Iraqi journal of mechanical and material engineering

The determination of temperature distribution within a turbine blade is
important in regard to avoid excessive high metal temperatures and temperatures
gradients. The prediction of temperature distribution was achieved through the use of
the finite difference technique, developed to solve the problem with the transformation
and grid generation techniques. Steady-state two-dimensional conduction heat transfer
equation was applied to the internal nodes in mesh to get the temperature distribution,
where at the surface nodes (outer, inner), forced convection heat transfer equation was
applied. The solution of the problem was established using computer program, which
serves to solve the equations by using Gauss-Siedel iterative method. In the present
study, three cases are used for thermal analyses of the blade, which requires the
specification of external and internal boundary conditions. It is also found from the
results obtained that the best cooling method to the turbine blade have been obtained
for the third case when the blade cooled by impingement and film cooling method. It
was found in the film cooled blade that the blade temperature decreases about (170 K)
cooler than the blade cooled without the film cooling method. The results of thermal
analyses obtained were compared with the finite element results. The comparison
shows that the finite difference results give a good agreement with the finite element
results with a small difference were calculated to be (3.5%) as maximum value and it
fall to (0%) in most regions.

Mixed convection in a square enclosure with a rotating circular cylinder
located at different vertical locations is numerically studied. The horizontal and
vertical walls are kept at constant temperature Tc, while the surface of the rotating
circular cylinder is maintained at a constant temperature Th. A two dimensional
solution for steady laminar mixed convection is obtained by solving governing
equations in stream function-vorticity form with finite difference technique for
different Richardson number (Ri=Gr/Re2) varying over the range of 0.0 to 10.
Depending on the Richardson number the convection phenomena inside the enclosure
becomes natural, mixed, and forced convection. For the first time this study goes to
investigate the effect of changing the rotating circular cylinder positions along the
vertical centerline on the fluid flow and heat transfer inside the enclosure. The
phenomena inside the enclosure is analyzed through a streamlines, isothermal patterns
and average Nusselt numbers. The results show that the flow field and temperature
distribution inside the enclosure is strongly dependent on the Richardson numbers
and the position of the rotating circular cylinder, and the enclosure has maximum heat
transfer rate when the cylinder near the bottom wall (δ=0.25).

The aim of this work is to study the effect of different concentrations of nitric
acid (20%,40%,60)for each 100ml of distilled water on unsaturated polyester and
composite material. The composite material consists of unsaturated polyester
reinforced with powder of aluminum at (0.1, 0.25, 0.5)wt% for (2-10) days. Nitric
acid affects on unsaturated polyester through: physical degradation which represents
by yellowish of polymer, swelling, the formation of pits, and hydrolytic corrosion.
The presence of aluminum powder will inhibit the molecules of solution from
penetration into the cross-linked polymeric chains and consequently will decrease the
swelling at 0.1 wt% but the reinforcement with greater ratios of aluminum powder
will lead to increase in weight.

The dynamic response and stability of parametrically excited viscoelastic belts
are investigated in the current study. In this work, the generalized equation of motion
is obtained for a viscoelastic moving belt with geometric nonlinearity. Non
dimensional analysis of the model was built on some assumptions to simplify the
problem. The viscoelasticity of the model was modelled using Kelvin-Voigt model,
the dynamic equation of motion derived using perturbation technique. The
displacement of vibration found using the zeroth order solution that was subdivided
into two parts, real and imaginary parts, due to the nature of nonlinear system. In this
research effects of many elastic and viscoelastic parameters are studied, it was shown
that there exists an upper boundary for the existence condition of the summation
parametric resonance due to the existence of viscoelasticity. Effects of viscoelastic
parameters, excitation frequencies, excitation amplitudes, and the axial moving speed
on dynamic responses and existence boundaries were investigated.

In this work, the suitability of using local Kaolin and Kaolin Grog to reduce
shrinkage in clay product like firebrick was experimentally investigated and the
optimal ratio of Kaolin grog constituent determined. Ten samples of different
compositions were fired at a temperature of 1200ºC. Three of the samples (samples
8, 9, and 10) crumbled during firing. The surviving samples gave the following
limits of results:- Total shrinkage: 28%- 9.8%; apparent porosity: 63.6% - 77.13%;
water absorption: 47.83% - 60.2%; bulk density: 1.329g/cm3 - 1.281g/cm3; apparent
density: 5.60g/cm3 – 3.65g/cm3; and compressive strength: 61.5MPa – 52.11MPa.
The results showed that the first seven samples had good shrinkage and compressive
strength. Mixing ratio of 35:100 (representing weight in grams of water and Kaolin
respectively) which represent the critical water content.

