The automotive industry is one of the fastest growing industries worldwide with millions of vehicle productions and sales every year globally. Some of the vehicles have their engines in rear end, which means there is no incoming airflow from the front and the engine cannot cool down efficiently. The main aim of the research is to study the flow behavior for a duct that can detour the incoming air to the radiator for vehicles those have their engines located at the back. The duct collects the incoming air from the front of the vehicle and detour it to the engine located at the back. This helps in cooling down the engine in order to protect it from being overheated. The research is conducted to understand the detailed parameters to be accounted for while designing such a prototype. It is important to understand the essence of a cooling effect as the efficiency of the vehicle engine can only be maintained under a stable temperature. The research is important as it can be applied to diverse engineering problems. There are three cases for the experiment, each with different lengths. However, the inlet and outlet have identical dimensions for all three cases. There is a certain scale factor used to scale down the dimensions from a previously studied CAD model. These scaled down dimensions are then utilized to fabricate the prototype. Once the model has been constructed, a mesh is located at the outlet, which helps recording velocity magnitude and direction at each of the respective node of the mesh. One of the key elements of the research is to extensively understand the type of flow at different points of the duct and how they affect the efficiency of the design. For example, the curved parts where channels are installed along the length of the duct experience turbulent air flow. Hence, it is important to understand the influence of these flows on the efficiency of the design.

One of the important parameters in the reduction of greenhouse gas emission can be considered as the energy efficiency of the building. The building sector is constantly innovating in its use of materials with regards to sustainability. There is a need to use cost-effective, environmentally friendly materials and technologies which lessen the impact of a construction in terms of its use of non-renewable resources and energy consumption. For the reduction in energy consumption, thermally insulating materials can be installed inside the building envelope. It prevents heat loss and provides thermal comfort for the occupants. The introduction of the organic waste materials for thermal insulation is recent and little is known for their environmental effect in comparison with the conventional materials. Present study consists of experimental analysis to investigate the composition of wood powder and ash brick as a brick. Different modifications have been performed to determine the best methodology for the change in standard ash brick. The study has been concluded with the help of heat transmission factor and compressive strength.

A combined computational/ experimental analysis is conducted to investigate the cooldown behavior of a surrogate engine mount assembly. The engine mount in an automobile is often in the close proximity of the catalytic converter, and may heat up significantly during operation of the vehicle. When the vehicle is parked after operation, the mount cools due to heat loss by natural convection and radiation. The objective of this study is to develop a model that is capable of accurately predicting the spatio-temporal evolution of the mount temperature during this cooldown process. Carefully controlled experiments were first conducted, during which temperatures were recorded at 41 different locations. A Computational Fluid Dynamics (CFD) model that includes natural convection and radiation was next developed to simulate the same experiments. The simulations were conducted using roughly 5–6 million control volume (cells). The mesh was generated using ANSA™ and parallel computations of the governing equations were conducted using Ansys-Fluent™. The CFD results were found to agree with the measured temperatures to within a few tens of degrees. The discrepancies may be attributed to differences in initial conditions (measured versus numerical) and due to the fact that thermal contact resistances were neglected. However, the study revealed that to obtain reasonably close agreement, one must use very small time step sizes — small enough to sufficiently resolve the rapidly changing unsteady natural convection patterns — making such computations extremely time-consuming.

