces (DR). Velocity and velocity-rms contours over 4 different airfoil suction surfaces under no wake condition are shown in Fig.2. Due to the existence of incoming wakes, as shown in Fig. 3, the separation bubble, which can be regarded as main cause of the high cascade loss, was considerably suppressed. This was also confirmed in the experiments (Fig. 4). Through these research efforts, our group have found a cascade loss map with respect to DR, a measure of the loading level, as shown in Fig. 5. This map clearly revealed that there exists a certain DR that gives the minimum loss value for each Reynolds number.

Key words

Aero-Engine, Low-Pressure Turbine, Aerodynamic Loss, Unsteady Flow Effects, Experiment

Figures

Fig. 1 Tested cascades with different loading levels and deceleration rate over the suction surfaces

Fig. 2  Velocity and velocity-rms contours over 4 different airfoil suction surfaces under no wake condition

Fig. 3  Velocity and velocity-rms contours over 4 different airfoil suction surfaces under no wake condition

Fig. 4  Velocity and velocity-rms contour over Design E (largest loading airfoil) suction surface under wake passing condition.

Fig.5 Normalized aerodynamic loss data for several cascades with different DR at three Reynolds number conditions