The NASA Turbulent Heat Flux Experiments: Summary and Lessons Learned

The Turbulent Heat Flux (THX) experiments were conducted at NASA Glenn
Research Center (GRC) in order to collect measurements of velocities and temperatures for
computational fluid dynamics (CFD) validation of heated flows, with a focus on propulsion
system components. The experiments spanned 5 phases; four of which were conducted in the
GRC AeroAcoustic Propulsion Laboratory (AAPL) using the Small Hot Jet Flow Rig
(SHJAR). In addition to making velocity measurements with Particle Image Velocimetry
(PIV), the THX experiments introduced a new Raman-scattering based capability to measure
temperatures. Computational studies were also conducted for each of the experimental
configurations, in order to provide a baseline of expected CFD results and conduct an
assessment of the capability of various CFD approaches for calculating flows where the
turbulent transport of heat was important. Two of the collected sets of data were used for
American Institute of Aeronautics and Astronautics (AIAA) Propulsion Aerodynamic
Workshops (PAWs). The data set from the 5th phase, collected for heated supersonic jets, was
also used to construct new validation cases for the NASA Turbulence Model Resource (TMR).
This paper provides an overview of the experiments and associated computations for each of
the 5 test phases. Key experimental findings are presented. Lessons learned are provided
concerning the effect of computational modeling choice on accuracy of predicting turbulent
flows where thermal transport is important. Emphasis is placed on comparing Reynolds-
averaged Navier-Stokes approaches with large-eddy simulation approaches. The benefits of
utilizing a conjugate heat transfer method in conjunction with CFD solver for film cooling is
demonstrated.