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Results for “RADIAL FLOW”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Evidence for the Collective Nature of Radial Flow in Pb+Pb Collisions with the ATLAS Detector

Anisotropic flow and radial flow are two key probes of the expansion dynamics and properties of the quark-gluon plasma (QGP). While anisotropic flow has been extensively studied, radial flow, which governs the system’s radial expansion, has received less attention. Notably, direct experimental evidence for the global and collective nature of radial flow fluctuations has been lacking. This Letter presents the first measurement of transverse momentum (𝑝 T ) dependence of radial flow fluctuations (𝑣 0 ⁡(𝑝 T )) over 0.5 < 𝑝 T < 10 GeV and demonstrates its collective nature using a two-particle correlation method in Pb+Pb collisions at $\sqrt{𝑠_{NN}}$ = 5.02 TeV. The data reveal three key features supporting the collective nature of radial flow: long-range correlation in pseudorapidity, factorization in 𝑝 T , and centrality-independent shape in 𝑝 T . The comparison with a hydrodynamic model demonstrates the sensitivity of 𝑣 0 ⁡(𝑝 T ) to bulk viscosity, a crucial transport property of the QGP. These findings establish a new, powerful tool for probing collective dynamics and properties of the QGP.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1992

Raman scattering of InGaAs/InP grown by uniform radial flow epitaxy

Uniform radial flow epitaxy, a novel growth technique, has been used to grown InGaAs films on InP. Epitaxial layers above and below the critical thickness for the onset of slip were grown. Raman spectroscopy was used to characterize the quality of epitaxial layers, determine alloy composition, and measure the strain. Raman spectra from both pseudomorphic (strained) and relaxed (unstrained) InGaAs films were obtained at 300 and 80 K. The difference in the frequencies of their GaAs-like longitudinal optical phonons was used to calculate stress for the strained InGaAs/InP, leading to a direct formula for the evaluation of the layer stress.

Feng, Z. C.↗
DOE OSTI2025

Imaging nuclear shape through anisotropic and radial flow in high-energy heavy-ion collisions

Most atomic nuclei exhibit ellipsoidal shapes characterized by quadrupole deformation β 2 and triaxiality γ, and sometimes even a pear-like octupole deformation β 3 . The STAR experiment introduced a new ‘imaging-by-smashing’ technique to image the nuclear global shape by colliding nuclei at ultra-relativistic speeds and analyzing outgoing debris. Features of nuclear shape manifest in collective observables like anisotropic flow vn and radial flow via mean transverse momentum [p T ]. We present new measurements of the variances of v n (n = 2, 3, and 4) and [p T ], and the covariance of $v$$^{2}_{n}$ with [p T ], in collisions of highly deformed 238 U and nearly spherical 197 Au. Ratios of these observables between the two systems effectively suppress common final-state effects, isolating the strong impact of uranium’s deformation. By comparing results with state-of-the-art hydrodynamic model calculations, we extract β 2U and γ U values consistent with those deduced from low-energy nuclear structure measurements. Measurements of v 3 and its correlation with [p T ] also provide the first experimental suggestion of a possible octupole deformation for 238 U. These findings provide significant support for using high-energy collisions to explore nuclear shapes on femtosecond timescales, with implications for both nuclear structure and quark-gluon plasma studies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2000

Radial Flows in Supergranules

We determine the radial component of the supergranular flow velocity by examining the center-to-limb variation of the Doppler velocity signal. We acquire individual Doppler images obtained with the MDI instrument on the SOHO spacecraft and process them to remove the p-mode oscillation signal, the axisymmetric flows, the convective blueshift signal, and instrumental artifacts. The remaining Doppler signal contains only cellular flow structures. The Doppler signal from the horizontal flows in these cells varies like sin p, where p is the heliocentric angle from disk center. The Doppler signal from radial flows varies like cos p. We fit the center-to-limb variation of the mean squared velocity signal to a straight line in sin(exp 2) rho over the central portion of the disk. The intercept of this line at disk center gives the amplitude of the radial component of the flow. The slope of the line gives the amplitude of the horizontal component. We find that the radial flows for typical supergranules have speeds about 10% that of their associated horizontal flows or about 30 m/s. The ratio of the radial to horizontal flow speed increases from 9% to about 18% as the size of the cells decreases from > 60 Mm to approximately 5 Mm. We use data simulations to check these results and find a ratio that increases from 5% to only about 12% over the same range of cell sizes. These smaller ratios are attributed to an underestimation of the horizontal flow speeds due to the fact that, the transverse component of the horizontal flow is not detected by the Doppler measurements.

