Numerical modeling of gas-liquid flows in a swirl nozzle

Erkki Laurila

Numerical modeling of gas-liquid flows in a swirl nozzle

Julkaisun otsikon käännös: Neste-kaasuvirtausten numeerinen mallintaminen pyörresuuttimessa

Erkki Laurila

Energia- ja konetekniikan laitos

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Tämä väitöskirja lukeutuu virtausmekaniikan tutkimusalaan. Työssä tutkitaan teollista ruiskutus- ja pisaroitumisprosessia laskennallisen virtausmekaniikan (CFD) menetelmin. Ruiskutuksessa esiintyvät kaksifaasivirtaukset mallinnetaan käyttäen hyväksi nestepinnan tarkan ratkaisun mahdollistavaa VOF-nestetilavuusmenetelmää. Uusiutuvien biomassapohjaisten polttoaineiden motivoimana työssä keskitytään korkean viskositeetin nesteisiin. Kyseisissä sovelluksissa polttoaineen pisaroituminen ja pisaroiden koko liittyy läheisesti palamisprosessin tehokkuuteen. Tarkemmin sanoen työssä tutkitaan nesteen ruiskutusta suurikokoisesta ja epäsymmetrisestä pyörresuuttimesta eri operointiolosuhteissa. Pyörresuuttimiin liittyvä aikaisempi tutkimus on keskittynyt lähinnä pienikokoisiin ja symmetrisiin suuttimiin. Sekä suuttimen sisäisiä virtausominaisuuksia että syntyvän nestekalvon hajoamista tutkitaan yksityiskohtaisilla numeerisilla simulaatioilla. Julkaisut I ja II keskittyvät matalan Reynoldsin luvun alueen (420 ≤ Re ≤ 5300) tarkasteluun. Kyseisellä parametrialueella suuttimen virtausominaisuuksista ja pääruiskutusparametreistä ei tähän asti ole ollut täyttä kokonaiskuvaa. Lisäksi julkaisussa II numeerisia tuloksia verrataan kokeellisiin tuloksiin. Julkaisussa III suutinvirtausta tutkitaan liittyen ruiskutustapauksiin, missä suuttimen sisällä on tilavuudeltaan merkittävä määrä kaasukuplia. Kyseisiä virtausolosuhteita ei ole aiemmin systemaattisesti tutkittu pyörresuuttimiin liittyen ja käyttäen numeerisia menetelmiä. Työn uutuusarvo syntyy korkean resoluution simulaatioiden soveltamisesta suurikokoisen pyörresuuttimeen tutkimiseen. Työn päätulokset ovat seuraavat. (1) Suuttimen sisäisen virtauksen rakenne ja virtausominaisuudet selitetään yksityiskohtaisesti. (2) Suuttimen ulkopuolelle muodostuvan nestekalvon ominaisuuksia tarkastellaan ja havaitut suihkutyypit luokitellaan Reynoldsin luvun funktiona. (3) Kaasukuplien vaikutusta suuttimen sisäiseen virtaukseen ja nestekalvon käyttäytymiseen tarkastellaan. Tämän ohella raportoidaan suuttimen pääruiskutusparametrit, kuten avautumiskulmat, purkauskerroin ja nestekalvon nopeus. Lisäksi työssä käytetyn numeerisen ratkaisumenetelmän soveltuvuus suutinsovelluksissa osoitetaan käyttäen hyväksi numeerisia herkkyystarkasteluja, standareja testitapauksia sekä kokeellista validointia.

Julkaisun otsikon käännös	Neste-kaasuvirtausten numeerinen mallintaminen pyörresuuttimessa
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Vuorinen, Ville, Vastuuprofessori Järvinen, Mika, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-64-0378-6
Sähköinen ISBN	978-952-64-0379-3
Tila	Julkaistu - 2021
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

virtausmekaniikka
kaksifaasivirtaus
ruiskutus
pisaroituminen
pyörresuutin

YK:n kestävän kehityksen tavoitteet

Tämä tuotos edistää seuraavia kestävän kehityksen tavoitteita:

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-64-0379-3

Science-IT
Hakala, M. (Manager)
Perustieteiden korkeakoulu
Laitteistot/tilat: Facility

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@phdthesis{de5cfece8ab74373acf0c64faf6e36a7,

title = "Numerical modeling of gas-liquid flows in a swirl nozzle",

abstract = "The present dissertation belongs to the research area of fluid dynamics. In particular, scale-resolving computational fluid dynamics (CFD) methods are utilized to investigate liquid injection and atomization processes in industrial context. The two-phase flows are solved using the volume-of-fluid (VOF) method utilizing a sharp interface capturing framework. The work is motivated by high-viscosity, biomass-based renewable fuel injection where the atomization process and the size of the liquid droplets may relate to the overall quality of the combustion process. In this work, liquid injection from a large-scale asymmetric pressure-swirl atomizer is studied in different conditions. In contrast, previous research has mainly concentrated on small-scale nozzles with symmetric designs. Detailed simulations of both the inner-nozzle flow characteristics and the onset of liquid sheet breakup are carried out. Publications I and II investigate the low-Reynolds-number regime (420 ≤ Re ≤ 5300) in detail. Full understanding of the atomizer flow characteristics and key spray parameters has been so far lacking for the studied parameter range. In addition, comparison with experimental measurements is carried out in Publication II. In Publication III, bubbly flow in the atomizer is studied with relevance to injection scenarios where significant volume of gas is present inside the nozzle. Thus far, such conditions have remained relatively unexplored by detailed simulations in the context of swirl nozzles. The novelty of the present work relates to the application of highly resolved numerical simulations to study a large-scale swirl atomizer in conditions relevant for industrial applications. The main outcomes of the dissertation are as follows: (1) Detailed description of the inner-nozzle flow characteristics is provided. (2) Near-nozzle liquid sheet characteristics are analyzed and the existence of different spray patterns at different Reynolds numbers is demonstrated. (3) The effects of bubbly flow on the atomizer performance and liquid film characteristics are assessed. In addition, practically relevant nozzle key parameters, such as the spray opening angle, discharge coefficient, and film velocity, are reported. Also, the applicability of the used computational approach in the present application field is demonstrated via sensitivity tests, numerical benchmarks and experimental validation.",

