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Film Cooling From Two Staggered Holes Rows of Opposite Injection Angles with Downstream Row Embedded In Arc Trench
التبریدالغشائي الناجم من صفي ثقوب متعرجة ذات فتحات نفث متعاكسة مع وضع الصف السفلي في شق قوسي

Authors: Assim H Yousif --- Humam Kareem Jalghaf
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 1 Part (A) Engineering Pages: 1-12
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Experimental investigation of film cooling from two staggered rows holes,backward and forward; of opposite injection angles has been done. The forward holes row was embedded in arc trench. The aim of using arc trench is to enhance the poor mechanical properties of that in rectangular trench. The results of film cooling performance are given here in a form of adiabatic cooling film effectiveness and heattransfer coefficients. In the tests test warm air is blown through tunnel, and cold air through the plenum chamber. When the warm air flowed through the test section it heated the model downstream. Infrared camera is used to measure the model surface temperatures. The comparison with the same holes arrangements and same holes and trench dimensions between existing rectangular trench results and present arc trenchedshowed that the film cooling thermal performance for both cases are approximately very close with slight differences, these differences are more or less according to the values of blowing ratios.


Article
Effect of Coolant Jet Holes Direction on Film Cooling Performance
تأثير اتجاه فتحات البثق البارد على الاداء الحراري لغشاء التبريد

Authors: Assim H. Yousif,.Amer --- M. Al-Dabaghand --- Muwafag Sh. Alwan
Journal: Thi-Qar University Journal for Engineering Sciences مجلة جامعة ذي قار للعلوم الهندسية ISSN: 20759746 Year: 2015 Volume: 6 Issue: 2 Pages: 65-79
Publisher: Thi-Qar University جامعة ذي قار

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Abstract

The film cooling effectiveness and local heat transfer coefficient for coolant jet holes direction (orientation angle), have been investigated. Experimental investigations were done on a flat plate by using a single test transient IR thermograph technique. Evaluation of the cooling performance is obtained by estimated both film cooling effectiveness and heat flux ratios. Three models of coolant jet holes are investigated, each model consists of two rows of holes arranged in a staggered way with different orientation angles. Model (1) downstream row with acute angle and the upstream row with obtuse angle; model (2) both rows with obtuse angles, while model (3) both rows with acute angles. The holes diameter is 4mm, the longitudinal distance between the upstream and downstream rows (X/D) is 4D, and the span distance between two neighboring holes (S/D) is 3D. Three blowing ratios of (BR= 0.5, 1.0, and 1.5) were used in the investigation program. In order to predict the flow behavior numerically for the cases under investigation CFD code is introduced. The numerical investigation shows two large vortices, pair of counter rotating vortex and horseshoe vortices, both vortices have major effects on cooling performance. The experimental results showed that the film cooling effectiveness increases as blowing ratio increases for models (1 and 2), while decreases for model (3), and model (1) provide better performance than the others at high blowing ratios.

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