Rotary-wing aircrafts are the best-suited option in many cases for its vertical take-off and landing capacity, especially in any congested area, where a fixed-wing aircraft cannot perform. Rotor aerodynamic loading is the major reason behind helicopter vibration, therefore, determining the aerodynamic loadings are important. Coupling among aerodynamics and structural dynamics is involved in rotor blade design where the unsteady aerodynamic analysis is also imperative. In this study, a Bo 105 helicopter rotor blade is considered for computational aerodynamic analysis. A fluid-structure interaction model of the rotor blade with surrounding air is considered where the finite element model of the blade is coupled with the computational fluid dynamics model of the surrounding air. Aerodynamic coefficients, velocity profiles, and pressure profiles are analyzed from the fluid-structure interaction model. The resonance frequencies and mode shapes are also obtained by the computational method. A small-scale model of the rotor blade is manufactured, and experimental analysis of similar contemplation is conducted for the validation of the numerical results. Wind tunnel and vibration testing arrangements are used for the experimental validation of the aerodynamic and vibration characteristics by the small-scale rotor blade. The computational results show that the aerodynamic properties of the rotor blade vary with the change of angle of attack and natural frequency changes with mode number.

Paper production is an energy intensive industry but due to the wastes of its process (black liquor, waste biomass, sludge) has the capacity to generate most of its energy internally. Central to this balance are cogeneration units that guarantee the internal production of heat and electricity. These are sized for the company’s thermal load, with excess electricity injected into the grid. The efficient use of endogenous resources is a major route for improving the energy and environmental efficiency of the plant. Some of the waste materials include biomass wastes, sludges and other industrial wastes such as plastics. The present work aims to identify the opportunity of introducing a waste biomass gasification plant and the use of the produced synthesis gas, replacing the natural gas currently used in the turbine included in the company’s cogeneration unit. In this scenario, one of the cogeneration units in its current configuration has two steam boilers (one biomass; one black liquor) and a gas turbine whose waste heat feeds a recovery boiler to produce steam. The work involved several steps: the energy balance of the unit, the characterization of biomass residues (mixing bark, pine bark, eucalyptus bark, and refuse fibers), the test experimental analysis of residual biomass gasification and the characterization of the synthesis gas produced. In the electric and thermal energy producing units, gas turbines have a working efficiency above 35% while the steam turbines is considerably lower (15%). The efficiency of the chemical recovery boiler (79.5%) is lower than that of the biomass boiler (89.5%). From the experimental analysis of biomass it was found that most of them have a carbon and hydrogen content higher than 48 % and 5 %, respectively. In terms of higher calorific value (HHV), for the biomass where it was possible to determine it, the value is between 19.3 and 23.6 MJ/kg. These properties reveal that the selected biomasses from within the company, have potential as fuels. The limitation on its use may be due to the ash content, which tends to exceed 10 %. A gasification test (90 % eucalyptus biomass and 10 % mixture biomass) was also carried out to produce syngas and further characterization. The calorific value of the gas produced was 18 MJ/kg, with an absolute density of 1.17 kg/m3. It can thus be seen that for a gas turbine with a 35.8 % efficiency with a workload of 29.9 MWe 4.6 kg/s of syngas is required.

Subsea wet gas compressors have been successfully in operation for approximately 5 years. Their use has proven to increase the recovery by approximately 10% and achieve a reliability up to 98%. Further developed and operation of subsea wet gas compression require detailed knowledge of compressor operability and how shift in operational conditions affect the compressor system. The compressors ability to handle wet gas is documented in detail for a gas volume fraction limited down to 0.90. The 4–5 last year of operation proves the wet gas concepts capability. As years pass by, well pressure and production rate declines which causes the compressor operation point to shift towards the high head and low flow (surge) area of the characteristics. In addition, compressor inlet transients increase due to pipe surge (slugs), requiring a robust control system to prevent instabilities, e.g. compressor surge. It is therefore vital to understand how the compressor inlet flow device behaves at different wet operation conditions. The article documents how a standard dry gas venturi tube behave at different wet gas operation conditions. The venturi is designed according to ISO5167-4 for dry gas conditions and is tested at the low-pressure air water compressor test rig at NTNU. The primary objective of the work has been to visualize the wet flow regime through the transparent venturi tube and to document the wet gas flow rate measurements by means of single-phase meters. The venturi tube is tested in a GMF range from 1 to 0.83 at an air volume flow rate of 1.3m 3 /s.

