Downstream flat plate as the flow-induced vibration enhancer for energy harvesting

2017 ◽  
Vol 24 (16) ◽  
pp. 3555-3568 ◽  
Author(s):  
Nurshafinaz Mohd Maruai ◽  
Mohamed Sukri Mat Ali ◽  
Mohamad Hafiz Ismail ◽  
Sheikh Ahmad Zaki Shaikh Salim
Keyword(s):  
Flat Plate ◽  
Electrical Power ◽  
High Amplitude ◽  
Test Model ◽  
Square Cylinder ◽  
Flow Induced Vibration ◽  
Amplitude Response ◽  
Current Test ◽  
Wake Interference ◽  
Lower Magnitude

The prospect of harvesting energy from flow-induced vibration using an elastic square cylinder with a detached flat plate is experimentally investigated. The feasibility of flow-induced vibration to supply an adequate base excitation for micro-scale electrical power generation is assessed through a series of wind tunnel tests. The current test model of a single square cylinder is verified through a comparable pattern of vibration amplitude response with previous experimental study and two-dimensional numerical simulations based on the unsteady Reynolds averaged Navier–Stokes (URANS). In addition, a downstream flat plate is included in the wake of the square cylinder to study the effects of wake interference upon flow-induced vibration. A downstream flat plate is introduced as the passive vibration control to enhance the magnitude of flow-induced vibration and simultaneously increases the prospect of harvesting energy from the airflow. The study is conducted by varying the gap separation between the square cylinder and flat plate for 0.1≤ G/ D ≤3. The highest peak amplitude is observed for the gap G/ D = 1.2 with yrms/ D = 0.46 at UR = 17, which is expected to harvest ten times more energy than the single square cylinder. The high amplitude vibration response is sustained within a relatively broader range of lock-in synchronization. Meanwhile, for G/ D = 2 the vibration is suppressed, which leads to a lower magnitude of harvested energy. Contrarily, the amplitude response pattern for G/ D = 3 is in agreement with the single square cylinder. Hence, the flat plate has no significance to the wake interference of the square cylinder when the gap separation is beyond 3 D.

Flow-induced vibration of a square cylinder and downstream flat plate associated with micro-scale energy harvester

2018 ◽  
Vol 175 ◽  
pp. 264-282 ◽  
Author(s):  
Nurshafinaz Mohd Maruai ◽  
Mohamed Sukri Mat Ali ◽  
Mohamad Hafiz Ismail ◽  
Sheikh Ahmad Zaki
Keyword(s):  
Flat Plate ◽  
Energy Harvester ◽  
Square Cylinder ◽  
Flow Induced Vibration ◽  
Micro Scale

scholarly journals Energy harvesting from flow-induced vibration of a low-mass square cylinder with different incidence angles

AIP Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 025126
Author(s):  
Peng Han ◽  
Qiaogao Huang ◽  
Guang Pan ◽  
Wei Wang ◽  
Tianqi Zhang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Square Cylinder ◽  
Flow Induced Vibration ◽  
Low Mass

scholarly journals The Transient Liquid Crystal Technique: Influence of Surface Curvature and Finite Wall Thickness

2004 ◽  
Author(s):  
G. Wagner ◽  
M. Kotulla ◽  
P. Ott ◽  
B. Weigand ◽  
J. von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Flat Plate ◽  
Hollow Cylinder ◽  
Wall Thickness ◽  
Reduction Method ◽  
Radius Of Curvature ◽  
Test Model ◽  
Curvature Effects ◽  
Transient Liquid Crystal Technique

The transient liquid crystal technique is nowadays widely used for measuring the heat transfer characteristics in gas turbine applications. Usually, the assumption is made that the wall of the test model can be treated as a flat and semi-infinite solid. This assumption is correct as long as the penetration depth of the heat compared to the thickness of the wall and to the radius of curvature is small. However, those two assumptions are not always respected for measurements near the leading edge of a blade. This paper presents a rigorous treatment of the curvature and finite wall thickness effects. The unsteady heat transfer for a hollow cylinder has been investigated analytically and a data reduction method taking into account curvature and finite wall thickness effects has been developed. Experimental tests made on hollow cylinder models have been evaluated using the new reduction method as well as the traditional semi-infinite flat plate approach and a third method that approximately accounts for curvature effects. It has been found that curvature and finite thickness of the wall have in some cases a significant influence on the obtained heat transfer coefficient. The parameters influencing the accuracy of the semi-infinite flat plate model and the approximate curvature correction are determined and the domains of validity are represented.

scholarly journals Prediction of flow induced vibration of a flat plate located after a bluff wall mounted obstacle

2019 ◽  
Vol 190 ◽  
pp. 23-39 ◽  
Author(s):  
A. Torregrosa ◽  
A. Gil ◽  
P. Quintero ◽  
A. Ammirati ◽  
H. Denayer ◽  
...  
Keyword(s):  
Flat Plate ◽  
Flow Induced Vibration

Modeling and Design of Micro-Grooved Flat Plate Evaporator

2005 ◽  
Author(s):  
Naoki Shikazono ◽  
Yasushi Suehisa ◽  
Nobuhide Kasagi ◽  
Hiroshi Iwata
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Flat Plate ◽  
Void Fraction ◽  
Local Heat ◽  
Curvature Radius ◽  
Test Model ◽  
Vapor Compression ◽  
Compression Cycle ◽  
Region Model

