A Shape Memory Alloy-Based Morphing Axial Fan Blade: Part II — Blade Shape and CFD Analyses

2015 ◽  
Author(s):  
Alessio Suman ◽  
Annalisa Fortini ◽  
Nicola Aldi ◽  
Mattia Merlin ◽  
Michele Pinelli
Keyword(s):  
Wind Tunnel ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fluid Dynamic ◽  
Rotational Velocity ◽  
Strong Relationship ◽  
Operating Conditions ◽  
Automotive Application ◽  
Axial Fan ◽  
Fan Performance

The ability of a morphing blade to change its geometry according to the different operating conditions represents a challenging approach for the optimization of turbomachinery performance. In this paper experimental and CFD numerical analyses on a morphing blade for a heavy-duty automotive cooling axial fan are proposed. Starting from the experimental results proposed in the first part of this work, a morphing blade, made of Shape Memory Alloy (SMA) strips embedded in a polymeric structure, was thoroughly tested. In order to assess the ability of the strips to reach a progressive and smooth shape changing evolution, several experiments were performed in a purpose-built wind tunnel. The morphing blade changed its shape as the strips were thermally activated by means of air stream flow. The bending deformation evolution with the increasing number of thermal cycles was evaluated by digital image analysis techniques. After the analyses in the wind tunnel CFD numerical simulations of a partially shrouded fan composed of five morphing blades were performed in order to highlight the evolution of the fan performance according to air temperature conditions. In particular, the capability of the blade activation was evaluated by the comparison between the fan performance with non-activated blades and with activated blades. The results show a progressive stabilization of the shape memory behavior after the first cycle. The blade deformation led to a significant improvement in fan performance at a constant rotational velocity. The CFD numerical simulation points out the differences in the overall performance and of three-dimensional fluid dynamic behavior of the fan. This innovative concept is aimed at realizing a sensorless smart fan control, permitting (i) an energy saving that leads to fuel saving in the automotive application fields and (ii) an increase in engine life thanks to a strong relationship between the engine thermal request and the cooling fan performance.

A Shape Memory Alloy-Based Morphing Axial Fan Blade—Part II: Blade Shape and Computational Fluid Dynamics Analyses

2015 ◽  
Vol 138 (6) ◽  
Author(s):  
Alessio Suman ◽  
Annalisa Fortini ◽  
Nicola Aldi ◽  
Mattia Merlin ◽  
Michele Pinelli
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Automotive Application ◽  
Axial Fan ◽  
Fan Performance

The ability of a morphing blade to change its geometry according to the different operating conditions represents a challenging approach for the optimization of turbomachinery performance. In this paper, experimental and computational fluid dynamics (CFD) numerical analyses on a morphing blade for a heavy-duty automotive cooling axial fan are proposed. Starting from the experimental results proposed in the first part of this work, a morphing blade, made of shape memory alloy (SMA) strips embedded in a polymeric structure, was thoroughly tested. In order to assess the ability of the strips to reach a progressive and smooth shape changing evolution, several experiments were performed in a purpose-built wind tunnel. The morphing blade changed its shape as the strips were thermally activated by means of air stream flow. The bending deformation evolution with the increasing number of thermal cycles was evaluated by digital image analysis techniques. After the analyses in the wind tunnel, CFD numerical simulations of a partially shrouded fan composed of five morphing blades were performed in order to highlight the evolution of the fan performance according to air temperature conditions. In particular, the capability of the blade activation was evaluated by the comparison between the fan performance with nonactivated blades and with activated blades. The results show a progressive stabilization of the shape memory behavior after the first cycle. The blade deformation led to a significant improvement in the fan performance at a constant rotational velocity. The CFD numerical simulation points out the differences in the overall performance and of three-dimensional fluid dynamic behavior of the fan. This innovative concept is aimed at realizing a sensorless smart fan control, permitting (i) an energy saving that leads to fuel saving in the automotive application fields and (ii) an increase in engine life, thanks to a strong relationship between the engine thermal request and the cooling fan performance.

