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Dan H Neuhart

Publications and source records attributed to Dan H Neuhart.

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

TPSAS-NF1676L-10819-DND

Additional aerodynamic data for the benchmark configuration of partially-dressed cavity-closed nose landing gear (PDCC-NLG), obtained at a flow Mach number of 0.166, are provided in this presentation. A detailed account of the unsteady surface pressure fluctuations acquired with a Kulite transducer designed to be mobile is also given. The roving nature of the transducer allowed the sensor to be placed at numerous locations where high-amplitude pressure fluctuations are expected. The measured surface pressure spectra are mainly broadband in nature, lacking any local peaks associated with coherent vortex shedding. This finding is in agreement with off-surface flow measurements based on particle image velocimetry, which revealed the flow field to be a collection of separated shear layers without any dominant vortex shedding processes.

Mehdi R Khorrami↗
NASA NTRS2010

TPSAS-NF1676L-10756-DND

Additional aerodynamic data for the benchmark configuration of partially-dressed cavity-closed nose landing gear (PDCC-NLG), obtained at a flow Mach number of 0.166, are provided in this presentation. A detailed account of the unsteady surface pressure fluctuations acquired with a Kulite transducer designed to be mobile is also given. The roving nature of the transducer allowed the sensor to be placed at numerous locations where high-amplitude pressure fluctuations are expected. The measured surface pressure spectra are mainly broadband in nature, lacking any local peaks associated with coherent vortex shedding. This finding is in agreement with off-surface flow measurements based on particle image velocimetry, which revealed the flow field to be a collection of separated shear layers without any dominant vortex shedding processes.

Mehdi R Khorrami↗
NASA NTRSDate not supplied

Unsteady Pressure Measurement on a Simplified High-Lift Configuration of the Common Research Model using Active Flow Control

The High-Lift Common Research Model (CRM-HL) is a product of the NASA Advanced Air Transport Technology (AATT) Project intended to study various high-lift aerodynamic phenomena including enhanced lift, acoustic noise generation, and optimum placement of leading and trailing-edge devices. The current study was conducted in the NASA Langley 14-by 22-Foot Subsonic Tunnel (14x22) for the purpose of evaluating enhanced lift through the use of active flow control (AFC). The current paper documents the effect of sweeping-jet actuation combined with steady blowing on a simplified high-lift configuration using unsteady pressure measurements. The time-series parameters for the measurements are documented as well as the data acquisition system used to acquire the data. An uncertainty analysis will be presented in order to document the system performance and provide an estimate of the data quality. Repeatability of the data will be shown along with trends associated with model angle of attack, and those associated with changes in the nozzle pressure ratio (NPR) of the AFC system.

Common Research Model↗
NASA NTRSDate not supplied

A Method for Obtaining Surface Flow Vectors and Its Implementation in Interferometric Skin Friction Measurement

A new method was developed to extract surface flow vectors from an oilflow visualization image that has oil streaklines. The method is analogous to the PIV processing where the image is divided into interrogation windows. A representative flow direction is obtained for each interrogation window using image processing with a line-detection algorithm. Repeating the process for the entire image, one can find the surface vector field. The Hough transformation, Radon transformation and Machine Learning were used as line-detection algorithms. The obtained vector field is then postprocessed to filter spurious vectors and to apply smoothing. The method was tested on 2D and 3D models with different flow complexities. The method was able to predict surface flow vectors for all cases tested. The predicted surface flow vectors were used in obtaining the surface skin friction. The successful implementation of the surface flow vectors enables interferometric skin friction measurements on surfaces beneath 3D complex flows. In addition, the surface flow vectors can be superimposed on the oilflow visualization images to better explain the surface flow topology.

Surface flow vectors↗