A micro-grooved flat plate evaporator is modeled and its heat transfer characteristics are investigated numerically and experimentally. A test model is developed for the vapor compression cycle evaporator, where pressure gradient drives the vapor and the liquid flow. In this study, the effect of pressure gradient is implicitly introduced through the Smith’s equation for predicting void fraction from given quality. The film thickness profile in the micro region near the contact line is obtained by solving the 4th order differential equation. Then the local heat flux is obtained by assuming that the heat conduction through the liquid is one dimensional in the wall normal direction. The shape of liquid-vapor interface is assumed to be a circular arc in the macro region, whose radius is directly linked to the void fraction. This curvature radius is used as the boundary condition for the micro region model at the micro-macro interface. Finally, the heat transfer coefficient on a micro-grooved flat plate evaporator is measured in a HFC134a experimental loop and compared with the numerical prediction. The present model assumptions are validated and assessed.

Experimental study and modelling of unsteady aerodynamic forces and moment on flat plate in high amplitude pitch ramp motion

2018 ◽  
Vol 846 ◽  
pp. 82-120 ◽  
Author(s):  
Yuelong Yu ◽  
Xavier Amandolese ◽  
Chengwei Fan ◽  
Yingzheng Liu
Keyword(s):  
Flat Plate ◽  
Normal Force ◽  
Unsteady Aerodynamics ◽  
High Amplitude ◽  
Point Location ◽  
Pivot Point ◽  
Moderate Reynolds Number ◽  
Main Effect ◽  
Dependent Model ◽  
Time Dependent Model

This paper examines the unsteady lift, drag and moment coefficients experienced by a thin airfoil in high-amplitude pitch ramp motion. Experiments have been carried out in a wind tunnel at moderate Reynolds number ($Re\approx 1.45\times 10^{4}$), using a rigid flat-plate model. Forces and moments have been measured for reduced pitch rates ranging from 0.01 to 0.18, four maximum pitch angles ($30^{\circ },45^{\circ },60^{\circ },90^{\circ }$) and different pivot axis locations between the leading and the trailing edge. Results confirm that for reduced pitch rates lower than 0.03, the unsteady aerodynamics is limited to a stall delay effect. For higher pitch rates, the unsteady response is dominated by a buildup of the circulation, which increases with the pitch rate and the absolute distance between the pivot axis and the $3/4$-chord location. This circulatory effect induces an overshoot in the normal force and moment coefficients, which is slightly reduced for a flat plate with a finite aspect ratio close to 8 in comparison with the two-dimensional configuration. A new time-dependent model has been tested for both the normal force and moment coefficients. It is mainly based on the superposition of step responses, using the Wagner function and a time-varying input that accounts for the nonlinear variation of the steady aerodynamics, the pivot point location and an additional circulation which depends on the pitch rate. When compared with experiments, it gives satisfactory results for $0^{\circ }$ to $90^{\circ }$ pitch ramp motion and captures the main effect of reduced pitch rate and pivot point location.

Friction Factor Behavior From Flat-Plate Tests of 12.15 mm Diameter Hole-Pattern Roughened Surfaces

2011 ◽  
Author(s):  
Thanesh Deva Asirvatham ◽  
Dara W. Childs ◽  
Stephen Phillips
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Friction Factor ◽  
Dynamic Pressure ◽  
Reynolds Numbers ◽  
Stagnation Temperature ◽  
Flat Plates ◽  
Number Range ◽  
Current Test ◽  
Rough Plate

A flat-plate tester is used to measure the friction-factor behavior for a hole-pattern-roughened surface facing a smooth surface with compressed air as the medium. Measurements of mass flow rate, static pressure drop and stagnation temperature are carried out and used to find a combined (stator + rotor) Fanning friction factor value. In addition, dynamic pressure measurements are made at four axial locations at the bottom of individual holes of the rough plate and at facing locations in the smooth plate. The description of the test rig and instrumentation, and the procedure of testing and calculation are explained in detail in Kheireddin in 2009 and Childs et al. in 2010. Three hole-pattern flat-plates with a hole-pattern diameter of 12.15 mm were tested having depths of 0.9, 1.9, and 2.9 mm. Tests were done with clearances at 0.254, 0.381, and 0.653 mm, and inlet pressures of 56, 70 and 84 bar for a range of pressure ratios, yielding a Reynolds-number range of 100,000 to 800,000. The effects of Reynolds number, clearance, inlet pressure, and hole depth on friction factor are studied. The data are compared to friction factor values of three hole-pattern flat-plates with 3.175 mm diameter holes with hole depths of 1.9, 2.6, and 3.302 mm tested in the same rig described by Kheireddin in 2009. The test program was initiated mainly to investigate a “friction-factor jump” phenomenon cited by Ha et al. in 1992 in test results from a flat-plate tester using facing hole-pattern plates where, at elevated values of Reynolds numbers, the friction factor began to increase steadily with increasing Reynolds numbers. Friction-factor jump was not observed in any of the current test cases.

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