A Shape Memory Alloy-Based Morphing Axial Fan Blade: Functional Characterization and Fluid Dynamic Performance

2016 ◽  
Author(s):  
Alessio Suman ◽  
Annalisa Fortini ◽  
Nicola Aldi ◽  
Mattia Merlin ◽  
Michele Pinelli
Keyword(s):  
Control System ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fluid Dynamic ◽  
High Energy ◽  
Time Range ◽  
Axial Fan ◽  
Polymeric Compound ◽  
Intended Application ◽  
Blade Tip

In a traditional automotive cooling system, energy optimization could be achieved by controlling the engine temperature by means of several sensors placed inside the cooling circuit. Nevertheless, in some cases the increasing use of a great number of sensor devices makes the control system too bulky, expensive and not sufficiently robust for the intended application. This paper presents the development of a heavy-duty automotive cooling axial fan with morphing blades activated by Shape Memory Alloy (SMA) strips that work as actuator elements in the polymeric blade structure. The application of smart materials to compact, high-energy density devices as well as the development of modeling and control systems has been of great interest during the last decade. SMAs are frequently combined within monolithic or composite host materials to produce adaptive structures whose properties could be tuned in response to external stimuli. The blade was designed to achieve the activation of the strips (purposely thermo-mechanically treated) by means of an air stream flow. With the aim of studying the morphing capability of the adaptive structure together with the recovery behavior of the NiTi strips, four different polymeric compounds have been compared in a specifically-designed wind tunnel. Digital image analysis techniques have been performed to quantitatively analyze the blade deflections and to evaluate the most suitable polymeric matrix for the intended application. As the airstream flow increases in temperature, the strips recover the memorized bent shape, leading to a camber variation. To study the possibility of employing SMA strips as actuator elements, a comparison with common viscous clutch behavior is proposed. The time range actuator response indicates that the SMA strips provide a lower frequency control that fits well with the engine coolant thermal requirement. The experimental results demonstrate the capability of SMA materials to accommodate the lower power actuators in the automotive field. Finally, the blade tip airfoils, reconstructed using a CAD procedure, were used to study the fluid dynamic behavior of the blade tip airfoil. A CFD numerical simulation was carried out in order to highlight the differences in the airfoil performance due to the different shapes of the blade. The analyses showed that the activated blade tip airfoil led to an increase in the lift coefficient according to the stiffness provided by the polymeric compound. This innovative passive control system results from the selection of (i) the memorized shape of the SMA strips and (ii) the polymeric compound used for the blade structure.

A Shape Memory Alloy-Based Morphing Axial Fan Blade—Part I: Blade Structure Design and Functional Characterization

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Annalisa Fortini ◽  
Alessio Suman ◽  
Nicola Aldi ◽  
Mattia Merlin ◽  
Michele Pinelli
Keyword(s):  
Shape Memory ◽  
Solid Phase ◽  
Functional Characterization ◽  
Structure Design ◽  
Operating Conditions ◽  
Surface Pattern ◽  
Fluid Temperature ◽  
Axial Fan ◽  
Polymeric Matrices ◽  
Air Stream

The possibility to realize adaptive structures is of great interest in turbomachinery design, owing to the benefits related to enhanced performance and efficiency. To accomplish this, a challenging approach is the employment of shape memory alloys (SMAs), which can recover seemingly permanent strains by solid phase transformations whereby the so-called shape memory effect (SME) takes place. This paper presents the development of a heavy-duty automotive cooling axial fan with morphing blades activated by SMA strips that works as actuator elements in the polymeric blade structure. Concerning the fan performance, this new concept differs from a conventional viscous fan clutch solution especially during the nonstationary operating conditions. The blade design was performed in order to achieve the thermal activation of the strips by means of air stream flow. Two polymeric matrices were chosen to be tested in conjunction with a commercially available NiTi binary alloy, whose phase transformation temperatures (TTRs) were experimentally evaluated by imposing the actual operating thermal gradient. The SMA strips were then thermomechanically treated to memorize a bent shape and embedded in the polymeric blade. In a specifically designed wind tunnel, the different polymeric matrices equipped with the SMA strips were tested to assess the fluid temperature and surface pattern behavior of the blade. Upon heating, they tend to recover the memorized shape and the blade is forced to bend, leading to a camber variation and a trailing edge displacement. The recovery behavior of each composite structure (polymeric matrix with the SMA strips) was evaluated through digital image analysis techniques. The differences between the blade shape at the initial condition and at the maximum bending deformation were considered. According to these results, the best coupling of SMA strips and polymeric structure is assessed and its timewise behavior is compared to the traditional timewise behavior of a viscous fan clutch.

