Different Angles Of Inclination Research Articles

CFD Analysis of Steady Laminar Natural Convection Heat Transfer from a Pin Finned Isothermal Vertical Plate

AbstractHeat transfer behavior with both the conductive and nonconductive fins have been analyzed by examining variations of the local and average Nusselt numbers in two‐dimensional flow. The main objective of this study is to quantify and compare the natural convection heat transfer enhancement of fin array with different fin aspect ratio and at different angles of inclination. It is found that significant heat transfer augmentation is obtained for both conductive and nonconductive fins. For conductive fins 20% higher augmentation factor is obtained when the fin aspect ratio is 6, angle of inclination is 60° and the pitch‐to‐length ratio is 0.2. For nonconductive fins, 10% higher augmentation factor is obtained when fin aspect ratio is 8, angle of inclination is 45° and pitch‐to‐length ratio at 0.5. A general correlation has been developed to predict the average Nusselt number and heat transfer augmentation factor for conductive and nonconductive fin arrays as a function of different fin configurations.

Enhancing the piston effect in underground railway tunnels

The air flows induced by train movement in tunnels can be used for the purposes of underground railway ventilation. The magnitude of such air flows depends strongly upon the blockage ratio (the ratio of the train and tunnel cross-sectional areas) of the train. This study investigates the impact on the generated air flows due to the alteration of the aerodynamic resistance of the train, as a means of varying the blockage ratio. The alteration in aerodynamic resistance was achieved by using an aerofoil at a variety of different angles of inclination. A two-dimensional computational fluid dynamics model of a train travelling through a tunnel was developed and validated using experimental data from literature. This model was then used to investigate the influence of an aerofoil upon the volume of displaced air and the effect upon the aerodynamic work done by the train (work done by the train due to air drag). The results of this study show that ventilating air flows can be increased by 3% using an aerofoil at a fixed angle of 10° without increasing aerodynamic work. Through using a combination of different angles during different phases of train motion, a maximum increase in air displacement of 8% can be achieved, while not increasing the aerodynamic work done by the train. This equates to the train generated air displacement delivering an extra 1.6m3s-1 of air supply during the period of train motion.

The Influence of Hybrid Material Parameters in Socked-pin Connection on the Value of Opening Force

Different types of techniques are used in joining of aircraft structures. The classical solutions are mechanical or bonding joining. A prospective alternative to the currently used connections (e.g. mechanical, adhesive and hybrid ones) is a socket - pin connection type. Generally, they are purely mechanical joints. Depending on the shape, they have different commercial names such as: Interlock, Snaplock, Snapfit Gridlock. The idea of these connections relies on the fact, that between the socket and the pin we need a suitable interference fit or specially formed clip to carry the load. The advantages of this type of connection of different structural parts is very fast assembly after pressing joined parts together. The use of socket - pin connection eliminates the presence of the human error and reduces production costs as an individual connection is made by CNC machine tools.The paper presents an analysis of the influence of a several technological problems concerning the socket and the pin manufacturing, on the value of force required for the joint connection and disconnection. A number of numerical simulations was made in ABAQUS program to examine the effect of such parameters as: the presence of interference fit, the use of spherical latches, the use of different rigidity in the shaft by making cuts with variable width and length, the use of different angles of inclination of the working part of the slot.

The effects of natural and mixed convection on heat transfer across adjacent micro-channels, in extreme pressure and temperature conditions

This abstract summarizes a mainly experimental investigation of heat transfer across an insulation pack specimen used to protect the upper surface of the Hot Box Dome of an advanced gas cooled nuclear reactor from the hot gas above it, under actual operating conditions. The pack consists of multiple stainless steel layers forming narrow channels, less than 1mm wide between them. The facility developed, can operate at pressures of 40bar, temperature differences across the insulation pack of up to 500°C, with and without flow through the pack channels and at horizontal and inclined orientations. Measurements led to the calculation of the effective thermal conductivity and also the mapping of the temperature variation across the pack for a range of flow rates, and also for angles to the horizontal of up to 30°. The effective conductivity data show how, under these extreme pressure and temperature conditions, the rate at which thermal energy is transferred to the lower, cold side, of this multi-channel pack, depends on the Rayleigh and Reynolds numbers at different angles of inclination. The corresponding local temperature measurements advance understanding of the local thermal characteristics and suggest the presence of strong flow structures. The most striking finding is the strong influence of buoyancy for all flow rates investigated, even for the horizontal cases. Tests at inclined orientations suggest the presence of flow reversal. Complementary conjugate heat transfer numerical analysis, using a simplified two-dimensional representation of the pack, has also been carried out. For the inclined case the computed flow features are consistent with those suggested by the local temperature data.