keywords = "fluid dynamics, two-phase flow, liquid injection, atomization, swirl nozzle, virtausmekaniikka, kaksifaasivirtaus, ruiskutus, pisaroituminen, py{\"o}rresuutin, fluid dynamics, two-phase flow, liquid injection, atomization, swirl nozzle",

author = "Erkki Laurila",

year = "2021",

language = "English",

isbn = "978-952-64-0378-6",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "67",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Numerical modeling of gas-liquid flows in a swirl nozzle

AU - Laurila, Erkki

PY - 2021

Y1 - 2021

N2 - The present dissertation belongs to the research area of fluid dynamics. In particular, scale-resolving computational fluid dynamics (CFD) methods are utilized to investigate liquid injection and atomization processes in industrial context. The two-phase flows are solved using the volume-of-fluid (VOF) method utilizing a sharp interface capturing framework. The work is motivated by high-viscosity, biomass-based renewable fuel injection where the atomization process and the size of the liquid droplets may relate to the overall quality of the combustion process. In this work, liquid injection from a large-scale asymmetric pressure-swirl atomizer is studied in different conditions. In contrast, previous research has mainly concentrated on small-scale nozzles with symmetric designs. Detailed simulations of both the inner-nozzle flow characteristics and the onset of liquid sheet breakup are carried out. Publications I and II investigate the low-Reynolds-number regime (420 ≤ Re ≤ 5300) in detail. Full understanding of the atomizer flow characteristics and key spray parameters has been so far lacking for the studied parameter range. In addition, comparison with experimental measurements is carried out in Publication II. In Publication III, bubbly flow in the atomizer is studied with relevance to injection scenarios where significant volume of gas is present inside the nozzle. Thus far, such conditions have remained relatively unexplored by detailed simulations in the context of swirl nozzles. The novelty of the present work relates to the application of highly resolved numerical simulations to study a large-scale swirl atomizer in conditions relevant for industrial applications. The main outcomes of the dissertation are as follows: (1) Detailed description of the inner-nozzle flow characteristics is provided. (2) Near-nozzle liquid sheet characteristics are analyzed and the existence of different spray patterns at different Reynolds numbers is demonstrated. (3) The effects of bubbly flow on the atomizer performance and liquid film characteristics are assessed. In addition, practically relevant nozzle key parameters, such as the spray opening angle, discharge coefficient, and film velocity, are reported. Also, the applicability of the used computational approach in the present application field is demonstrated via sensitivity tests, numerical benchmarks and experimental validation.

AB - The present dissertation belongs to the research area of fluid dynamics. In particular, scale-resolving computational fluid dynamics (CFD) methods are utilized to investigate liquid injection and atomization processes in industrial context. The two-phase flows are solved using the volume-of-fluid (VOF) method utilizing a sharp interface capturing framework. The work is motivated by high-viscosity, biomass-based renewable fuel injection where the atomization process and the size of the liquid droplets may relate to the overall quality of the combustion process. In this work, liquid injection from a large-scale asymmetric pressure-swirl atomizer is studied in different conditions. In contrast, previous research has mainly concentrated on small-scale nozzles with symmetric designs. Detailed simulations of both the inner-nozzle flow characteristics and the onset of liquid sheet breakup are carried out. Publications I and II investigate the low-Reynolds-number regime (420 ≤ Re ≤ 5300) in detail. Full understanding of the atomizer flow characteristics and key spray parameters has been so far lacking for the studied parameter range. In addition, comparison with experimental measurements is carried out in Publication II. In Publication III, bubbly flow in the atomizer is studied with relevance to injection scenarios where significant volume of gas is present inside the nozzle. Thus far, such conditions have remained relatively unexplored by detailed simulations in the context of swirl nozzles. The novelty of the present work relates to the application of highly resolved numerical simulations to study a large-scale swirl atomizer in conditions relevant for industrial applications. The main outcomes of the dissertation are as follows: (1) Detailed description of the inner-nozzle flow characteristics is provided. (2) Near-nozzle liquid sheet characteristics are analyzed and the existence of different spray patterns at different Reynolds numbers is demonstrated. (3) The effects of bubbly flow on the atomizer performance and liquid film characteristics are assessed. In addition, practically relevant nozzle key parameters, such as the spray opening angle, discharge coefficient, and film velocity, are reported. Also, the applicability of the used computational approach in the present application field is demonstrated via sensitivity tests, numerical benchmarks and experimental validation.

KW - fluid dynamics

KW - two-phase flow

KW - liquid injection

KW - atomization

KW - swirl nozzle

KW - virtausmekaniikka

KW - kaksifaasivirtaus

KW - ruiskutus

KW - pisaroituminen

KW - pyörresuutin

KW - fluid dynamics

KW - two-phase flow

KW - liquid injection

KW - atomization

KW - swirl nozzle

M3 - Doctoral Thesis

SN - 978-952-64-0378-6

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Numerical modeling of gas-liquid flows in a swirl nozzle

Abstrakti

Tutkimusalat

YK:n kestävän kehityksen tavoitteet

Pääsy asiakirjaan

Sormenjälki

Laitteet

Science-IT

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