2024-03-29T08:54:30Z
https://erjm.journals.ekb.eg/?_action=export&rf=summon&issue=10531
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
INFLUENCE OF TRAILING EDGE FLAPS ON HORIZONTAL AXIS WIND TURBINE PERFORMANCE
A.
Abd Elmotalip
G. A. Z.
Mousa
An experimental study has been carried out to investigate the performance of a horizontal axis wind turbine model. The test has be done without and with flaps at trailing edge of turbine rotor, one flap placed on pressure side of rotor blade and the other on its suction side. The turbine rotor consists of three blades with tip diameter of 260 mm. The study covers the influence of different blade angles with and without flaps on the wind turbine performance. Test data obtained *om horizontal axis wind turbine rotor model tested in an open wind tunnel at different tip speed ratios and different blade angles is used as a reference to make a comparison when rotor tested with trailing edge flaps. The turbine torque and power are evaluated by the direct measurement of rotational speed, and wind velocity. It was found that blade angle p of 45" is the better angle giving maximum power coefficient of 22.6 % without flaps. Then turbine model is tested with flaps on pressure and suction sides of its rotor blade at trailmg edge for p of 45'. Also, it is noticed that flaps on pressure and suction sides of turbine rotor blade at trailing edge can improve wind turbine performance. Also using flap of both pressure and suction sides increases power coefficient of turbine model. The maximum improvement achieved was a 13.27 % increase in power coefficient in case of model with pressure side flap for (L/CF = 0.75), and a 10.62 % in case of model with suction side flap for (L/CF = 0.5). Flaps of pressure and suction sides achieved an improvement of 19.47 % in turbine model power coefficient for pressure side flap with (L/CF = 0.75), and suction side flap with &/CF = 0.5).
Wind energy
Wind Turbines
and Power Augmentation
2009
04
01
109
117
https://erjm.journals.ekb.eg/article_69396_070f4ff40acefc609db4dbbd3888c1ed.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
MODELING OF SANDWICH HETEROGENEOUS PROPELLANT WITH TWO STEPS CHEMICAL KINETICS AND FLUID MECHANICAL EFFECTS
A. M.
Hegab
The numerical procedure for the burning of Ammonium Perchlorate (AP) with a Fuel-Binder (Hydroxyl Terminated Polybutadience HTPB) is presented. This model accounts for the two-steps reaction mechanism for the primary diffusion flame between the decomposition products of the Binder (B) and the oxidizer AP and the primary premixed AP flame. Moreover, this current model allowed for the complete coupling between the gas-phase physics, the condensed-phase physics, and the unsteady non-uniform regression of the propellant surface. The parameters used in this model are fitted to experimental data for the combustion of APVHTPB. The propagation of the unsteady non-planer regression surface is described, using the Essentially-Non-Oscillatory (ENO) scheme with the aid of the level set strategy. The Alternating-Direction-Implicit (ADI) solver is employed to solve the full Navier-Stokes equations in the gas phase for the variable density model. The results show the effect of various parameters on the surface propagation speed, flame structure, and the burning surface geomew. A comparison between the computational and experimental results is presented.
Solid rocket propellants
Moving interfaces
Level set method
sandwich propellant
AP/HTPB
2009
04
01
119
130
https://erjm.journals.ekb.eg/article_69397_3f58cbe0f0dbcfd34f30bf970c42c7ac.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
STUDY OF TURBULENT FLOW IN RECTANGULAR CHANNEL WITH INCLINED BAFFLES
M.
Nasr
A.
Abdel- fattah
W. A.
El-Askary
Experimental and numerical studies investigate the pressure recovery coefficient along the wall of a rectangular channel fitted by inclined-perforated and solid baffles. Two baffles of same overall size are used in the experiment. The upstream baffle is attached to the top surface, while the position, orientation, and the shape of the other baffle are varied. Different inflow Reynolds number for this study is tested and ranged between 71,000 and 122,500. Experimental results show that the pressure recovery distribution is strongly depended on the position, orientation, and geometry of the second baffle plate. The pressure drop goes down with an increase in the Reynolds number, but its value depends on the arrangement of baffles. The pressure drop is much higher for two inclined baffles (one perforated on the upper wall and one solid on the lower wall). For the sake of numerical simulation, the turbulent governing equations are solved by a control volume-based finite difference method and using the standard as well as the RNG k- E turbulence model associated with wall function to describe the turbulent structure. A modification includimg the effect of streamline curvature is considered in the turbulence model. The velocity and pressure terms of momentum equations are solved by SIMPLE (semi-implicit method for pressure-lied equation) method. Satisfied comparisons are achieved to verify the turbulence model used. The results show that the wall pressure recovery coefficient is strongly affected by the geometry and location of baffles in the duct. Also, the comparisons of the numerical results given by using turbulence models indicate the quality of the k - E including the streamline curvature in the turbulence model
Rectangular channel flow
Baffle
Inclined baffle
Pressure drop
2009
04
01
131
143
https://erjm.journals.ekb.eg/article_69434_4467a5568eab94f731f29328dcbd5da3.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
