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Flow Field Diagnostics

NASA is advancing flow field diagnostics by developing and applying cutting-edge measurement techniques to study aerodynamic and propulsion systems.

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A digital rendering of the Particle Image Velocimetry (PIV) diagnostic system on a black background. The image features a large blue frame on the left and a complex metallic apparatus with pipes and cylinders on the right. See caption for more detail.
Particle Image Velocimetry (PIV) diagnostic system installed in the Aero-Acoustic Propulsion Lab (AAPL). The PIV system measures the flow velocity across a planar region illuminated by a pulsed laser system. Cameras record the images of particles injected into the flow stream which are illuminated by the laser sheet to measure the flow velocity. The rendering shows the PIV system, installed on a large traverse which enables mapping the flow field velocities at several stations downstream from the jet exit. The effects of different types of flow mixers (internal and external to the jet) can be analyzed by measuring the flow field downstream from the jet. PIV velocity measurements at a few axial planes are shown near the nozzle exit.
NASA

Overview

Real Time Background Oriented Schlieren (RT-BOS) is a simple technique for measuring density gradients in shock laden flows. A small camera mounted on one side of a flow field is used to image a speckled image displayed on a large monitor on the opposite side. RT-BOS enables the image correlation processing that provides the density gradients across the imaged field to be performed in real time. RT-BOS is a valuable tool in some of our large test facilities as it provides a real-time indication of the set point/operating conditions in the flow. (POC: Mark Wernet)

The layout of the Aero-Acoustic Propulsion Lab is shown, where all the surfaces are covered in noise-absorbing wedges. The location of the BOS camera and 4K monitor are shown.
A Real Time Background Oriented Schlieren installation at the Aero-Acoustic Propulsion Laboratory (AAPL) at NASA’s Glenn Research Center in Cleveland. A small camera mounted on the wedge wall is used to image a speckled image displayed on a large monitor.
The shocks with the core flow stream are shown on top and bottom of the nozzle center plug.
This image shows the shock structure forming on a plug nozzle test article in the Aero-Acoustic Propulsion Laboratory (AAPL).
NASA

Particle Image Velocimetry

Particle Image Velocimetry is a laser-based flow field diagnostic that provides planar or volumetric maps of velocity vectors in subsonic and supersonic flows. (POC: Mark Wernet)

A green laser light sheet is illuminating a plane downstream from the exist of a twin rectangular jet nozzle.
Particle Image Velocimetry (PIV) installation in the Aero-Acoustic Propulsion Laboratory (AAPL) for a twinjet model investigation of the interaction of the two adjacent jet plumes for noise reduction. The laser light sheet is illuminating particles in the flow that are used to measure the jet flow velocity.
NASA

Raman Scattering

Rotationally Resolved Raman Scattering is a laser-based diagnostic for measuring gas temperature. (POC: Mark Wernet)

Implementation of the Raman scattering diagnostic system in the Aero-Acoustic Propulsion Laboratory (AAPL). The Raman system is mounted on a large traverse to enable measurements at multiple axial stations. The Raman collection optics are mounted on a smaller translation stage, which enables moving the measurement location to different heights above the film-cooled plate.
Implementation of the Raman scattering diagnostic system in the Aero-Acoustic Propulsion Laboratory (AAPL). The Raman system is mounted on a large traverse to enable measurements at multiple axial stations. The Raman collection optics are mounted on a smaller translation stage, which enables moving the measurement location to different heights above the film-cooled plate.
NASA
Line profiles of the measured gas temperature are shown above a film cooled plates. The spheres used as markers are color coded by their temperature.
Rotationally Resolved Raman scattering was used to acquire gas temperature measurements in a test where a heated jet flow is blowing over a plate equipped with film cooling. The colored symbols show line profiles of the gas temperature above the plate at various axial stations.
NASA

Rayleigh Scattering

Molecular Rayleigh scattering is a laser-based flow diagnostic that is capable of measuring gas density, temperature, and a single component of velocity, simultaneously. A time-resolved Rayleigh measurement system has been implemented in various aeroacoustics studies in the Aero-Acoustic Propulsion Laboratory (AAPL) and other free jet facilities at NASA Glenn in support of jet noise reduction research. (POC: Amy Fagan)

There are two green laser beams propagating through the flow field of a 1-inch diameter round nozzle flow and lens systems to image molecularly scattered light into optical fibers.
A Rayleigh scattering system installed in the CW-17 small free jet test rig in the Engine Research Building (ERB). The optical spectrum of the laser light scattered from gas molecules in the jet flow is analyzed with a Fabry-Perot interferometer to provide the gas flow properties at a single point in the flow. The system shown with two laser beams can be used to measure two spatially separated points in the flow simultaneously.
NASA

Contact

Area of ExpertiseResearcher NameEmail
Background Oriented SchlierenMark Wernetmark.p.wernet@nasa.gov
Particle Image VelocimetryMark Wernetmark.p.wernet@nasa.gov
Raman ScatteringMark Wernetmark.p.wernet@nasa.gov
Rayleigh ScatteringAmy Faganamy.fagan@nasa.gov

NASA Glenn facilities where this research is conducted:

Aero-Acoustic Propulsion Laboratory

With over 20 years of testing experience in acoustic research and development the AAPL is a world-class facility providing outstanding testing services in aircraft propulsion acoustic noise reduction and performance research.