On the prediction of the daily global solar radiation intensity on south-facing plane surfaces inclined at varying angles

Over the years, some authors have used different models to estimate the solar radiation intensity over inclined surfaces, but none of them has tested and evaluated the accuracy of these models for various inclinations. In this study, by using the acquired data from Meteonorm, five best models studied previously by the authors have been used in order to predict the daily global solar radiation intensity DGSRI received on an inclined surface to the south and to evaluate the day by day performance of these models using a statistical analysis performed by several statistical indicators. The analysis of results revealed that the selected models haven’t the same accuracy, and it is concluded that there are models that can be preferred for the prediction of the DGSRI received on a tilted surface with different angle of inclination at the considered site, Tetuan city in northern Morocco. Empirical correlations between solar radiation intensity fallen on south-facing plane surfaces with various inclination and that receive on horizontal surfaces have been developed. As mean of results of the statistical indicator errors and excluding 20°, 60° and 70° inclinations and the coefficient of determination R2 values, El Mghouchi model is performing comparatively better than the others for all inclinations ranging from 0° (horizontal plane) to 90° (vertical plane) in steps of 10°.

Contemplation of thermal characteristics by filling ratio of Al2O3 nanofluid in wire mesh heat pipe

An experimental investigation on the thermal efficiency and thermal resistance with respect to the inclined angle using heat pipe was carried out. The working fluids used for this are Al2O3 nanofluid and deionized water. The performance of heat pipe in terms of overall heat transfer coefficient and thermal resistance is quantified by varying the volume of working fluid and the performance parameters are contemplated. For this purpose Al2O3 nanoparticles with a density of 9.8g/cm3 and a volume concentration of 1% are used as the working fluid in experimental heat pipe. The performance of heat pipe was evaluated by conducting experiments with different thermal loads and different angle of inclinations. Thermocouples are used to record the temperature distribution across the experiment. Volume of nanoparticles in the base fluid and the consequence of filling ratio on the thermal resistance of the nanofluids are investigated. The results provide evidence that the suspension of Al2O3 nanoparticles in the base fluid increases the thermal efficiency of heat pipe and can be used in practical heat exchange applications.

Calculation model of technological process of soil crumbling by means of tillage working organs

Working organs being used currently for subsurface tillage do not comply with agrotechnical requirements. In particular, the crumbling of soil layer is unequal across the width of cutting plane of working organ. The scientific hypothesis is that variable cutting angle along the length of blade improves the crumbling of soil layer. The mathematical model of interaction between the soil and a wedge is proposed. As the result, the theoretical dependencies of resistance force of soil to destruction and of thickness of shear layer on the setting angle of tillage tool are obtained. A set of dihedral wedges with different angles of inclination has been used in experimental studies. The tests have been performed in media with a wide range of physical and mechanical properties (ordinary humus, sand, clay). It is determined experimentally that all media interacting with the wedge have some common characteristics depending on the parameters of wedge, in spite of differences of physical and mechanical properties and the appearance of layer formation. The experimental dependence of equivalent stresses on cutting angle of the wedge is obtained. Experimental and theoretical results agree well with each other. On the basis of these studies, the working organs with variable cutting angle are developed. It is revealed that the blade with variable cutting angle creates more tension in the soil layer than a blade with constant cutting angle. It is experimentally confirmed that the working organs with variable cutting angle along the length of the coulter crumble the layer by 20-50% better than serial working organs. The economic effect of the introduction of working organs with variable cutting angle is 200-1300 rubles per hectare of cultivated area.

