The Impact and Mechanism Analysis of Effect of Incoming Flow Velocity on Aerodynamic of Flying Wing Model with Low Aspect Ratio

2012 ◽

Cited By ~ 3

Author(s):

Thorsten Selic ◽

Davide Lengani ◽

Andreas Marn ◽

Franz Heitmeir

Keyword(s):

Aspect Ratio ◽

Guide Vane ◽

Low Pressure ◽

Tip Clearance ◽

Pressure Probe ◽

Model Parameters ◽

Leakage Flow ◽

Low Pressure Turbine ◽

Low Aspect Ratio ◽

The Impact

This paper presents the effects of an unshrouded low pressure turbine (LPT) onto the following exit guide vane row (EGV). The measurement results were obtained in the subsonic test turbine facility at Graz University of Technology by means of a fast response pressure probe in planes downstream of the rotor as well as oil flow visualisation. The test rig was designed in cooperation with MTU Aero Engines and represents the last 1.5 stages of a commercial aero engine. Considerable efforts were put into the adjustment of all relevant model parameters to reproduce the full scale LPT situation. Different tip clearances were evaluated by means of CFD obtained using a commercial Navier-Stokes code and validated with experimental results. The goal is to evaluate the effect of the varying leakage flow on the flow in the low aspect ratio EGV. Special attention is given to the impact on the development of secondary flows as well as the flow structures downstream of the EGV. The effect of the leakage flow causes a change of the flow structure of the EGV, particularly losses. Considering the largest investigated tip-clearance, the losses increased by 71% when compared to a zero-leakage case.

Download Full-text

MAST and the impact of low aspect ratio on tokamak physics

Plasma Physics and Controlled Fusion ◽

10.1088/0741-3335/46/12b/040 ◽

2004 ◽

Vol 46 (12B) ◽

pp. B477-B494 ◽

Cited By ~ 20

Author(s):

B Lloyd ◽

J-W Ahn ◽

R J Akers ◽

L C Appel ◽

D Applegate ◽

...

Keyword(s):

Aspect Ratio ◽

Low Aspect Ratio ◽

The Impact

Download Full-text

Efficiency evaluation of energy harvesting from discrete gust response for plate wing

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220968122 ◽

2020 ◽

pp. 095440622096812

Author(s):

Yun Cheng ◽

Daochun Li ◽

Jinwu Xiang

Keyword(s):

Energy Harvesting ◽

Aspect Ratio ◽

Electrical Energy ◽

Evaluation Methods ◽

Energy Output ◽

Efficiency Evaluation ◽

Plate Model ◽

Low Aspect Ratio ◽

Wing Model ◽

Gust Response

Gust response of aircraft can become a potential energy source thanks to energy harvesting (EH) methods, one of which can transform mechanical energy to electrical energy, applying piezoelectric ceramic transducers (PZTs). Harvested electrical energy needs to be evaluated for reuse, but current beam-model-based evaluation methods of EH performance for a plate model are insufficient because the plate is two-dimensional. This paper proposes two types of EH evaluation methods to analyze the gust exciting low-aspect-ratio plate wing model. One method focuses on the ratio of electrical energy to kinetic energy, and the other reflects energy output density per unit weight. These two methods can reveal the higher energy harvesting efficiency positions when utilizing PZTs on the flight EH system. Plate model, three-dimensional doublet lattice unsteady aeroelastic method and piezoelectric equation are used to build piezoaeroelastic wing model, and 1-cosine discrete gust load is the base excitation. A time-domain aero-electro-elastic state-space equation of the low-aspect-ratio piezoaeroelastic plate wing model is established, and the time-history analysis is used to solve the EH output. Results show that EH outputs are influenced by various parameters including load resistance, PZT thickness, gust intensity and wavelength, and PZT location variation. The optimal values of the proposed EH efficiency evaluation methods are found and explained.

