I roto i te ine wai ahumahi, he wero motuhake ngā wai kapi i ngā matūriki—pērā i te wai para, i ngā paru keri, i te hinu mata me te paru rānei. He maha ngā wā ka raru ngā mita rere tuku iho, pērā i te tāhūhū, i ngā tauira nekehanga pai rānei, ki ēnei wai: ka ārai, ka pakaru, ka poke rānei ngā wāhanga o roto, ka hua ake he wā kore mahi me ngā pānui hē. Heoi, ka whakatauhia tēnei raruraru e ngā mita rere Doppler mā te whakamahi i te pānga Doppler mō te ine pono, kāore e pokanoa, ka waiho hei mea nui i roto i ngā wāhanga e kitea whānuitia ana ngā wai paru, rerekē rānei.
Kei te ngako o te mahi a te mita rere Doppler ko te pānga Doppler, he āhuatanga ā-tinana e huri ai te auau o te ngaru i te nekehanga o te pūtake me te kaimātakitaki tetahi ki tetahi. Mō te ine rere, e rua ngā wāhanga matua o te mita: he ine (e whakanohoia ana ki waho i runga i te paipa) me te tukatuka tohu. Ka tukuna e te ine ngā ngaru ultrasonic auau-teitei (te nuinga o te 0.5 MHz ki te 5 MHz) ki roto i te pakitara paipa; ka haere ēnei ngaru mā roto i te pakitara ka uru ki roto i te wai e rere ana. Ina tūtaki ngā ngaru ki ngā matūriki iri, ngā mirumiru, te pōrearea rānei i roto i te wai, ka whakaatahia anō ki te ine.
Ko te tirohanga nui i konei ko ngā matūriki neke e whakarerekē ana i te auau o ngā ngaru whakaata. Ko ngā matūriki e haere ana i te ahunga o te rere o te wai (ki te transducer) ka pēhi i te ngaru whakaata, ka whakanui ake i tōna auau. I tetahi atu taha, ko ngā matūriki e neke atu ana i te transducer ka totoro i te ngaru, ka whakaiti i tōna auau. Ka tatau te tukatuka tohu i te nekehanga auau i waenga i ngā ngaru kua tukuna me ngā ngaru whakaata, kātahi ka whakamahi i ēnei raraunga—kua honoa ki ngā tawhā kua whakaritea i mua pērā i te diameter o te paipa me ngā āhuatanga o te wai—hei tatau i te tere o te wai, ā, i te mutunga, tōna tere rere. Ka puta katoa tēnei tukanga me te kore e pā te mita ki te wai, e whakararuraru rānei i tōna rere, ka whakakore i te mōrearea o te aukati, te kino rānei o te wāhanga.
Ko te hoahoa kore-whakaeke o ngā mita rere Doppler tētahi o ngā painga tino whai pānga, inā koa mō ngā wai e kī ana i ngā matūriki. Kāore i rite ki ngā mita rere ā-roto e hiahia ana kia tapahia te paipa me te whakauru i ngā wāhanga ki roto i te awa wai, ka whakamahia e ngā tauira Doppler ngā whakawhiti whakapiri e piri tika ana ki waho o te paipa. He maha ngā hāora (ehara i te rā) mō te tāutanga, ā, kāore e hiahiatia he kati tukanga—he painga nui mō ngā ahumahi pēnei i te maimoatanga waipara, ina mutu te rere ka arahi pea ki ngā tārua pūnaha, ki ngā takahi ture rānei. Hei tāpiri, nā te mea kāore he wāhanga o roto, kāore he mōrearea o ngā matūriki kia mau ki roto i ngā takirere, i ngā pūoko rānei, ka whakaiti i ngā utu tiaki me te whakaroa i te roa o te ora o te mita. Hei tauira, i roto i ngā mahi keri, kei reira ngā paru kei roto ngā kohuke whakakoi pēnei i te waro, te rino rānei, ka karohia e ngā mita rere Doppler te kakahu me te haehae ka tere te whakakore i te mita tāpoi.
