فهرست مطالب

Mechanical Engineering Transactions of ISME - Volume:23 Issue: 2, Sep 2022

Iranian Journal of Mechanical Engineering Transactions of ISME
Volume:23 Issue: 2, Sep 2022

  • تاریخ انتشار: 1401/09/19
  • تعداد عناوین: 7
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  • E. Kouhi, A. Bak Khoshnevis * Pages 5-32
    This paper focuses on a selected set of results from extensive experimental tests to characterize the wake aerodynamics of an SD7062 wind turbine airfoil in steady-state and pitch oscillating motion. Investigating the wake of an airfoil provides outstanding information on physical aspects of the downstream. Wake measurements were accomplished through hot-wire anemometers in the Laboratory of Aerodynamics at the Hakim Sabzevari University. The impact of AoA and Reynolds number were both examined in the steady-state. Regarding the pitching airfoil motion, the effect of reduced frequency, Reynolds number, symmetric, and asymmetric oscillation were also investigated. The results revealed that in both the pitching and the steady-state cases, strength of the vortices is highly related to the airfoil shape, amplitude, and Reynolds number. In respect of pitching state, the TI value is decreased as the Reynolds number increases, while it grows up with increasing the reduced frequency. Besides, TI in asymmetry oscillation is significantly higher than in symmetric oscillation, which is probably due to the formation of larger vortices. For steady-state, the instantaneous TI and velocity are almost the same as their mean values. Hence, statistical data could be used to calculate aerodynamic forces on a static airfoil. It is necessary to meticulously consider the effect of mean and instantaneous forces in the pitching state, as the forces acting on the pitching airfoil could reach several times its average state in some moments during its impact. As a result, the importance of these instantaneous loads is required to be considered enabling us to select the proper material for the airfoil.
    Keywords: Wind Tunnel, pitching airfoil, hot-wire, Aerodynamic forces, Experimental Investigation
  • H. Taghadosi, F. Tabatabai Ghomsheh *, N. Jafarnia Dabanloo, A. Farajidavar Pages 33-47
    In this paper, a three-dimensional electromechanical model is presented to investigate the effect of calcium and potassium ionic channels on the contractile behavior of human gastric wall smooth muscle cells with the finite element approach. In this model, simultaneous electrical and mechanical interactions of 240-cells and 548-links were considered. Electrophysiological interactions of cells through ion channels with the extrascellular environment and gap junctions with adjacent cells lead to the production and propagation of slow waves in smooth muscle. This wave causes contraction and peristaltic movements in the muscles of the gastric wall. By blocking calcium and potassium ionic channels by pharmacological agents can be improved disorders caused by these movements and contractions and brought them closer to the physiological state.
    Keywords: Electromechanical Model, Smooth Muscle Cell, Gastric, Ion Channel Blocker, Contraction
  • H. Moeeni, M. Javadi *, S. Raissi Pages 48-62
    In addition to standard design and production, its economics is also vital. Design and production organizations must pay special attention to the design process's cost category, selecting materials and determining production methods continually. Flexibility, access to data and information from multiple materials and the possibility of examining production methods based on the material and dimensions designed are the features of this research's results. Identifying and selecting suitable and accessible materials can be helpful in design dimensions using pressure vessel design formulas. The design and its outputs can significantly affect the weight and price of materials, production method and cost. The actual design, effects of permitted structures on material and production cost and the final total cost of a pressure vessel have been studied. The total cost values ​​were compared and validated with target values ​​compared with past research results. This method can be used as a general cost-based method for selecting suitable designs to identify and produce other products considering strengths, reliability and safety factors.
    Keywords: Product design, Production cost, cost analysis, engineering design, cost Evaluation
  • H. Safikhani, M. Modabberifar *, H. Nazaripoor Pages 63-79