Dielectric Barrier Discharge plasma actuators are simple devices with great potential for active flow control applications. They have very interesting features which have made them a topic of interest for many researchers, for instance they present very low mass, fast response time, low cost, easy implementation and they are fully electronic with no moving parts. The dielectric material used in the construction of these devices present an important role in their performance. The variety of dielectrics studied in the literature is very restrict and the majority of the authors make use of Kapton, Teflon, Macor ceramic or PMMA. Furthermore, several authors reported difficulties in the durability of the dielectric layer when actuators operate at high levels of voltage and frequency. Considering this background, the present study focus on the experimental testing of alternative dielectric materials which can be used for DBD plasma actuators fabrication. Considering this, plasma actuators with dielectric layers made of Poly-Isobutylene rubber, Poly-Lactic acid and Acetoxy Silicon were experimentally tested. Although these dielectric materials are not commonly used in plasma actuators, their values of dielectric strength and dielectric permittivity indicate they can be good solutions. The plasma actuators facbricated with these alternative dielectric materials were experimentally analysed in terms of electrical characteristics and induced flow velocity, and the obtained results were compared with an actuator made of Kapton which is, currently, the most common dielectric material for plasma actuators. The effectiveness of the actuators was estimated and the advantages and disadvantages of the use of each dielectric material were discussed.

A comparative experimental analysis of three common hemming processes used in the automotive industry is presented. These processes are die hemming, table hemming, and roll hemming. We aim to determine which one of the three processes provides the better quality hemming. The die hemming and table hemming used in this study were performed with custom made tooling and a 35 tonne hydraulic press. Similarly, roll hemming was performed using a custom made workbench with a three-degree of freedom system of rolls. The material used for testing was aluminum sheet (6011); three rolling directions were taken in account: 0°, 45°, and 90° for the manufacture of the samples. Hemming quality was determined from the geometric variables such as: lip high, pre-hemming angle, tool position, roll radius (roll hemming only). As a result, the comparison of roll in/out and wrinkle defects are reported and compared.

With the development of modern industry, the separation of suspended droplets from the gaseous flow has become increasingly important. In many industrial applications it is required to control the fine liquid droplets concentration in moving gaseous media. Refrigeration and Heating Ventilation Air Conditioning (HVAC) system is one major application. Electrostatic Precipitator (ESP) can be adopted for separation of fine droplets in gases, since corona discharge could charge these droplets, then use of electrostatic force to implement separation and collection. However, separation of droplets in gaseous flow is a complex process which is combination of electrostatic and flow field. The current study investigates effects of key parameters like applied voltage, flow temperature, flow velocity and particle’s size on particles separation efficiency using a wire-cylinder assembly. Monodisperse particles are used in this study where above mentioned parameters have shown significant effect on the separation efficiency.

The current study shows computational and experimental analysis of multiphase flows (gas-liquid two-phase flow) in channels with sudden area change. Four test sections used for sudden contraction and expansion of area in experiments and computational analysis. These are 0.5–0.375, 0.5–0.315, 0.5–0.19, 0.5–0.14, inversely true for expansion channels. Liquid Flow rates ranging from 0.005 kg/s to 0.03 kg/s employed, while gas flow rates ranging from 0.00049 kg/s to 0.029 kg/s implemented. First, single-phase flow consists of only water, and second two-phase Nitrogen-Water mixture flow analyzed experimentally and computationally. For Single-phase flow, two mathematical models used for comparison: the two transport equations k-epsilon turbulence model (K-Epsilon), and the five transport equations Reynolds stress turbulence interaction model (RSM). A Eulerian-Eulerian multiphase approach and the RSM mathematical model developed for two-phase gas-liquid flows based on current experimental data. As area changes, the pressure drop observed, which is directly proportional to the Reynolds number. The computational analysis can show precise prediction and a good agreement with experimental data when area ratio and pressure differences are smaller for laminar and turbulent flows in circular geometries. During two-phase flows, the pressure drop generated shows reasonable dependence on void fraction parameter, regardless of numerical analysis and experimental analysis.

The machining of complicated surface is a hot spot in manufacturing industry in nowadays. The complicated surfaces should be machined with five-axis machine tools because of its geometric characteristics. In this paper, the characteristic of workpiece surface called open and close angle of surface is defined. The transition area from open angle to close angle will cause the twist and singularity of the surface. The twist mainly affects the principle errors of surface. And the singularity will cause the mutation of rotation axis movement and make an influence on the contour errors. To test the influence of the open and close angle on the contour error, a workpiece with special surface characteristics is designed. With the theoretical, simulational and experimental analyses, the influence law from the open and close angle is found out. The conclusion can be helpful for the tool trajectory planning.

