C. Randall Truman | University of New Mexico (original) (raw)

Papers by C. Randall Truman

International Journal of Computational Methods and Experimental Measurements, Oct 31, 2017

Daltons and Amagats laws (also known as the law of partial pressures and the law of partial volum... more Daltons and Amagats laws (also known as the law of partial pressures and the law of partial volumes respectively) are two well-known thermodynamic models describing gas mixtures. Our current research is focused on determining the suitability of these models in predicting effects of shock propagation through gas mixtures. Experiments are conducted at the Shock Tube Facility at the University of New Mexico (UNM). The gas mixture used in these experiments consists of approximately 50% sulfur hexafluoride (SF6) and 50% helium (He) by moles. Fast response pressure transducers are used to obtain pressure readings both before and after the shock wave; these data are then used to determine the velocity of the shock wave. Temperature readings are obtained using an ultra-fast mercury cadmium telluride (MCT) infrared (IR) detector, with a response time on the order of nanoseconds. Coupled with a stabilized broadband infrared light source (operating at 1500 K), the detector provides pre-and postshock line-of-sight readings of average temperature within the shock tube, which are used to determine the speed of sound in the gas mixture. Paired with the velocity of the shock wave, this information allows us to determine the Mach number. These experimental results are compared with theoretical predictions of Daltons and Amagats laws to determine which one is more suitable.

Annual Interceptor Technology Conference

... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wa... more ... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wall region of a turbulent channel flow, for example, large scalar fluctuations which occupy only about 30 percent of the volume produce about 60 percent of the phase error.

23rd Thermophysics, Plasmadynamics and Lasers Conference

A thin-shear-layer computational method and semiempirical model for optical degradation were used... more A thin-shear-layer computational method and semiempirical model for optical degradation were used to assess the optical quality of four different supersonic shear layers. The shear layers were designed to represent the mixing layer formed between the high-speed stream of an aerowindow and a low-speed atmospheric stream. The mixing layers differed only in window gas composition (Ar, N2, He, 0.62 He/0.38 Ar). Predicted time-averaged quantities were used in the semiempirical correlation to predict optical quality. While the predictions reproduce the ranking of the optical quality of the gases seen experimentally, an absolute comparison with the measured optical degradation was less than satisfactory. Differences between the predictions and measurements are discussed and an adjustment to the correlation constant which greatly enhanced agreement is described.

We present an experimental study of planar shock interaction with an initially cylindrical, diffu... more We present an experimental study of planar shock interaction with an initially cylindrical, diffuse density interface, where the angle α between the plane of the shock and the axis of the cylinder can be zero (planar normal interaction) or non-zero (oblique interaction). The interface is formed by injecting a laminar jet of a heavy gas mixture (sulfur hexafluoride, acetone, nitrogen) into quiescent air. The jet is stabilized by an annular co-flow of air to minimize diffusion. Interaction between the pressure gradient (shock front) and density gradient leads to vorticity deposition, and during the subsequent evolution, the flow undergoes mixing (injected material-air) and eventually transitions to turbulence. Several parameters affect this evolution, including the angle α, the Atwood number (density ratio), and the Mach number of the shock. For quantitative and qualitative characterization of the influence of these parameters, we use flow visualization in two planes that relies on planar laser-induced fluorescence (PLIF) in acetone, which forms part of the injected material.

The deflection of a thin laser beam as it passes through a heated jet was estimated using tempera... more The deflection of a thin laser beam as it passes through a heated jet was estimated using temperature signals as references. Various positions and time lags for the temperature probes were investigated to provide the best possible prediction of beam deflection using Linear Stochastic Estimation (LSE). In the near-field of the jet, as few as two temperature probes provided sufficient

Abstract A model based on a transport equation for the variance of index-of-refraction fluctuatio... more Abstract A model based on a transport equation for the variance of index-of-refraction fluctuations in a turbulent shear layer is proposed for predicting optical degradation. The model avoids making a mixing-length assumption to relate the phase error to the time-...

... 4:23 PM–4:36 PM. Preview Abstract. Authors: C. Randall Truman Amol Palekar Peter Vorobieff (U... more ... 4:23 PM–4:36 PM. Preview Abstract. Authors: C. Randall Truman Amol Palekar Peter Vorobieff (Univ. of New Mexico). Predictions of a sonic jet of air or helium injected into a Mach 2 crossflow are presented. The injection is transverse, characterized as a jet in crossflow (JICF). ...

