Al-Qadisiyah Journal for Engineering Sciences

Convergent-Divergent nozzle has many applications especially in steam turbine. The aim of this work is to see the effect of varying inlet pressure on steam behavior through the C-D nozzle. This was done experimentally and numerically. In the experimental part, a C-D nozzle was designed and fabricated in a test section. Steam was fed from boiler at range of (0.69-0.36) bar at saturation temperature for each pressure. Shadowgraph optical method was used to see the formation of shock waves and condensation zone. In the numerical part, the nozzle was simulated using FLUENT under ANSYS code 15.0. In the experimental results, it was found that the most important influence of rapid condensation on the pressure distribution is occurred downstream the through area, when the flow in the divergent part is termed supersonic the heat release causes a pressure rise in the zone of rapid condensation. Shock wave appears in the divergent part due to over-expansion. Each of condensation zone and shock wave were showed by using shadowgraph optical method. In the numerical approach, droplet growth rate contour are presented. The maximum droplet growth rate is (1020 micron /sec) and occurred downstream the throat area. The comparison of experimental and numerical results show good agreement.

The control of lightweight flexible robot using delayed measurements (i.e. vision sensor measurements) and moving along predefined paths is the focus of this work. The flexible robot dynamics is derived on the basis of a Lagrangian-assumed modes method. Noised and delayed tip deflection vision measurements are used beside the base tracking position for state variables estimation process. In order to generate the required control inputs a special state estimation approach is proposed to overcome noise and time delay and noise problems in the measurements. Two state estimators are suggested for each of the measurements, and the states resulted from these two estimators are combined in order for the end effector to follow the desired response. The one link flexible arm prototype dynamic model is chosen for developing a case study. Extensive simulation results are illustrated and discussed.

Jack arch slab is still widely used southern Iraq although it is old roof system due to number of practical and economical advantages including simple construction technique, speed in construction, low cost availability of local labor skills. The study of seismic performance of this roofs in south of Iraq is important due to the last earthquakes activity in Iraq and relatively high earthquakes magnitudes of about 6 degrees according to Richter scale, especially in Misan Province. Static tests were conducted to determine the properties of clay brick and gypsum mortar used for jack arch slab in south of Iraq, then the properties of masonry unit is obtained. The effect of camber configuration on ultimate strength and maximum deflection for both flat and 2 cm camber masonry arch specimens is investigated experimentally. The horizontal seismic loads is determined according to UBC while detailed procedure to determine vertical seismic load according to both UBC and Iranian codes is presented due to its govern the design. Finite element numerical analyses are then conducted using STAADPRO software to investigate the effects of a seismic loads on the behavior of slab and evaluate the safety of this type of roofs when subjected to seismic load. It is concluded that the flexural stresses are govern the behavior of jack arch slab not membrane stresses. Based on finite element analysis, the compressive stresses developed in the slab are less than allowable stress but tensile stresses is critical, also the deflection and stresses of IPE steel beams is not exceed the allowable limits.

Electrodeposition process coupled with ultrasonic vibration (sonoelectrodeposition) was used to deposit nanosized copper powder from acidic solution of copper sulphate. Thecathodic current density and the amplitude of vibration used are 37.5 mA/cm2 and 35% from the maximum capacity of vibration respectively. Purity, morphology and size of the nanosized powder were studied. The XRD studies also reported.The copper powderhas a high purity with mean size of particles about 52 nanometer. XRD analysis confirms that the crystals, sizes are in nanosized range

This paper investigates the effect of process parameters (approach angle, nose radius, cutting speed and feed rate) on surface roughness in turning machine. The experiments was conducted based on Taguchi’s L8 orthogonal array and assessed with analysis of variance and signal to noise ratio. According to this, it was observed that surface roughness correlates negatively with nose radius and positively with approach angle. The ability of the independent values to predict the dependent values was 95.1% for mean. Minimum surface roughness was predicted as 4.207 μm with approach angle 5°, nose radius 1.5mm, cutting speed of 455 rpm and feed rate of 0.19 mm/rev. From analysis of variance ANOVA, the feed rate was the most significant parameter for minimum surface roughness, cutting speed was next significant parameter for minimum surface roughness, then nose radius, while approach angle was the last.

