Fluid Flow Through Serieal Parallel Circular Cylinder Arranged In Tandem

The Fluid flow through circular cylinders in serieal parallel positions arranged in tandem were analyzed computationally and experimentally at nine levels of Reynolds number, ReD 34,229; 47,921; 61,612; 75,304; 88,996; 102,688; 116,379; 130.071 and 143,763 The variation in the ratio of the distance between the front and rear cylinders is determined as M / D = 0.3, M / D = 0.5, M / D = 0.7, M / D = 0.9, and M / D = 1.1. While the distance between cylinder number 2 and 3 we set constantly and determined as N / D = 5 cm. The results displayed are flow velocity with computational approach validated by flow visualization, computational pressure contour, and drag coefficient through experimental testing. The results showed that the smallest boundary layer thickness was obtained in the model with a distance ratio of M / D = 2.5, using both computational and experimental approaches. The characteristics of the minimum pressure contour and the lowest drag coefficient (CD) = 0.7572 were also obtained at the ratio of the distance M / D = 0.25 and at upstream speed of 21 m / s

Comparison of Aerodynamic Characteristics of NACA 0012 and NACA 2412 Airfoil

A comparison between NACA 0012 and NACA 2412 has been made by comparing the lift co- efficient, drag co-efficient, pressure contour and velocity contour at various angles of attack. The process has been done taking steady state flow around NACA-0012 and NACA-2412 airfoil using 1m chord length and a velocity of 88.65m/s. The main aim is to understand the aerodynamic characteristics of both the airfoils at different angles of attack and draw a conclusion on which performs better under the same conditions. Modelling and numerical analysis has been carried out by using commercially available CFD software, which is a convenient method of analysis since computational methods are more preferred to experimental methods due to low expenses involved. The numerical results demonstrated are compatible with those of the theory. This confirms the validity of using Computational Fluid Dynamics (CFD) as a reliable alternative to experimental procedures.

Investigation on Reduction of Pressure Fluctuation for a Double-Suction Centrifugal Pump

Double-suction centrifugal pumps have been applied extensively in many areas, and the significance of pressure fluctuations inside these pumps with large power is becoming increasingly important. In this study, a double-suction centrifugal pump with a high-demand for vibration and noise was redesigned by increasing the flow uniformity at the impeller discharge, implemented by combinations of more than two parameters. First, increasing the number of the impeller blades was intended to enhance the bounding effect that the blades imposed on the fluid. Subsequently, increasing the radial gap between the impeller and volute was applied to reduce the rotor-stator interaction. Finally, the staggered arrangement was optimized to weaken the efficacy of the interference superposition. Based on numerical simulation, the steady and unsteady characteristics of the pump models were calculated. From the fluctuation analysis in the frequency domain, the dimensionless pressure fluctuation amplitude at the blade passing frequency and its harmonics, located on the monitoring points in the redesigned pumps (both with larger radial gap), are reduced a lot. Further, in the volute of the model with new impellers staggered at 12°, the average value for the dimensionless pressure fluctuation amplitude decreases to 6% of that in prototype pump. The dimensionless root-mean-square pressure contour on the mid-span of the impeller tends to be more uniform in the redesigned models (both with larger radial gap); similarly, the pressure contour on the mid-section of the volute presents good uniformity in these models, which in turn demonstrating a reduction in the pressure fluctuation intensity. The results reveal the mechanism of pressure fluctuation reduction in a double-suction centrifugal pump, and the results of this study could provide a reference for pressure fluctuation reduction and vibration performance reinforcement of double-suction centrifugal pumps and other pumps.