Learn More about Aero-Acoustic Propulsion Laboratory
Nozzle Acoustic Test Rig (NATR) in the Aero-Acoustic Propulsion Laboratory
Nozzle Acoustic Test Rig (NATR) in the Aero-Acoustic Propulsion Laboratory.
NASA

Engine Research Building

Supporting research in all aspects of engine development, the ERB provides superior testing of turbomachinery, aerodynamics flow, physics, aeropropulsion heat transfer, mechanical components, and combustor facilities.

Learn More about Engine Research Building
NASA Glenn technician Ariana Miller checks the wheel mount and drive hardware assembly on a Curiosity wheel
NASA Glenn technician Ariana Miller checks the wheel mount and drive hardware assembly on a Curiosity wheel for tests at the Traction and Excavation Capabilities Lab.
NASA

Key Publications

Publication TitleAuthor(s)SourceTypeYear
Real-Time Background Oriented Schlieren Using a Digitally Generated and Displayed Speckle PatternWernet, M. P.Invited Presentation at AIAA ConferencePresentation2022
Plug20 Test Report: Particle Image Velocimetry (PIV) MeasurementsJames Bridges, Mark P. Wernet, Puja UpadhyayNASA TMReport2023
Particle Seeding System Upgrades in the NASA GRC 1′ × 1′ Supersonic Wind TunnelHeath H Reising, Puja Upadhyay, Mark P WernetAIAA Aviation PaperConference Paper2023
Noise of Internally Mixed Exhaust Systems with External Plug for Supersonic Transport ApplicationsBridges, J., Wernet, M.P. Conference Paper2022
Mach Number and Heating Effects on Turbulent Supersonic JetsGeorgiadis, N., Wernet, M.P., Locke, R. J., Eck, D.G.AIAA JournalJournal Article2023
PIV and Rotational Raman-Based Temperature Measurements for CFD Validation of a Perforated Plate Cooling Flow: Part IIPesich, J.M., Georgiadis, N.J., Wernet, M.P., Locke, R.J., Thurman, D.R., Poinsatte, P.E. Conference Paper2022
Summary of the 5th Propulsion Aerodynamics Workshop Nozzle Test Case: Heated Nozzle Exhaust Passing Over A Film-Cooled PlateGeorgiadis, N. J., Wernet, M.P., Crowe, D.S., Woeber, C.D., Karman-Shoemake, K.C., Winkler, C.M. Conference Paper2022
Velocity, Temperature, and Density Measurements in Supersonic JetsWernet, M.P., Georgiadis, N.J., Locke, R.J. Journal Article2021
Rayleigh-scattering-based measurement of ‘trapped waves’ in high-speed jetsFagan, Amy, and Zaman, KhairulAIAA AVIATION 2020, Virtual Meeting, June 2020, AIAA Paper No. 2020-2524.Conference Paper2020
Two-Point Dynamic Rayleigh Scattering Measurements in a Free JetFagan, Amy F., Elam, Kristie A., and Zaman, Khairul32nd AIAA Aerodynamic Measurement Technology and Ground Testing Conference, AIAA Aviation, June 2016, Washington, D.C., Paper no. AIAA-2016-3109Conference Paper2016
Enthalpy-Flux/Momentum-Flux Coupling in the Acoustic Spectrum of Heated JetsAfsar, Muhammad Z., Goldstein, Marvin E., and Fagan, Amy F.AIAA Journal, vol. 49, No. 11, 2011, pp. 2522-2531.Journal Article2011
Hot Jets and Sources of Jet NoiseKhavaran, Abbas, Kenzakowski, Donald C., and Mielke-Fagan, Amy F.International Journal of Aeroacoustics, vol. 9, No. 4 & 5, 2010, pp. 491-532.Journal Article2010
Dynamic Measurement of Temperature, Velocity, and Density in Hot Jets Using Rayleigh ScatteringMielke, Amy F. and Elam, Kristie A.Experiments in Fluids, Vol. 47, No. 4, October 2009, pp. 673-688.Journal Article2009
Multiproperty Measurements at High Sampling Rates Using Rayleigh ScatteringMielke, Amy F., Elam, Kristie A., and Sung, Chih-JenAIAA Journal, Vol. 47, No. 4, April 2009, pp. 850-862.Journal Article2009

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