NUMERICAL SIMULATIONS OF NON-EQUILIBRIUM TURBULENT BOUNDARY LAYER FLOWING OVER A BUMP
W. A.
El-Askary
Largeeddy simulation (LES) and Reynolds-averaged Navier-Stokes simulations (RANS) with different turbulence models (including the standard k - E , the standard k - 0, the shear stress transport k - 0 (SST- k - w model) and Spalart-Allmaras (S-A)-turbulence models) have been employed to compute the turbulent flow of a two-dimensional turbulent boundary Iayer over an unswept bump. The predictions of the simulations were compared to available experimental measurements in the literature. The comparisons of the LES and the SST- k - w model including the mean flow and turbulence stresses are in satisfied agreements with the available measurements. Though the flow experiences a strong adverse pressure gradient along the rear surface, the boundary layer is unique in that intennittent detachment occurring near the wall. The numerical results indicate that the boundary layer is not followed by mean-flow separation or incipient separation as that shown from the numerical results. The resolved turbulent shear stress is in a reasonable agreement with the experimental data, though the computational result of LES shows that its peak is over-predicted near the trailing edge of the bump, whiIe the other used turbulence models, except the standard k - & , under-predicts it. Analysis of the numerical results from LES confirms the experimental data, in which the existence of intemal layers over the bump surface upstream of the summit and along the downstream flat plate. It also demonstrates that the quasistep increase in skin fiiction is due to perturbations in pressure gradient. The surface curvature enhances the near-wall shear production of turbulent stresses and is responsible for the formation of the internal layers.
The present investigation also explains the capability of the used RANS turbulence models to capture the driving mechanism for the surprisingly rapid return to equilibrium boundary layer over the trailing flat plate found in the measurements.
Boundary layer
Bump flow
R4NS
LES
2009
04
01
145
161
https://erjm.journals.ekb.eg/article_69400_d3916d2f4cd82c521e73178c25cb6d81.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
EFFECT OF ROCK TEXTURE ON SLOPE STABILITY
Mostafa Ahmed
Ismail
The research reported in this article focused on the effect of rock texture on the slope stability in open cast mines Physical models were made from cement, sands, basalt particles of different sizes in order to produce artificial rock differing in their texture. Three kinds of rock textures were yielded. They are coarse, medium and fme texture. The bench height, berm and the angle of slope were also varied to study the effects of rock texture on the stability of open cast bench slope having coarse texture grains larger than 5mm. It was found that the benches of rock which will be only stable when the height of bench is equal or less than 1.4 times its berm and the slope angle less than 75 degree. Failures will occur at slope angle near 90 degree as result of both tension and shear stresses. No failure would occur for rock having fme texture, with the medium texture rocks the failure will
2009
04
01
163
167
https://erjm.journals.ekb.eg/article_69401_163bab04b27a0d1388c1059a654d327f.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
NEW APPROACH FOR REDESIGNING THE INGASSANA CHROMITE MINE IN SUDAN
Mostafa Ahmed
Ismail
The present article deals with the use of a computer program which has been used to design the methods of minerals extraction. The work was carried out on the chromite deposits at Ingassana in Sudan, in order to improve the working, i.e. increasing the extraction ratio of the ore and increasing the safety at the stopping areas. The (ARMPS) computer program which being universally used to design metallic and non-metallic ores mining methods, was applied on the Sudanese chromite ores at Ingassana. Using this program the stope and pillar mining method which its pillars are irregularly shaped and sized and either randomly located or located in low grade ore, was changed to room and pillar method having sequre cross sectional pillars (sized and shaped) instead of rectangular cross section pillars. An increase in the extraction ratio of 12% was achieved at a safe factor of 1.6 which is usually adopted in the extraction of mineral ores and coal.
2009
04
01
169
171
https://erjm.journals.ekb.eg/article_69402_546497b3e7773fd32a2f023943af9f4a.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
EXPERIMENTAL INVESTIGATION OF COLLECTION EFFICIENCY IN GAS - SOLIDS CYCLONE SEPARATORS
M. A.
Hosien
From a number of studies in gas -solids cyclone separators which have been reported in literature, it is shown that, developing more efficient cyclone separators have been essentially based on experiments rather than mathematical models. One of the main perfolmance characteristics of the gas - solids cyclone separators is the collection efficiency. The principle object of this work is to study experimentally the effect of some of the major controlling parameters that have direct effect on the cyclone performance, essentially on the gas - solids cyclone separators collection efficiency. These parameters are the cyclone size, properties of solid phase and air inlet velocity. The results obtained showed that collection efficiency increases with increasing the cyclone size, particle size and inlet velocity.