Hathaway, D. H.↗
NASA NTRS1986

Laser velocimeter measurements in shrouded and unshrouded radial flow pump impellers

Shrouded and unshrouded versions of a four-vaned radial flow impeller with a design flow coefficient of 0.063 were tested in a volute pump using a two-component frequency-shifted laser velocimeter. Velocity profiles were measured at six flow rates and at four radial and six circumferential positions in the volute. The variations of the velocity from blade to blade and in the axial direction were measured and are presented. A passage vortex caused by tip leakage and relative casing wall velocity was found in the unshrouded impeller. The tip leakage did not accumulate in the suction wake region; the suction wake region was only 30 to 50 percent as large in the unshrouded impeller as compared to the shrouded impeller. The slip was 30 percent higher in the unshrouded impeller and the variation of slip with flow rate is presented. At no measured position in the impellers did the slip factor reach unity; the closest approach was 0.90. Reverse loadings of the vanes at outer radii were found for flow rates below the impeller/volute matching point for both impellers.

Hamkins, C. P.↗
NASA NTRS1995

Non-radial flow in the solar wind

Although the radial component of the solar wind dominates the solar wind speed, significant non-radial velocity components are also present. These flows are more difficult to measure accurately, but we now have data sets including the east-west (tangential) and north-south (normal) flows from PVO at Venus, IMP 8 at Earth, and Voyagers 1 and 2 from 1 to 45 AU. We compare the non-radial flow observations from these spacecraft. One of the more interesting features is that the north-south flow angle observed at Earth and Venus oscillates with the period of a local (Earth or Venus) year. These oscillations occur throughout two solar cycles in the IMP 8 data set and are very apparent in the PVO data from 1978 to 1986 but less obvious after this. We will report on the origin of this feature. The tangential flow observed by both IMP 8 and Voyager is on average slightly positive (approximately 1.75 km/s). The magnitudes of the nonradial velocity components decrease with distance from the Sun.

Richardson, J. D.↗
DOE OSTI2026

Long-Range Transverse-Momentum Correlations and Radial Flow in Pb-Pb Collisions at the LHC

This Letter presents measurements of long-range transverse-momentum correlations using a new observable, 𝑣 0⁡ (𝑝 T ), serving as a probe of event-by-event radial-flow fluctuations, the underlying radial expansion, and the medium’s properties in heavy-ion collisions. Results are reported for inclusive charged particles, pions, kaons, and protons across various centrality intervals in Pb-Pb collisions at $\sqrt{𝑠_{\textrm{NN}}}$ = 5.02 TeV, recorded by the ALICE detector. A pseudorapidity-gap technique, similar to that used in anisotropic-flow studies, is employed to suppress short-range correlations. At low 𝑝 T , a characteristic mass ordering consistent with hydrodynamic collective flow is observed. At higher 𝑝 T (>3 GeV/𝑐), protons exhibit larger 𝑣 0 ⁡(𝑝 T ) than pions and kaons, in agreement with expectations from quark-recombination models. Comparisons to viscous hydrodynamic calculations with varying bulk viscosity and equation of state demonstrate the sensitivity of the 𝑣 0 ⁡(𝑝 T ) observable to these key medium properties. The findings establish 𝑣 0 ⁡(𝑝 T ) as a valuable addition to the set of observables used in Bayesian analyses for extracting the transport properties and constraining the equation of state of strongly interacting matter, while also helping to systematically explore its sensitivity and impact within such global studies.

Acharya, S. [INFN] (ORCID:0000000292135329)↗
DOE OSTI2026

Electromagnetic Tomography of Radial Flow in the Quark-Gluon Plasma

We present a novel multimessenger approach to extract the effective radial flow of the quark-gluon plasma (QGP) by jointly analyzing thermal photon and dilepton spectra in heavy-ion collisions. A key feature of this method is that it circumvents the need for a directly unmeasurable reference—the photon temperature in the absence of flow—by establishing, within a calibrated model framework, a stable, approximately linear correlation with the dilepton-inferred temperature. This construction defines an experimentally constructible quantity, 𝑣$^{eff}_{𝑟}$, which reflects early-time collectivity and exhibits a strong correlation with the spacetime-averaged radial velocity of the QGP. Together with previous results linking dilepton slopes to the initial QGP temperature, our work establishes a consistent framework for electromagnetic tomography of the QGP. Here, our framework quantifies the experimental precision target, thereby providing a concrete road map for future measurements at RHIC and the LHC and opening a new avenue to probe the early-time dynamics of hot QCD matter.

Collective flow↗
NASA NTRS1959

Estimated Performance of Radial-Flow Exit Nozzles for Air in Chemical Equilibrium

The thrust, boundary-layer, and heat-transfer characteristics were computed for nozzles having radial flow in the divergent part. The working medium was air in chemical equilibrium, and the boundary layer was assumed to be all turbulent. Stagnation pressure was varied from 1 to 32 atmospheres, stagnation temperature from 1000 to 6000 R, and wall temperature from 1000 to 3000 R. Design pressure ratio was varied from 5 to 320, and operating pressure ratio was varied from 0.25 to 8 times the design pressure ratio. Results were generalized independent of divergence angle and were also generalized independent of stagnation pressure in the temperature range of 1000 to 3000 R. A means of determining the aerodynamically optimum wall angle is provided.