    In this paper, the effect of vortex finder shape on the performance and flow field of the new design cyclones is numerically investigated using CFD techniques. Nine different geometries of vortex finder are studied in three categories each with three geometries. In the first category, the effect of vortex finder flattening is investigated. In the second category, vortex finders with three different cross section geometries circular, square and triangular are investigated. Finally, in the third category, circular vortex finders with three different diameters are modeled. The new design cyclone is based on the idea of improving cyclone collection efficiency and pressure drop by increasing the vortex length. The Eulerian-Lagrangian computational procedure is used to predict particles tracking in the cyclones. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). The results show that in the flat category, vortex finder without flattening (circular cross section) possess the maximum efficiency and the lowest pressure drop and with flattening, the cyclone efficiency dramatically decreases while pressure drop remarkably increases. Among the vortex finder with different cross section, maximum efficiency is associated to the circular vortex finder while the lowest pressure drop is assigned to the triangle one.
    Keywords: Vortex finder shape, New design cyclone, Flat tube, CFD, DRW
  • F. Jalili, S. M. Malekjafarian *, A. Safavinejad, H. Masoumi Pages 80-104
    In this work, a modification has been made to increase the efficiency and convergence of the harmony search algorithm. Then, the capability of this amendment was investigated by applying it to the following aerodynamic problems for the first time. First, the methods of airfoil shape parametrization (Bezier curves, Parsec method, and NACA 4-digit airfoil) were investigated using an inverse optimization design by the present modified harmony search optimization algorithm. Then, inverse and direct optimization of an airfoil were carried out by the modified algorithm. Aerodynamic analysis of the problem was obtained using compressible Reynolds-Averaged Navier-Stokes (RANS) equations along with the Spalart-Allmaras turbulence model. Results showed that the Bezier curves and the Parsec method have higher flexibility than the NACA 4-digit airfoil. The Parsec method was introduced as the best approach, because of fewer control parameters. The inverse optimization results showed that the present airfoil shape optimization set can obtain the target shape with high accuracy. The Direct optimization with a maximum lift to drag ratio target function revealed that the shock waves significantly weaken at the optimum airfoil. Generally, the results obtained verify that using the modified harmony search algorithm together with the Parsec method provides a powerful tool for direct and inverse aerodynamic optimization.
    Keywords: Inverse optimization design, Direct optimization, Meta-heuristic optimization
  • H. Vahidi, M. Shahgholi *, A. Rahmani Hanzaki, A. Mohamadi Pages 105-128
    The current paper presents the free vibration characteristic of axially moving conical shells made of shape memory alloy based on Donnell’s shell theory. The material behavior is simulated based on the Boyd-Lagoudas model. By applying the suitable airy function, the strain compatibility equation, and the Galerkin method, two sets of equations of motion are obtained. The compatibility equation is solved by using the steady-state form of equations and employing the suitable flexural mode shape concerning radial displacement. The effects of moving in the axial direction and using the SMA are investigated with the aid of the frequency responses curves. The phase transformation would decrease the quantity of the critical velocity. The results have been evaluated by means of the available data.
    Keywords: Conical shell, Axially moving, stability, Shape memory alloy
  • A. Fattahi Avati, M.R. Karafi * Pages 129-144
    Ultrasonic vibrations are used in many fields to reduce friction forces. In this paper, the reasons for reducing friction in solid surfaces are investigated using the friction model of Dahl and the elastic-plastic contact model. Based on the theoretical model, four parameters: relative velocity, contact surface, the distance between surfaces, and Young modulus, are effective in the frictional force reduction. This study is validated using experimental tests. The results showed that the effects of oscillations of the relative velocity and changes of contact surfaces on the friction reduction are 51% and 12%, respectively. The minimum effect, among the factors, was related to the Young modulus with a value of 1%. The reason for the force reduction is the nonlinear behavior of the contact surface, contact stiffness, and the friction force functions. Moreover, fluctuations in their input parameters cause an asymmetric oscillation in the value of those functions. This feature changes these functions’ average value and reduces the friction forces.
    Keywords: Ultrasonic, Friction, Dahl Model, Elastic-Plastic Contact