Yuav Ua Li Cas Lub Tube Ovality (0.5% Vs. 2%) Ntawm Titanium Sheath Heater Tom Qab Khoov cuam tshuam rau Lub Chaw Kub Kub Flux Distribution thiab Lub Sij Hawm Ua Rau Cov Kub Kub Kub Npuas Ncauj Thaum Khoov apex?
Tso lus
Tube ovality tom qab khoov- qhov sib txawv ntawm qhov sib txawv ntawm lub voj voog zoo meej - ntu - tsom rau cov cua sov ntawm qhov khoov apex. Cov ovality siab dua (2% vs. 0.5%) ua rau cov cua sov hauv zos nce los ntawm 10-25% vim txo cov phab ntsa tuab ntawm lub vojvoog sab nraud. Cov cua kub ntau dua nce qhov kub hauv zos los ntawm 10-25 degree, ua kom lub thermal qaug zog tawg. Ovality ntawm 0.5% yog siv tau rau feem ntau daim ntawv thov, thaum ovality ntawm 2% txo lub sij hawm incubation rau thermal qaug zog tawg los ntawm 50-70%. Qhov khoov apex yog qhov chaw muaj kev phom sij tshaj plaws vim nws tau ntsib ob qho tib si ovality siab tshaj plaws thiab qhov siab tshaj qhov seem ntawm kev khoov.
Lub Mechanism ntawm Ovality-Induced Heat Flux Concentration
Thaum lub raj yog khoov, lub vojvoog sab nraud (extrados) ntsib phab ntsa nyias, thaum lub vojvoog sab hauv (intrados) ntsib phab ntsa tuab. Cov phab ntsa hauv zos ntawm qhov khoov apex tuaj yeem suav ua t_apex=t_nominal × (1 - 0.5 × ovality). Rau lub nominal 1.5 hli phab ntsa nrog 2% ovality, qhov tsawg kawg nkaus phab ntsa thickness ntawm lub apex yog 1.38-1.41 hli. Lub tshav kub hauv zos yog inversely proportional rau phab ntsa thickness: q_apex / q_nominal=t_nominal / t_apex. Lub zos kub nce yog ΔT_apex=q_apex × t_apex / k. Kev sib xyaw ua ke ntawm txo cov thickness thiab nce flux tsim qhov kub ntawm qhov khoov apex.
Quantitative Ovality, Thaum tshav kub kub Flux, thiab kub nce
Rau 20 hli OD raj nrog nominal 1.5 hli phab ntsa thiab 5D khoov vojvoog ntawm lub nominal kub flux ntawm 20 W / cm², cov kev sib raug zoo hauv qab no tau tsim. Ntawm 0% ovality (zoo meej raj), qhov tsawg kawg nkaus phab ntsa ntawm khoov apex yog 1.50 hli, lub zos tshav kub flux nce yog 0%, thiab qhov kub ntawm lub apex saum toj no ncaj seem yog 0 degree. Ntawm 0.5% ovality, 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. Ntawm 1.0% ovality, qhov tsawg kawg nkaus phab ntsa yog 1.44-1.47 hli, qhov nce yog 5-10%, thiab kub nce yog 5-10 degree. Ntawm 1.5% ovality, qhov tsawg kawg nkaus phab ntsa yog 1.41-1.44 hli, qhov nce yog 10-15%, thiab qhov kub siab yog 10-15 degree. Ntawm 2.0% ovality, qhov tsawg kawg nkaus phab ntsa yog 1.38-1.41 hli, qhov nce yog 15-25%, thiab qhov kub siab yog 15-25 degree. Ntawm 3.0% ovality, qhov tsawg kawg nkaus phab ntsa yog 1.32-1.36 hli, qhov nce yog 25-40%, thiab kub nce yog 25-40 degree.
Thermal Fatigue Incubation Lub Sijhawm Ua Haujlwm ntawm Ovality
Cyclic testing nrog kub viav vias ntawm 100℃(50℃rau 150 degree) dhau 10,000 cycles tau tsim cov voj voog hauv qab no kom tawg pib rau Qib 2 titanium. Ntawm 0.5% ovality, lub voj voog mus rau qhov pib tawg yog 8,000-12,000, thiab lub sij hawm incubation txo qis rau 0% ovality yog lub hauv paus. Ntawm 1.0% ovality, lub voj voog yog 5,000-8,000, thiab qhov txo qis yog 30-40%. Ntawm 1.5% ovality, lub voj voog yog 3,000-5,000, thiab qhov txo qis yog 50-60%. Ntawm 2.0% ovality, lub voj voog yog 2,000-3,500, thiab qhov txo qis yog 65-70%. Ntawm 3.0% ovality, lub voj voog yog 1,000-2,000, thiab qhov txo qis yog 80-85%.
Ovality Control and Bending Method Guide
Cov lus hauv qab no muab qhov siab tshaj plaws ovality rau titanium sheath heaters raws li kev xav tau thermal cycles thiab cov kev pom zoo khoov txoj kev.
| Cia siab Thermal Cycles over Service Life | Maximum tso cai Ovality (%) | Pom zoo txoj kev khoov | Cia siab tias yuav mus Crack Initiation |
|---|---|---|---|
| <1,000 (low cycle) | 2.0 | Compression dabtsi yog khoov | >1,000 |
| 1,000-5,000 (mob nruab nrab voj voog) | 1.5 | Mandrel khoov | 3,000–5,000 |
| 5,000-20,000 (Hloov voj voog) | 1.0 | Mandrel + kev txhawb nqa sab hauv | 5,000–8,000 |
| 20,000-50,000 (hloov siab heev) | 0.5 | Rotary kos duab khoov | 8,000–12,000 |
| >50,000 (lub voj voog loj heev) | <0.5 | Rotary kos + mandrel | >12,000 |
Engineering Beyond Ovality Control
Qib titanium cuam tshuam rau thermal qaug zog tiv thaiv. Qib 7 muaj qhov rhiab heev rau ovality tab sis siab zog intrinsic qaug zog, nce mus rau tawg pib los ntawm 20-30% rau tib ovality. Qib 12 muaj kev txhim kho nruab nrab. Phab ntsa thickness cuam tshuam lub nominal kub nce; phab ntsa tuab (2.0 hli) muaj lub hauv paus siab dua ΔT tab sis tus txheeb ze nce los ntawm ovality yog me dua. Lub vojvoog khoov kuj cuam tshuam ovality; lub vojvoog khoov loj (10D) tsim cov ovality tsawg dua li qhov khoov nruj (3D). Ncej- khoov kev ntxhov siab rau kev ntxhov siab ntawm 540℃rau 30 feeb txo qis kev ntxhov siab tab sis tsis kho ovality.
Ua ib qho kev qhia tshwj xeeb
For a titanium sheath heater with a bent section that will experience more than 5,000 thermal cycles, specify a maximum ovality of 1.0%. Require mandrel bending with internal support to achieve this ovality. Measure ovality at the bend apex using an optical comparator or a set of calipers at four angles. For high-cycle applications (>20,000 cycles), qhia 0.5% ovality thiab rotary kos dabtsi yog khoov. Rau cov cua sov uas twb muaj lawm nrog ovality tshaj 1.5%, txo cov cua sov los ntawm 20% los them rau qhov chaw kub, lossis nruab ib lub tshuab hluav taws xob. Los ntawm kev tswj ovality qis dua 1.0%, tus kws tshaj lij tswj xyuas cov khoom siv hluav taws xob sib txawv thiab txuas ntxiv lub neej thermal qaug zog ntawm qhov khoov apex.