Ko te tika tētahi atu āhuatanga motuhake o ngā mita rere Doppler hou, ahakoa he uaua ngā wai. I raru ngā tauira o mua ki te tika i roto i ngā awa matūriki iti te kukū, engari nā ngā whanaketanga i roto i te tukatuka tohu—pēnei i te tātari mamati me te whakatikatika ngaru urutau—kua whakatikahia tēnei herenga. Ka taea e ngā mita Doppler o ēnei rā te pupuri i te tika i roto i te ±1% ki te ±3% o te pānui mō ngā wai me ngā kukū matūriki he iti iho i te 10 wāhanga ia miriona (ppm), e pai ai mō ngā tono pēnei i te tukatuka matū, me whai whakaaro ki ngā matūriki iti (hei tauira, ngā paitini whakakorikori). He tino pai hoki rātou ki te ine i ngā tere rere rerekē: he rerekē ki ētahi mita tuku iho e ngaro ana te tika i ngā tere iti, ka taea e ngā tauira Doppler te kite i te rere puhoi tae atu ki te 0.1 mita ia hekona (m/s), he whakaritenga matua mō ngā ahumahi pēnei i te tukatuka kai, kei reira ngā parai matotoru (hei tauira, te whakapiri tōmato, te tiakarete rānei) e rere ana i ngā tere iti.
E whakaatu ana ngā tono o te ao tūturu i te maha o ngā mahi a ngā mita rere Doppler. I roto i te maimoatanga waipara o ngā tāone, ka aroturukihia e rātou te rere o te waipara mata—kī tonu i ngā para me ngā matūriki rauropi—mā roto i ngā paipa, kia pai ai te mahi a ngā tipu maimoatanga. I roto i te umanga hinu me te hau, ka inehia e rātou te rere o te hinu mata kei roto he onepu, he wai rānei, hei āwhina i ngā kaiwhakahaere ki te whai i ngā rahinga whakaputa me te kore e tūpono ki te kino o ngā taputapu utu nui. Ahakoa i roto i ngā taiao ahuwhenua, ka whakamahia hei aroturuki i te rere o ngā paru tongi, kia tika ai te tono ki ngā hua.
Heoi anō, ehara ngā mita rere Doppler i te otinga kotahi-rahi-e pai ana mō te katoa. Me iti rawa te kukū o ngā matūriki (10 ppm, neke atu rānei) hei whakaputa i tētahi tohu e taea ai te whakamahi; mō ngā wai ma pēnei i te wai inu, ngā matū tino-parakore rānei, he pai ake te whiriwhiri i ngā mita rere ultrasonic wā-haere. Hei tāpiri, ka pā pea ngā rauemi paipa me te matotoru ki te tuku tohu—he pai ngā paipa whakarewa (hei tauira, te maitai), engari me whakarerekē pea ngā paipa kirihou matotoru ki te whakatakotoranga o te transducer. Engari mō ngā wai e kī ana i ngā matūriki, nā te hoahoa kore-whakaeke me te tika o aua mea kāore e taea te whakataurite.
Hei whakamutunga, kua hurihia e ngā mita rere Doppler te ine i ngā wai e kapi ana i ngā matūriki mā te huri i tētahi wero—ngā awa paru, rerekē—hei kaha. Mā te whakamahi i te pānga Doppler, ka tukuna e rātou he raraunga tika, pono hoki, me te kore e whakararuraru i ngā tukanga, e tūpono rānei ki te kino o ngā wāhanga. I te mea kei te whakahaere tonu ngā ahumahi i ngā wai uaua, ka tipu haere te tūranga o ngā mita rere Doppler ki te whakarite i te whai huatanga, te tutuki i ngā whakaritenga, me te penapena utu, ka whakapūmau i tō rātou tūranga hei taputapu nui i roto i te whakahaere wai hou.
Wā tuku: Hepetema-25-2025