The paper proposes a novel concept for axels dry braking system in off-road vehicles by implementing an oil recovery system in the friction plates chamber. The new system is able to remove the oil in the discs’ chamber when they are not engaged and to replenish it when the braking system is activated and the heat generated has to be dissipated. Thus, the energy losses due to the oil splashing will be significantly reduced with remarkable effects on the fuel consumption of the vehicle. Since experimental measurements are very difficult to carry out on a real system, a simplified geometry is designed and an ad-hoc test rig realized. Fast imaging techniques are used to capture the multiphase flow pattern within the friction plates chamber at different rotational speeds of the axel. The experimental results are used to validate a full 3D multi-phase CFD approach. A good agreement between the measurements and the calculations is found. The numerical modeling is therefore employed to predict the flow distribution in the real geometry and under actual operating conditions. A modular approach is adopted for the domain subdivision in order to represent accurately the three dimensional geometrical features, while the volume of fluid approach is used to model the multi-phase flow that characterizes the component. A conjugate heat transfer model is also adopted to predict the heat transferred from the discs to the working fluid and how the fluid is dissipating the heat within the component. By means of the numerical analysis the geometry of the real system is designed in order to improve the performance of the dry braking systems both in terms of energy saving and oil cooling.

The motion of the target plate is important in some industrial applications which apply multiple jet impingement, such as reflow soldering, drying and food processing. Multiple jet impingement is widely used due to its ability to generate high heat transfer rates over large and complex areas. This convective process is characterized by several flow interactions essentially due to adjacent jets mixing prior the impingement, wall jets collision after the impingement, as well as crossflow interactions induced by the motion of the wall jets that flow through the exits of the domain. These interactions lead to strong flow recirculation, pressure gradients and boundary layer development. However, the complexity of the flow interactions is increased with the surface motion in confined space, due to the generation of strong shear regions. These interactions can induce problems and product defects due to complicated thermal behavior and non-uniform heating or cooling, being important to fully understand the process in order to reduce time and costs. This work addresses the experimental analysis of multiple air jets impinging on a moving flat plate. The experiments are conducted on a purpose-built test facility which has been commissioned, using a 2D-PIV system. Through this technique, the flow structure and velocity profiles will be analyzed in detail. The effects of the impinging plate motion on the resulting global and local velocity profile is compared with a static flat plate. The multiple jet configuration consists on air flowing through 14 circular nozzles, at a Reynolds number of 690 and 1,380. The experiments are conducted for a nozzle-to-plate distance of 8 and a jet-to-jet spacing of 2. The target plate motion remains constant throughout the experiments and equal to 0.03 m/s. The results are compared for both stationary and moving flat plates cases and express the increased complexity of the flow due to strong interaction between jets and the target surface, which affects the heat transfer performance. The results obtained experimentally are important to clearly define this complex flow and these data can be used in future works for numerical model validation.

In metal cutting, some of the generated forces do not contribute to chip formation. These forces are referred to as plowing forces and are induced mainly as result of the finite sharpness of the tool (cutting edge radius) and the tool’s land (flank). Determining the magnitude of these forces is essential to developing a better understanding of the mechanics and physics of applications that involve cutting at minimal feed values (e.g., micro-machining and vibration-assisted-micro-machining. It is well recognized that plowing forces increase with tool wear. This research estimates these forces by employing analytical and numerical simulations. An extensive experimental analysis is utilized to verify the simulated values of the plowing forces. The experimental verification is designed to measure these forces as a function of several cutting parameters. The developed methodology relates the plowing forces to geometric factors and process parameters such as cutting-edge radius, tool feed, and cutting speed.