Development and Evaluation of Inclined Plate Metering Mechanism for Onion Pelleted Seeds

Development and Evaluation of Inclined Plate Metering Mechanism for Onion Pelleted Seeds The ability to place seeds at a given distance apart in a row is an important performance factor of a planter with single seed metering mechanism. Inclined plate seed metering device was developed and evaluated in laboratory for singulation and uniform placement of onion seeds with different pelleting ratio viz. 1:1, 1:2 and 1:3 pelleted. Metering device was tested at three inclinations of 40°, 45°and 50° using plates having three different groove number 18, 24 and 30 on cells. Average seed spacing obtained at in S3 seed, θ2 angle in forward speed 2.0 km/h, the average spacing was observed to be 5.90, 5.35 and 5.15 cm for 18, 24 and 30 groove plate respectively. Missing index at 2.0 km/h forward speed with 24 groove seed metering plate with 45o inclination angle was 5.0% and multiple index was 11.0%. The overall quality of feed index obtained with these parameters was 84.0% which is maximum when compared with other seed treatments, forward speeds and types of seed metering plate combinations with different angle of inclination of plates. The selection of plate inclination and type of metering cell for the planter was purely based on average spacing, missing index, multiple index and quality of feed index. With 24 groove seed metering plate with 45o inclination angle and forward speed of 2.0 km/h was selected for the field evaluation..

The Influence of Geometrical Parameters in Socket - Pin Connections on the Value of Opening Force / Wpływ Parametrów Geometrycznych W Połączeniach Typu Gniazdo - Trzpień Na Wartość Siły Otwierającej

The paper presents an analysis of the influence of a number of technological aspects of both the socket and the pin on the value of the force required for joint disconnection. A number of numerical simulations were made in Abaqus program to examine effects of such parameters as: presence of an interference fit, use of spherical latches, application of different rigidity of the pin by making cuts with variable width and length, use of different angles of inclination of the working part of the connection. Models of different simple joints presented in this work, can also operate in large structures forming panels of aircraft structures. For this purpose one of the analyzed geometry of the connection was applied to create a 3-D panel model of the structural element in CAD - SolidWorks program. All analysed models with different geometries were subjected to simulation of opening process. The corresponding critical forces were estimated for the beginning of the failure process. The detailed discussion of all model parameters was included to specify their influence on the whole disconnection of joints. It should be noted that aerospace structures work under complex loading states and further numerical studies are required to extend the presented results.

An experimental investigation of natural convection heat transfer enhancement from perforated rectangular fins array at different inclinations

The main objective of this experimental study is to quantify and compare the natural convection heat transfer enhancement of perforated fin array with different perforation diameter (4–12mm) and at different angles of inclination (0–90°). The variables for this natural convection cooling with the help of finned surfaces are orientation and geometry. In this study, the steady state heat transfer from the solid fin and perforated fin arrays are measured. The increase in the heat transfer coefficient was achieved with perforated fins of 12mm perforation diameter at the angle of orientation 45°, which shows about 32% enhanced heat transfer coefficient as opposed to the solid fin array with nearly 30% saving in material by mass.

Mechanical strength of soda-lime glass sandblasted by gravitation

Abstract Damage to a glass surface by sandblasting has a remarkable effect on its mechanical properties and strength. In this study, we analyze the superficial deterioration of soda-lime glass and its influence on the mechanical strength. Sandblasting by gravitation from a fixed height causes damages by the free fall of different quantities of sand, which we performed for a selected grain size and at different angles of inclination. To characterize the surface state, we used different roughness measures (the arithmetic mean value of the roughness R a, the root mean square roughness R q, and the maximum roughness R max) and measured the optical transmission (transmittance) at different points on the specimen surface using a profilometer. To determine the mechanical strength, we proceeded by two methods: first, by a shock ball (falling ball), and then by biaxial bending using circular supports. The effects of the surface damage on the optical transmission and the mechanical strength of the glass are graphically presented and discussed in this paper.

Spatial and angular finite element method for radiative transfer in participating media

