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Advisor(s)
Abstract(s)
A indĂșstria propulsiva Ă© confrontada cada vez mais com maiores exigĂȘncias ao nĂvel de desempenho e emissĂ”es. A busca incessante por dispositivos propulsivos que sejam mais eficientes e em simultĂąneo tenham menor peso, dimensĂ”es e emissĂ”es leva a que uma maior diversidade de dispositivos seja agora explorado. Este Ă© o caso dos dispositivos PDE, que tĂȘm sido alvo de estudos como promissora substituição dos sistemas propulsivos existentes nos dias atualmente, sobretudo na indĂșstria aeronĂĄutica.
Para compreender a viabilidade de um determinado dispositivo Ă© necessĂĄrio conhecer ou prever o seu desempenho. Para tal existem duas formas: construção de protĂłtipos ou realização de simulaçÔes computacionais. A primeira das duas Ă© demasiado dispendiosa para a indĂșstria, pela segunda opção torna-se mais viĂĄvel.
Neste estudo Ă© abordada a forma como diversos modelos numĂ©ricos resolvem simulaçÔes computacionais, escolhendo-se um deles para a simulação de um tubo combustor. O tubo combustor Ă© dimensionado com o objetivo fazer transitar uma deflagração para detonação â processo de DDT.
Pretende-se saber se a existĂȘncia de nervuras espaçadas de forma regular no interior do tubo promove o processo de DDT. SĂŁo realizadas, com a ferramenta Fluent da ANSYS, duas simulaçÔes computacionais semelhantes, em que varia apenas a geometria do tubo â um dos tubos tem nervuras e o outro nĂŁo. Ă usada uma mistura pobre de etano-ar para as duas simulaçÔes.
Ambas as simulaçÔes são repartidas em 4 etapas: (1) regime estacionårio sem introdução de espécies; (2) regime estacionårio com introdução de espécies; (3) regime transiente com as mesmas propriedades que a etapa anterior; e (4) regime transiente com ignição de escoamento. São comparados os resultados das simulaçÔes para as etapas (1), (2) e (4) e retiram-se conclusÔes.
Propulsive industry is getting increasingly more challenged by the demands on efficiency level and emissions. The unceasing search for efficient propulsive devices that simultaneously are smaller and lighter has opened news ways for a varied set of devices to be developed. This the case of PDE devices, which are being focused by several research studies as a promising alternative for existent propulsive systems, particularly in the aeronautical industry. To understand the feasibility of a device it is necessary to know or predict its performance. There are two ways for this: the construction of a prototype or performing computational simulations. The former is too expensive for the industry application, making the second option the most viable one. In this study the method that several numerical models use to solve computational simulations is approached, and one of them is selected to simulate a combustion tube. The combustion tube is dimensioned aiming to accelerate a deflagration into a detonation â DDT process. It is intended to know if the existence of obstacles equally spaced inside the tube promotes the DDT process. With Fluent tool from ANSYS, two similar computational simulations are performed, where the only difference is the geometry of the tube â one has obstacles and the other donât. A lean mixture of ethane and air is used for the simulations. Both simulations are divided into 4 stages: (1) stationary regime with no introduction of species; (2) stationary regime with the introduction of species; (3) transient regime with the same properties as the stage before; and (4) transient regime with the ignition of the flow. The results from stages (1), (2) and (4) of both simulations are compared and conclusions are made.
Propulsive industry is getting increasingly more challenged by the demands on efficiency level and emissions. The unceasing search for efficient propulsive devices that simultaneously are smaller and lighter has opened news ways for a varied set of devices to be developed. This the case of PDE devices, which are being focused by several research studies as a promising alternative for existent propulsive systems, particularly in the aeronautical industry. To understand the feasibility of a device it is necessary to know or predict its performance. There are two ways for this: the construction of a prototype or performing computational simulations. The former is too expensive for the industry application, making the second option the most viable one. In this study the method that several numerical models use to solve computational simulations is approached, and one of them is selected to simulate a combustion tube. The combustion tube is dimensioned aiming to accelerate a deflagration into a detonation â DDT process. It is intended to know if the existence of obstacles equally spaced inside the tube promotes the DDT process. With Fluent tool from ANSYS, two similar computational simulations are performed, where the only difference is the geometry of the tube â one has obstacles and the other donât. A lean mixture of ethane and air is used for the simulations. Both simulations are divided into 4 stages: (1) stationary regime with no introduction of species; (2) stationary regime with the introduction of species; (3) transient regime with the same properties as the stage before; and (4) transient regime with the ignition of the flow. The results from stages (1), (2) and (4) of both simulations are compared and conclusions are made.
Description
Keywords
Motor de Detonação Por Pulso (Pde) Nervuras. Processo de Transição de Deflagração Para Detonação (Ddt)