Download Full-text

Numerical simulation of support interference characteristics on a low-aspect ratio flying-wing model

Journal of Physics Conference Series ◽

10.1088/1742-6596/1600/1/012036 ◽

2020 ◽

Vol 1600 ◽

pp. 012036

Author(s):

Yaobing Zhang ◽

Bin Li ◽

Pengcheng Cui ◽

Naichun Zhou ◽

Xiaojun Wu

Keyword(s):

Numerical Simulation ◽

Aspect Ratio ◽

Low Aspect Ratio ◽

Wing Model ◽

Support Interference

Download Full-text

Challenges and Opportunities for the Turbine Performance Improvement Through Stator Clocking and Vane Bowing

Volume 6: Turbo Expo 2007, Parts A and B ◽

10.1115/gt2007-28008 ◽

2007 ◽

Cited By ~ 1

Author(s):

Antoni Smolny ◽

Jaroslaw R. Blaszczak ◽

Jan Krysinski ◽

Tomasz Borzecki

Keyword(s):

Aspect Ratio ◽

Secondary Flow ◽

Three Dimensional ◽

Secondary Flows ◽

Flow Structures ◽

Major Influence ◽

Two Stage ◽

Local Flow ◽

Low Aspect Ratio ◽

The Impact

The paper describes experimental and numerical investigations of turbine vane clocking effects on the flow process in a two-stage turbine with low-aspect ratio stators. The data present clocking effects that can be observed both for local flow patterns and external characteristics for the entire machine in terms of efficiency. A low-aspect ratio and high turning create a highly three-dimensional flow that is dominated by secondary flows. The aim was to reduce the impact of the secondary flows by bowing the first stator vanes by means of different vane bending and the stator clocking. Another major objective was to show how wake trajectory features can be applied in a turbine design. The changes in the secondary flow structures of the first stator were performed by leaning and bowing the airfoils to achieve load reduction near end walls. This can lead to a weaker end wall secondary flow structures and lower losses. Bowed blades are nowadays often adopted for high-pressure gas and steam turbines. The results demonstrate that incoming interacting streamwise vortices have a major influence on the secondary flows and loss generation mechanisms of the downstream airfoil rows. Using the clocking concept, the secondary flow structures are forced to interact one with another at different positions of the stators. This procedure reveals the best nature of such interactions and shows the resulting benefits. The data acquired by clocking the upstream cascade can identify the effects of incoming vortices, particularly when they entering the leading edge regions of the downstream cascade airfoil. The results for this test indicate that the size and strength of the secondary flows for the downstream cascade should be lower than those obtained without interaction. It is apparent from these investigations that incoming stream-wise vortices may have a potential effect on the flow distribution for downstream airfoil rows. The first part of the paper presents results of the stator clocking identification for different geometries of the first stator. An introduction of the vane bowing has redesigned the first stator. The cylindrical version and two combinations of the bowed vanes with low and high curvature have been considered for the first stator. The authors have found that modified vanes produce smaller and weaker secondary flow structures. The second part presents experimental and numerical results of the clocking investigations for the above-mentioned versions. The experiments have shown that clocking effects seem to be related to the stator wake and vortex structures which produce low momentum fluid areas. These areas interact with boundary layers or secondary flow regions of the second stator where the fluid momentum is already low. Clocking effects on external flow parameter are analyzed versus the low momentum area trajectories due to the first stator vane bowing. The present work focuses on the structures that are formed downstream as a result of the exit flow field of the upstream stage, and examines the implication for efficiency improvement. This paper therefore deals with an interaction of complex three-dimensional stator-rotor flow structures in the two-stage axial turbine.

Download Full-text

Preliminary investigation on experimental modal analysis of high aspect ratio rectangular wing model

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.13.21348 ◽

2018 ◽

Vol 7 (4.13) ◽

pp. 151

Author(s):

N. A. Rosly ◽

M. Y. Harmin ◽

D. L. A. A. Majid

Keyword(s):

Aspect Ratio ◽

Modal Analysis ◽

Mode Shape ◽

High Aspect Ratio ◽

Preliminary Investigation ◽

Experimental Modal Analysis ◽

Geometric Nonlinearities ◽

Wing Model ◽

Bending Modes ◽

The Impact

Procedure of conducting an experimental modal analysis (EMA) of roving hammer test for high aspect ratio (HAR) wing containing geometric nonlinearities is presented along with consideration of various tip store sizes. Two sets of test setups of vertical and horizontal arrangements have been considered, which respectively demonstrates the undeformed and deformed cases. Modal properties in terms of natural frequency and mode shape were experimentally measured using the LMS Test.Lab package and the results were then compared between the undeformed and its corresponding deformed configuration. From the finding, it confirms that the chordwise and torsional modes of the undeformed configurations has respectively turned into chordwise-torsion and torsion-chordwise modes as they are in deformed configuration. Meanwhile, the impact related to bending modes is insignificant. Hence, this may result in inaccurate prediction if conventional aeroelastic solution is employed for HAR wing configuration.

Download Full-text