A computational approach for the modeling of multi-dimensional radiative transfer in participating media, including scattering, is presented. The approach is based on the sequential use of angular and spatial Finite Element Methods for the discretization of the Radiative Transfer Equation (RTE). The angular discretization is developed with an Angular Finite Element Method (AFEM) based on the Galerkin approach. The AFEM leads to a counterpart of the RTE consisting of a coupled set of transient-advective–reactive equations that are continuously dependent on space and time. The AFEM is ideally suited for so-called h- and/or p-refinement for the discretization of the angular domain: h-refinement is obtained by increasing the number of angular elements and p-refinement by increasing the order of the angular interpolating functions. The spatial discretization of the system of equations obtained after the angular discretization is based on a Variational Multi-Scale Finite Element Method (VMS-FEM) suitable for the solution of generic transport problems. The angularly and spatially discretized system is solved with a second-order accurate implicit predictor multi-corrector time stepper together with a globalized inexact Newton–Krylov nonlinear solver. The overall approach is designed and implemented to allow the seamless inclusion of other governing equations necessary to solve coupled fluid–radiative systems, such as those in combustion, high-temperature chemically reactive, and plasma flow models. The combined AFEM and VMS-FEM for the solution of the RTE is validated with two- and three-dimensional benchmark problems, each solved for 3 levels of angular partitioning (h-refinement) and for 2 orders of angular basis functions (p-refinement), i.e. piecewise constant (P0) and piecewise linear (P1) basis over spherical triangles. The overall approach is also applied to the simulation of radiative transfer in a parabolic concentrator with participating media, as encountered in solar thermochemical applications, for different values of absorption and scattering coefficients, and for different angles of inclination of the incident radiation.

Numerical estimates of convective stability in the inclined layer of a porous medium

A numerical study of natural convection in a plane highly porous layer placed in an impenetrable array at different angles of inclination to the horizontal plane is presented. Porosity, thermal conductivity, thermal diffusivity and some other parameters are assumed to be constant for both media. Investigations of convective flows in inclined layers usually consider layers with constant temperature at boundaries. In the present work, temperature is set constant at horizontal boundaries surrounding the impenetrable array, and the vertical boundary is considered as heat insulation. This problem formulation conforms to real conditions of geological sections. The problem has been solved by the finite difference method on non-uniform rectangular grids. For horizontal and vertical grid dimensions, hx> hzat α 45 are taken, respectively Thickness of the permeable layer is chosen as the unit of length. Estimates were made for the critical Rayleigh-Darcy number at different inclinations of the permeable layer, and the corresponding stability curve was plotted. It is shown that with increasing angle the convective flow stability decreases. An increase in the size of the surrounding array leads to a slight decrease in stability. The structural changes that occur in convection also take place. The number of realized convective cells decreases with increasing angle of inclination. This result is qualitatively consistent with the structure of convection in an inclined porous layer with constant temperature at boundaries. It has been found that the distribution of the heat flow over the surface of the surrounding array depends significantly on the depth and orientation of the layer and on the Rayleigh-Darcy number. Positive and negative density anomalies (comparable in amplitude) of the heat flow are intrinsic to the layers with a small angle.

Outdoor performance and durability testing of antireflecting and self-cleaning glass for photovoltaic applications

Creating an artificial system for imparting self-cleaning and antireflective properties to photovoltaic panels by employing organic and inorganic materials has attracted much attention among researchers recently. This has been done primarily to elevate roughness and modify surface chemistry. However, such materials suffer from durability issues when placed outdoors. Therefore, this paper elaborates upon the self-cleaning and antireflective performance of hydrophilic nanostructured glass substrates. Nanostructured glass substrates were subjected to an outdoor exposure of 12weeks at different angles of inclination. Their performance was measured in terms of optical transmission, water contact angle, analysis of dust accumulation and application to solar modules as packaging covers. The nanostructured glass samples showed improvement in self-cleaning performance of solar modules, with only an insignificant drop of 0.3% in efficiency relative to a 2% drop in a planar glass solar module over a long term exposure period.

Study of the Propagation Rules of Stress Wave in Bedding Rock Slope

After analyzing the propagation of stress wave at different angles of inclination, strength parameters and the group number of structural plane. The results of research are summarized as follows: Due to the change of propagation direction in structural planes with different angles of inclination, the original propagation rule of stress wave changes too, the peak velocity of the monitory point gets relatively flat as the strength parameters of structural plane turn greater. Stress wave repeatedly refracts and reflects in many groups of structural plane, then the appropriate dynamic characteristics of the wave no longer maintains as the number of group increases or decreases. By analyzing and verifying the slope instance, the test result provides a reference for studying dynamic response rules.