Cyclone separators
Gas- solids
Particle size
2009
04
01
173
179
https://erjm.journals.ekb.eg/article_69403_8da6884519fdedcfeed9050915c68601.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
EXPERIMENTAL INVESTIGATION OF PRESSURE DROP IN GAS - SOLIDS CYCLONE SEPARATORS
M. A.
Hosien
S. M.
Selim
The effects of cyclone size, inlet velocity, and particle size on the pressure drop across the gas -solids cyclone separator are presented experimentally. The experiments were conducted at four different cyclone sizes Of 7.5,10,14 and 16mm, various particle sizes ranged from 70 to 510~ and various dust loading varied from 50 to 350gram,,li&g,~. The results showed that the pressure drop across the cyclone decreases with increasing the cyclone size and increased considerable with increasing the inlet velocity. The results indicated that the pressure drop is found to increase sharply with increasing the particle size from 75pm to 225~ and then increases gradually with particle size larger than 225~. The study reported very interesting correlation not previously addressed and represents an addition to knowledge which leads to the prediction of the actual pressure drop of dusty air from tests on clean air
Cyclone separators
Gas
solids
Particle size
2009
04
01
181
188
https://erjm.journals.ekb.eg/article_69404_939bdb3dd5d08d40aadf1d2b89fa76b4.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
POWER QUALITY IMPROVEMENT FOR ARC FURNACE AND CONVERTER FED UNDER-GROUND METRO LOADS
Ekramy
Saad
H.
Shaaban
G.A.
Morsy
Power quality problem
Passive tuned filter
Converter loads
Electric Arc Furnace loads (EAF)
2009
04
01
189
199
https://erjm.journals.ekb.eg/article_69408_ce0fe0421b4c8cc2b98806198cf7a990.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
A STABLE ADAPTIVE FLUX OBSERVER FOR A VERY LOW SPEED-SENSORLESS INDUCTION MOTOR DRIVES INSENSITIVE TO STATOR RESISTANCE VARIATIONS
Moharned S.
Zaky
n recent years, numerous attempts have been made to improve the performance of speedsensorless induction motor drives. Adaptive flux observer (AFO) is one of the machine model based methods of speed estimation. Parameter variations, low-speed operation and the difficulty encountered in the design of the feedback gain and the adaptation mechanism are the most critical aspects affecting the accuracy and stability of this method. In this paper, design of the observer feedback gain is proposed to ensure the stability over a wide range of operation especially in the low-speed region. The characteristic equation of the closed loop speed estimator is derived. The values of the adaptive law parameters corresponding to the marginal system stability are determined based on Routh-Hunvitz criterion. The sensitivity of AFO to stator resistance mismatch is studied. A stator resistance adaptation scheme for accurate speed estimation at low speeds is derived using Popov's hyper-stability theory. The relation between the identification error of the rotor speed and adaptive gains is clarified. An experimental setup based on a DSP system is implemented. The simulation and experimental results confirm the efficacy of the proposed approach
Sensorless control
Stability analysis
adaptive law design
low speed
stator resistance estimation
2009
04
01
201
210
https://erjm.journals.ekb.eg/article_69410_fe056b509f583e4bef212097d132922a.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
EXCITATION TECHNIQUES FOR PERMANENT MAGNET BRUSHLESS DC MOTOR DRIVE
Mohamed. A.
Enany
Hamed. M.
Elshew
E.
Abdel-kader
This paper presents four excitation techniques for Permanent Magnet Brushless DC motor 'drive. These techniques are single phase excitation technique, two phase excitation technique, three phase excitation technique and single phase I two phase excitation technique. Waveforms of phase current and torque for all excitation techniques are analyzed and discussed. The operation of the motor drive at different excitation techniques for same load is studied and discussed. The results of this studying reports an investigation into the characteristics of such techniques according to torque, no load speed, efficiency, supply current and control circuit. Computer simulation result had shown a noticeable difference between four excitation techniques
Brushless DC motor drive
excitation technique
2009
04
01
211
216
https://erjm.journals.ekb.eg/article_69414_87bb236478955294cdf6fc53790cf111.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
PERFORMANCE IMPROVEMENT OF BRUSHLESS DC MOTOR THROUGH SWITCH-ON ANGLE CONTROL
Mohamed. A.
