Starting in 2013 and completing in 2019, the Heatshield for Extreme Entry Environment Technology ... more Starting in 2013 and completing in 2019, the Heatshield for Extreme Entry Environment Technology (HEEET) project has been working to mature a 3-D Woven Thermal Protection System (TPS) to Technical Readiness Level (TRL) 6 to support future NASA missions to destinations with extreme entry environments such as Venus, Saturn, Uranus, Neptune and highspeed sample return missions to Earth. A key aspect of the project has been the building and testing of a 1-meter base diameter Engineering Test Unit (ETU) representative of what could be used for a Saturn probe. This paper provides a high-level overview of the HEEET project including 1) manufacturing and testing of the ETU for structural model verification, 2) establish system capability and 3) verify manufacturing workmanship.
The application of a nonintrusive laser-interferometer skin-friction meter, which measures skin f... more The application of a nonintrusive laser-interferometer skin-friction meter, which measures skin friction with a remotely located laser interferometer that monitors the thickness change of a thin oil film, is extended both experimentally and theoretically to several complex wind-tunnel flows. These include two-dimensional seperated and reattached subsonic flows with large pressure and shear gradients, and two and three-dimensional supersonic flows at high Reynolds number, which include variable wall temperatures and cross-flows. In addition, it is found that the instrument can provide an accurate location of the mean reattachment length for separated flows. Results show that levels up to 120 N/sq m, or 40 times higher than previous tests, can be obtained, despite encountering some limits to the method for very high skin-friction levels. It is concluded that these results establish the utility of this instrument for measuring skin friction in a wide variety of flows of interest in aer...
The present study examines the effects of a strong adverse pressure gradient on a 3D turbulent bo... more The present study examines the effects of a strong adverse pressure gradient on a 3D turbulent boundary layer in an axisymmetric spinning cylinder geometry. Velocity measurements made with a three-component laser Doppler velocimeter include all three mean flow components, all six Reynolds stress components, and all ten triple-product correlations. Total Reynolds shear stress diminishes as the flow becomes 3D. Lower levels of shear stress were found to persist under adverse pressure gradient conditions. This low stress level was observed to roughly correlate with the magnitude of the crossflow. Variations in the pressure gradient do not alter this correlation. It is inferred that a 3D boundary layer is more prone to separate than a 2D boundary layer.
D. M. Driver, D.T. Ellerby(Presenting Author), M. J. Gasch, M. Mahzari, F. S. Milos, O. S. Nishio... more D. M. Driver, D.T. Ellerby(Presenting Author), M. J. Gasch, M. Mahzari, F. S. Milos, O. S. Nishioka, K. H. Peterson, M. M. Stackpoole, E. Venkatapathy, Z. W. Young, P. J. Gage, T. Boghozian, J. F. Chavez-Garcia, G. L. Gonzales, G. E. Palmer, D. K. Prabhu, J. D. Williams, C.D. Kazemba, A. S. Murphy, S. L. Langston, C. C. Poteet, S. C. Splinter, M. E. Fowler, C. M. Kellermann, NASA Ames Research Center Moffett Field, CA 94035, Neerim Corp Moffett Field, CA 94035, Analytical Mechanics Associates, Inc. Moffett Field, CA 94035, Science and Technology Corp, Moffett Field, CA 94035, Millennium Engineering and Integration Co. Moffett Field, CA 94035,NASA Langley Research Center Hampton, VA 23681, NASA Johnson Space Center Houston, TX 77058, Jacobs Technology, Inc. Houston, TX 77058
Skin Friction Measurements on a Hovering Full‐Scale Tilt Rotor. [Journal of the American Helicopt... more Skin Friction Measurements on a Hovering Full‐Scale Tilt Rotor. [Journal of the American Helicopter Society 44, 312 (1999)]. Alan J. Wadcock, Principal Scientist, Gloria K. Yamauchi, Aerospace Engineer, David M. Driver, Research Scientist. Abstract. ...
This NRC Decadal Survey white paper, provided by the thermal protection technology community, is ... more This NRC Decadal Survey white paper, provided by the thermal protection technology community, is a general assessment of the current capability of thermal protection systems (TPS) with respect to the scientific exploration of Venus as well as anticipated TPS requirements in support of future Venus missions 1,3,5. The paper begins with a brief history of
Report describes experiment to measure effects of adverse pressure gradient on three-dimensional ... more Report describes experiment to measure effects of adverse pressure gradient on three-dimensional turbulent boundary-layer flow; effect of streamwise gradient of pressure on crossflow of particular interest. Production of turbulent kinetic energy grows rapidly in vicinity of step as result of steep mean-flow velocity gradients. Dissipation grows less quickly than production; leading to net growth with distance along streamline.