The failure mechanism in stretch bending over a small die radius for Advanced High Strength Steels (AHSS), commonly referred as “shear fracture”, has rendered the Forming Limit Diagrams (FLD) fail to predict it based on the initiation of a localized neck. As shown in previous studies using a Stretch-Forming Simulator (SFS) and Bending Under Tension (BUT) test, shear fracture depends not only on the radius-to-thickness (R/T) ratio but also on the tension/stretch level applied to the sheet during bending. Although the stress-base empirical fracture limit criterion was developed for various AHSS grades, the fracture limit was not well implemented in the computer simulations to predict stretch bending fracture. In this paper, the new developed experimental analysis is conducted on the modified bending under tension test to further investigate the stretch bending fracture mechanism under the production die condition. Various AHSS grades including DP590, DP780, DP980 and DP1180 are included in the study. Based on numerous experimental results, the maximum shear stress at failure, the thinning strain and strain gradient across the die radius are obtained for all test materials. Results demonstrate that the presence of the large strain gradient is the cause for fracture in stretch bending AHSS over a small die radius. The maximum shear stress at failure and the limit thinning strain on the die radius in the stretch bending condition are determined and used as the new fracture criteria, which can be easily implemented in the computer simulations.

Cancellous bone contains bone marrow where hematopoietic stem cells (HSCs) are produced. Those cells represent an interest in the treatment of leukemia during which transplantation of bone marrow is performed to replace patient degraded cells. HSCs are usually harvested by a puncture in the cancellous bone of the donor’s ilium using a needle. However, this procedure can cause severe burden to the donor because of its high invasiveness. The flow of bone marrow is strongly related to the harvesting of HSCs and permeability is one of the major parameters to characterize cancellous bone. Previous researches have already shown an anisotropy of permeability in femur, whereas punctures are usually performed in the iliac cancellous bone. The objective of this paper is to characterize the anisotropic permeability of iliac cancellous bone. Digital images of a porcine iliac cancellous bone sample were obtained by micro-computed tomography (micro-CT), and three locations were selected to fabricate bone models, reproduced by 3D printing at three times magnification. To compare the structure of manufactured models, porosity and its variations along X, Y and Z direction were evaluated from micro-CT images. To measure permeability, a specific perfusion system was developed. The pressure drop between the upstream and the downstream of bone models were measured at different flow rates, reaching a Reynolds number of 27–158, appropriate for the aspiration condition. Darcy-Forchheimer’s law was then applied to calculate the permeability and Forchheimer coefficient of bone models. Results revealed different porosities and resultant permeabilities for each bone nodels. A positive correlation links those two parameters. Different fluctuations of porosity were evaluated along each direction although no significant difference of average porosity was observed. On the other hand, different permeabilities and Forchheimer coefficients were measured in each direction with various degrees of anisotropy. Permeabilities in three orthogonal directions of the model ranged from 1.96 × 10 −10 to 4.29 × 10 −10 m 2 . Results indicate that transport properties in cancellous bone depend on the flow directions. The anisotropy of permeability can be used for evaluation of flow in cancellous bone.