Anany
Hamed. M.
Elshewy
Fathy. E.
Abdel-kader
This paper presents a method for improving the performance of Brushless DC motor drive. This method depends on the varying of switch-on angle of motor phase current. The phase current and torque for proposed method are discussed. The operation of motor drive at different switchdn angle for same speed is studied and discussed. The results of this studying report an investigation into the motor characteristics of such method according to torque, efficiency and torque ripples factor. Computer simulation result had shown a noticeable improvement in motor performance. .& J.& ,&ii & Jd d_YiJl +XI MI &I dP .IJ @ &A lir &
Brushless DC motor drive
performance improvement
Switch-on angle
2009
04
01
217
222
https://erjm.journals.ekb.eg/article_69416_057720bed35e01937db82036ceae43b8.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH CARBON FIBER REINFORCED POLYMERS
Ayman G.
Abdel-Rahman
Faiz A.
Mirza
Strengthening of structures is a complex task. Different systems can be used in order to utilize the fiber reinforced polymer in the most efficient way. Two techniques for surface reinforcement in reinforced concrete beams are addressed in this paper, namely, extemally bonded laminates (EBL) and near surface mounted strips (NSM). The experimental work involves seven !XI-scale reinforced concrete beams strengthened with carbon fiber reinforced polymers (CFRF') and tested up to failure to illustrate two methods of field application and construction techniques of strengthening. The performance and effectiveness of these techniques are demonstrated by comparing the test results of both strengthened and un-strengthened beams. Test results indicate that both techniques are effective in increasing the flexural capacity of R.C. beams. Also it was observed that the beams strengthened with NSM reinforcements show different failure modes than the externally bonded FRP. Applications of the two methods of strengthening R.C beams are suitable for all cases, but prior to the installation of surface bonded CFRP reinforcement, attention should be directed toward investigating the surface concrete on which the composites are to be bonded.
Flexural Strengthening
Carbon Fiber Reinforced Polymers
Externally Bonded Laminates
Near Sulfate Mounted Strips
Modes of Failure
2009
04
01
223
231
https://erjm.journals.ekb.eg/article_69419_ec88a7c4966bcc2d0c648ae10809255a.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
FINITE ELEMENT ANALYSIS OF PRESTRESSED STEEL BEAMS
Ahmed
Almohamady
The concept of prestressing steel structures has only recently been widely considered, despite a long and successful history of prestressing concrete members. The configuration of the beam affects the straining actions and deformations of the prestressed steel beams. In this research, the behavior of the prestressed steel beams is illustrated using fmite element analysis. The dimensions of the beam have been changed to fmd out their effect. The existence of vertical stiffeners has been also studied to fmd out its influence on prestressed steel beams compared with non-prestressed beams. This study has been catried out under the same static loads. The results show that it is better to increase the flange width to improve the stiffness of the prestressed beams while it is better to increase the web depth to improve the stifhess of the nonprestressed beams. It has been also noticed that there is not any obvious benefits of using vertical stiffeners
Pre-stressed
Stiffeners
Finite Element Analysis (FEA)
Steel beam
2009
04
01
233
238
https://erjm.journals.ekb.eg/article_69421_cbe290ecea3edb650610db49fcfcca68.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
CONTRACTOR EQUIPMENT MANAGEMENT PRACTICES
E.M.
ELKASSAS
M.A.
ELGANAINY
H.H.
ELammary
2009
04
01
239
248
https://erjm.journals.ekb.eg/article_69426_33932d4d23e2c7e5136a5c2029c3785b.pdf
ERJ. Engineering Research Journal
1110-1180
1110-1180
2009
32
2
AN EXPERIMENTAL STUDY ON THE BOLTED JOINT CONNECTIONS IN GFRE [0/90jzs LAMINATES
A. I.
Selmy
U. A.
Khashaba
T. A.
Sebaey
Bolts provide the prima'y means of connecting composite parts in the construction of aircrafts and aerospace vehicles. The objective of the present study is to determine the effect of bolt / hole clearance and the cut-off angle on the failure load and mode of laminated Glass Fiber Reinforced Epoxy laminates (GFRE) with 0.4 fiber volume fraction. Five clearance values were used. The results showed that the specimen Failure Load decreased by increasing the clearance value and the failure mode did not affected. Four cut of angles were tested. The results showed that the failure load decreased as the cut-off angle increased up to 30 ' and then increased
experimental
Bolted Joint
Composite
Bolt / Hole Clearance
Cut-off angle
GFRE
2009
04
01
249
253
https://erjm.journals.ekb.eg/article_69428_38b9cf4c6bd016a9b5ad5cffadbb8842.pdf