Development and wind tunnel evaluation of a shape memory alloy based trim tab actuator for a civil aircraft

2013 ◽  
Vol 22 (9) ◽  
pp. 095025 ◽  
Author(s):  
P Senthilkumar ◽  
S Jayasankar ◽  
Satisha ◽  
V L Sateesh ◽  
M S Kamaleshaiah ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Civil Aircraft

Force transmissibility characteristics of a pseudoelastic oscillator

2019 ◽  
Vol 31 (3) ◽  
pp. 349-363 ◽  
Author(s):  
Sebin Jose ◽  
Goutam Chakraborty ◽  
Ranjan Bhattacharyya
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Cooling Rate ◽  
Operating Conditions ◽  
Vibration Isolator ◽  
Resonant Frequencies ◽  
Single Degree Of Freedom ◽  
Thermomechanical Behaviour ◽  
Rigid Mass ◽  
Force Transmissibility

The force transmissibility characteristics of a passive vibration isolator in the form of shape memory alloy bar are investigated. The shape memory alloy bar, together with a rigid mass, constitutes a single-degree-of-freedom system. The force isolation ability of the oscillator is evaluated for both isothermal and convective environmental conditions. The transmissibility curve of an isothermal pseudoelastic oscillator displays single and double jumps depending upon the forcing amplitude. The shape memory alloy oscillator with coupled thermomechanical behaviour depends on the cooling rate near resonant frequencies. Increased cooling rate reduces both peak amplitude and the resonant frequency of the transmissibility curve. The force isolation provided by shape memory alloy oscillator is independent of the operating conditions.

A study of fan-distortion interaction within the fan rotor

2020 ◽  
pp. 095765092092004
Author(s):  
Zhihui Li ◽  
Juan Du ◽  
Qianfeng Zhang ◽  
Guofeng Ji ◽  
Hongwu Zhang
Keyword(s):  
High Performance ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Stagnation Pressure ◽  
Detached Eddy Simulation ◽  
Axial Fan ◽  
Fan Performance ◽  
Inlet Distortion

Boundary-layer-ingesting fans and compressors in the next-generation turbofan engines require high-performance operations under distorted inflow. The aim of this work is to study the effects of inlet distortions including inlet stagnation pressure and temperature distortion, on the aerodynamic performance of a transonic axial fan. Firstly, the validated full-annulus, unsteady, three-dimensional computational fluid dynamic code in conjunction with detached Eddy simulation approach is used here to simulate the fan flows assembly with individual inlet stagnation pressure/temperature distortion. Then, the propagation process of the inlet distortion waves is analyzed to understand how the aerodynamic performance degradation is triggered. The simulation results show that the fan performance is remarkably degraded when the inlet distortion is introduced. The leading-edge spillage, the trailing edge back flow and the “tornado vortex” occur when parts of fan blades encounter the incoming distorted flows. Finally, the responses of fan to the combined inlet stagnation distortion effects are discussed in this paper. It is found that the combined distortion effects can be predicted based on the sum of the performance responses to the individual constituent distortions. Furthermore, the relative location of the constituent distortions shows a non-ignorable influence on the overall fan performance, especially for the intensified inlet distortion.

Failures of Mechanical Springs

2021 ◽  
pp. 402-414
Author(s):  
Dana J. Medlin
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fatigue Failure ◽  
Failure Mechanisms ◽  
Operating Conditions ◽  
Material Defects ◽  
Common Causes ◽  
Mechanical Components ◽  
Fatigue Failures

Abstract Mechanical springs are used in mechanical components to exert force, provide flexibility, and absorb or store energy. This article provides an overview of the operating conditions of mechanical springs. Common failure mechanisms and processes involved in the examination of spring failures are also discussed. In addition, the article discusses common causes of failures and presents examples of specific spring failures, describes fatigue failures that resulted from these types of material defects, and demonstrates how improper fabrication can result in premature fatigue failure. It also covers failures of shape memory alloy springs and failures caused by corrosion and operating conditions.

scholarly journals Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5564
Author(s):  
Rosario Lanzafame ◽  
Stefano Mauro ◽  
Michele Messina ◽  
Sebastian Brusca
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Time Step ◽  
Vertical Axis Wind Turbines ◽  
2D Model

The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

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