With the advent of advanced numerical methods and high performance computing technology, it is now possible to explore dynamic thermal energy conversion devices at a very high level of detail. This offers the promise of improved efficiency and reliability, while reducing the cost of design and product cycle turn-around time.
NASA Glenn is using computational fluid dynamics along with experimental testing to better understand dynamic space power devices, such as the free-piston Stirling convertor. During testing, the convertor is equipped with temperature sensors along the external perimeter as well as throughout the interior of the test hardware. The external temperatures are then used as boundary conditions for the computational model, which is tuned by varying the contact resistances until the interior temperatures match those measured during testing. This tuned model is then used to obtain a prediction of the Net Heat Input utilized by the convertor, which aids in assessing its performance. Other convertor applications include generating dynamic computational models to predict the flow physics inside of the convertor and obtaining predictions of various temperature-sensitive internal components.
Experimental and Computational Geometry for Advanced Stirling Convertor Net Heat Input Testing. Select an image to view larger.
Computational fluid dynamics is also used for Fission Surface Power applications, where it is important to know the flow characteristics of a component prior to large scale build-up and testing of a fluid-convertor system, such as the Power Conversion Unit. Pre-test predictions are a valuable tool for evaluating the behavior of components, which provides the opportunity to modify, or improve the design of any component that will part of the larger-scale system.
Heat Exchanger Manifold for Fission Surface Power Application. Select an image to view larger.