Kolsky Bar systems are subjected to inherent system error as all measurement devices are. This is especially true in that as the bar diameter decreases, the system becomes more sensitive to errors such as friction and misalignment. In this work we present a technique for identifying and quantifying the error of a Kolsky system. We also present a method of generating statistically significant bounds for Kolsky systems so that anomalous or improperly executed experiments can be quantitatively identified. This method does not rely on the intuition of the experimentalist to identify an anomalous experiment. After presenting our method for error identification, a series of tests are performed on 2024Aluminum alloy samples. A method is then presented where the system error, as well as some error contributed by a variance in sample dimension, are removed from the calculated error related to the stress on the samples. The result shows the effective variance of the sample response is quite high in the elastic loading period, but reduces when plasticity dominates. This is attributed to the presence of high frequency content in the travelling elastic waves which cannot be accurately measured currently, but is effectively damped out when plastic deformation dominates.

In any congested area, where a fixed-wing aircraft cannot perform, rotary-wing counterparts are the best-suited option for its vertical take-off and landing capacity. The vibration induced by the rotor blade is a significant problem in helicopter performances. Rotor aerodynamic loading, rotor dynamics, and fuselage dynamics are the elements that contribute to the vibration of a helicopter. Among these elements, the key reason for the helicopter vibration is the aerodynamic loading. Determining aerodynamic loading is one of the most important criteria to design a rotor blade and to minimize vibration. Rotor harmonic airloads are generated from the rapid variation of flow around the rotor blade due to the vortex wake. A rapid drop in the circulation near the blade tip causes tip vortices which are the reason for the maximum lift at the tip of the blade. Consequently, tip vortices become the primary source of harmonic airloads. In this study, a specimen of Bo 105 helicopter rotor blade is considered to observe the aerodynamic characteristics under the external flow of air. The coefficients of lift and drag of the specimen for different angles of attack and azimuth angles are estimated. The resonance frequencies and the mode shapes are obtained. Computational results are validated by the experimental analyses of a small-scaled model of the rotor blade. From the study, the coefficient of lift is found to increase with the angle of attack up to a critical value. Similarly, the coefficient of drag increases with the angle of attack. The resonance frequencies significantly change with scaling the rotor blade.

The superalloy products formed by multi-pass conventional spinning are widely used in rotary forming parts with complex shapes. As the connection of each forming pass, the attaching-mandrel process has an important influence on forming quality and production efficiency. The hot spinning process is usually adopted in superalloy forming because its poor plasticity in normal temperature, meanwhile, it brings the poor surface quality of the parts and huge energy consumption. For this reason, the cold spinning and the attaching-mandrel process of nickel-base superalloy GH3030 are studied. The combination method of experiment and simulation is used to study the attaching-mandrel process based on one-forward-pass spinning process. The effects of pass pitch and the attaching-mandrel velocity on the tool forces, parts stress field, strain field and wall thickness distribution are analyzed. The microstructure of the part is divided into three layers: outer, middle and inner layer. The grain size of each layer is compared. Then the effect of different pass pitch on the grain structure is clarified. The results show that the reasonable pass pitch and the attaching-mandrel velocity can improve the forming quality and production efficiency. The multi-pass cold spinning process on superalloy GH3030 is feasible. The excessive pass pitch can cause seriously grain elongation, the grain boundaries are blurred, and even cracking.

Incremental forming (IF) is a novel sheet material forming process which promises significant energy savings within the low and medium volume sheet production industries. This advantage stems from IF’s dieless forming nature, which alleviates the need for time and energy input towards die fabrication and offers significantly greater flexibility. However, a distinct disadvantage of this process is its relatively low forming rate compared to conventional stamping, which reduces its feasibility of use in higher volume productions. Springback is one disadvantage of incremental forming which has hindered its implementation within industry. Spring-back reduction methods, as well as springback characterization, can be found throughout literature. However, very few publications disclose the clamping dimensions used for fixturing work-pieces. This study numerically determines the springback effect of utilizing various clamping structures and presents an empirical solution for determining the springback of truncated pyramid geometries for various constraining areas. The resulting equation was found to have an acceptable degree of error relative to experimental analysis.

