2018-07-22T03:25:39Z
http://ijstm.shirazu.ac.ir/?_action=export&rf=summon&issue=237
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
Simulation of free surface wave pattern due to the moving bodies
Steady three-dimensional free surface waves generated by three dimensional moving bodies are presented. By applying Green’s theorem and the Green function method, an integral equation for the perturbation velocity potential is obtained based on the potential flow theory. The method uses constant-strength doublet and source density distribution over the foil body surface and Neumann-type condition. On the undisturbed free surface source density is applied to satisfy the free surface condition that is defined by the first and second order solutions. After solving the doublet on the body and source on the free surface, the computational results of pressure, lift, wave drag, wave pattern and wave elevation can be calculated at various Froude numbers. The results for the surface piercing (such as strut and Wigley hull) and submerged moving hydrofoils have been presented. The validity of the numerical results is examined by comparing it with the experimental results.
Free surface
pressure distribution
lift and drag
wave pattern
Wigley hull
2010
04
28
117
134
http://ijstm.shirazu.ac.ir/article_906_1b167018046dc0a27c3de495affbd785.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
A complete treatment of thermo-mechanical ALE analysis; Part I: Formulation
Arbitrary Lagrangian Eulerian (ALE) finite element method is extensively used for numerical simulation of solid mechanics problem. The versatility of the mesh in ALE approach makes it particularly effective and efficient in solving large deformation problems. In this work, a complete treatment of fully coupled ALE formulation is presented incorporating inertial, rate and thermal effects. The formulation may be used in conjunction with thermo-elasto-viscoplactic material models. A consistent and efficient tangent operator is developed in closed form to handle stress integration. The applications of this formulation are given in the second part of this paper.
Arbitrary Lagrangian Eulerian
Finite element method
large deformation
implicit dynamic analysis
thermo-mechanical
viscoplastic
2010
04
28
135
148
http://ijstm.shirazu.ac.ir/article_907_29460d72e828b527625e55250004123d.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
A complete treatment of thermo-mechanical ALE analysis; Part 2: Finite element equations and applications
In the first part of this paper series, a complete formulation for fully coupled ALE analysis of large deformation solid mechanic problems was developed. The formulation incorporated inertial, rate and thermal effects, and the treatment of rate and temperature dependent constitutive equations were presented. In this part, the ALE equations are discretized to form finite element equations. An algorithm for the treatment of mesh motion is described and example problems are presented to demonstrate the capability of the proposed formulation.
Arbitrary Lagrangian Eulerian
Finite element method
large deformation
implicit dynamic analysis
thermo-mechanical
viscoplastic
2010
04
28
149
165
http://ijstm.shirazu.ac.ir/article_908_ea1a71982ba265fc6b4ac4b60dc6c305.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
Durability of a small agricultural engine on biogas/diesel dual fuel operation
Biogas from anaerobic digestion of organic waste is a potential alternative to the partial substitution of petroleum derived fuels because it is from renewable resources that are widely available. The effect of long term durability tests using biogas/diesel dual fuel operation on wear characteristics is evaluated and presented in this paper. Steady state tests were performed on a small, single cylinder, naturally aspirated, 4-stroke, direct injection diesel engine at a speed of 1500 rpm, coupled to a generator set to generate electricity for over 3500 hours. Lubricating oil samples were collected during the test run and were subjected to the analysis of various wear metal traces present and the changes in their properties. After completion of the endurance test, the engine was dismantled for physical inspection and wear assessment of vital parts. Formation of carbon deposits on in-cylinder surfaces was not found to be problematic. Injector tip coking did not occur. Surface wear and accumulations of metal debris in crankcase lubricating oil samples were analyzed and found to increase with time, but not at an unusual rate. Properties of used lubricating oils did not alter significantly from their original values. Wear was not significantly different in the test engine fueled with the biogas/diesel combination. An overall evaluation of the results indicated that the biogas/diesel duel fuel operation could be substituted for diesel fuel in electricity generation and worked satisfactorily under long term engine operation without any major troubles.
Biogas
compression ignition
dual fuel
endurance test
renewable energy
Wear
2010
04
28
167
177
http://ijstm.shirazu.ac.ir/article_909_0c4071db88f1e20c741a642ffee710e3.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
A three-dimensional study of the motion of a drop in plane poiseuille flow at finite Reynolds number
Three-dimensional simulations are presented on the motion of a neutrally buoyant drop between two parallel plates at a finite-Reynolds-number in plane Poiseuille flow, under conditions of negligible gravitational force. The full Navier-Stokes equations are solved by a finite difference/front tracking method that allows a fully deformable interface between the drop and the suspending medium and the inclusion of the surface tension. In the limit of a small Reynolds number (
Drop
Poiseuille flow
finite difference/front tracking method
capillary number
2010
04
28
179
196
http://ijstm.shirazu.ac.ir/article_910_ff371bd414e83da62ee2f926df86ba78.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
Explicit minimum fuel intercept strategy for high-order dynamics
An optimal fuel guidance strategy with acceleration limit is derived for interception of maneuvering targets. The guidance/control system is assumed as a linear time-varying arbitrary-order and is identical in each channel. An approximate model for drag acceleration is also considered in the solution. The optimal fuel strategy has some detrimental effects in most practical situations, if it is used entirely to the end. This strategy can be used at the beginning of the guidance phase for large initial heading errors in order to quickly reduce it with minimum effort. An explicit guidance law is then developed for minimum and nonminimum phase autopilots in order to modify the undesirable effects of the optimal fuel guidance law.
Intercept guidance
minimum fuel
acceleration limit
2010
04
28
197
213
http://ijstm.shirazu.ac.ir/article_911_398448083271cac325d657cddc257ce8.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
Rotor mass effect on nonlinear dynamic behavior of aerodynamic noncircular journal bearing systems
This paper presents the effect of rotor mass on nonlinear dynamic behavior of a rigid rotor supported by aerodynamic noncircular journal bearings. A finite element method has been employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in horizontal and vertical directions under different operating conditions, dynamic trajectory, power spectra, Poincare maps and bifurcation diagrams are used. Results of this study reveal how the complex dynamic behavior of two types of noncircular bearing systems comprising periodic and -periodic responses of the rotor center varies with changes in rotor mass values.
Aerodynamic noncircular bearing
rotor mass
poincare map
Bifurcation
2010
04
28
215
230
http://ijstm.shirazu.ac.ir/article_912_b1d792f1830a5ffca6b1d6a0ea50c4a6.pdf
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
2228-6187
2010
34
2
Influence of particle size on corrosion resistance of electroless Ni-P-SiC composite coatings
High phosphorus electroless nickel bath has been used to prepare composite coatings containing SiC particles (40 nm, 3 mm and 7 mm). The coated samples were subjected to heat treatment at 400 °C for 1h. The effect of heat treatment on the microstructure of Ni-P-SiC composite coatings was investigated by X-ray diffraction. Potentiodynamic polarization measurements made on these deposits in 3% sodium chloride solution showed that corrosion resistance in nano-composite coatings was much higher than micro-composite coatings. The corrosion rate results for nano-composite coatings showed a 6 fold improvement as compared to the micro-composite coatings.
Particle size
Ni-P-SiC
electroless
corrosion resistance
2010
04
28
213
234
http://ijstm.shirazu.ac.ir/article_913_a0fa34929684f2ffde21c1be8d0e7c5f.pdf