The burning velocity is defined as the velocity at which unburned gases move
through the combustion wave in the direction normal to wave surface. It is used in
many areas of combustion science such as in designing burners and predicting
explosions.
In this research a data acquisition system has been designed to measure the
laminar burning velocity using a modern technique, which uses thermocouples as
measuring sensors connected to a an interface computer. The hardware has been
designed to connect three groups of sensors to the computer. A program has been
used to access the interface and to acquire the huge measured data which is filtered
through reading in a suitable manner. The results made it possible to achieve an
imperical equation can be used in evaluating laminar burning velocity of parraffin
gaseous fuels, the experimental investigations show acceptable computations
compared with previous research results.

The primary purpose of the present work was to study the effect of different
annealing and aging temperature on the mechanical properties of 16%Ni cast
Maraging steels. In addition subsidiary studies were made of the hardening
mechanism responsible for high strength. It was found the annealing temperature must
be done above approximate 750C◦ but not exceed 1250C◦ to give the good hardness
during aging.. Marked hardening occurred within several minutes during from 485oC
to545 oC but only after several hours in the range between 325 to 375 oC Heat
treatment of 3 hour at 485 oC of cast alloys was most satisfactory. While the aging at
485 oC for long time decrease this hardening caused softening due to the reversion of
the body centered cubic matrix to austenite. The aging kinetics mechanism refer to
that lattice defect were influencing the reaction rate. X-ray diffraction evident
indicated the formation of any bcc structure of matrix as martensite and the appeared
that hardness was due to coherent precipitate having concentration in matrix that
formed as Fe2CoNi, Ni3Ti and Ni3Mo phases. The double aging of cast alloys in
different temperature given normal hardening result.

Loss of the lower limb can cause loss of mobility. At all places and at all
times, efforts have always been made to make up for such a loss. The basis of this
investigation is to research current prosthetic in order to design and build a more
human like prosthesis. Also this investigation aims at combining these characteristics
in order to achieve a more multi functional prosthesis. In undertaking such a design,
the new prosthesis will be exhibit a broader range of characteristics than those
displayed in current prosthetic feet. In doing so, the new prosthesis will enable a
closer representation of the functions inherent of a normal human foot. The
characteristics involved in normal walking include dorsiflexion, impact absorption
and fatigue foot test. The characteristics displayed in the manufactured new foot
tested were compared to those of SACH foot. The characteristics exhibited by
prostheses which compared favorably to those of a human foot were investigated
further. A new prosthetic foot is designed and manufactured from polyethylene and a
comparison study with SACH foot was used to determine if there are differences in
the gait pattern while wearing the NEW foot and whether these differences would be
problematic. The basis of the new prosthetic design combines current prosthetic
design elements, such as materials and components. The analytical part presents the
results of the static and fatigue analysis by methods; numerical methods (Finite
Element method FEM) and experimental methods. The new foot was designed and
the number of cycles, dorsiflexion and impact were measured. The new prosthetic foot
has a good characteristic when compared with the SACH foot, such as good
dorsiflexion (7.8-6.4o), force transmitted at impact heel (9.82N-9.50N) and life of
foot (2,103,445-896,213) cycles respectively.

The present research aims to study the effect of shot peening time (SPT)
using metal balls (stainless steel balls) on surface roughness ,hardness and residual
stresses .the above first two parameters (roughness, hardness) were measured before
and after shot peening،While the third parameter i.e. the residual stresses were
calculated based on the original yield stress of the ALUMINUM ALLOY 2024. The
above three parameters were empirically modeling using the curve fitting equations
The following conclusions can be drawn from this work:
1- Surface roughness increases with increasing the (SPT).
2- The hardness increases with increasing SPT (For the current study an
improvement of 36.75%) using shot peening of 2024-Al alloy.
3- The compressive residual stresses increases with increasing SPT (for the
present study an improvement of 11%using shot peening of 2024 –Al alloy.