An improved approach for modeling discrete cracks in two-dimensional anisotropic functional graded materials FGMs by XFEM is described. A general node meshing type-T3 with sub-triangle technique for enhancing the Gauss quadrature accuracy near the crack is applied to increase the accuracy of numerical results. Also, the useful incompatible interaction integral method (M-integral method) is used to calculate the stress intensity factors. Numerical simulations have proved that provides accurate results by less number of nodes (DOFs) in comparison with reference. The results of LEFM (liner elastic fracture mechanics) have been compared with the reference results, showing the reliability, stability, and the efficiency of present meshing of XFEM. Matlab program (M-file) is used to solve the aim of this paper.

Air-springs are characterized by strongly anisotropic material behavior and can simultaneously undergo large elastic deformations. This attribute involves an appropriate constitutive model for an adequate numerical simulation of these components' complex response. The present paper discusses the manufacturing process of an air-spring and deals with the use of anisotropic-based hyperelastic constitutive model in the context of thin membranes inflation. In order to investigate the capability of the proposed model, some finite element analysis were conducted by using ANSYS 15.0. The proposed model shows a good predictive ability and exhibits a good agreement when compared to the experimental work of the present paper.

In this paper an experimental (field and laboratory) study was conducted on measuring the amount of suspended sediment transport in Al- Diwaniyah River and introducing a new formula to estimate sediments transport in this river. The application of this study required the selection of 25 sections along the river and its branches and the hydraulic parameters of these sections as well as the slope of bed were measured, and many samples from the river were taken to the laboratory. Samples of suspended sediment in water were taken at each section in the river and analyzed in the laboratory. A new formula was introduced using the dimensional analysis and DataFit 9.1 software corresponding to the field and laboratory measurements in this study. The results were compared with other formulas such as Engelund – Hansen, Laursen, and Einstein formulas and indicate a good exception.

The traditional approaches employ massive components to moderate temperature fluctuations. The thermo-physical properties of the construction materials will have a strong influence on a building’s energy consumption. Within a passive solar design, the heat capacity of the inner wall layer is dominated. This approach is applicable in locations that have effective daily temperature variations, else that, heavy weight constructions can give rise to problems of excessive thermal mass and cost. The nature of the climate of Iraq can be represented in a two typical seasons; short and cold winter and long, hot and dry summer with short periods of the moderate months. The daily temperature variation is very limited and causes to accumulated heat in the buildings of heavy mass. The use of cooling system, in hot climate, is increased especially with heavy mass constructions. In Iraq, more than 6 million new building unit should be added until 2020, the rapid growth in building sectors become the largest consumer of electric power produced, where the building sector consumes more than 38% from the total energy produced. In this investigation, the phase change materials behaviour was embedded within traditional heavyweight building internal surfaces. The two identical simple single zones modelled and simulated in a professional energy systems program called ESP-r. Global meteorological database software called Meteonorm7 has been used to generate a climate file for Baghdad city (33.3 oN and 44.4oE) into ESP-r program. The results represent a preliminary investigation into the effect of PCM modelling with heavy structured construction under hot climate. In addition, a comparison of an internal surface with different phase change temperature ranges. It is found that the presence of PCM could have a significant effect on the internal surfaces and thus the zone temperatures. The results encourage a full yearly investigation for the tested model, the simulation under realistic operational loads and with fixed internal boundary conditions underneath control loops using appropriate heating, cooling and ventilation strategies.

