عملکرد آیرودینامیکی پایا و ناپایای ایرفویل لیفت-بالا توربین (High-lift Turbine Airfoil); آزمون تونل باد و شبیه سازی عددی دقیق
Aerodynamic Performance of a High-Lift Turbine Airfoil Under Various Free-Stream Reynolds Numbers, Turbulence Intensities and Unsteady Wake Flow
Significant efforts have been devoted to the design, manufacturing, and integration of gas turbine aeroengines in order to enhance the thrust-to-weight ratio. Consideration of unsteady flow phenomena within the framework of aerodynamic design methodologies is one of the key factors in addressing challenges associated with turbine blade profile optimization. Upstream wake flows constitute the primary source of unsteadiness within turbomachinery flow fields. Consequently, accurate characterization of these flows is essential, particularly
.for controlling wake–blade interactions
Several fundamental questions arise, the answers to which can be directly applied to the aerodynamic design of turbine airfoils. Among
them are the following
What are the effects of Reynolds number and free-stream turbulence intensity (FSTI) on the overall aerodynamic performance of a turbine airfoil?0
How do different inlet boundary conditions, specifically variations in Reynolds number and FSTI, influence the transition process, separation bubble length, wake width, local drag, and total drag?0
What is the transient effect of upstream wake flow kinematics on turbine blade loading and pressure distribution?Are there wake-induced different responses during wake convection time-interval?0
How strong is the wake flow within the blade passage? Is there a suitable parameter or methodology to quantify wake strength?0
How does reduced frequency (f) affect the aerodynamic performance of turbine blades?0
In a comprehensive research project entitled “Aerodynamic Performance of a High-Lift Turbine Airfoil Under Various Free-Stream Reynolds Numbers, Turbulence Intensities and Unsteady Wake Flows”, all the aforementioned questions were systematically investigated. Both steady and unsteady numerical simulations, along with experimental measurements, were employed. The experiments were conducted in the open-circuit subsonic wind tunnel of the Aerodynamics and Turbomachinery Research Laboratory at the Iran University of Science and Technology (IUST-ATLab). A photograph of the modified wind tunnel used in the present study is shown in the following figure.
Reynolds number and FSTI have been ranged between 12000 and 352000 × 105 and 1.4 and 3.7%, respectively, which are consistent with high-lift turbine blades under typical cruise conditions of aircraft. A photograph of the test model installed in the test section is presented in the following figure. The test configuration consisted of five high-lift axial turbine blades arranged in a linear cascade.0
To generate unsteady flow conditions for the unsteady experiments, a wake generator mechanism was redesigned and manufactured at IUST-ATLab to produce controlled upstream wake flows ahead of the blades cascade. A photograph and schematic representation of this apparatus are shown in the following figure.0
Some of the measuring instruments are illustrated in the following figure.0
The computational domains corresponding to the blade cascade for both steady and unsteady analyses are illustrated in the figure below. As shown, a moving domain was implemented in the unsteady simulations to model the linear motion of the wake-generating rods. Boundary condition types are also indicated in the figure. The inlet boundary condition was specified in terms of air velocity, while static pressure was prescribed at the outlet.0