Experiments were conducted on a scale model thermal storage tank to study the initial formation o... more Experiments were conducted on a scale model thermal storage tank to study the initial formation of the thermocline in a cold water tank and to identify the factors affecting thermocline formation. By means of flow visualization, a traveling density current was found to be the preferred dominant mechanism in formation of the thermocline. Also the inlet densimetric Froude number was

33rd Plasmadynamics and Lasers Conference, 2002

Laser wavefront diagnostics of a heated mixing layer. Pat Chavez, C Randall Truman 33 rd AIAA Pla... more Laser wavefront diagnostics of a heated mixing layer. Pat Chavez, C Randall Truman 33 rd AIAA Plasmadynamics and Lasers Conference, Maui, HI, 2002. The wavefront aberration of a collimated laser beam propagating through a heated mixing layer is studied. ...

The problem of a planar shock interaction with gas curtains (cylinders) whose plane (axis) of sym... more The problem of a planar shock interaction with gas curtains (cylinders) whose plane (axis) of symmetry is parallel to the plane of the shock has been well studied both experimentally and numerically, and in this case, the flow evolution driven by Richtmyer-Meshkov instability is well characterized. However, for a similar oblique interaction, with the plane of the shock and the plane (axis) of the density interface being non-parallel, presently only numerical results exist. This problem, however, would be quite interesting to study experimentally both because of a variety of relevant applications and because oblique shock interaction adds large-scale three-dimensionality to the initial conditions. Here we report on the progress of our work on the development of a tiltable Mach 3 shock tube designed specifically to produce such oblique shock interactions and equipped with diagnostics suitable for studies of three-phase flow (light gas, heavy gas, and particles/droplets). The presence of the droplets (or particles) introduces several additional interesting issues here, including the possible effect of shock focusing on the non-gaseous phase carried by the flow.

ABSTRACT We present quantitative analysis of image sequences of multi-stream injection nozzle flo... more ABSTRACT We present quantitative analysis of image sequences of multi-stream injection nozzle flows with several different injection geometries. Image sequences were acquired by A.M. Ragheb and G.S. Elliott (UIUC) using planar laser-induced fluorescence (PLIF) in iodine to visualize flow mixing. The injection nozzle was comprised of a slot, ejector and injector block, with rows of ejector and injector holes along the slot length. The ejector flow exits in an underexpanded state so that upon expanding it forces the slot and injector flows together to enhance mixing. For this study, the diameter and geometry of ejector holes were varied to assess their effect on mixing. Two configurations of ejector holes were used, each with two different diameters for a total of 4 cases with data collected at downstream stations. We carried out a quantitative mixing analysis for these configurations, using two parameters to quantify the mixing. The first parameter, the mixing quality criterion, is assessed from the statistics of the PLIF image intensity histograms, which are bimodal for poorly-mixed flows and have a single peak in well-mixed flows. The second parameter is mixing interface length. Our analysis shows that one injection scheme significantly enhances mixing by stretching the mixing interface.

ABSTRACT When a planar shock wave generated in a shock tube accelerates a nominally two-dimension... more ABSTRACT When a planar shock wave generated in a shock tube accelerates a nominally two-dimensional density interface, the large-scale flow structure is usually regarded as quasi-two-dimensional. We examine the limitations of this assumption due to interaction with wall boundary layers, growth of three-dimensional instabilities, and other factors. The initial conditions are produced by a laminar cylindrical jet of gas vertically injected into the test section of the shock tube. Flow visualization images in several planes intersecting the flow reveal a non-trivial three-dimensional structure. Experiments are conducted both for ``classical'' Richtmyer-Meshkov instability and for its multiphase analog induced by particle seeding.

AIAA and SDIO, Annual Interceptor Technology …, 1992

... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wa... more ... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wall region of a turbulent channel flow, for example, large scalar fluctuations which occupy only about 30 percent of the volume produce about 60 percent of the phase error.

A thin-shear-layer computational method and semiempirical model for optical degradation were used... more A thin-shear-layer computational method and semiempirical model for optical degradation were used to assess the optical quality of four different supersonic shear layers. The shear layers were designed to represent the mixing layer formed between the high-speed stream of an aerowindow and a low-speed atmospheric stream. The mixing layers differed only in window gas composition (Ar, N2, He, 0.62 He/0.38 Ar). Predicted time-averaged quantities were used in the semiempirical correlation to predict optical quality. While the predictions reproduce the ranking of the optical quality of the gases seen experimentally, an absolute comparison with the measured optical degradation was less than satisfactory. Differences between the predictions and measurements are discussed and an adjustment to the correlation constant which greatly enhanced agreement is described.

Journal of Fluids Engineering, 1980

In accordance with the provisions of this statute, 1 hereby requatt permission to moll the public... more In accordance with the provisions of this statute, 1 hereby requatt permission to moll the publication named In Item 1 at the phased postage rates presently authorized by 39 U. S. C. 3626.

