Numerical Conjugate Heat Transfer Analysis of a Roots Blower

master's thesis

• Title (croatian): Numerička analiza spregnutog prijelaza topline u Roots-ovom puhalu
• Author: Mario Matuzović
• Mentor: Željko Tuković (mentor)
• Mentor: Ahmed Kovačević https://orcid.org/0000-0002-8732-2242 (komentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2022-05-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Process Energy Engineering

Abstract

This thesis deals with Conjugate Heat Transfer analysis of an oil-free Roots blower which is a Positive Displacement Machine used for low pressure ratio applications. Prediction of temperature distribution is critical in the design of rotor-to-rotor and rotor-to-casing clearance gaps inside these compressors. The aim of the study is to numerically analyse the heat transfer from pressurized air to rotors and casing and provide the temperature distribution over structural elements. These problems are too complex to be solved analytically so this thesis will employ High Performance Computing to perform CFD simulations and find an approximate numerical solution of the heat transfer problem. Internal flow inside the blower is highly transient and to predict its characteristic we need to tackle one of the most challenging deforming mesh problems where working medium is displaced during simulation. To allow for mesh deformation, due to intermeshing of the rotors, the moving mesh technique will be employed in this thesis. A numerical framework for 3D simulation of complex flow field inside a Roots blower compressor is established and presented. The framework employs Finite Volume Method. Five cases are investigated, each for different operating condition. In order to evaluate the accuracy of the developed numerical model, extensive validation is performed for several operating conditions. The numerical solution is compared to the overall performance of an equivalent experimentally measured compressor. The experimental data were provided by City University London and they include measurements of surface and air temperature, mass flow rate, pressure ratio, and effective power measurements. The comparison between numerical results has shown good agreement with the experimental data. The outcome of this research contribute to the understanding of the effects of leakage flow phenomena and can help design more efficient compressors.

Abstract (croatian)

Ovaj diplomski rad bavi se analizom spregnutog prijelaza topline Roots-ovog puhala koji radi bez podmazivanja te se primjenjuje za niske kompresijske omjere. Procjena temperaturne raspodjele ključna je pri projektiranju zazora koji se nalaze u kućištu ovih kompresora. Cilj rada je numerički analizirati prijenos topline s komprimiranog zraka na rotore i kućište te dati temperaturnu raspodjelu na površinama rotora i kućišta. U radu će se koristiti računalni klasteri s visokom učinkovitošču za izvođenje CFD simulacija i pronalaženje približnog numeričkog rješenja problema prijenosa topline. Predstavljena je numerička metoda za simulaciju kompleksnog strujanja radnog medija unutar Roots-ovog puhala. Metoda koristi numeričku metodu kontrolnih volumena. Provedeno je 5 simulacija, svaka za jedan ispitni uvjet. Kako bi se procjenila točnost numeričkog modela, u radu je provedena opsežna validacija za nekoliko ispitnih uvjeta. Numeričko rješenje uspoređeno je s eksperimentalnim rezultatima ekvivalentnih ispitnih točki mjerenog kompresora. Eksperimentalne podatke je dao na raspolaganje fakultet City, Sveučilišta u Londonu. Podaci uključuju mjerenja temperature površine i zraka, masenog protoka, kompresijskog omjera te mjerenja efektivne snage. Usporedba je pokazala dobro slaganje numeričkog rješenja s eksperimentalnim podacima. Ishod ovog istraživanja doprinosi razumijevanju gubitaka u volumetrijskim kompresorima te može doprinijeti povećanju njihove efikasnosti.

• Keywords: Conjugate Heat Transfer; Roots blower; Positive Displacement Machine; Numerical analysis; High Performance Computing; Computational Fluid Dynamics; Moving mesh; Finite Volume Method; Leakage flow
• Keywords (croatian): Spregnuti prijelaz topline; Roots-ovo puhalo; Numerička analiza; Računalni klasteri; Računalna dinamika fluida; Metoda kontrolnih volumena
• Language: english
• URN:NBN: urn:nbn:hr:235:315521
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-05-11 20:43:48