The Best Estimate Plus Uncertainty (BEPU) method has been applied by the authors to analysis of the “intentional depressurization of steam generator secondary side” which is an accident management procedure in a small break loss-of-coolant accident with high pressure injection system failure. In the present study, experimental analyses using the RELAP5/MOD3.2 code were carried out for the ROSA/Large Scale Test Facility (LSTF) secondary-side depressurization tests. The two test cases were selected with different break sizes and different depressurization conditions to ensure the reliability for the accident scenario analyses. The uncertainty propagation analyses were performed through the random variations of input parameters whose uncertainty ranges and distributions were determined previously by the PIRT and the separate effects tests. One thousand random calculations were conducted to get the 95% upper limit values of the peak cladding temperature (PCT) by the Monte Carlo method. Furthermore, the 95%/95% tolerance limits for the PCT were obtained according to Wilks formula. It was confirmed that the code predicted well the major event progressions such as rod surface temperature and the 95% uncertainty bands included the measured values. Furthermore, the 95% upper limit values of the PCT are below the 95%/95% tolerance limit values. However, the statistical fluctuation of the tolerance limit values by Wilks first order formula is as large as the uncertainty value itself. The statistical fluctuation decreases with increasing order of Wilk formula. It is desirable to increase the order of Wilks formula to more than the second order to get the reliable safety margin.

Fused deposition modelling (FDM) creates three-dimensional parts by feeding a rigid thermoplastic filament through a heated barrel to achieve a semi-fluid state and then extruding it layer-by-layer to create a part geometry. The melt flow behavior within FDM must be analyzed in order to correctly understand the temperature gradients within the system to promote part quality, process control, and efficiency. The presented research consists of analyzing the melt flow behavior of polymer poly(lactic) acid (PLA) within FDM. This includes an experimental analysis of the power output of the resistive heat source, a theoretical analysis of external coefficients of heat-transfer, and an experimental validation of liquefier temperatures. A three-dimensional fluid-flow model is created using the accurate geometry of the extruder assembly, calculated conditions from initial experimental results, and referenced material properties. Results of this research include a significant temperature difference between the areas of the liquefier assembly close in proximity to the power source to those further away such as the inlet and outlet, suggesting that external heat transfer mechanisms play a significant role in liquefier dynamics, contrary to the more common assumption of constant wall temperature or constant heat flux used in modeling. The research presented provides new information regarding the melt flow of PLA, a method of modeling external heat transfer, and a way of understanding power consumption that can lead to liquefier design improvements. The process itself will also aid in identifying modeling considerations for further investigations of melt flow involving various extruder designs and material options. Specifically, the use of this type of comprehensive model is of interest to the additive manufacturing community with respect to thermally sensitive component specification and heating and cooling needs within process based on changing system parameters such as extrusion temperature and mass flow rates (i.e. material feed rate and/or change in extrusion diameter).

Magnetorheological (MR) dampers have emerged as a viable means of semi-active damping in multiple industry applications. The semi-active nature of these dampers is a significant attribute since the damper functions as a passive damper in the event of a failure. While there have been other smart materials like ferroelectric, piezoelectric, shape memory alloys, etc. that have been successfully used, MR fluids exhibit a unique combination of completely reversible effect, very low response time, high durability and very low energy requirements that make them suitable for vibration control in a wide variety of applications. This paper presents results from an experimental investigation that has been carried out to evaluate the performance of a MR damper for vibration mitigation. The capability of a commercial MR damper to isolate a payload from base excitation is analyzed and the damper parameters are identified to simulate the capability of the damper with regards to transmissibility. Multiple iterations of testing are performed in order to evaluate the influence of variables such as input current to the electromagnet, mass of the payload, excitation frequency and excitation amplitude. Results indicate that the MR damper is successful in mitigating vibrations transmitted to the payload. Vibration mitigation is quantified through multiple means such as comparing the root mean square (RMS) of the time history of acceleration of the base with that of the payload, comparing the frequency response and evaluating the hysteresis plots. Displacement transmissibility results directly demonstrate the variable damping capability of the MR damper. Although the stiffness constant of the damper may also change, it is not seen to vary appreciably in this study since the excitation amplitude is limited to a low threshold. The damper is found to be robust with an inherent ability of handling payload and excitation variability. It is observed that increasing the input current to the electromagnet around the MR fluid results in an increase in damping, therefore, making the use of these dampers viable in applications where payloads and excitation inputs are expected to change during operation.

