Yuav Ua Li Cas Lub Tube Ovality (0.5% vs. 2%) ntawm Titanium Sheath rhaub tom qab khoov cuam tshuam rau lub tshav kub Flux Distribution thiab lub sij hawm incubation rau Thermal Fatigue Cracking ntawm Khoov Apex?

Tube ovality tom qab khoov - qhov kev hloov pauv los ntawm qhov sib thooj tag nrho -section – concentrates heat flux ntawm qhov khoov apex. Qhov siab dua ovality (2% piv rau 0.5%) ua rau 10-25% nce hauv cov cua sov hauv zos vim yog cov phab ntsa me me ntawm lub vojvoog sab nraud. Cov cua kub ntau dua ua rau qhov kub thiab txias hauv zos los ntawm 10-25 degree, thiab li no txhim kho thermal qaug zog tawg. Ovality ntawm 0.5% yog siv tau rau feem ntau daim ntawv thov. Ovality ntawm 2% txo qis lub sij hawm incubation rau thermal qaug zog tawg los ntawm 50-70%. Qhov khoov apex yog thaj chaw uas muaj kev phom sij tshaj plaws vim nws muaj qhov siab tshaj plaws ovality thiab feem ntau seem seem ntawm kev khoov.

Mechanism ntawm ovality induced heat flux concentration

Thaum lub raj yog khoov, phab ntsa ua nyias ntawm lub vojvoog sab nraud (extrados) thiab thicker ntawm sab hauv vojvoog (intrados). Lub zos phab ntsa tuab ntawm khoov apex tuaj yeem suav ua t_apex=t_nominal x (1-0.5xovalitiy). Rau lub nominal 1.5 hli phab ntsa nrog ib tug ovality ntawm 2%, qhov tsawg kawg nkaus phab ntsa thickness ntawm lub apex yog 1.38-1.41 hli. Cov cua sov hauv zos yog qhov sib npaug ntawm cov phab ntsa tuab: qapex / qnominal=tnominal / tapex. Qhov kub nce hauv zos yog ∆Tapex=qapextapex/k. Kev sib xyaw ua ke ntawm qis thickness thiab siab dua flux tsim ib qho chaw kub nyob ze ntawm lub apex ntawm qhov nkhaus.

Quantitative Heat Flux, Kub nce, thiab Ovality

Cov kev sib raug zoo hauv qab no tau tsim los rau 20 hli OD raj nrog nominal 1.5 hli phab ntsa thiab 5D khoov vojvoog ntawm nominal kub flux ntawm 20 W / cm². Rau 0% ovality (zoo tagnrho raj) qhov tsawg kawg nkaus phab ntsa ntawm qhov khoov apex yog 1.50mm, lub zos kub ntws nce yog 0% thiab qhov kub siab ntawm lub apex nrog rau qhov ncaj seem yog 0 degree. Lub ovality yog 0.5%, qhov tsawg kawg nkaus phab ntsa yog 1.47-1.49 hli, lub tshav kub flux nce yog 2-5%, thiab kub nce yog 2-5 degree. Rau ovality 1.0%, qhov tsawg kawg nkaus phab ntsa 1.44-1.47 hli, nce 5-10%, kub nce 5-10℃. 1.5% ovality yam tsawg phab ntsa yog 1.41-1.44 hli, qhov nce yog 10-15%, thiab kub nce yog 10-15 degree. Ntawm 2.0% ovality qhov tsawg kawg nkaus phab ntsa yog 1.38-1.41 hli Nce yog 15-25% Kub nce yog 15-25 degree. Ntawm 3.0% ovality yam tsawg kawg nkaus phab ntsa yog 1.32-1.36 hli, nce yog 25-40%, kub nce yog 25-40 degree.

Ovality Dependence ntawm Thermal Fatigue Incubation Time

Cyclic testing nrog kub viav vias ntawm 100℃(50℃mus rau 150 degree) tshaj 10,000 cycles tau qhia cov voj voog hauv qab no kom tawg pib rau Qib 2 titanium: Rau ovality ntawm 0.5%, tus naj npawb ntawm cov voj voog mus rau tawg yog 8,000-12,000 induction lub sij hawm induction. ovality yog 1.0%. Lub voj voog yog 5,000-8,000. Qhov txo qis yog 30-40% . 3,000-5,000 cycles ntawm 1.5% ovality thiab 50-60% txo. 2.0% ovality, 2,000-3,500 cycles, 65-70% txo. Cycles 1,000-2, 000. 3.0% ovality. Txo 80-85%

Cov Lus Qhia ntawm Txoj Kev Khoov thiab Ovality Control

Cov lus hauv qab no qhia txog qhov siab tshaj plaws ovality rau titanium sheath heaters rau qhov xav tau thermal cycles thiab pom zoo txoj kev khoov.

Qhov siab tshaj plaws uas tau tso cai Ovality (%) Xav Tau Thermal Cycles dhau Kev Pabcuam Lub Neej Pom Zoo Khoov Txoj Kev Cia Siab Rau Kev Ua Haujlwm Ua Haujlwm<1,000 (low cycle) 2.0 Compression bending >1,000 1,000–5,000 (moderate cycle) 1.5 Mandrel bending 3,000–5,000 5,000–20,000 (high cycle) 1.0 Mandrel + internal support 5,000–8,000 20,000–50,000 (very high cycle) 0.5 Rotary draw bending 8,000–12,000 >50,000 (lub voj voog loj heev)<0.5 Rotary draw + mandrel >12,000
Engineering Beyond Ovoidity Control

Qhov zoo ntawm titanium cuam tshuam cov thermal qaug zog tsis kam. Qib 7 nthuav tawm qhov sib piv rhiab heev rau ovality tab sis muaj zog dua intrinsic qaug zog, uas ua rau nce 20-30% nyob rau hauv cycles rau tawg pib rau tib ovality. Qib 12 yog kev txhim kho nruab nrab. Lub thickness ntawm phab ntsa hloov lub nominal kub nce. Phab ntsa tuab (2.0 hli) muaj qhov loj dua ΔT tab sis tus txheeb ze nce vim ovality me dua. Lub vojvoog khoov kuj cuam tshuam rau ovality, lub vojvoog khoov loj (10D) yuav muaj ovality tsawg dua li qhov khoov nruj (3D). Tom qab khoov khoov kev ntxhov siab anneal ntawm 540℃rau 30 min txo qis kev ntxhov siab tab sis tsis kho ovality

Sau Cov Lus Qhia Tshwj Xeeb

3. Specify a maximum ovality of 1.0% for a titanium sheath heater with a bent section that will be subjected to more than 5,000 thermal cycles. This ovality has to be bent on a mandrel with internal support. Using a set of calipers or an optical comparator, measure the ovality at the bend apex at four angles. For high cycle applications (>20,000 cycles) muab 0.5% ovality thiab rotary kos dabtsi yog khoov. Rau cov cua sov uas twb muaj lawm nrog lub ovality ntau dua 1.5%, txo cov cua sov los ntawm 20% los kho qhov chaw kub los yog tsim kom muaj cua sov. Ib homogeneous heat flux faib thiab txuas ntxiv thermal qaug zog lub neej ntawm qhov khoov apex tau ua tiav nrog ovality tswj <1.0%.