NASA Scientific and Technical Aerospace Reports

Because the temperature rise on the capillary tube during testing for the RP-1 fuels was not significant, a new standard for
the testing conditions should be developed for these types of fuels.
Author
Thermal Stability; High Reynolds Number; Hydrocarbon Fuels; Capillary Tubes; Surface Temperature
20040121069 NASA Langley Research Center, Hampton, VA, USA
Investigation of Particle Sampling Bias in the Shear Flow Field Downstream of a Backward Facing Step
Meyers, James F.; Kjelgaard, Scott O.; Hepner, Timothy E.; [1990]; 22 pp.; In English; Fifth International Symposium on
Applications of Laser Techniques to Fluid Mechanics, 9-12 Jul. 1990, Lisbon, Portugal; Original contains color illustrations;
No Copyright; Avail: CASI; A03, Hardcopy
The flow field about a backward facing step was investigated to determine the characteristics of particle sampling bias
in the various flow phenomena. The investigation used the calculation of the velocity:data rate correlation coefficient as a
measure of statistical dependence and thus the degree of velocity bias. While the investigation found negligible dependence
within the free stream region, increased dependence was found within the boundary and shear layers. Full classic correction
techniques over-compensated the data since the dependence was weak, even in the boundary layer and shear regions. The
paper emphasizes the necessity to determine the degree of particle sampling bias for each measurement ensemble and not use
generalized assumptions to correct the data. Further, it recommends the calculation of the velocity:data rate correlation
coefficient become a standard statistical calculation in the analysis of all laser velocimeter data.
Author
Backward Facing Steps; Flow Distribution; Shear Flow; Particles
20040121085 NASA Langley Research Center, Hampton, VA, USA
Transonic Navier-Stokes Solutions about a Complex High-Speed Accelerator Configuration
Ghaffari, F.; Bates, B.; Luckring, J.; Thomas, J.; [1990]; 17 pp.; In English; 28th Aerospace Sciences Meeting, 8-11 Jan. 1990,
Reno, NV, USA
Contract(s)/Grant(s): NAS1-18585
Report No.(s): AIAA Paper 90-0430; Copyright; Avail: CASI; A03, Hardcopy
Three dimensional transonic viscous flow computations are presented for a generic high-speed accelerator model which
includes wing, body, filets,and a no-flow through engine nacelle. solutions are obtained from an algorithm for the compressible
Navier-Stokes equations which incorporated an upwind-biased, flux-vector-splitting approach along with longitudinallypatched
grids. Results are presented for fully turbulent flow assumptions and include correlations with wind tunnel data. A
good quantitative agreement for the forebody surface pressure distribution is achieved between computations and the available
wind-tunnel measurements at M(sub infinity) = 0.9. Furthermore, it is demonstrated that the flow is stagnating around the
boattail region due to separation from the aft-engine cowl lip.
Author
Computational Fluid Dynamics; Navier-Stokes Equation; Viscous Flow; Accelerators; High Speed; Three Dimensional Flow;
Transonic Wind Tunnels; Mathematical Models; Aerodynamic Configurations
20040121087 NASA Langley Research Center, Hampton, VA, USA
A Fast Upwind Solver for the Euler Equations on Three-Dimensional Unstructured Meshes
Frink, Neal T.; Pirzadeh, Shahyar; January 2004; 16 pp.; In English
Report No.(s): AIAA Paper 91-0102; Copyright; Avail: CASI; A03, Hardcopy
An upwind scheme is presented for solving the three-dimensional Euler equations on unstructured tetrahedral meshes.
Spatial discretization is accomplished by a cell-centered finite-volume formulation using flux-difference splitting. Higherorder
differences are formed by a novel cell reconstruction process which results in computational times per cell comparable
to those of structured codes. The approach yields highly resolved solutions in regions of smooth flow while avoiding
oscillations across shocks without explicit limiting. Solutions are advanced in time by a 3-stage Runge-Kutta time-stepping
scheme with convergence accelerated to steady state by local time stepping and implicit residual smoothing. Solutions are
presented for a range of configurations in the transonic speed regime to demonstrate code accuracy, speed, and robustness. The
results include an assessment of grid sensitivity and convergence acceleration by mesh sequencing.
Author
Unstructured Grids (Mathematics); Upwind Schemes (Mathematics); Euler Equations of Motion; Three Dimensional Flow;
Tetrahedrons; Grid Generation (Mathematics)
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