International Journal of Computational Methods and Experimental Measurements, Oct 31, 2017

Daltons and Amagats laws (also known as the law of partial pressures and the law of partial volum... more Daltons and Amagats laws (also known as the law of partial pressures and the law of partial volumes respectively) are two well-known thermodynamic models describing gas mixtures. Our current research is focused on determining the suitability of these models in predicting effects of shock propagation through gas mixtures. Experiments are conducted at the Shock Tube Facility at the University of New Mexico (UNM). The gas mixture used in these experiments consists of approximately 50% sulfur hexafluoride (SF6) and 50% helium (He) by moles. Fast response pressure transducers are used to obtain pressure readings both before and after the shock wave; these data are then used to determine the velocity of the shock wave. Temperature readings are obtained using an ultra-fast mercury cadmium telluride (MCT) infrared (IR) detector, with a response time on the order of nanoseconds. Coupled with a stabilized broadband infrared light source (operating at 1500 K), the detector provides pre-and postshock line-of-sight readings of average temperature within the shock tube, which are used to determine the speed of sound in the gas mixture. Paired with the velocity of the shock wave, this information allows us to determine the Mach number. These experimental results are compared with theoretical predictions of Daltons and Amagats laws to determine which one is more suitable.

Annual Interceptor Technology Conference

... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wa... more ... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wall region of a turbulent channel flow, for example, large scalar fluctuations which occupy only about 30 percent of the volume produce about 60 percent of the phase error.

23rd Thermophysics, Plasmadynamics and Lasers Conference

A thin-shear-layer computational method and semiempirical model for optical degradation were used... more A thin-shear-layer computational method and semiempirical model for optical degradation were used to assess the optical quality of four different supersonic shear layers. The shear layers were designed to represent the mixing layer formed between the high-speed stream of an aerowindow and a low-speed atmospheric stream. The mixing layers differed only in window gas composition (Ar, N2, He, 0.62 He/0.38 Ar). Predicted time-averaged quantities were used in the semiempirical correlation to predict optical quality. While the predictions reproduce the ranking of the optical quality of the gases seen experimentally, an absolute comparison with the measured optical degradation was less than satisfactory. Differences between the predictions and measurements are discussed and an adjustment to the correlation constant which greatly enhanced agreement is described.

We present an experimental study of planar shock interaction with an initially cylindrical, diffu... more We present an experimental study of planar shock interaction with an initially cylindrical, diffuse density interface, where the angle α between the plane of the shock and the axis of the cylinder can be zero (planar normal interaction) or non-zero (oblique interaction). The interface is formed by injecting a laminar jet of a heavy gas mixture (sulfur hexafluoride, acetone, nitrogen) into quiescent air. The jet is stabilized by an annular co-flow of air to minimize diffusion. Interaction between the pressure gradient (shock front) and density gradient leads to vorticity deposition, and during the subsequent evolution, the flow undergoes mixing (injected material-air) and eventually transitions to turbulence. Several parameters affect this evolution, including the angle α, the Atwood number (density ratio), and the Mach number of the shock. For quantitative and qualitative characterization of the influence of these parameters, we use flow visualization in two planes that relies on planar laser-induced fluorescence (PLIF) in acetone, which forms part of the injected material.

The deflection of a thin laser beam as it passes through a heated jet was estimated using tempera... more The deflection of a thin laser beam as it passes through a heated jet was estimated using temperature signals as references. Various positions and time lags for the temperature probes were investigated to provide the best possible prediction of beam deflection using Linear Stochastic Estimation (LSE). In the near-field of the jet, as few as two temperature probes provided sufficient

Abstract A model based on a transport equation for the variance of index-of-refraction fluctuatio... more Abstract A model based on a transport equation for the variance of index-of-refraction fluctuations in a turbulent shear layer is proposed for predicting optical degradation. The model avoids making a mixing-length assumption to relate the phase error to the time-...

... 4:23 PM–4:36 PM. Preview Abstract. Authors: C. Randall Truman Amol Palekar Peter Vorobieff (U... more ... 4:23 PM–4:36 PM. Preview Abstract. Authors: C. Randall Truman Amol Palekar Peter Vorobieff (Univ. of New Mexico). Predictions of a sonic jet of air or helium injected into a Mach 2 crossflow are presented. The injection is transverse, characterized as a jet in crossflow (JICF). ...

