In this paper, the authors describe an innovative jet engine noise measurement and prediction tool. The tool measures sound-pressure levels and frequency spectra in the far field. In addition, the tool provides predicted results while the measurements are being made. The predictions are based on an existing computational fluid dynamics database coupled to an empirical acoustic radiation model based on the far-field approximation to the Lighthill acoustic analogy. Preliminary tests of this acoustic measurement and prediction tool produced very encouraging results.
Results of a computational study on the effectiveness of various passive devices for the control of combustion instabilities are presented. An axi-symmetric combustion chamber is considered. The passive control devices investigated are, baffles, Elmholtz resonators and quarter-waves. The results show that a Helmholtz resonator with a smooth orifice achieves the best control results, while a baffle is the least effective for the frequency tested. At high sound pressure levels, the Helmholtz resonator is less effective.It is also found that for a quarter wave, the smoothness of the orifice has the opposite effect than the Helmholtz resonator, i.e. results in less control.
To support the NASA Space Exploration Mission, an in-house program called Combustion Devices Injector Technology (CDIT) is being conducted at the NASA Marshall Space Flight Center (MSFC) for the fiscal year 2005. CDIT is focused on developing combustor technology and analysis tools to improve reliability and durability of upper-stage and in-space liquid propellant rocket engines. The three areas of focus include injectorkhamber thermal compatibility, ignition, and combustion stability. In the compatibility and ignition areas, small-scale single-and multi-element hardware experiments will be conducted to demonstrate advanced technological concepts as well as to provide experimental data for validation of computational analysis tools. In addition, advanced analysis tools will be developed to eventually include 3-dimensional and multielement effects and improve capability and validity to analyze heat transfer and ignition in large, multi-element injectors. The task on thermal compatibility and heat transfer is to reduce local peak heat flux due to element o r injector design. It is applicable to all systems, but is especially relevant to inspace engines and upper stage engines with expander cycles. Selected small-scale injectors are being hot-fire tested at The Pennsylvania State University in a highly-instrumented, 1inch internal diameter heat sink combustion chamber with liquid oxygen and gaseous hydrogen propellants. Combustor wall local heat flux is calculated from an array of Medtherm coaxial thermocouples. These experimental data are being compared to model results from the Finite-Difference Navier-Stokes (FDNS) CFD code currently in use a t the NASA MSFC. An unstructured code called STREAM using the Loci parallel processing platform is currently being developed and will be validated in the future with these test data.
I AbstractThis paper documents key aspects of the Constellation University Institutes Project (CUIP) Thrust Chamber Assembly (TCA) Virtual Institute (VI). Specifically, the paper details the TCA VI organizational and functional aspects relative to providing support for Constellation Systems. The TCA VI vision is put forth and discussed in detail. The vision provides the objective and approach for improving thrust chamber assembly design methodologies by replacing the current empirical tools with verified and validated CFD codes. The vision also sets out ignition, performance, thermal environments and combustion stability as focus areas where application of these improved tools is required. Flow physics and a study of the Space Shuttle Main Engine development program are used to conclude that the injector is the key to robust TCA design.Requirements are set out in terms of fidelity, robustness and demonstrated accuracy of the design tool. Lack of demonstrated accuracy is noted as the most significant obstacle to realizing the potential of CFD to be widely used as an injector design tool. A hierarchical decomposition process is outlined to facilitate the validation process. A simulation readiness level tool used to gauge progress toward the goal is described.Finally, there is a description of the current efforts in each focus area. The background of each focus area is discussed. The state of the art in each focus area is noted along with the TCA VI research focus in the area. Brief highlights of work in the area are also included. I1 Introduction A CUIP ObjectivesThe NASA Constellation University Institutes Project (CUP) is a consortium of universities charged with addressing technical challenges in NASA's Exploration Systems Mission Directorate's development programs, particularly fundamental technical challenges of importance and relevance to Constellation Systems.The overall objectives of'the CUIP are to perform research and development that addresses critical Constellation needs; enhance and broaden the ability of the nation's universities to meet the needs of NASA's programs; expand the nation's talent base for NASA mission-related research and development and technology maturation; and strengthen NASA's ties to academia through long-term, directed, and sustained investment. The Project provides technical oversight 1 https://ntrs.nasa.gov/search.jsp?R=20060047784 2018-05-11T09:27:56+00:00Z for the university research efforts, performs financial management, manages the review processes, and fosters relevant relationships between the university researchers and NASA Constellation Alabama at Huntsville). In total, the three institutes that make up CUIP are comprised of 17 geographically disparate universities, nearly 60 technical tasks, 100 researchers and 130 students.Last year, the CUD? supported over 200 workshop, conference, and archival publications. B Strategy for meeting the CUIP objectivesThe CUTE' Management Team strategy for meeting the CUIP objectives noted above centered on a three-pronged set of orga...
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