SIMULASI NUMERIK PENGARUH VARIASI RASIO PANJANG LEADING EDGE TERHADAP KARAKTERISTIK AERODINAMIKA PADA MOBIL PICK UP

The aerodynamic style influences fuel consumption due to drag and the stability of the vehicle speed due to the force lift. Varying the geometry of the leading edge is estimated to have an effect on aerodynamics. This study uses a car pickup model with dimensions like the actual size. Geometry Leading Edge can be modified so that in the variation of the ratio of length leading edge of the vehicle's overall length ( ): ; and . The research method used is a 2-D numerical simulation underconditions steady and unsteady using software ANSYS FLUENT 2019 R3. The mesh using Hybrid model, its triangular and rectangular shape. The viscous model used by k-epsilon Realizable with variation Reynolds Number 7.15 x 104; 2.6 x 106; 3.26 x 106 and 3.91 x 106. The result data analyzed are coefficient lift (CL), coefficient drag (CD), velocity contour, velocity streamline, and pressure contour. From the simulation results, varying ratio of the length of leading edge can affect aerodynamic characteristics of the car. The greater leading edge ratio can delay separation above the car. In addition, the momentum deficit behind the vehicle is also getting smaller. Variation of the length ratio of leading edge is the best variation, having a coefficient drag (CD) of 0.72 with a percentage decrease of 4% and a coefficient lift (CL) of 0.07 with a reduction percentage of 36.36% of the standard variation. CD and CL values go down making fuel consumption more efficient and the car more stable.

A Study of Contact Interface for an Anti-Rotation Rivet Using Ultrasonic Detection

This work measures the contact area between an anti-rotation rivet and an aluminum plate under different riveting loads based on the regional scanning of ultrasound. The contact image is a novel disclosure for the anti-rotation rivet contact. The 2D maps show an apparent change not only in area sizes but also in contact shapes under various normal forces applied. The 3D contact images also provide useful information to show the intensity of contact. The contact area between the anti-rotation rivet and the aluminum is calculated using an image analysis software package. The range of contact areas varies from 6.3 mm2 to 57.2 mm2, depending on the applied forces and the definition of the contrast ratio. Furthermore, a calibration of data fitting is performed to provide a useful polynomial equation for contact area estimation. In addition, maps of both a reflection coefficient and a pressure contour distribution are presented. The range of peak contact pressure varies from 7.1 MPa to 11.2 MPa.

Effect of Angle of Attack on Pressure and Lift Coefficient of ONERA OA206 Wing Model Using Computational Fluid Dynamics Method

In this study, we computed the lift force of the aircraft with ONERA OA206 airfoil type. It was positioned at 0%, 25%, 50%, 75%, and 100% of the wingspan for Angle of Attack (AoA) variations of 0o, 4o, 8o, 12o, and 16o. The research was to determine the effect of AoA on pressure, pressure coefficient (Cp), and lift coefficient (CL) on the ONERA OA206 aircraft wing. It shows that the greater AoA on the result of the pressure contour causes the increase in the difference of span at AoA 0o to 16o t these are 0.25%; 0.26%; 0.43%; 0.52%; and 0.53%. Through the graph of the pressure coefficient (Cp) against x/c, it can be seen that the greater AoA, the expansion point, and the stagnation point will shift to the right with the direction of x/c. In addition, the Cp at the lower is greater than the upper of the airfoil. Based on the research results, it was found that CL at the position of 0% to 50% increased when given AoA from 0o to 12o (CL max) and decreased at AoA = 16o (stall). Meanwhile, CL at 75% to 100% increased when given AoA from 0o to 8o (CL max) and decreased at AoA = 12o (stall). With these results, it can be concluded that the maximum AoA that can be applied to the wing of the ONERA OA206 aircraft is 8o. The closer to the end position of the airfoil, the higher the CL measured.

A preliminary approach to study the behavior of human fingertip at contact via experimental test and numerical model

<p>How human fingertip deforms during the interaction with the environment represents a fundamental action that shapes our perception of external world. In this work, we present the <em>proof of concept</em> of an experimental <em>in vivo</em> set up that enables to characterize the mechanical behavior of human fingertip, in terms of contact area, force and a preliminary estimation of pressure contour, while it is put in contact against a flat rigid surface. Experimental outcomes are then compared with the output of a 3D Finite Element Model (FEM) of the human fingerpad, built upon existing validated models. The good agreement between numerical and experimental data suggests the correctness of our procedure for measurement acquisitions and finger modeling. Furthermore, we will also discuss how our experimental data can be profitably used to estimate strain limiting deformation models for tactile rendering, while the here reported 3D FE model has also been profitably employed to investigate hypotheses on human tactile perception.</p>