Experiments were conducted on a scale model thermal storage tank to study the initial formation o... more Experiments were conducted on a scale model thermal storage tank to study the initial formation of the thermocline in a cold water tank and to identify the factors affecting thermocline formation. By means of flow visualization, a traveling density current was found to be the preferred dominant mechanism in formation of the thermocline. Also the inlet densimetric Froude number was

33rd Plasmadynamics and Lasers Conference, 2002

Laser wavefront diagnostics of a heated mixing layer. Pat Chavez, C Randall Truman 33 rd AIAA Pla... more Laser wavefront diagnostics of a heated mixing layer. Pat Chavez, C Randall Truman 33 rd AIAA Plasmadynamics and Lasers Conference, Maui, HI, 2002. The wavefront aberration of a collimated laser beam propagating through a heated mixing layer is studied. ...

The problem of a planar shock interaction with gas curtains (cylinders) whose plane (axis) of sym... more The problem of a planar shock interaction with gas curtains (cylinders) whose plane (axis) of symmetry is parallel to the plane of the shock has been well studied both experimentally and numerically, and in this case, the flow evolution driven by Richtmyer-Meshkov instability is well characterized. However, for a similar oblique interaction, with the plane of the shock and the plane (axis) of the density interface being non-parallel, presently only numerical results exist. This problem, however, would be quite interesting to study experimentally both because of a variety of relevant applications and because oblique shock interaction adds large-scale three-dimensionality to the initial conditions. Here we report on the progress of our work on the development of a tiltable Mach 3 shock tube designed specifically to produce such oblique shock interactions and equipped with diagnostics suitable for studies of three-phase flow (light gas, heavy gas, and particles/droplets). The presence of the droplets (or particles) introduces several additional interesting issues here, including the possible effect of shock focusing on the non-gaseous phase carried by the flow.

ABSTRACT We present quantitative analysis of image sequences of multi-stream injection nozzle flo... more ABSTRACT We present quantitative analysis of image sequences of multi-stream injection nozzle flows with several different injection geometries. Image sequences were acquired by A.M. Ragheb and G.S. Elliott (UIUC) using planar laser-induced fluorescence (PLIF) in iodine to visualize flow mixing. The injection nozzle was comprised of a slot, ejector and injector block, with rows of ejector and injector holes along the slot length. The ejector flow exits in an underexpanded state so that upon expanding it forces the slot and injector flows together to enhance mixing. For this study, the diameter and geometry of ejector holes were varied to assess their effect on mixing. Two configurations of ejector holes were used, each with two different diameters for a total of 4 cases with data collected at downstream stations. We carried out a quantitative mixing analysis for these configurations, using two parameters to quantify the mixing. The first parameter, the mixing quality criterion, is assessed from the statistics of the PLIF image intensity histograms, which are bimodal for poorly-mixed flows and have a single peak in well-mixed flows. The second parameter is mixing interface length. Our analysis shows that one injection scheme significantly enhances mixing by stretching the mixing interface.

ABSTRACT When a planar shock wave generated in a shock tube accelerates a nominally two-dimension... more ABSTRACT When a planar shock wave generated in a shock tube accelerates a nominally two-dimensional density interface, the large-scale flow structure is usually regarded as quasi-two-dimensional. We examine the limitations of this assumption due to interaction with wall boundary layers, growth of three-dimensional instabilities, and other factors. The initial conditions are produced by a laminar cylindrical jet of gas vertically injected into the test section of the shock tube. Flow visualization images in several planes intersecting the flow reveal a non-trivial three-dimensional structure. Experiments are conducted both for ``classical'' Richtmyer-Meshkov instability and for its multiphase analog induced by particle seeding.

AIAA and SDIO, Annual Interceptor Technology …, 1992

... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wa... more ... Authors: Truman, CR. Affiliation: AA(New Mexico, University, Albuquerque). ... In the near-wall region of a turbulent channel flow, for example, large scalar fluctuations which occupy only about 30 percent of the volume produce about 60 percent of the phase error.

A thin-shear-layer computational method and semiempirical model for optical degradation were used... more A thin-shear-layer computational method and semiempirical model for optical degradation were used to assess the optical quality of four different supersonic shear layers. The shear layers were designed to represent the mixing layer formed between the high-speed stream of an aerowindow and a low-speed atmospheric stream. The mixing layers differed only in window gas composition (Ar, N2, He, 0.62 He/0.38 Ar). Predicted time-averaged quantities were used in the semiempirical correlation to predict optical quality. While the predictions reproduce the ranking of the optical quality of the gases seen experimentally, an absolute comparison with the measured optical degradation was less than satisfactory. Differences between the predictions and measurements are discussed and an adjustment to the correlation constant which greatly enhanced agreement is described.

Journal of Fluids Engineering, 1980

In accordance with the provisions of this statute, 1 hereby requatt permission to moll the public... more In accordance with the provisions of this statute, 1 hereby requatt permission to moll the publication named In Item 1 at the phased postage rates presently authorized by 39 U. S. C. 3626.