Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : cascade


Estimating Reference Evapo- transpiration in Mosul (Iraq) Using Cascade Neural Networks

Fatin Mahmoud Shehab; Raid Rafi Omar; Radhwan Yousif Sedik

Engineering and Technology Journal, 2014, Volume 32, Issue 9, Pages 2277-2285

Recently artificial neural network (ANN) has been applied for estimating reference evapo-transpiration (ETₒ).In this study a mathematical model was built by application the cascade forward network technique (CCANN) to estimate the daily reference evapo-transpiration in the city of Mosul, north of Iraq .The input parameters for the CCANN were the: temperature, solar radiation, wind speed at 2m height, and relative humidity. A check for the accuracy of the performance of the network was made using values of reference evapo-transpiration obtained from pan evaporation method. The results revealed linear correlation between the network output and the data of the measured pan evapo-transpiration with correlation coefficient of (0.9679). This indicates the possibility of use of CCANN to determine the daily reference evapo- transpiration. The results also show that the CCANN model performs better more accurate compared to other models.

Effect of Exit Pressure of Steam Turbine Last Stage Cascade Blade on Two Phases of Saturated Vapor and Water Droplet

Assim H. Yousif; Amer M. Al-Dabbagh; Reyadh Ch. Mahawi

Engineering and Technology Journal, 2013, Volume 31, Issue 2, Pages 235-244

Experimental investigation was carried out in low pressure steam turbine cascade to determine the effect of exit pressure on two phases of saturated vapor and fine water droplet. Numerical investigation was also presented by assuming the flow is two dimensional, compressible, turbulent, viscous, with the aid of the classical nucleation model applied for the mass transfer in the transonic conditions to predict the two phases behavior in the cascade. Comparison between experimental and theoretical results for the cascade flow was found to be fairly acceptable. Experimentally it was found that the most important influence of rapid condensation on the pressure distribution is on the suction surface. Also when the outlet is termed supersonic the heat release causes a pressure rise in the zone of rapid condensation, therefore the term "condensation shock" for this feature is misleading. In the numerical approach when the flow is regard subsonic the rapid condensation zone occurs downstream the throat and not accompanied by a pressure rise, while in the experimental test for the same case there is no sign of this condensation.

Validation of Numerical Computations and Turbulence Models Combinations for Gas Turbine Cascade Blade Flow

Assim Yousif Hameed; Hakem Tarteb

Engineering and Technology Journal, 2011, Volume 29, Issue 14, Pages 2880-2899

The accuracy of computer codes for turbo-machinery turbulent flow field
calculations relies strongly on the type and behavior of the turbulence model used
in the computations. Analysis of different Reynolds Average Navier-Stokes
Equation (RANS) based turbulence models was applied to predict the flow field in
the linear first stage gas turbine cascade blade. The experimental investigation is
also introduced to validate the accuracy of turbulence models. This was done by
using five linear cascade blades tested in an open jet type low-speed subsonic wind
tunnel. The static pressure distribution was measured at the midspan of cascade
middle blade by using static pressure taps. The numerical results obtained from
different turbulence model simulations is individually reviewed for the correctness
of its predictions and compared with the experimental data in terms of integrated
flow parameters, such as static pressure coefficient distribution on both blade sides.
The results show that RNG k-e turbulence model gave the best prediction of
pressure distribution when compared with the experimental data. Prediction of
standard k-ε and k-ω turbulence models fail to predict accurately the flow field
parameters in cascade passage. Prediction of (k-ε) turbulence model overestimate
the turbulence kinetic energy values, especially in the regions of high velocity at
blade suction side, also not accurately predict the flow separation on the blade
suction side.

One Parameter Composite Semigroups of Linear Bounded Operators in Strong Operator Topology of Schatten Class Cp

Samir Kasim Hassan; Al-Taie M; Al-Malki Anam; Al-Attar Abeer; Mustafa Khaleel Ismael; Fatema Ahmed Sadeq; Radhi A .Zboon; Jehad R.Kider; Samir K .Hassan; Hussain J. M. Alalkawi; Raad H. Majid; Rawaa A. Alomairy; Luma Abdul Ghani Zghair; Hadia Kadhim J.Al-Ogili; Assifa M. Mohamad; Abbas Sheyaa Alwan; Haider L. Aneed; Assim H Yousif; Salema Sultan Salman; Abbas Hussien Miry; Abduladhem A.Ali; Mohammed Zeki Al-Faiz; Sabah N. mahmood; Khansaa Dawood Selman; Shaymaa Tareq Kadhim

Engineering and Technology Journal, 2011, Volume 29, Issue 8, Pages 1463-1470

For semigroups of linear bounded operators on Hilbert spaces, the problem of
being in Cp , 0 Keywords

Evaluation of Aerodynamic Coefficients of High Temperature Gas Turbine Cascade of Cooled Blade

Haider L. Aneed; Assim H Yousif

Engineering and Technology Journal, 2011, Volume 29, Issue 8, Pages 1563-1579

The aerodynamic force coefficients of five linear cascade of existing film cooling
turbine blades are evaluated numerically. The blade is geometrically identical to the
first rotor blades of the high pressure (HP) turbine of the F-100-PW-220 military
turbofan. Cascade turbine blade test rig has been designed, constructed, and calibrated
to introduce experimental work for the same flow conditions of the numerical solution
to validate correctness of the numerical results. The numerical simulation shows
acceptable agreement with experimental. Also it was found experimentally that both
lift and drag coefficients are increased slightly with add of film cooling.
The local Mach number distributions outside the boundary layer on both blade
sides of the cascade blade are evaluated numerically and compared with the results of
well known CFD code (Fine/Turbo) for existing gas turbine rotor stage of identical
blade. The computational results obtained for both cases show that the Mach number
distributions trend along both blade sides for rotor stage and cascade are approximately
the same, and the values of Mach number of rotor stage are higher than that for the
corresponded cascade. Also it was found that the Mach number distributions on both
blade sides are reduced in values by the addition of air cooling, and the local Mach
numbers for the cascade case is reduced in values among the rotor stage for the two
cases with and without film cooling on both blade sides.