Design of serrate-semi-circular riblets with application to skin friction reduction on engineering surface

Drag reduction in wall-bounded flows can be achieved by the passive flow control technique through the application of bio-inspired riblet surfaces. This paper presents the innovative design of Serrate-Semi-Circular riblet surfaces particularly focusing on the intrinsic relationship between the riblet features and the turbulent boundary layer structure resulting from these surfaces in engineering applications. The available experimental facilities, instrumentation (i.e. hotwire) and measurement techniques (i.e. velocity spectra) have been employed to investigate the boundary layer velocity profiles and skin friction for flat plate and Serrate-Semi-Circular riblet surfaces. Both the simulation and experimental wind tunnel testing results show that the Serrate-Semi-Circular riblet surface can provide 7% drag reduction, which is better than other riblet configurations, such as V and U shaped ones

Re-Thinking "Emotionally": Central of Business District (CBD) of Alexandria City as a Retailing Center

The decisions of the Alexandria Local Authorities would be a key motive power of the flourishing process in Alexandria City Center as a retailing center. The objective of this study is to pay more attention toward re-thinking "Emotionally" to identify any planning policies at various levels. This new tendency would be helpful for having a prosperous city center, after losing its significance as a retailing center. This degradation due to the presence of "Malls and Plazas" like 'City Center Mall," "Green Plaza," and "Down Town Plaza" lying on the peripheral of the city as well as many other reasons. Studying the Saad Zaghloul Street is part of this paper to prove that re-thinking "Emotionally" is the answer to the enhancement Alexandria City Center as a retailing center

Comparative study of the noise generated by the moto-compressor and that generated by the turbo-compressor

The fundamental aim of this study is to compare between the noise generated by the moto-compressor and the noise generated by the turbo-compressor operating  24H/24H on the continuous function mode; these two machines make part of the equipment of the GP1Z, a factory of hydrocarbon treatment. To attain the principal objective of this study we divided our work into two parts, in the first part we followed and evaluated the average level of the noise emitted by the two machines, whereas in the second part we studied the noise propagation emitted by the two machines and its impact on the generation of the noise. The results obtained from this study demonstrate that the noise generated by the turbo-compressor is higher than the noise generated by the  moto-compressor.Keywords: noise; moto-compressor; turbo-compressor; noise maping

Towards Environmental Retrofitting of Egyptian Transitional Spaces: Courtyard-Building in Alexandria University, Egypt

Consuming huge amount of energy and emitting large amount of heat can be assumed as one of the main problems facing urban environment in the world today. These problems associated with current high urban density and less of vegetation within urban fabric. For instance, in Egypt, Universities are today facing rising problem of offering more educational spaces especially in large cities such as Cairo and Alexandria. The study thus focuses on Revival Egyptian buildings in Alexandria University based on hierarchical transitional spaces. As Egyptian transitional spaces, such as courtyards historically were essential outdoor spaces for multiple uses and purposes. As part of retrofitting research project of existed transitional spaces in Alexandria University, this paper focused on one parameter which is building height. This is by targeting to find the maximum height of courtyard building with minimum negative effect on air and thermal flow. This simulation is done with consideration to the surrounding urban context in Alexandria University. The simulation approach is based on two years of field measurement of thermal conditions and air velocity in the Universityrsquos transitional spaces. The study is usingfield-measurement data for nurturing the Computational Fluid Dynamics (CFD) model, and for validating the simulation results. The Computational Fluid Dynamics (CFD) study is done by introducing four cases of different building heights to investigating the changing air and thermal flow inside the existed courtyard. nbs

Characterization of Single SAW Velocities of Ti–6Al–4V Alloy as a Function of Porosity by SAM Simulation for Applications

Rayleigh wave modes depend on porosity of Ti–6Al–4V alloy with porosities between 60–75%. It is very important in many applications and understanding of bonding arrangements at propagating surface acoustic-wave velocities. These velocities are deduced from the analysis of the topped acoustic signatures’ curves obtained by recording the output signal VV. We used simulation of acoustic microscopy to measure Rayleigh velocities. The acoustic parameters were determined as follow: longitudinal (VL), transverse (VT), and Rayleigh (VR) velocities from 1139 ms⁻¹ to 285 ms⁻¹, from 87 ms⁻¹ to 143 ms⁻¹, and from 562 ms⁻¹ to 136 ms⁻¹, respectively, for porosity from 60% to 75%.Режимы волн Рэлея зависят от пористости сплава Ti–6Al–4V, которая составляет 60–75%. Это очень важно для многих приложений и понимания связующих устройств при распространении поверхностных акустических волн. Скорости определялись с помощью анализа усечённых кривых акустических характеристик, полученных путём регистрации выходного сигнала VV. Моделированием поверхностных акустических волн измерялись скорости Рэлея. Определены акустические параметры: продольные (VL), поперечные (VT) скорости и скорость Рэлея (VR) — от 1139 мс⁻¹ до 285 мс⁻¹, от 87 мс⁻¹ до 143 мс⁻¹ и от 562 мс⁻¹ до 136 мс⁻¹ соответственно (при пористости от 60% до 75%).Режими Релейових хвиль залежать від пористости стопу Ti–6Al–4V, яка становить 60–75%. Це дуже важливо для багатьох застосувань і розуміння сполучних пристроїв при поширенні поверхневих акустичних хвиль. Швидкості визначалися за допомогою аналізи усічених кривих акустичних характеристик, одержаних шляхом реєстрації вихідного сиґналу VV. Моделюванням поверхневих акустичних хвиль вимірювалися Релейові швидкості. Визначено акустичні параметри: поздовжні (VL), поперечні (VT) швидкості та швидкість Релея (VR) — від 1139 мс⁻¹ до 285 мс⁻¹, від 87 мс⁻¹ до 143 мс⁻¹ та від 562 мс⁻¹ до 136 мс⁻¹ відповідно (при пористості від 60% до 75%)

