Studi Eksperimen Pengaruh Variasi Jarak Inlet Disturbance Body Terhadap Aliran Melalui Square Duct Dengan Elbow 90°

Firriisqiia, Aqfha Hardhian Sandhityawan (2017) Studi Eksperimen Pengaruh Variasi Jarak Inlet Disturbance Body Terhadap Aliran Melalui Square Duct Dengan Elbow 90°. Undergraduate thesis, INSTITUT TEKNOLOGI SEPULUH NOPEMBER.

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Abstract

Instalasi-instalasi saluran fluida tidak hanya menggunakan sistem perpipaan dengan pipa lurus, melainkan dapat juga menggunakan pembelokan aliran, penggabungan aliran, ataupun percabangan aliran. Hal tersebut sering kita sebut dengan istilah fitting perpipaan. Salah satu penggunaan fitting perpipaan adalah dengan menggunakan elbow 90°. Pemasangan fitting perpipaan ini akan membuat aliran di dalam elbow mengalami pressure drop yang lebih besar karena adanya friction loss, separation loss, dan secondary flow yang terjadi setelah melewati aksesoris tersebut. Salah satu usaha untuk mengurangi pressure drop yang terjadi di dalam elbow 90° adalah menambahkan sebuah bodi pengganggu silinder Inlet Disturbance Body (IDB). Penelitian ini dilakukan secara eksperimen dengan model saluran berpenampang bujursangkar (square duct) dengan diameter hidrolis (Dh = 125 mm) yang terdiri dari : upstream duct (straight duct) dengan panjang (l = 7Dh), Inlet Disturbance Body (IDB) dengan diameter (D = 12,5 mm), elbow 90° dengan rasio kelengkungan (R/Dh = 1,5), dan dilengkapi downstream duct (straight duct) dengan panjang (l = 15Dh), serta induced draft fan. Pengukuran dalam penelitian ini menggunakan pitot static tube, inclined manometer, dan pressure transducer. Pengujian dilakukan dengan variasi jarak (l/Dh = 0,1 - 0,5); dan gap konstan (g/D = 0,2) dengan ReDh sebesar 8,74x104 untuk mendapatkan profil kecepatan sepanjang downstream duct, pressure drop antara downstream duct dan upstream duct, serta pressure drop elbow 90° antara inlet elbow 90° dan outlet elbow 90° berupa nilai pressure coefficient, koefisien loss minor elbow 90° pada variasi nilai ReDh sebesar 3,97x104 < ReDh < 13,5x104. Hasil studi eksperimen ini diperoleh bahwa penempatan IDB efektif untuk proses recovery aliran dan menanggulangi timbulnya secondary flow. Penempatan IDB pada saluran dengan jarak l = 0,1Dh merupakan jarak paling efektif untuk meningkatkan intensitas turbulensi dan menurunkan pressure drop, dimana pada sisi inner outlet elbow 90° memiliki intensitas turbulensi tertinggi yaitu sebesar 30,92%, sedangkan nilai intensitas turbulensi terendah terjadi pada saluran yang menggunakan IDB dengan jarak l = 0,5Dh yaitu sebesar 8,07%. Saluran dengan IDB l = 0,1Dh juga memiliki pressure drop terendah dengan persentase penurunan nilai pressure drop sebesar 17,68% terhadap saluran tanpa IDB, sedangkan pada jarak IDB l = 0,5Dh memiliki pressure drop tertinggi. Secara fungsi Reynolds Number, jarak IDB l = 0,1Dh memiliki nilai koefisien losses elbow 90º paling rendah dengan dengan persentase penurunan koefisien losses elbow 90º sebesar 9,74% terhadap saluran tanpa IDB, sedangkan pada variasi tanpa menggunakan IDB memiliki nilai koefisien losses elbow 90º paling tinggi. Perbedaan nilai Pressure Coefficient (ΔCp) yang cukup signifikan pada elbow 90º dengan saluran tanpa IDB dan menggunakan IDB, dimana didapatkan bahwa ΔCp pada jarak IDB l = 0,1Dh terlihat lebih kecil dibandingkan pada jarak l = 0,5Dh maupun tanpa menggunakan IDB. =================================================================================================== Many installations of the ducting system are not only use the piping system with straight duct, but it also use to turning the flow, clustering the flow, or divide the flow. It usually called fitting system. One of the using on fitting system is the using of elbow 90°. Installation of fitting system will makes the flow inside elbow 90° consist excess of pressure drop, it caused by the presence of friction loss, separation loss, and secondary flow that occurs after through the accesories. One of the effort to reduce the pressure drop inside elbow 90° is add a body disturbance called Inlet Disturbance Body (IDB). This research did as an experimental investigation with square duct with hydraulic diameter (Dh= 125 mm) that consist of : upstream duct (straight duct) with length (l = 7Dh), Inlet Disturbance Body (IDB) with diameter (D = 12,5 mm), elbow 90° with curvature ratio (R/Dh= 1,5), and featured by downstream duct (straight duct) with length (l = 15Dh), also an induced draft fan. The measurements of this experiment use pitot statis tube, inclined manometer, and pressure transducer. This experiment did with distance variant (l/Dh = 0,1 - 0,5) and constant gap (g/D = 0,2) with ReDh 8,74x104 to obtain the velocity profi le along downstream duct, pressure drop between downstream duct and upstream duct, also pressure drop elbow 90° between inlet elbow 90° and outlet elbow 90° in the value of pressure coefficient (Cp), minor losses coefficient of elbow 90° with ReDh variant 3,97x104 < ReDh < 13,5x104. The results of this experimental study shows that the placement of IDB is effective to recovery process and reduce secondary flow. The placement of IDB in the duct with distance variant l = 0,1Dh is most effective to increase the turbulent intensity and reduce the pressure drop, which in the inner outlet elbow 90° has highest turbulent intensity with percentage 30,92%, whereas the lowest turbulent intensity occurs in the duct with distance variant l = 0,5Dh with percentage 8,07%. Duct with distance variant l = 0,1Dh also has the lowest pressure drop with percentage of reducing pressure drop 17,68% toward the duct without IDB, whereas in the duct with distance variant l =0,5Dh has the highest pressure drop. Based on the function of Reynolds Number, duct with distance variant l =0,1Dh has lowest minor losses coefficient of elbow 90° with percentage of reducing minor losses coefficient of elbow 90° 9,74% toward the duct without IDB, whereas in the duct without using IDB has the highest minor losses coefficient of elbow 90°. The difference of Pressure Coefficient (ΔCp) between duct using IDB and duct without using IDB on elbow 90° showns significant enough, which has obtained that ΔC pin the duct with IDB l = 0,1Dh seems smaller than distance variant l = 0,5Dh and without IDB

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: Inlet Disturbance Body (IDB); Profil Kecepatan; Pressure Drop; Square Duct; Elbow 90°
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Faculty of Industrial Technology > Mechanical Engineering
Depositing User: - AQFHA HARDHIAN SANDHITYAWAN FIRRIISQIIA
Date Deposited: 30 Mar 2017 01:41
Last Modified: 30 Mar 2017 01:41
URI: https://repository.its.ac.id/id/eprint/2426

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