Daimi ve Sıkıştırılamaz Boru Akışında Giriş Uzunluğunun Sayısal Analizi

Yıl 2018, Cilt: 8 Sayı: 2/2, 1 - 12, 27.12.2018

Hasan Düz

Öz

Dairesel boru akışlarında, viskoz etkiler sonucu boru girişinden itibaren akış önce gelişir ve sonra tam gelişmiş akış olur. Kayma gerilmesi, hız profili ve türbülans akış istatistikleri gibi akış özellikleri gelişen akışta değişirken tam gelişmiş akışta ise bunlar değişmez olur. Bu nedenle tam gelişmiş boru akışları çeşitli ampirik bağıntılarla çözüm bulurken gelişen boru akışları hala tam olarak çözülebilmiş değildir. Boru girişinden itibaren tam gelişmiş akış oluşuncaya kadar ölçülen mesafeye giriş uzunluğu denir. Özellikle ısıtma ve soğutma gibi kısa borulu ısı transfer işlemlerinde giriş uzunluğunun bilinmesi basınç kayıplarının hesaplanması için oldukça önemlidir. Bu nedenle bu çalışmada daimi ve borulu su akışlarında giriş uzunluğu, farklı boru çapı, pürüzlülüklerinde ve 2000-25000 aralığındaki Reynolds sayılarında sayısal çözümle araştırılmıştır. Analizler sonucunda boyutsuz giriş uzunluğu için sayısal verilerle uyumlu sayısal bir bağıntı önerilmiştir.

Anahtar Kelimeler

giriş uzunluğu, boru akışı, sayısal boru akışı

Numverical Analysis of Entrance Length in Steady and Incompressible Pipe Flow

Öz

In circular pipe flows, due to viscous effects the flow develops first from pipe inlet then becomes a fully developed
flow. Flow characteristics such as shear stress, velocity profile and turbulence flow statistics while change in the
developing flow, they do not change in the fully developed flow. Therefore, while the fully developed pipe flows
find solutions with various empirical relations, the developing pipe flows is still not fully solved. The distance
measured from the pipe inlet until the fully developed flow exists is called the entrance length. Especially in shortpipe heat transfer processes such as heating and cooling, to know the entrance length is very important to
determine the pressure losses. Therefore, in this study, the entrance length were investigated with numerical
solution across different pipe diameters, roughnesses and Reynolds numbers ranging from 2000 to 25000 in the
steady and tubular water flows. As a result of the analysis, a numerical correlation was proposed for the
dimensionless entry length which was well agree with the numerical data

Anahtar Kelimeler

entrance length, pipe flow, numerical pipe flow

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