Gyro-Chirality Effect of Bianisotropic Substrate On the operational of Rectangular Microstrip Patch Antenna

yesIn this paper, the gyrotropic bi-anisotropy of the chiral medium in substrate constitutive parameters (ξc and ηc) of a rectangular microstrip patch antenna is introduced in order to observe its effects on the complex resonant frequency, half-power bandwidth and input impedance. Numerical calculations and analysis based on the dominant mode are carried out to show that the latter is directly related to the former. This paper is based on the Moment Method as full-wave spectral domain approach using sinusoidal basis functions. Two new results, namely the appearance of the difference (ξc-ηc) and sum (ξc+ηc) of the two magneto-electric elements are obtained in the electric transverse components and Green tensor expressions, respectively. These new results can be considered as a generalisation form of the previously published work

Design of a sequential axial turbocharger for automotive application

Copyright © 2019 by the authors. In the last few years, the perspective of climate change, energy, competitiveness, and fuel consumption in the transportation sector has become one of the most significant public policy issues of our time. As different methods are being adapted into light-duty vehicles like engine downsizing, on the other hand, the increase in carbon emissions of heavy-duty trucks is becoming a major concern. Although previous researches have studied the methodology for selecting optimized turbocharger performance, still further investigation is needed to create a method for achieving the highest performance for a sequential axial turbocharger. Therefore, in this study, the design of a two-stage turbocharger system that consists of a radial turbine connected in series to an axial turbine is considered. The specific two-stage turbine was designed specifically and will be tested on a MAN 6.9 L diesel truck engine. With the engine already equipped with a radial type turbine, the newly designed two-stage turbine will be adapted to the engine to give more efficiency and power to it. Firstly, the modelling and simulation of the engine were done in Gt-Power, to achieve the same power and torque curves presented in the MAN engine specification sheet. Once that was achieved, the second task was to design and optimise a radial and axial turbine, which will form part of a two-stage system, through Computational Fluid Dynamics (CFD) analysis. Necessary data were gathered from the engine’s output conditions, for the ability to design the new turbo system. Lastly, the new turbine data were entered into the new two-stage turbo GT-Power model, and a comparison of the results was made. The CFD analysis, executed in ANSYS, for the radial turbine gave an 83.4% efficiency at 85,000 rpm, and for the axial turbine, the efficiency achieved was 81.74% at 78,500 rp

Influence of Boron Adding on the Acoustic Materials Signature Curves for Computing of Surface Acoustic Wave Velocities of Ti64 Alloys

The effect of Boron admixture with five different concentrations x = 0.0, 0.04, 0.09, 0.30 and 0.55% wt. B on elastic properties of Ti–6Al–4V alloy is investigated. The values of velocities of propagating surface acoustic wave as well as bulk wave for additional structures are deduced. As found, with the increasing of Boron content in Ti–6Al–4V alloy, its acoustic material signature (Young’s modulus E, shear modulus G, bulk modulus B), longitudinal velocities, and shear velocities increase from 113 to 126 GPa, from 42.5 to 47.4 GPa, from 110.8 to 123.5 GPa, from 6148 to 6492 m/s, from 3097 to 3171 m/s, respectively. Using angular spectrum model, we calculate the reflectance function and the acoustic materials signature of Ti–6Al–4V–xB, which show an oscillatory behaviour. The spectral treatment of these signatures provides the exact definition of Rayleigh wave velocity.Исследовано влияние примеси бора при пяти значениях концентрации x = 0,0, 0,04, 0,09, 0,30 и 0,55% масс. B на упругие свойства сплава Ti–6Al–4V. Определены значения скоростей распространяющейся поверхностной акустической волны, а также объёмной акустической волны для дополнительных структур. Установлено, что при увеличении содержания бора в сплаве Ti–6Al–4V акустические характеристики материала (модуль Юнга E, модуль сдвига G, объёмный модуль B), продольные скорости и скорости сдвига увеличиваются от 113 до 126 ГПа, от 42,5 до 47,4 ГПа, от 110,8 до 123,5 ГПа, от 6148 до 6492 м/с, от 3097 до 3171 м/с соответственно. С использованием модели углового спектра вычислены функция отражения и акустические характеристики материала Ti–6Al–4V–xB, которые проявляют осциллирующее поведение. Спектральная обработка этих характеристик позволяет точно определить скорость волны Рэлея.Досліджено вплив домішки Бору за п’ятьох значень концентрації x = 0,0, 0,04, 0,09, 0,30 та 0,55% мас. B на пружні властивості стопу Ti–6Al–4V. Визначено значення швидкостей поширюваної поверхневої акустичної хвилі, а також об’ємної акустичної хвилі для додаткових структур. Встановлено, що при збільшенні вмісту Бору в стопі Ti–6Al–4V акустичні характеристики матеріялу (модуль Юнґа E, модуль зсуву G, об’ємний модуль B), поздовжні швидкості та швидкості зсуву збільшуються від 113 до 126 ГПа, від 42,5 до 47,4 ГПа, від 110,8 до 123,5 ГПа, від 6148 до 6492 м/с, від 3097 до 3171 м/с відповідно. З використанням моделю кутового спектру розраховано функцію відбивання й акустичні характеристики матеріялу Ti–6Al–4V–xB, які проявляють осцилівну поведінку. Спектральна обробка цих характеристик забезпечує можливість точного визначення швидкости Релейової хвилі