Pressure Contours inside and outside of duct.

Pressure Contours Inside and Outside of Duct

The Launch Systems Testbed (LST) uses analytical methods and tools to determine vibro-acoustic load environments, develop launch management systems, and predict rocket exhaust plume effects. Methodologies such as Computational Fluid Dynamics (CFD), Finite Element Modeling (FEM), and Statistical Engergy Analysis (SEA) are employed to predict and evaluate propulsion-generated impacts on ground support equipment and other structures within the near and far fields. Analytical results are verified using test data generated using the Trajectory Simulation Mechanism at the LST test facility.

Noise from supersonic jets flowing in enclosed ducts is numerically simulated with the aid of CFD and Kirchhoff integral formulation. While CFD will identify the sound sources in the nonlinear nearfield region, the Kirchhoff integral will be considered to determine the noise radiation in the linear far-field. This approach will considerably reduce the computational time. The method will also be extended to study the effect of vehicle drift on launch structures/GSE by employing the Flowcs Williams-Hawkings (FW-H) formulation.

The scaling laws for the simulation of noise from subsonic and supersonic jets are being examined with regard to their applicability to deduce full scale conditions from small scale model testing. The limitations of cold jet data in estimating high temperature supersonic jet noise levels provide another area of study.

Also in work is the development of a user-friendly finite element program for the solution of the acoustic problems related to rocket engines. The user will be able to obtain the solution to the compressible Navier Stokes equations all in one environment, starting with the raw data and resulting in post-processing and analysis of the results.

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NASA Official: James Heald ( , Director, Spaceport Engineering and Technology Directorate
Curator: Bruce Vu (
Last Revised: October 6, 2004

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