Manyetik Alan Altinda Nanoakişkanlarin Akiş Karakteristiklerinin İncelenmesi

Year 2022, Volume: 25 Issue: 3, 1309 - 1317, 01.10.2022

Zeynep Aytaç

https://doi.org/10.2339/politeknik.1147953

Abstract

Uydu soğutma uygulamalarında olduğu gibi, harici olarak indüklenen bir manyetik alanın varlığı/uygulanması, nanoakışkanlarla kullanıldığında ısı transferinde bir azalmaya neden olur. Sunulan çalışma, laminar rejim altında dış bir manyetik alana maruz kalan su, alumina nanoakışkanı ve kobalt ferrit nanoakışkanının akış davranışlarını ve hız profillerini incelemektedir. Analizler ANSYS Fluent MHD modülü kullanılarak gerçekleştirilmiştir. Nanoakışkanların konsantrasyonları %2, Reynolds sayısı 10, ve Hartmann sayısı da 25, 50, ve 150 olarak alınmıştır. Hız profilleri ve akış karakteristikleri, manyetik alan büyüklüğü dışındaki tüm değişkenler sabit tutularak incelenmiştir. Sonuç olarak, dış bir manyetik alan uygulamasının nanoakışkanların, özellikle de kobalt ferrit nanoakışkanının, hız profillerinde bozulmaya sebep olduğu, ancak su üzerinde kritik bir etkisinin bulunmadığı görülmüştür. Manyetik alan büyüklüğü 2 katına çıkarıldığında akışkan hızının %6 azaldığı, 0 Tesla olan manyetik alan büyüklüğü 50 Tesla’ya çıkarıldığında ise akışkan hızının %9 azaldığı görülmüştür. Bu doğrultuda, manyetik alan büyüklüğünü artırmanın etkisinin, manyetik alanı ilk kez uygulamanın etkisinden daha az olduğu saptanmıştır. Ayrıca, 50 Tesla için kıyaslama yapıldığında, elde edilen maksimum hızın alumina nanoakışkanı için suyunkinden %5.1, kobalt ferrit nanoakışkanı için de %28.57 daha az olduğu görülmüştür.

Keywords

Nanoakışkan, manyetik nanoakışkan, manyetohidrodinamik, hesaplamalı akışkanlar dinamiği.

The Investigation of Flow Characteristics in Nanofluids Under Magnetic Field

Abstract

The existence/application of an externally induced magnetic field, like in satellite cooling applications, causes a decrement in heat transfer when used with nanofluids. This study investigates the flow characteristics and velocity profile of distilled water, alumina nanofluid, and cobalt ferrite ferrofluid in a horizontal cylindrical heat pipe flowing in a laminar regime and being exposed to an external magnetic field. All of the simulations were performed with ANSYS Fluent MHD module, for a concentration of 2%, Reynolds number of 10, and Hartmann numbers of 25, 50, and 150. The velocity profiles, pressure drops, and flow characteristics are examined by varying the magnetic field intensity while keeping all other parameters constant. It is concluded that an external magnetic field causes a deterioration in the velocity profiles of the nanofluid, especially in cobalt ferrite, while it does not have a significant effect on water. When the magnitude of the magnetic field is increased by 2 times, it is seen that the velocity of the fluid decreases by 6% and increasing the magnetic field from 0 to 50 Tesla causes a deceleration rate of 9%, which leads to the conclusion that application of a magnetic field for the first time has a more significant slowing effect when comparing it to increasing the magnetic field. In addition, when a magnetic field of 50 Tesla is considered, the maximum velocity of alumina is lower than that of water by 5.10%, and the maximum velocity of cobalt ferrite is lower by 28.57%.

Keywords

Nanofluid, ferrofluid, magnetohydrodynamics, computational fluid dynamics.

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