Magnetorheological (MR) fluids contain suspensions that exhibit a rapid, reversible and tunable transition from a free-flowing state to a semi-solid state upon the application of an external magnetic field. This behavior has attracted significant attention in the development of dampers, shock absorption system, military and defence system and safety devices in aerospace engineering. However, many of the issues pertaining to MR damper behavior in impact and shock applications are relatively unknown. This study provides an experimental analysis and simulation analysis by using COMSOL multyphysics of MR dampers when they are subjected to impact and shock loading. To this end, a novel MR damper with a four-stage piston and independent input currents is designed and analyzed. In this paper, two-dimension symmetrical Computational Fluid Dynamics (CFDs) simulation for the laminar flow of an incompressible MR fluid in the annular gap in the presence of a varying magnetic field. The purpose of this research is to study the couple effect of electromagnetic field and the fluid flow field and magnitude of damping force in a macroscopic view. The governing differential equations describing the magnetic field and fluid flow in the annular gap are solved numerically by COMSOL Multiphysics. Through the electromagnetic analysis and flow field analysis, the coupling effect of the magnetic field between the coil and the multiphysics coupling effect of novel MR was be found. For the each coil has an independent power supply, so it can provide a wider range damping force by combining the electromagnetic field of coils.

Results of numerous studies and experiments show that cepstrum analysis has the ability of simplifying the equally spaced sideband feature in the spectrum and highlights the signal components of defects. However, for most cases of early gear failure, the periodic phenomenon is always buried in strong background noises and the interference of the rotating frequency with its harmonics. Moreover, the features would be further weakened by the average effect of Fourier transform after cepstrum processing. In this paper, an improved cepstrum method named local cepstrum is proposed. The detection principle of local cepstrum is mainly based on the part of spectrum information to enhance the capability of extracting periodical features of detected signals. Besides, the autocorrelation and extended Shannon Entropy Function are also involved enhancing the periodic impulsive features. In the end, only several distinct lines with larger magnitudes would be left in the local cepstrum, which is very effective for gear fault detection and identification. Both simulation and experimental analysis show that the proposed method, which is more sensitive to the gear failure compared with conventional cepstrum analysis, could partially eliminate the interference of background noise and extract the periodical features of premature failure signals effectively.

A direct methanol fuel cell can convert chemical energy in the form of a liquid fuel into electrical energy to power devices, while simultaneously operating at low temperatures and producing virtually no greenhouse gases. Since the direct methanol fuel cell performance characteristics are inherently nonlinear and complex, it can be postulated that artificial neural networks represent a marked improvement in performance prediction capabilities. Artificial neural networks have long been used as a tool in predictive modeling. In this work, an artificial neural network is employed to predict the performance of a direct methanol fuel cell under various operating conditions. This work on the experimental analysis of a uniquely designed fuel cell and the computational modeling of a unique algorithm has not been found in prior literature outside of the authors and their affiliations. The fuel cell input variables for the performance analysis consist not only of the methanol concentration, fuel cell temperature, and current density, but also the number of cells and anode flow rate. The addition of the two typically unconventional variables allows for a more distinctive model when compared to prior neural network models. The key performance indicator of our neural network model is the cell voltage, which is an average voltage across the stack and ranges from 0 to 0:8V. Experimental studies were carried out using DMFC stacks custom-fabricated, with a membrane electrode assembly consisting of an additional unique liquid barrier layer to minimize water loss through the cathode side to the atmosphere. To determine the best fit of the model to the experimental cell voltage data, the model is trained using two different second order training algorithms: OWO-Newton and Levenberg-Marquardt (LM). The OWO-Newton algorithm has a topology that is slightly different from the topology of the LM algorithm by the employment of bypass weights. It can be concluded that the application of artificial neural networks can rapidly construct a predictive model of the cell voltage for a wide range of operating conditions with an accuracy of 10 −3 to 10 −4 . The results were comparable with existing literature. The added dimensionality of the number of cells provided insight into scalability where the coefficient of the determination of the results for the two multi-cell stacks using LM algorithm were up to 0:9998. The model was also evaluated with empirical data of a single-cell stack.