Forming processes are a convenient means for bulk production of parts. These parts are used in a wide range of applications from automotive industries to micro-devices in bioengineering. Manufactured parts are required to be precise in their final dimension, and since the billet material undergoes significant plastic deformation during forming, billet material characterization and prediction of final form is essential. In this study, miniaturized bowl-shaped samples of 3003-H14 aluminum alloy were formed using a die and punch manufactured using the stereolithography (SLA) additive manufacturing method. Tensile testing was performed in order to characterize the material properties of the SLA resin. Using the SLA-created die and punch, hemispherical bowl-shaped forms were generated. In order to investigate possible small size effects, experimental load versus displacement results were obtained for billet plate thicknesses of 0.4–0.8 mm. A numerical finite element model was developed to predict the required punch load to manufacture various thickness bowl-shaped forms. A comparison was made between the load verses displacement curves for the different thicknesses, and the numerical model was validated by the experimental results. The validated computational model can then be used to predict the process parameters prior to starting bulk production. Finally, a model with grains was developed and simulated to show the virtual microstructural morphology of the circular plates before and after the forming operation.

In this work, we investigated the effect of geometric parameters on the payload capacity of Ti-6Al-4V flexure hinges taking plastic deformation as a boundary failure criterion into account. Finite element and experimental analysis were performed in combination to increase the significance of the findings. For both simulations and experiments rectangular cross section flexure hinges were designed with varying thickness, length and width. While varying one of the parameters, the others were kept constant in order to see the individual influence of that particular parameter. The samples were fabricated using laser cutting of Ti-6Al-4V (Grade 5) metal sheets to ensure optimum dimensional accuracy. In the experimental procedure, the samples were fixed at the proximal end and exposed to gradually increasing vertical loads at the distal end by using weights. Simultaneously, they were exposed to a counteracting moment by pull-wire actuation attached on the tip to simulate the realistic actuation-loading behavior. For the sake of a uniform comparison of the samples with different dimensions, a state of equilibrium was defined such that the proximal and distal ends of the hinge were parallel. As soon as this state was achieved, the poses in each loading state were documented by a digital microscope for later postprocessing. On the other hand, the simulations were constructed in a way that permitted the experimental approach to be reflected in the simulation environment as realistically as possible. While performing a deformation-based simulation, the surface on which the payload was acting was blocked against rotation around the lateral axis so that the state of equilibrium could be maintained. The hinges were deflected with gradually increasing deformation in the vertical axis until 0.2% plastic strain occurred in the unloaded state. At this point the deformations in the vertical axis for both loaded and unloaded states were recorded to be compared with the experimental values. The forces leading to the deformation in the loaded state were calculated as output of the simulation and recorded as payload capacity. Consequently, the deformations obtained by analyzing the images captured during the experiments were compared and matched with the ones obtained from the simulations. The experimental loads leading to these deformations were recorded as experimental payload values. In the first step towards the evaluation of the results, payload values obtained from experiments and simulations were compared to check the consistency of the process. Subsequent to verifying the consistency, the effect of the geometric parameters on the payload progression was analyzed based on the simulation results. Nonlinear multidimensional regression was performed to come up with a design guideline which approximates the payload capacity based on the dimensional parameters. The proposed guideline estimates the payload value as proportional to width, inversely proportional to length and proportional to the 1.6 th power of thickness.

Energy is a major area of concern for many industrial and engineering applications. For the development of energy efficient heat exchangers, heat transfer enhancement by passive inserts have growing research potential. The present study gives the numerical and experimental analysis of twisted tape insert in a circular tube for the range of Reynolds number between 5000 to 15000 with heat flux variation from 500W/m 2 to 1.5 kW/m 2 with air as working medium. A circular tube of 52.5 mm internal diameter, 60 mm outer diameter and 1000 mm length is used as test section with uniform heat flux. Twisted tape used is of Aluminum material having a pitch of 100 mm. Outside surface temperatures are measured at different locations on test section. Two ‘T’ type thermocouples are used to measure air temperature at inlet and outlet of test section. From numerical and experimental analysis it is observed that the Nusselt number increases for twisted tape as compared to smooth bare tube by 2.2–3.1 times. Again the Nusselt numbers obtained for smooth tube is compared with Dittus-Boelter and Gnielinski correlation and it is observed that the error is within acceptable limit of 10% variation. An error of 10% variation is observed in friction factor obtained by experimental analysis and Blasius and Petukov correlations.

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.

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.

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.

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 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.

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.

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.