The increasing of air traffic causes the building of new airports close to the cities. This development triggered, in addition to the well-known problems related to the pollution, a new problem that affects the quality of life of those who lives close to the airports: the noise developed by the aircraft engines especially during the take-off. RECORD (Core Research on Noise Reduction) is a project designed to reduce the noise produced by the aircraft. It involves some of the major factories producing aircraft engines and some European universities including the Politecnico of Milano, specifically its Energetic Department. The goal of the RECORD project is to reduce the core noise produced by the engine with the help of studies that aim to separate as much as possible the different factors that generate it. The core noise is distributed around the engine and, considering the progress that has been made in recent years related with the reduction of turbine noise and fluid noise, it also include the combustion noise. RECORD focuses primarily on the studying of the combustion noise and of its interactions with the turbine noise, with the aim of trying to limit its amplification. To achieve the goal existing test rig in which, at least in the first stage, the combustor will be replaced by a generator of entropy and vorticity will be adapted and modified. It is well known that the non-uniformity in the flow of hot air produced by the combustor or the presence of vorticity or hot spots, is an indirect source of noise when the flow is accelerated in a nozzle or in a turbine. As a consequence, the attempt is to measure those non-uniformities that occours through changes in entropy and, therefore, temperature. This is the context in which this thesis develops, namely the studying of the construction of a fast response micro-thermocouple which is able to capture as much as possible the temperature fluctuations caused by the generator of entropy in the test rig of the project. After the building of the micro-thermocouple, we will proceed to its characterization: the probe will be dynamically calibrated by a Shock Tube to certify the frequency response, aerodynamically tuned for the recovery factor and statically calibrated by the use of a thermocouple oven.
L’aumento del traffico aeroportuale europeo testimoniato anche dal crescente numero di aeroporti, porta ad avere spesso lo sviluppo di queste strutture, più o meno estese, vicino ai centri abitati. Questo sviluppo ha innescato oltre alle problematiche ben note relative all’inquinamento anche una nuova tipologia di problema che influenza la qualità della vita di chi vive vicino agli aeroporti: il rumore sviluppato dai motori aeronautici soprattutto in fase di decollo. Con l’esigenza di ridurre il rumore prodotto dai motori aeronautici nasce il progetto europeo RECORD (Research on Core Noise Reduction) che coinvolge alcune fra le maggiori case di costruzione di motori aeronautici e università europee fra le quali il Politecnico di Milano ed in particolare il Dipartimento di Energia. L’obiettivo del progetto Record è quello di ridurre il core noise prodotto dal propulsore attraverso studi che riescano a separare il più possibile i vari contributi che lo formano. Il core noise è il rumore che “avvolge” il motore aeronautico ed è costituito anche dal rumore di combustione visto i progressi che sono stati compiuti negli anni passati riguardanti la riduzione del rumore di turbina e del rumore fluidodinamico. RECORD si concentra soprattutto sullo studio del rumore di combustione e su come questo rumore interagisca con la turbina per cercare di limitarne l’amplificazione. Per raggiungere l’obiettivo verranno riadattati e modificati banchi prova già esistenti in cui almeno in una prima fase, il combustore verrà sostituito da un generatore di entropia e di vorticosità. E’ noto che disuniformità nel flusso di aria calda prodotta dal combustore, ovvero la presenza di vorticosità o di punti caldi, è fonte di rumore indiretto quando il flusso viene accelerato in un ugello o in una turbina. Si cerca quindi di misurare queste disuniformità che si manifestano attraverso delle variazioni di entropia e quindi di temperatura. E’ in questo contesto che si sviluppa questo lavoro di tesi, ovvero lo studio della realizzazione di una micro-termocoppia a risposta veloce che sia in grado di cogliere il più possibile le fluttuazioni di temperatura causate dal generatore di entropia nel banco prova (test rig) del progetto. Dopo aver costruito la micro-termocoppia, si procederà alla sua caratterizzazione: la sonda andrà tarata dinamicamente mediante un Tubo d’Urto per certificarne la risposta in frequenza, verranno effettuate prove di taratura aerodinamica per studiarne il recovery factor, e infine verrà tarata staticamente utilizzando un fornetto per termocoppie.
Sviluppo ed analisi del comportamento di una micro-termocoppia ad elevata prontezza
PASTORI, LORENZO
2012/2013
Abstract
The increasing of air traffic causes the building of new airports close to the cities. This development triggered, in addition to the well-known problems related to the pollution, a new problem that affects the quality of life of those who lives close to the airports: the noise developed by the aircraft engines especially during the take-off. RECORD (Core Research on Noise Reduction) is a project designed to reduce the noise produced by the aircraft. It involves some of the major factories producing aircraft engines and some European universities including the Politecnico of Milano, specifically its Energetic Department. The goal of the RECORD project is to reduce the core noise produced by the engine with the help of studies that aim to separate as much as possible the different factors that generate it. The core noise is distributed around the engine and, considering the progress that has been made in recent years related with the reduction of turbine noise and fluid noise, it also include the combustion noise. RECORD focuses primarily on the studying of the combustion noise and of its interactions with the turbine noise, with the aim of trying to limit its amplification. To achieve the goal existing test rig in which, at least in the first stage, the combustor will be replaced by a generator of entropy and vorticity will be adapted and modified. It is well known that the non-uniformity in the flow of hot air produced by the combustor or the presence of vorticity or hot spots, is an indirect source of noise when the flow is accelerated in a nozzle or in a turbine. As a consequence, the attempt is to measure those non-uniformities that occours through changes in entropy and, therefore, temperature. This is the context in which this thesis develops, namely the studying of the construction of a fast response micro-thermocouple which is able to capture as much as possible the temperature fluctuations caused by the generator of entropy in the test rig of the project. After the building of the micro-thermocouple, we will proceed to its characterization: the probe will be dynamically calibrated by a Shock Tube to certify the frequency response, aerodynamically tuned for the recovery factor and statically calibrated by the use of a thermocouple oven.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/87084