Exhaust gas temperature of diesel engine is higher compared with a petrol engine and also creates higher pollution in the environment. Exhaust gas recirculation system and many other systems have used for reuse of exhaust gas to improve the performance of diesel engine, but the use of diesel engine for production of potable water production is still unattended by the researchers. The main aim of this research work is to use the waste heat of exhaust gas for potable water production from the low capacity desalination system integrated with evaporator and condenser unit. In this work, single pass evaporator and water cooled condenser used for evaporation and condensation of saline water were designed and fabricated by locally available materials. The experiments were performed on a 10 HP Diesel engine with varying the load to get potable water. It has found that, 4.2 Liter/hr of potable water is obtained from the exhaust gas without varying the performance of the engine. Also, it has found that, temperature of saline water is heated more than 70 degrees Celsius in the condenser unit.

Recent advances in technology have given the opportunity of developing structures of nanometer scale suitably dispersed in base fluids. The term nanofluids, introduced by Stephen U.S Choi, describes the liquid suspensions which contain these structures (nanoparticles, nanotubes, nanodroplets etc). Even though the branch of nanotechnology, where nanofluids can be categorized, is in its infancy the growth of research work in terms of engineering applications that has been done already indicates the interest of researchers in nanofluids. As mentioned above a lot of research work, both experimental and computational, has been done in the field of nanofluids. As far as heat transfer is concerned, all researchers reach the same conclusion: heat transfer is enhanced while using nanofluids as means of cooling or heating due to the improved, among others, thermal conductivity of nanofluids compared to the conductivity of the base fluid which in most cases is water. The purpose of this review is to present the research that has been done on heat transfer calculations as well as the basic properties of the nanofluids. For this reason the structure of the review is divided into two topics. In the first topic models of calculating the effective thermal conductivity and the effective dynamic viscosity of nanofluids are presented. The aforementioned models have derived from both theoretical and experimental analysis. The second section concentrates on summarizing the correlations which calculate the Nusselt number and thus the convection coefficient.

In this paper, experimental and numerical studies on drilling of multi-material made of CFRP laminate sandwiched with aluminum part have been carried out. These tests have been conducted using carbide drills (K20) to study the influence of spindle speed, feed rate and lip length of the double cone drill on cutting forces and holes quality. From the experimental study it was found that the double cone drills used for the experimental analysis encountered less thrust force compared to the standard twist drill. In addition the quality of the holes after drilling was evaluated, and found that no delamination (entry and exit of the hole of the composite part) even at higher feed rate (> to 0.1 mm/rev). By numerical modeling, it was noticed that, after machining with standard twist drill at higher feed rates, the thrust force generated induces a small opening at the CFRP/Al interface.

The deep drawing process is commonly used in the industry because its ability to produce parts with reduced weight and good mechanical properties at a high production rates. However, the elasto-plastic deformation mechanism of deep drawing is complex and difficult to analyse; this because there are many process parameters and variables involved that affect the quality of final products. Among these variables are the geometric parameters, which have been proved to have a great influence on the process. Theoretical and experimental analyses reported in the literature have been mainly focused on conventional cylindrical cup deep drawing. Few research works have dealt with the deep drawing analysis of non-cylindrical parts, particularly the influence of geometrical parameters on the deep drawing performance. This paper presents an analysis of the effect of geometrical parameters on the allowable deep drawing height (DDH) of rectangular parts before fracture. The aim is to identify the influence of the main geometrical parameters on the DDH, Numerical analyses based on the Finite Element Method (FEM) were used to investigate the influence of geometrical parameters, such as the radii, the metal sheet thickness, and the aspect ratio, among others, on the DDH.