Rocket Based combined cycle engines are the prime focus of research these days due to their enhanced advantage over the limitations presented by the gas turbines engines for supersonic and hypersonic speeds. The gas turbines which have been used in most commercial and military airplanes imply several structural and design restrictions because of presence of rotating parts in the engines and hence resulted in achievement of the highest possible speed of Mach 2. Modern propulsion systems are a result of combination of solid propellent rockets and ramjets to create a Ramjet. These systems are capable of modifying their operation mode from pure rocket to ramjet and then scramjet depending on the Mach number by slight modification in the geometry. The rocket combustor in the engine is basically the integral part that serves as a booster and the ramjet engine sustains the operation up to the higher speeds. These systems are highly efficient in terms of propulsive performance, compactness and possess high maneuverability. This study focuses on the operating conditions of laboratory (CNR-IENI Milano) based RBCC Engine in with the main focus on the Rocket mode operation. Several tests were performed in the facility in which the setup was run in the rocket only mode in order to study in detail, the rocket motor characteristics under different operating conditions with and without ignition of the fuel. Same operating conditions were maintained during the ignition/non ignition tests in order to better understand the behavior of the rocket motor. Gaseous fuel and oxidizer were fed through the injectors in to the combustion chamber of the nozzle and pressure and temperature measurement were performed during the whole duration of the test which is a fraction of second because of the volume of fuel and oxidizer fed. The pressure and temperature readings were then utilized to numerically evaluate the thrust, combustion efficiency & specific impulse. Mach numbers at the various locations were evaluated using different averaging techniques which leaded to the evaluation of thrust. The thrust data set was then compared with the one measured using the load cell during the tests in order to cross check the validity of the pressure and temperature measurements.
I motori a ciclo combinato basati su endoreattore sono attualmente al centro della ricerca grazie ai vantaggi rispetto ai motori turbogas per velocità supersoniche e ipersoniche. Le turbine a gas che sono state utilizzate nella maggior parte degli aerei commerciali e militari implicano diverse restrizioni strutturali e di progettazione a causa della presenza di parti rotanti nei motori che portano al raggiungimento di un valore massimo del numero di Mach di volo pari a 2. I moderni sistemi di propulsione sono il risultato di una combinazione di endoreattori a propellente solido e ramjets. Questi sistemi sono in grado di modificare la loro modalità operativa da puro endoreattore a ramjet e quindi scramjet, a seconda del numero di Mach, mediante lievi modifiche nella geometria. L’endoreattore funge da acceleratore e il motore ramjet sostiene il volo fino alle velocità più elevate. Questi sistemi sono altamente efficienti in termini di prestazioni propulsive e compattezza, e possiedono un'elevata manovrabilità. Questo studio si concentra sulle condizioni operative del motore RBCC disponibile presso il laboratorio CNR-ICMATE di Milano con l'obiettivo principale di studiare il funzionamento in modalità endoreattore. Diversi test sono stati eseguiti in esclusiva modalità endoreattore al fine di studiare in dettaglio le caratteristiche dell’endoreattore in diverse condizioni operative con e senza accensione della miscela combustibile. Durante le prove di accensione / non accensione sono state mantenute le stesse condizioni operative per comprendere meglio il comportamento dell’endoreattore. Il combustibile e l'ossidante gassosi sono stati alimentati attraverso gli iniettori nella camera di combustione e la misura della pressione e della temperatura è stata condotta durante l'intera durata della prova, che è solo una frazione di secondo a causa del volume di combustibile e ossidante alimentato. Le letture di pressione e temperatura sono state quindi utilizzate per valutare numericamente la spinta, l'efficienza di combustione e l'impulso specifico. I numeri di Mach nelle varie posizioni sono stati valutati usando diverse tecniche di calcolo della media che hanno portato alla valutazione della spinta. Il set di dati di spinta è stato quindi confrontato con quello misurato utilizzando la cella di carico durante le prove al fine di verificare la validità delle misure di pressione e temperatura.
Rocket mode operational analysis of a rocket based combined cycle model engine
FRAZ, NOMAN AHMED
2017/2018
Abstract
Rocket Based combined cycle engines are the prime focus of research these days due to their enhanced advantage over the limitations presented by the gas turbines engines for supersonic and hypersonic speeds. The gas turbines which have been used in most commercial and military airplanes imply several structural and design restrictions because of presence of rotating parts in the engines and hence resulted in achievement of the highest possible speed of Mach 2. Modern propulsion systems are a result of combination of solid propellent rockets and ramjets to create a Ramjet. These systems are capable of modifying their operation mode from pure rocket to ramjet and then scramjet depending on the Mach number by slight modification in the geometry. The rocket combustor in the engine is basically the integral part that serves as a booster and the ramjet engine sustains the operation up to the higher speeds. These systems are highly efficient in terms of propulsive performance, compactness and possess high maneuverability. This study focuses on the operating conditions of laboratory (CNR-IENI Milano) based RBCC Engine in with the main focus on the Rocket mode operation. Several tests were performed in the facility in which the setup was run in the rocket only mode in order to study in detail, the rocket motor characteristics under different operating conditions with and without ignition of the fuel. Same operating conditions were maintained during the ignition/non ignition tests in order to better understand the behavior of the rocket motor. Gaseous fuel and oxidizer were fed through the injectors in to the combustion chamber of the nozzle and pressure and temperature measurement were performed during the whole duration of the test which is a fraction of second because of the volume of fuel and oxidizer fed. The pressure and temperature readings were then utilized to numerically evaluate the thrust, combustion efficiency & specific impulse. Mach numbers at the various locations were evaluated using different averaging techniques which leaded to the evaluation of thrust. The thrust data set was then compared with the one measured using the load cell during the tests in order to cross check the validity of the pressure and temperature measurements.File | Dimensione | Formato | |
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THESIS-Complete Results and Conslusions.pdf
Open Access dal 13/04/2021
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https://hdl.handle.net/10589/139549