Teeb meem Vibration
PTFE tshav kub exchanger raj yog hloov tau. Lawv qhov qis elastic modulus (0.5 GPa vs . 200 GPa rau steel) txhais tau tias lawv deflect ntau dua nyob rau hauv ib tug muab load thiab muaj qis dua ntuj frequencies dua hlau raj ntawm tib qhov ntev. Qhov qis dua ntuj zaus coj lawv los ze zog rau cov excitation frequencies uas muaj nyob rau hauv cov txheej txheem tso tsheb hlau luam -agitator hniav- dhau zaus (2-}10 Hz), twj tso kua mis vane-dhau zaus (20-100 Hz), thiab ntws turbulence (broadband).
Yog hais tias lub raj lub ntuj zaus coincides nrog ib tug excitation zaus, resonance tshwm sim. Lub raj vibrates nrog loj amplitude, cuam tshuam cov hlab uas nyob ib sab los yog hnav ntawm lub phaj txhawb cov ntsiab lus. Lub vibration ua kom qaug zog puas tsuaj thiab tuaj yeem ua rau lub raj tsis ua haujlwm ntxov ntxov.
Tus naj npawb ntawm cov paib txhawb nqa - uas txiav txim siab qhov tsis txhawb nqa ntev ntawm kev txhawb nqa - yog tus qauv tsim qauv hloov pauv tswj lub raj ntau zaus. Kev txhawb nqa ntau dua txhais tau tias luv luv, ntau dua ntuj zaus, thiab tsawg dua kev pheej hmoo ntawm resonance.
Natural Frequency Calculation
Lub ntuj zaus ntawm ib qho -span tube ntawm ob qho kev txhawb nqa yog: f_n=(π / 2L²) × √(EI / m), qhov twg L yog qhov ntev ntawm kev txhawb nqa, E yog lub flexural modulus ntawm PTFE ntawm qhov kev ua haujlwm kub, Kuv yog thaj tsam lub sij hawm ntawm inertia ntawm lub raj hla lub raj ({4}) yog qhov ntev ntawm qhov sib txawv muaj chav / condensate).
Qhov zaus yog inversely proportional rau lub square ntawm qhov ntev. Halving lub ncua ntev (ob npaug ntawm tus naj npawb ntawm kev txhawb nqa) quadruples lub ntuj zaus. Qhov kev vam khom muaj zog no ua rau kev txhawb nqa qhov sib txawv ntawm cov cuab yeej tsim tau zoo tshaj plaws rau kev tswj kev vibration.
Rau 10 hli OD × 1 hli phab ntsa PTFE raj ntawm 80℃(E ≈ 300 MPa), lub ntuj zaus rau ntau qhov ntev yog:
| Qhov ntev (mm) | Tus naj npawb ntawm kev txhawb nqa (3m raj) | Ntuj zaus (Hz) |
|---|---|---|
| 1,500 | 1 (kev txhawb nqa kawg nkaus xwb) | 2.5 |
| 750 | 3 | 10 |
| 500 | 5 | 22.5 |
| 375 | 7 | 40 |
| 300 | 9 | 62.5 |
| 250 | 11 | 90 |
Txoj Kev Tiv Thaiv Kev Tiv Thaiv Resonance
Txhawm rau kom tsis txhob muaj suab nrov, lub raj lub cev yuav tsum muaj tsawg kawg yog 20% siab tshaj qhov xav tau siab tshaj plaws, lossis tsawg kawg 20% hauv qab qhov qis tshaj qhov xav tau excitation zaus. Rau ib tug raug agitated tank nrog ib tug agitator hniav-dav zaus ntawm 3-8 Hz thiab twj tso kua mis zaus ntawm 40-60 Hz, lub raj ntuj zaus yuav tsum yog qis dua 2.4 Hz (impractical rau feem ntau spans) los yog siab dua 72 Hz.
Ua kom tau raws li qhov ntau zaus ntawm 72 Hz yuav tsum muaj qhov ntev ntawm kwv yees li 280mm lossis tsawg dua -xws li 10 daim phiaj rau lub raj 3-meter. Qhov no yog ib tug conservative tsim uas muab kev tiv thaiv rau txhua yam excitation qhov chaw.
Yog hais tias lub agitator thiab twj tso kua mis zaus yog zoo -tus yam ntxwv thiab tswj, ib tug tsawg conservative tsim yuav tau txais. Ib ntu ntawm 375mm (7 kev txhawb nqa, ntuj zaus 40 Hz) yog qhov tsim nyog yog tias tus agitator ua haujlwm qis dua 32 Hz thiab lub twj tso kua mis qis dua 32 Hz (tsis zoo rau cov twj).
Txoj Kev Pabcuam Tswvcuab txwv
Txhua lub phaj txhawb nqa ntxiv tus nqi, tuav lub ntim ntim, thiab ua kom lub siab poob ntawm lub plhaub sab. Nws muaj kev txwv rau tus naj npawb ntawm kev txhawb nqa. Rau feem ntau daim ntawv thov, 5-9 cov ntawv txhawb nqa rau lub raj 3-meter (ntev 300-500mm) muab kev co txaus tsis muaj nqi ntau. Tus naj npawb raug txiav txim los ntawm qhov tshwj xeeb excitation ib puag ncig.
Cov ntsiab lus
The number of support plates determines the tube natural frequency, which must be separated from the excitation frequencies to avoid destructive resonance. A span length of 280mm or less (natural frequency >72 Hz) muab kev tiv thaiv rau feem ntau qhov chaw ua haujlwm excitation. Kev txhawb nqa phaj suav yog qhov tsim qauv tseem ceeb rau PTFE cov khoom siv hluav taws xob hloov pauv kev ntseeg tau hauv kev ntxhov siab lossis lub tshuab nqus dej.
Kev txhawb nqa engineering rau PTFE tube pob kev vibration tsom xam muaj nyob rau ntawm kev xa cov raj qhov ntev, raj ntev, agitator thiab twj tso kua mis specifications, thiab kev khiav hauj lwm kub.