Friction Stir Welding ( FSW ) is a solid –state process that leads to several advantages over the fusion welding methods. This is used in the welding of several non-expendable and is also responsible for generating sufficient heat for welding and the resulting friction. Rotational speed, as well as the welding speed- both play a major role to obtain the weld quality. This research examines the effect of the rotation speed and welding speed on the tensile properties of the Al-Zn-Mg by the Minitab 16 program used. It was concluded that the best tensile strength of (158Mpa) can be obtained when the variables were (X1 = 900 rpm) (X2 =52mm\min).Also results show that the variables, namely the rotation Speed (X1) &welding speed (X2) have a significant effect on tensile strength. However, the interactions of these factors have less significant effect on tensile strength. Moreover, the tensile strength increases with the increasing welding speed and decreasing rotation speed.

The growth of Scenedesmus algae, cultivated in a split-column airlift bioreactor under three
different light intensities (94, 187, 468 E /m .s 2  ) and two values of superficial gas velocities (0.3,
1 cm/s), was investigated. The physical properties of the culture medium were monitored by
various analytical methods (optical density, chlorophyll concentration). Samples were taken twice a
day (10:00 AM and 5:00 PM) for cell count and optical density measurements. The dynamic
growth rate of the algae was studied using the integrated three-state fluid dynamics model
developed by Eilers and Peeters (1988). The kinetic parameters for the system under defined
light/dark cycles were evaluated. The obtained results indicate that the growth rate and chlorophyll
content of the Scenedesmus algae directly proportional to light intensity and superficial gas velocity.

The idea of this research is to improve the properties of expansive soil, such as, liquid limit, plastic limit and shrinkage limit by adding different amount of Ordinary Portland Cement to expansive soil. All variable which effect on soil properties, such as: amount of water, the ratio of compacting, time of mixing and the time for testing should be constant, to determine the differences in liquid limit, plastic limit and shrinkage limit for expansive soil with and without different amount of Ordinary Portland Cement. Four different percentages of Ordinary Portland Cement were used in those experiments, 2.5, 5.0, 10, and 15% by dry weight, these amounts were added to the expansive soil, mix each ratio with an amount of expansive soil and then samples were compacted by a steel rod. After that, the samples were cured for 7 days by covering them with a damp cloth. The samples were weighted and the dimension was measured on the first day; then on the seventh day; and finally on the 28th day to see the differences in weight and volume for each sample. The results were compared to find out which percentage indicated more effect on expansive durability in 7 and 28 days.
Liquid limit and plastic limit were reduced when the amount of cement is equal to 5%, and also the ratio of shrinkage, reduced when the amount of cement was equal to 5%. While the liquid limit, plastic limit and ratio of shrinkage seem to be constant when the amount of cement is more than 5%. So the ratio of 5% cement seems to be more suitable and more economical to use to improve the expansive soil properties.

This paper numerically investigates laminar mixed convection flow through an octagonal cavity enclosure where four cases with different positions and directions of its lid-driven were simulated. The lid-driven moves in horizontal rightward and leftward on its upper wall in the first and second cases while it moves vertical upward and downward on its right side wall in the others cases. The numerical study was carried out by solving the governing equations (continuity, momentum and energy), and applying the tri-diagonal matrix algorithm (TDMA) method via ANSYS 11.0 program. Four of the eight external walls of the octagonal cavity enclosure are insulation walls and the other four walls were classified into two hot and two cold walls. The mixed convection flow and heat transfer characteristics through isotherms, streamlines and the average Nusselt number were considered based on different Richardson numbers (Ri = 0.01, 1, and 10). The results demonstrated that heat transfer mechanism, the flow pattern and formation of vortices are significantly dependent on values of the Richardson number. Within the enclosure, the lid-driven movements showed an improvement in the heat transfer rate where the direction of the sliding wall considerably affected the flow and temperature distributions for all values of the Richardson number. The Nusselt number of the lid-driven increased from 50 with the upward motion to 55 (10 % increase rate) with the downward motion counterpart, and increased from 12 to 17 (40 % increase rate) with the rightward and the leftward motions, respectively.