Englert, Gerald W.↗
NASA NTRS1989

An interactive grid generation procedure for axial and radial flow turbomachinery

A combination algebraic/elliptic technique is presented for the generation of three dimensional grids about turbo-machinery blade rows for both axial and radial flow machinery. The technique is built around use of an advanced engineering workstation to construct several two dimensional grids interactively on predetermined blade-to-blade surfaces. A three dimensional grid is generated by interpolating these surface grids onto an axisymmetric grid. On each blade-to-blade surface, a grid is created using algebraic techniques near the blade to control orthogonality within the boundary layer region and elliptic techniques in the mid-passage to achieve smoothness. The interactive definition of bezier curves as internal boundaries is the key to simple construction. This procedure lends itself well to zonal grid construction, an important example being the tip clearance region. Calculations done to date include a space shuttle main engine turbopump blade, a radial inflow turbine blade, and the first stator of the United Technologies Research Center large scale rotating rig. A finite Navier-Stokes solver was used in each case.

Beach, Timothy A.↗
NASA NTRS1990

An interactive grid generation procedure for axial and radial flow turbomachinery

A combination algebraic/elliptic technique is presented for the generation of three dimensional grids about turbo-machinery blade rows for both axial and radial flow machinery. The technique is built around use of an advanced engineering workstation to construct several two dimensional grids interactively on predetermined blade-to-blade surfaces. A three dimensional grid is generated by interpolating these surface grids onto an axisymmetric grid. On each blade-to-blade surface, a grid is created using algebraic techniques near the blade to control orthogonality within the boundary layer region and elliptic techniques in the mid-passage to achieve smoothness. The interactive definition of bezier curves as internal boundaries is the key to simple construction. This procedure lends itself well to zonal grid construction, an important example being the tip clearance region. Calculations done to date include a space shuttle main engine turbopump blade, a radial inflow turbine blade, and the first stator of the United Technologies Research Center large scale rotating rig. A finite Navier-Stokes solver was used in each case.

Beach, T. A.↗
DOE OSTI2026

Characterizing radial flow fluctuations in relativistic heavy-ion collisions at top RHIC and LHC energies

This study presents a systematic investigation of the transverse-momentum differential radial flow fluctuations observable 𝑣 0 ⁡ (𝑝 𝑇 ) in relativistic heavy-ion collisions at top Relativistic Heavy Ion Collider ($\sqrt{s_{NN}}$ = 200 GeV) and Large Hadron Collider ($\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV) energies. Using a multistage hydrodynamic model, this study assesses the sensitivity of 𝑣 0 ⁡(𝑝 𝑇 ) to a wide range of physical effects, including bulk and shear viscosities, off-equilibrium corrections at particlization, the presence of a hadronic afterburner, and the nucleon size in the initial conditions. By employing complementary rescaling strategies, this study demonstrates how different physical effects leave distinct imprints on the shape of 𝑣 0 ⁡(𝑝 𝑇 ). A combined double-rescaling of 𝑣 0 ⁡(𝑝 𝑇 )/𝑣 0 versus 𝑝 𝑇 /⟨𝑝 𝑇 ⟩ reveals a universality across a wide range of energies and model assumptions in the low-𝑝 𝑇 regime, a robust signature of collective behavior. This allows us to disentangle the universal dynamics of the bulk medium from model-specific features that emerge at higher 𝑝 𝑇 . These results establish 𝑣 0⁡ (𝑝 𝑇 ) as a powerful and complementary observable for constraining quark-gluon plasma transport properties and initial-state granularity, offering a unique probe of the created QCD medium.

Du, Lipei [University of California, Berkeley, CA ↗
DOE OSTI2025

Multi-scale dynamic modeling and validation of radial flow fixed bed contactors for post-combustion CO 2 capture using bench scale and pilot plant data

Here, in this work, a multi-scale model of a radial flow fixed bed contactor packed with a carbon sorbent is developed and validated with laboratory-scale and pilot plant scale dynamic data. For the lab scale system, the model results were compared with low, medium and high gas and sweep flowrates, yielding root mean square error (RMSE) of 0.80, 0.63, 0.96 CO 2 mol%, respectively, for the outlet CO 2 concentration profile considering the entire A-D cycle. For the bed outer temperature profile, maximum RMSE was found to be 5.5 °C considering all flowrates and entire A-D cycles. An experimental campaign was developed and applied to a pilot plant at Technology Center Mongstad (TCM), Norway. Approaches were developed for pre-processing of data including consideration of the effect of gas mixing, measurement delay, and determination of cyclic steady-state conditions. Considering profiles during A-D cycles for all test runs, it was found that the maximum RMSE for pressure drop, temperature for the outer section of the bed, temperature for the middle section of the bed, and outlet CO 2 concentration profile remained less than 1.5 mbar, 3.5 °C, 2.8 °C, and 1.3 CO 2 mol%, respectively. The validated model was used to perform sensitivity studies on several key design operating variables for the adsorption-desorption cycle. It was found that the flow rate and concentration of flue gas have dominant nonlinear effects on the breakthrough time while the desorption time was strongly affected by the sweep gas flowrate for the specific sorbent being evaluated in this study.

20 FOSSIL-FUELED POWER PLANTS↗