Modeling of gas turbine combustion chambers

Bu çalışmayı gerçekleştirebilmek için öncelikle silindirik polar koordinatlarda üç boyutlu bir geometride çözüm yapıldı. Yanma odasını idealleştiren bu geometride, sınırlandırılmış dönen akış ortamı içinde türbülanslı bir jet akış olduğu varsayıldı. Aynı zamanda yüksek türbülans yoğunluğu da olan bu akışın merkezine yerleştirilmiş helyum/hava karışımı jet akışkanı enjekte edilerek soğuk akış simülasyonu yapıldı. Bu akışın davranışı, üç boyuta genelleştirilerek ve dönme (swirl) etkisi de göz önüne alınarak incelendi. Türbülanslı akışların sayısal hesabı için türbülans modellerine ihtiyaç duyulmaktadır. Bu çalışmada çeşitli türbülans modellerinin bu akışın simülasyonundaki performansı da incelendi.Girdap etkisini bulmak için bir dizi sayısal çalışma teklif edildi. Sayısal hesaplamalar için üç boyutlu eliptik sonlu-elemanlar kodu ile silindirik koordinatlarda ANSYS CFD Flotran analiz programı kullanıldı. Elde edilen sonuçlar deneysel veya mevcut diğer sonuçlarla karşılaştırıldı ve uyumun iyi olduğu görüldü.For this investigation can be realized firstly, the solution was done in geometry which idealizes combustion chamber was defined three dimensional on cylindrical polar coordinate. We assumed that a turbulent jet mixing in a confined swirling flow environment in the model combustion chamber. The isothermal flow was simulated injecting helium/air as a jet fluid that is located centrally in this flow has also high turbulence intensity. This flow behavior was investigated being generalized in three dimensions and taking into consideration effects of swirl. For numeric calculation of turbulent fluids need turbulence models. In this study was also examined various turbulence models of how is the simulation performance of this flow which is in combustion chamber. Some sequence study was offered to find impression of swirl. For numeric computation was used ANSYS CFD Flotran analysis program with three-dimensional elliptic finite element codes on cylindrical coordinate. Results found were compared with experiment or other available results and indicated good correlations

Modeling of gas turbine combustion chambers

Bu çalışmayı gerçekleştirebilmek için öncelikle silindirik polar koordinatlarda üç boyutlu bir geometride çözüm yapıldı. Yanma odasını idealleştiren bu geometride, sınırlandırılmış dönen akış ortamı içinde türbülanslı bir jet akış olduğu varsayıldı. Aynı zamanda yüksek türbülans yoğunluğu da olan bu akışın merkezine yerleştirilmiş helyum/hava karışımı jet akışkanı enjekte edilerek soğuk akış simülasyonu yapıldı. Bu akışın davranışı, üç boyuta genelleştirilerek ve dönme (swirl) etkisi de göz önüne alınarak incelendi. Türbülanslı akışların sayısal hesabı için türbülans modellerine ihtiyaç duyulmaktadır. Bu çalışmada çeşitli türbülans modellerinin bu akışın simülasyonundaki performansı da incelendi. Girdap etkisini bulmak için bir dizi sayısal çalışma teklif edildi. Sayısal hesaplamalar için üç boyutlu eliptik sonlu-elemanlar kodu ile silindirik koordinatlarda ANSYS CFD Flotran analiz programı kullanıldı. Elde edilen sonuçlar deneysel veya mevcut diğer sonuçlarla karşılaştırıldı ve uyumun iyi olduğu görüldü. For this investigation can be realized firstly, the solution was done in geometry which idealizes combustion chamber was defined three dimensional on cylindrical polar coordinate. We assumed that a turbulent jet mixing in a confined swirling flow environment in the model combustion chamber. The isothermal flow was simulated injecting helium/air as a jet fluid that is located centrally in this flow has also high turbulence intensity. This flow behavior was investigated being generalized in three dimensions and taking into consideration effects of swirl. For numeric calculation of turbulent fluids need turbulence models. In this study was also examined various turbulence models of how is the simulation performance of this flow which is in combustion chamber. Some sequence study was offered to find impression of swirl. For numeric computation was used ANSYS CFD Flotran analysis program with three-dimensional elliptic finite element codes on cylindrical coordinate. Results found were compared with experiment or other available results and indicated good correlations

Acute flaccid myelitis outbreak through 2016-2018: A multicenter experience from Turkey

Aim: We aim to describe the demographic characteristics, etiology, neurophysiology, imaging findings, treatment, prognosis, and prognostic factors of acute flaccid myelitis. Methods: The clinical data, laboratory test and, magnetic resonance imaging (MRI) results of pediatric patients diagnosed with acute flaccid myelitis according to the Centers for Disease Control criteria between August 1, 2016, and December 31, 2018, from 13 centers in Turkey were reviewed. Results: Of the 34 cases identified, 31 were confirmed (91.2%). Eighteen patients (55.9%) were boys. The median patient age was 4 years (interquartile range 2.5–6.9 years). Most of the patients were admitted in 2018 (n = 27). A preceding history of a febrile illness was reported in all patients, with a median of 4 days (interquartile range 3–7 days) before symptom onset. Thirty-one patients had T2 hyperintensity on spinal MRI, and 18 patients had cerebrospinal fluid pleocytosis. The most common infectious agents were entero/rhinoviruses (n = 5) in respiratory specimens. All patients except one received immunotherapy either alone or in combination. Among 27 patients with follow-up data 24 had persistent weakness. Involvement of four limbs together with an abnormal brain MRI at onset were associated with a poor prognosis. Conclusion: The number of patients with acute flaccid myelitis increased since 2012, spiking with every 2-year interval, largely in the pediatric population. The median age decreases with every outbreak. Clinicians should be aware of the clinical picture for early collection of specimens and early start of rehabilitation programs. Further studies are needed to better characterize the etiology, pathogenesis, risk factors, and treatment of this rare condition