The object of this paper is to find the relationship between slop angle,
orientation for inclination roofs which used in frame building (steel & concrete) in
Baghdad city. (Latitude 33.3º North), and it's effect on the solar heat gain value which
transferred through that roofs and it's effect on the electrical power consumption for
summer cooling purpose.
The researcher is build (1 x 1 x 1)m frame building sample, it’s roof is rotated
horizontally eight times and is made by two parts, first part is called frontal part (it’s
slop angle would vary from 5° to 45°), the second part is called rear part (it’s slop
angle would vary from 90° to 5°).
Finally , the researcher was found the relationship between that angles will be
taken the following form :
 If frontal angle less than 20°, the minimum electrical energy was occur at
North , North East and North-West, when rear angle is 20°, while , for East,
West and East-South was occur at 10°, the another orientation at 5°.
 If frontal angle equal to 20°, the minimum electrical energy for cooling was
occur at 5° rear angle for all orientation.
 If frontal angle more than 20°, the minimum electrical energy was occur for
North & East North at 20° rear angle, while, for South orientation at 5°, while
the other orientation occurred at 10° rear angle.
And also, can notice that the roofs 20° frontal angle & 10° rear angle is
consuming lowest energy for cooling with all orientation.

The determination of temperature distribution within a turbine blade is
important in regard to avoid excessive high metal temperatures and temperatures
gradients. The prediction of temperature distribution was achieved through the use of
the finite difference technique, developed to solve the problem with the transformation
and grid generation techniques. Steady-state two-dimensional conduction heat transfer
equation was applied to the internal nodes in mesh to get the temperature distribution,
where at the surface nodes (outer, inner), forced convection heat transfer equation was
applied. The solution of the problem was established using computer program, which
serves to solve the equations by using Gauss-Siedel iterative method. In the present
study, three cases are used for thermal analyses of the blade, which requires the
specification of external and internal boundary conditions. It is also found from the
results obtained that the best cooling method to the turbine blade have been obtained
for the third case when the blade cooled by impingement and film cooling method. It
was found in the film cooled blade that the blade temperature decreases about (170 K)
cooler than the blade cooled without the film cooling method. The results of thermal
analyses obtained were compared with the finite element results. The comparison
shows that the finite difference results give a good agreement with the finite element
results with a small difference were calculated to be (3.5%) as maximum value and it
fall to (0%) in most regions.

A series of epoxy-acetone blends have been prepared with different acetone
percentages. After stiffening, the prepared epoxy samples are cured in 40°C for 24
hrs. Then a tensile test for the material specimens was performed by a universal
computer aided testing machine.
The measured tensile tests for the specimens reveal that as the acetone
percentage is increased, the elastic properties are increased. Nevertheless, when the
acetone percentage reaches a maximum value, the tensile properties decreases with
further increase in acetone percentages.
The results are explained in terms of that the acetone additions reduces the
cross linking density and reduce the brittle character of the prepared epoxy. When the
acetone content is more than (5%), the strength becomes to decrease due to severe
reduction of cross-linking density.

In this research, the main objectives of this investigation as, first, study the
effect of fibers orientation on fatigue strength for composite materials, second, study
the effect of fiber orientation on shape and direction of fracture surface for composite
materials. The experimental work using to study fatigue limit for composite material
with different fiber orientation as (00, 30o, 450, 60o, 90o) and study of the fatigue
surface (shape and direction of fatigue surface of composite material) for each fiber
orientation fiber.
The material using for composite material in this research are epoxy resin
matrix and glass reinforcement fiber with volume fracture of fiber in composite
material about (0.21). The results are endurance fatigue strength with number of cycle
for fiber orientation (00, 30o, 450, 60o, 90o) and the shape and direction of surface
fatigue of composite material.

A numerical model for the unsteady state cross flow heat exchanger with variable fluid parameters is
presented. The model contains many sophisticated assumptions that always avoided in the traditional
analyzing of cross flow heat exchanger like variation of fluid properties (density, viscosity, thermal
conductivity and convection heat transfer coefficient) and three dimensions unsteady state. The
hydrodynamic properties for both fluids are taken as fluid temperatures dependence. The heat transfer
from the hot fluid to the surrounding cold fluids, and the heat exchanged between the cold fluid and the
surrounding hot fluids channels and surrounding cold fluids ducts are taken in account. The air is used
as cold fluid, while the water as hot fluid. A numerical analysis by using Finite difference method is
used to solve the governing equations for both hot and cold fluids. The results shows that at small
values of dimensionless X-xis (X = ∆X - 3∆X) (∆X = 0.021625), the hot fluid temperature decreases at
a constant value of dimensionless Y-Axis (height). The hot and cold fluid temperature lines are curved
and lower values of the temperature in the left side (X = ∆X - 3∆X) and higher values of the
temperature in the right side (X = 5∆X - 8∆X). The hot and cold overall effectiveness of the system
increase with increased number of the cold duct per pass (ncp).