Günümüzde ülkemizdeki yüksek bina inşaatlarında belirgin bir artış göze çarpmaktadır. Binalarda y... more Günümüzde ülkemizdeki yüksek bina inşaatlarında belirgin bir artış göze çarpmaktadır. Binalarda yükseklik arttıkça rüzgar etkileri de önemini arttırmaktadır. Rüzgar esnek binalarla etkileşime girebilmekte, gerek rüzgar kuvvetlerini gerekse rüzgar kaynaklı bina salınımını ciddi miktarda arttırabilmektedir. Rüzgar tüneli deneyleri binalardaki rüzgar etkilerinin belirlenmesi için sıkça başvurulan bir yöntemdir. Ancak başarılı bir deney gerçekleştirmek için tünel içi akış koşullarının gerçeğe oldukça yakın oluşturulması gerekmektedir. Türkiye’de ilk defa gerçekleştirilen bu çalışmada kısa test kesitine sahip Ankara Rüzgar Tüneli’nde yönetmeliklerle tanımlanan rüzgar hız profilinin oluşturulması için yüzey pürüz elemanları tasarlanmış ve bu elemanların başarımları sayısal ve deneysel olarak sınanmıştır. Daha sonra yüksek frekanslı taban balansı yöntemi kullanılarak dikdörtgen kesitli yüksek bina modeli üzerindeki rüzgar etkileri incelenmiş, türbülans yoğunluğu, periyodik girdap etkisi ve...
An appropriate performance of an air intake is a critical parameter for the best flght of an airc... more An appropriate performance of an air intake is a critical parameter for the best flght of an aircraft using a jet engine. Since then it is expected to ensure of this performance clearly, otherwise, the engine could probably have diffiulties in breathing due to lack of proper functioning of the air intake. An Unmanned aerial vehicle - like any other aircraft – takes over a variety of flght regimes, since then the analysis of intake performance should be done in each condition. Due to the necessity of utilizing a jet engine in some of UAVs, it has been set to investigate the performance of an “S-shaped” air intake in the subsonic flght regime using numerical methods. Regarding to the lack of a professional experimental apparatus and the high level of knowledge required in the experiments the results then have to be compared and to be validated with experimental and numerical data obtained in previous similar efforts accomplished by aerodynamic and propulsion scientists all over the world.
Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1... more Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1D inviscid theory was used in designing a series of conical micronozzles of different expander half-angles (10°-50°). Aerospike micronozzle, a promising candidate to achieve high performance propulsion system, was designed with Angelino method (or Approximate method). Both micronozzles were fabricated using soft lithography, an inexpensive and relatively simple technique comparing to well-established deep reactive ion etching (DRIE) technique, with polydimethylsiloxane (PDMS) as structural material. Micronozzles with two different nozzle throat width, 53.5µm and 107µm, were fabricated for comparison. Microscopic inspections reveal 107µm is the more producible nozzle throat width with current equipments. The PDMS-based micronozzle can be used as cold gas microthruster system for micro- and nanosatellites.
Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1... more Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1D inviscid theory was used in designing a series of conical micronozzles of different expander half-angles (10°-50°). Aerospike micronozzle, a promising candidate to achieve high performance propulsion system, was designed with Angelino method (or Approximate method). Both micronozzles were fabricated using soft lithography, an inexpensive and relatively simple technique comparing to well-established deep reactive ion etching (DRIE) technique, with polydimethylsiloxane (PDMS) as structural material. Micronozzles with two different nozzle throat width, 53.5µm and 107µm, were fabricated for comparison. Microscopic inspections reveal 107µm is the more producible nozzle throat width with current equipments. The PDMS-based micronozzle can be used as cold gas microthruster system for micro- and nanosatellites.
The Atmospheric Boundary Layer (ABL) is a boundary layer of air over the ground surface whose thi... more The Atmospheric Boundary Layer (ABL) is a boundary layer of air over the ground surface whose thickness is the height which the surface friction no longer affects the general flow of wind. In many industrial aerodynamics and wind engineering applications, modelling conditions with velocity boundary layer are of special importance and it is usually assumed that the influence of heat convection is negligible. However during air pollution applications, the temperature structure of the boundary layer because of inversion level is in essential effort. In this paper, the governing equations in modelling of ABL in long Environmental Wind Tunnel (EWT) are discussed. The velocity boundary layer in long EWT is defined from the beginning of the wind tunnel’s test section. The modelling structure of its ABL is based on surface roughness of the prototype and wind tunnel floor for three defined exposures. Conversely, the starting position for the thermal boundary layer modelling would differ for ...