An experimental study of the flow over a backward-facing step at low Reynolds number was performe... more An experimental study of the flow over a backward-facing step at low Reynolds number was performed for the purpose of validating a direct numerical simulation (DNS) which was performed by the Stanford/NASA Center for Turbulence Research. Previous experimental data on back step flows were conducted at Reynolds numbers and/or expansion ratios which were significantly different from that of the DNS. The geometry of the experiment and the simulation were duplicated precisely, in an effort to perform a rigorous validation of the DNS. The Reynolds number used in the DNS was Re(sub h)=5100 based on step height, h. This was the maximum possible Reynolds number that could be economically simulated. The boundary layer thickness, d, was approximately 1.0 h in the simulation and the expansion ratio was 1.2. The Reynolds number based on the momentum thickness, Re(sub theta), upstream of the step was 610. All of these parameters were matched experimentally. Experimental results are presented in t...
In the interest of improving the predictability of high-lift systems at maximum lift conditions, ... more In the interest of improving the predictability of high-lift systems at maximum lift conditions, a series of fundamental experiments were conducted to study the effects of adverse pressure gradient on a wake flow. Mean and fluctuating velocities were measured with a two-component laser-Doppler velocimeter. Data were obtained for several cases of adverse pressure gradient, producing flows ranging from no reversed flow to massively reversed flow. While the turbulent Reynolds stresses increase with increasing size of the reversed flow region, the gradient of Reynolds stress does not. Computations using various turbulence models were unable to reproduce the reversed flow.
The oil film interferometry skin-friction technique is described and applied to flows in some of ... more The oil film interferometry skin-friction technique is described and applied to flows in some of the NASA Ames large wind tunnel facilities. Various schemes for applying the technique are discussed. Results are shown for tests in several wind tunnels which illustrate the oil film's ability to measure a variety of flow features such as shock waves, separation, and 3D flow
Starting in 2013 and completing in 2019, the Heatshield for Extreme Entry Environment Technology ... more Starting in 2013 and completing in 2019, the Heatshield for Extreme Entry Environment Technology (HEEET) project has been working to mature a 3-D Woven Thermal Protection System (TPS) to Technical Readiness Level (TRL) 6 to support future NASA missions to destinations with extreme entry environments such as Venus, Saturn, Uranus, Neptune and highspeed sample return missions to Earth. A key aspect of the project has been the building and testing of a 1-meter base diameter Engineering Test Unit (ETU) representative of what could be used for a Saturn probe. This paper provides a high-level overview of the HEEET project including 1) manufacturing and testing of the ETU for structural model verification, 2) establish system capability and 3) verify manufacturing workmanship.
The application of a nonintrusive laser-interferometer skin-friction meter, which measures skin f... more The application of a nonintrusive laser-interferometer skin-friction meter, which measures skin friction with a remotely located laser interferometer that monitors the thickness change of a thin oil film, is extended both experimentally and theoretically to several complex wind-tunnel flows. These include two-dimensional seperated and reattached subsonic flows with large pressure and shear gradients, and two and three-dimensional supersonic flows at high Reynolds number, which include variable wall temperatures and cross-flows. In addition, it is found that the instrument can provide an accurate location of the mean reattachment length for separated flows. Results show that levels up to 120 N/sq m, or 40 times higher than previous tests, can be obtained, despite encountering some limits to the method for very high skin-friction levels. It is concluded that these results establish the utility of this instrument for measuring skin friction in a wide variety of flows of interest in aer...
The present study examines the effects of a strong adverse pressure gradient on a 3D turbulent bo... more The present study examines the effects of a strong adverse pressure gradient on a 3D turbulent boundary layer in an axisymmetric spinning cylinder geometry. Velocity measurements made with a three-component laser Doppler velocimeter include all three mean flow components, all six Reynolds stress components, and all ten triple-product correlations. Total Reynolds shear stress diminishes as the flow becomes 3D. Lower levels of shear stress were found to persist under adverse pressure gradient conditions. This low stress level was observed to roughly correlate with the magnitude of the crossflow. Variations in the pressure gradient do not alter this correlation. It is inferred that a 3D boundary layer is more prone to separate than a 2D boundary layer.