A comparative experimental study on the natural convection heat transfer of different metal oxide nanopowders suspended in turbine oil inside an inclined cavity

An experimental study is conducted to investigate the effects of inclination angle on the natural convection of nanofluids inside a cubic cavity with the side size of 10cm. One of the surfaces of the cavity is kept in cold temperature and another one (opposite side) in hot temperature while the other four surfaces are insulated. The mixtures of three different types of nanoparticles including Al2O3, TiO2, and CuO within turbine oil (TO) are used as the heat transfer fluid. The heat transfer in the cavity is investigated in three inclination angles with respect to the horizontal position including 0°, 45° and 90° where the weight fractions of nanoparticles are 0.2%, 0.5%, and 0.8%. The Nusselt number results are presented for the three types of nanofluids, and different angles of inclination, Rayleigh number, and weight fraction of nanoparticles. The results reveal that the turbine oil has the highest Nusselt number in any inclination angle of the cavity compared to the nanofluids. Also, it is found that at the inclination angle of 90°, and the weight fraction 0.2%, the application of TiO2 particles results in the maximum Nusselt number while for weight fraction of 0.8%, the maximum Nusselt number is associated with the CuO nanopowders.

Effect of an Inclined Magnetic Field on Steady Poiseuilleflow between Two Parallel Porous Plates

The present work is to investigate the magnetohydrodynamic behaviour of two dimensional Poiseuille flow under the influence of an inclined magnetic field and constant pressure gradient for a viscous, incompressible and electrically conducting fluid between two infinite parallel plates of which the lower plate is taken to be porous. The solution of the fluid flow governing equation has been obtained by analytical method and expressed in terms of Hartmann number. The fluid flow profiles are represented through graphs for different values of Hartmann number with different angles of inclination for injection/suction. The effects of the other parameters such as pressure gradient, inclined magnetic field and suction/injection on the flow are also studied graphically. The resulting equation of motion has preferably been solved by the method of variation of parameters.

A new radiological method to detect dorsally penetrating screws when using volar locking plates in distal radial fractures

Penetration of the dorsal screw when treating distal radius fractures with volar locking plates is an avoidable complication that causes lesions of the extensor tendon in between 2% and 6% of patients. We examined axial fluoroscopic views of the distal end of the radius to observe small amounts of dorsal screw penetration, and determined the ideal angle of inclination of the x-ray beam to the forearm when making this radiological view. Six volar locking plates were inserted at the wrists of cadavers. The actual screw length was measured under direct vision through a dorsal approach to the distal radius. Axial radiographs were performed for different angles of inclination of the forearm at the elbow. Comparing axial radiological measurements and real screw length, a statistically significant correlation could be demonstrated at an angle of inclination between 5° and 20°. The ideal angle of inclination required to minimise the risk of implanting over-long screws in a dorsal horizon radiological view is 15°.

Experimental investigation of natural convection inside a upper part of vertical converging air channel using the Schlieren technique

The article concerns the selected application problem of gradient optical technique for the analysis of development of the thermal boundary layer. The recording of thermal boundary layer development was carried out using the modified Schlieren system. The modifications introduced to the optical measuring systems allowed the extension of the information carrier measuring range along with a reduction in the susceptibility of the systems to misalignment. As the information carrier, a collimated 25-mW He–Ne laser beam was used. The recording of the distribution of optical density of information carrier around the experimental model under analysis was carried out using a CCD matrix with the image acquisition card. The experimental model under consideration was a converging air channel in the form of a space enclosed by two inclined heating surfaces. The measurements of convective heat transfer were carried out for different angles of inclination (18°, 30° and 45°) and thermal conditions (320K, 370K and 490K) of the heating surfaces. The obtained results of experimental analysis were approximated with the power relationship Nux=C(Rax)a.

Correlations for transient natural convection in parallelogrammic enclosures with isothermal hot wall

Correlations of the type Nusselt–Rayleigh–Fourier are proposed to determine the convective exchanges that occur in transient regime in closed cavities of parallelogrammic section. They complement the correlations obtained in a previous work for steady state. The active vertical walls of these cavities are vertical, maintained isothermal and differentially heated, while the closing channel is adiabatic. This work covers a wide range of the Rayleigh number 1.84 × 105 ≤ Ra ≤ 1.70 × 109 and different angles of inclination ranging from −60° to 60°, enabling applications in several fields of engineering such as building, solar energy or power electronics. Correlations are obtained from numerical results based on the finite volume method and are validated by measurements.