Investigation of Wind Effects on Tall Buildings through Wind Tunnel Testing There has been signif... more Investigation of Wind Effects on Tall Buildings through Wind Tunnel Testing There has been significant increase in tall building construction in Turkey in the last decade. As the height of building increase, wind effects become more pronounced. Wind can interact with flexible buildings and can significantly magnify the wind loads and wind
An appropriate performance of an air intake is a critical parameter for the best flght of an airc... more An appropriate performance of an air intake is a critical parameter for the best flght of an aircraft using a jet engine. Since then it is expected to ensure of this performance clearly, otherwise, the engine could probably have diffiulties in breathing due to lack of proper functioning of the air intake. An Unmanned aerial vehicle - like any other aircraft – takes over a variety of flght regimes, since then the analysis of intake performance should be done in each condition. Due to the necessity of utilizing a jet engine in some of UAVs, it has been set to investigate the performance of an “S-shaped” air intake in the subsonic flght regime using numerical methods. Regarding to the lack of a professional experimental apparatus and the high level of knowledge required in the experiments the results then have to be compared and to be validated with experimental and numerical data obtained in previous similar efforts accomplished by aerodynamic and propulsion scientists all over the wo...
Günümüzde ülkemizdeki yüksek bina inşaatlarında belirgin bir artış göze çarpmaktadır. Binalarda y... more Günümüzde ülkemizdeki yüksek bina inşaatlarında belirgin bir artış göze çarpmaktadır. Binalarda yükseklik arttıkça rüzgar etkileri de önemini arttırmaktadır. Rüzgar esnek binalarla etkileşime girebilmekte, gerek rüzgar kuvvetlerini gerekse rüzgar kaynaklı bina salınımını ciddi miktarda arttırabilmektedir. Rüzgar tüneli deneyleri binalardaki rüzgar etkilerinin belirlenmesi için sıkça başvurulan bir yöntemdir. Ancak başarılı bir deney gerçekleştirmek için tünel içi akış koşullarının gerçeğe oldukça yakın oluşturulması gerekmektedir. Türkiye’de ilk defa gerçekleştirilen bu çalışmada kısa test kesitine sahip Ankara Rüzgar Tüneli’nde yönetmeliklerle tanımlanan rüzgar hız profilinin oluşturulması için yüzey pürüz elemanları tasarlanmış ve bu elemanların başarımları sayısal ve deneysel olarak sınanmıştır. Daha sonra yüksek frekanslı taban balansı yöntemi kullanılarak dikdörtgen kesitli yüksek bina modeli üzerindeki rüzgar etkileri incelenmiş, türbülans yoğunluğu, periyodik girdap etkisi ve...
An appropriate performance of an air intake is a critical parameter for the best flght of an airc... more An appropriate performance of an air intake is a critical parameter for the best flght of an aircraft using a jet engine. Since then it is expected to ensure of this performance clearly, otherwise, the engine could probably have diffiulties in breathing due to lack of proper functioning of the air intake. An Unmanned aerial vehicle - like any other aircraft – takes over a variety of flght regimes, since then the analysis of intake performance should be done in each condition. Due to the necessity of utilizing a jet engine in some of UAVs, it has been set to investigate the performance of an “S-shaped” air intake in the subsonic flght regime using numerical methods. Regarding to the lack of a professional experimental apparatus and the high level of knowledge required in the experiments the results then have to be compared and to be validated with experimental and numerical data obtained in previous similar efforts accomplished by aerodynamic and propulsion scientists all over the world.
Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1... more Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1D inviscid theory was used in designing a series of conical micronozzles of different expander half-angles (10°-50°). Aerospike micronozzle, a promising candidate to achieve high performance propulsion system, was designed with Angelino method (or Approximate method). Both micronozzles were fabricated using soft lithography, an inexpensive and relatively simple technique comparing to well-established deep reactive ion etching (DRIE) technique, with polydimethylsiloxane (PDMS) as structural material. Micronozzles with two different nozzle throat width, 53.5µm and 107µm, were fabricated for comparison. Microscopic inspections reveal 107µm is the more producible nozzle throat width with current equipments. The PDMS-based micronozzle can be used as cold gas microthruster system for micro- and nanosatellites.
Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1... more Micronozzle, a key component in micropropulsion system, has been designed and fabricated. Quasi 1D inviscid theory was used in designing a series of conical micronozzles of different expander half-angles (10°-50°). Aerospike micronozzle, a promising candidate to achieve high performance propulsion system, was designed with Angelino method (or Approximate method). Both micronozzles were fabricated using soft lithography, an inexpensive and relatively simple technique comparing to well-established deep reactive ion etching (DRIE) technique, with polydimethylsiloxane (PDMS) as structural material. Micronozzles with two different nozzle throat width, 53.5µm and 107µm, were fabricated for comparison. Microscopic inspections reveal 107µm is the more producible nozzle throat width with current equipments. The PDMS-based micronozzle can be used as cold gas microthruster system for micro- and nanosatellites.
The Atmospheric Boundary Layer (ABL) is a boundary layer of air over the ground surface whose thi... more The Atmospheric Boundary Layer (ABL) is a boundary layer of air over the ground surface whose thickness is the height which the surface friction no longer affects the general flow of wind. In many industrial aerodynamics and wind engineering applications, modelling conditions with velocity boundary layer are of special importance and it is usually assumed that the influence of heat convection is negligible. However during air pollution applications, the temperature structure of the boundary layer because of inversion level is in essential effort. In this paper, the governing equations in modelling of ABL in long Environmental Wind Tunnel (EWT) are discussed. The velocity boundary layer in long EWT is defined from the beginning of the wind tunnel’s test section. The modelling structure of its ABL is based on surface roughness of the prototype and wind tunnel floor for three defined exposures. Conversely, the starting position for the thermal boundary layer modelling would differ for ...
Investigation of Wind Effects on Tall Buildings through Wind Tunnel Testing There has been signif... more Investigation of Wind Effects on Tall Buildings through Wind Tunnel Testing There has been significant increase in tall building construction in Turkey in the last decade. As the height of building increase, wind effects become more pronounced. Wind can interact with flexible buildings and can significantly magnify the wind loads and wind
An appropriate performance of an air intake is a critical parameter for the best flght of an airc... more An appropriate performance of an air intake is a critical parameter for the best flght of an aircraft using a jet engine. Since then it is expected to ensure of this performance clearly, otherwise, the engine could probably have diffiulties in breathing due to lack of proper functioning of the air intake. An Unmanned aerial vehicle - like any other aircraft – takes over a variety of flght regimes, since then the analysis of intake performance should be done in each condition. Due to the necessity of utilizing a jet engine in some of UAVs, it has been set to investigate the performance of an “S-shaped” air intake in the subsonic flght regime using numerical methods. Regarding to the lack of a professional experimental apparatus and the high level of knowledge required in the experiments the results then have to be compared and to be validated with experimental and numerical data obtained in previous similar efforts accomplished by aerodynamic and propulsion scientists all over the wo...
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Papers by S. M. Nima Shojaee
to ensure of this performance clearly, otherwise, the engine could probably have diffiulties in breathing due to lack of proper functioning of the air
intake. An Unmanned aerial vehicle - like any other aircraft – takes over a variety of flght regimes, since then the analysis of intake performance
should be done in each condition. Due to the necessity of utilizing a jet engine in some of UAVs, it has been set to investigate the performance of
an “S-shaped” air intake in the subsonic flght regime using numerical methods. Regarding to the lack of a professional experimental apparatus and
the high level of knowledge required in the experiments the results then have to be compared and to be validated with experimental and numerical
data obtained in previous similar efforts accomplished by aerodynamic and propulsion scientists all over the world.
to ensure of this performance clearly, otherwise, the engine could probably have diffiulties in breathing due to lack of proper functioning of the air
intake. An Unmanned aerial vehicle - like any other aircraft – takes over a variety of flght regimes, since then the analysis of intake performance
should be done in each condition. Due to the necessity of utilizing a jet engine in some of UAVs, it has been set to investigate the performance of
an “S-shaped” air intake in the subsonic flght regime using numerical methods. Regarding to the lack of a professional experimental apparatus and
the high level of knowledge required in the experiments the results then have to be compared and to be validated with experimental and numerical
data obtained in previous similar efforts accomplished by aerodynamic and propulsion scientists all over the world.