D. M. Driver, D.T. Ellerby(Presenting Author), M. J. Gasch, M. Mahzari, F. S. Milos, O. S. Nishio... more D. M. Driver, D.T. Ellerby(Presenting Author), M. J. Gasch, M. Mahzari, F. S. Milos, O. S. Nishioka, K. H. Peterson, M. M. Stackpoole, E. Venkatapathy, Z. W. Young, P. J. Gage, T. Boghozian, J. F. Chavez-Garcia, G. L. Gonzales, G. E. Palmer, D. K. Prabhu, J. D. Williams, C.D. Kazemba, A. S. Murphy, S. L. Langston, C. C. Poteet, S. C. Splinter, M. E. Fowler, C. M. Kellermann, NASA Ames Research Center Moffett Field, CA 94035, Neerim Corp Moffett Field, CA 94035, Analytical Mechanics Associates, Inc. Moffett Field, CA 94035, Science and Technology Corp, Moffett Field, CA 94035, Millennium Engineering and Integration Co. Moffett Field, CA 94035,NASA Langley Research Center Hampton, VA 23681, NASA Johnson Space Center Houston, TX 77058, Jacobs Technology, Inc. Houston, TX 77058
Skin Friction Measurements on a Hovering Full‐Scale Tilt Rotor. [Journal of the American Helicopt... more Skin Friction Measurements on a Hovering Full‐Scale Tilt Rotor. [Journal of the American Helicopter Society 44, 312 (1999)]. Alan J. Wadcock, Principal Scientist, Gloria K. Yamauchi, Aerospace Engineer, David M. Driver, Research Scientist. Abstract. ...
This NRC Decadal Survey white paper, provided by the thermal protection technology community, is ... more This NRC Decadal Survey white paper, provided by the thermal protection technology community, is a general assessment of the current capability of thermal protection systems (TPS) with respect to the scientific exploration of Venus as well as anticipated TPS requirements in support of future Venus missions 1,3,5. The paper begins with a brief history of
Report describes experiment to measure effects of adverse pressure gradient on three-dimensional ... more Report describes experiment to measure effects of adverse pressure gradient on three-dimensional turbulent boundary-layer flow; effect of streamwise gradient of pressure on crossflow of particular interest. Production of turbulent kinetic energy grows rapidly in vicinity of step as result of steep mean-flow velocity gradients. Dissipation grows less quickly than production; leading to net growth with distance along streamline.
An experimental study of the flow over a backward-facing step at low Reynolds number was performe... more An experimental study of the flow over a backward-facing step at low Reynolds number was performed for the purpose of validating a direct numerical simulation (DNS) which was performed by the Stanford/NASA Center for Turbulence Research. Previous experimental data on back step flows were conducted at Reynolds numbers and/or expansion ratios which were significantly different from that of the DNS. The geometry of the experiment and the simulation were duplicated precisely, in an effort to perform a rigorous validation of the DNS. The Reynolds number used in the DNS was Re(sub h)=5100 based on step height, h. This was the maximum possible Reynolds number that could be economically simulated. The boundary layer thickness, d, was approximately 1.0 h in the simulation and the expansion ratio was 1.2. The Reynolds number based on the momentum thickness, Re(sub theta), upstream of the step was 610. All of these parameters were matched experimentally. Experimental results are presented in t...
In the interest of improving the predictability of high-lift systems at maximum lift conditions, ... more In the interest of improving the predictability of high-lift systems at maximum lift conditions, a series of fundamental experiments were conducted to study the effects of adverse pressure gradient on a wake flow. Mean and fluctuating velocities were measured with a two-component laser-Doppler velocimeter. Data were obtained for several cases of adverse pressure gradient, producing flows ranging from no reversed flow to massively reversed flow. While the turbulent Reynolds stresses increase with increasing size of the reversed flow region, the gradient of Reynolds stress does not. Computations using various turbulence models were unable to reproduce the reversed flow.
The oil film interferometry skin-friction technique is described and applied to flows in some of ... more The oil film interferometry skin-friction technique is described and applied to flows in some of the NASA Ames large wind tunnel facilities. Various schemes for applying the technique are discussed. Results are shown for tests in several wind tunnels which illustrate the oil film's ability to measure a variety of flow features such as shock waves, separation, and 3D flow
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