About

Jesse Little is the Director of the Aerospace Research Center and a Professor of Mechanical and Aerospace Engineering at The Ohio State University. His role involves leading research initiatives within the Aerospace Research Center, which is part of the College of Engineering. His work focuses on aerospace research, including areas such as aerodynamics, flow control, gas turbine engines, hypersonics, uncrewed aircraft systems, and automotive aeroacoustics. He is actively engaged in industry collaboration and research, contributing to advancements in aerospace technology and engineering.

Research topics

• Physics
• Mechanics
• Materials science
• Optics
• Composite material
• Aerospace engineering
• Geometry
• Mathematics
• Electrical engineering
• Engineering

Selected publications

• 3D Shock/Boundary Layer Interaction on a Delta Wing With a Compression Ramp

  2026-01-08

  articleSenior author

  This paper discusses an experimental study of a 3D shock/boundary layer interaction caused by various boundary layer states interacting with a highly swept delta wing with a trailing-edge compression ramp. A flat delta wing was also tested to explore boundary layer transition physics apart from the shock/boundary layer interaction itself. Experiments were conducted at Mach 6 in The Ohio State University Large Area Reflected Shock tunnel for unit Reynolds numbers ranging from 2.7 M/m to 8.6 M/m and wall temperature ratios (T

  PublisherDOI

• Numerical and Experimental Investigations of Transition in a Laminar Separation Bubble

  IUTAM bookseries · 2026-01-01

  book-chapter
  PublisherDOI

• The Ohio State University Large-Area Reflected Shock Tunnel: Overview and Characterization

  2026-01-08

  articleSenior author

  The Large Area Reflected Shock Tunnel at The Ohio State University Aerospace Research Center has been recommissioned and characterized to provide a large-scale university platform for experimental hypersonics research and testing. This paper documents the facility charac- teristics, operational envelopes, and flow quality. The facility features a 45-in diameter nozzle attached to a 9-ft diameter test cabin, enabling operation as a free jet. The current operational capability with air as a driver gas includes Mach numbers of 6, 7 and 8, with stagnation enthalpies up to approximately 2.2 MJ kg^−1 and unit Reynolds numbers ranging from 0.1 to 100 ×10^6 m^−1. The use of a helium driver extends the achievable enthalpy to approximately 7.8 MJ kg^−1 and permits operation to Mach 12+. LARS can be operated in either reflected shock or blowdown modes with typical run times of a few tens of ms and 150ms, respectively. Characterization measurements with a pitot-probe rake indicate mean flow uniformity of approximately 1% and freestream noise levels near 2% with spectral content that is consistent with other conventional hypersonic tunnels.

  PublisherDOI

• Transition and Separation Over a Hollow Cylinder-Flare at Mach 5

  2025-01-03

  articleSenior author
  PublisherDOI

• Structure and Unsteadiness of Fin-Induced Transitional Shock Boundary Layer Interactions at Mach 5

  2025-01-03

  articleSenior author
  PublisherDOI

• Mean Flow and Heat Flux Analysis of Swept Shock/Boundary Layer Interactions

  2025-01-03

  articleSenior author

  Mean static pressure and heat flux measurements using IR thermography are used to characterize swept impinging oblique shock/boundary layer interactions. Shock generators creating the interaction are swept back by 10°, 20°, 30° and 40° with the deflection angles adjusted to achieve the same increase in inviscid pressure coefficient normal to the shock (C_pn). This is done in an attempt to make the cases comparable and isolate the sweep influence. The incoming boundary layer is turbulent with M_infinity = 2.3. Static pressure measurements provide deeper insight into the mean flow field and the effect of sweep angle variation with constant C_pn. Heat flux measurements at varying wall temperatures are used to determine the adiabatic wall temperature (T_aw) and temperature recovery factor over the interaction. Results show that T_aw changes over the interaction. Local T_aw values are used to calculate Stanton number. It is shown that the common assumption of a constant T_aw leads to not only an absolute error but also to the Stanton number becoming dependent on the wall temperature. Finally, pressure, Stanton number and oil flow data are overlapped allowing the linking of Stanton number and surface pressure to near-wall flow features.

  PublisherDOI

• Active control of transition to turbulence in laminar separation bubbles

  Journal of Fluid Mechanics · 2025-08-07

  articleOpen access

  The impact of two-dimensional (2-D) periodic forcing on transition dynamics in laminar separation bubbles (LSBs) generated on a flat plate is investigated experimentally. Laminar separation is caused by the favourable-to-adverse pressure gradient under an inverted modified NACA $64_3\text{-}618$ and periodic disturbances are generated by an alternating current dielectric barrier discharge plasma actuator located near the onset of the adverse pressure gradient. Surface pressure and time-resolved particle image velocimetry measurements along the centreline and several wall-parallel planes show significant reductions in bubble size with active flow control. Periodic excitation leads to amplification of the Kelvin–Helmholtz (K–H) instability resulting in strong 2-D coherent roller structures. Spanwise modulation of these structures is observed and varies with the forcing amplitude. Intermediate forcing amplitudes result in periodic spanwise deformation of the mean flow at large wavelength ( $\lambda _z/L_{b,5kVpp} \approx 0.76$ ). For high-amplitude forcing, the spanwise modulation of the mean flow agrees with the much smaller wavelength of the difference interaction of two oblique subharmonic modes ( $\lambda _z/L_{b,5kVpp} \approx 0.24$ ). Modal decomposition shows nonlinear interaction of the forced 2-D mode leading to growth of subharmonic and harmonic content, and the observation of several half-harmonics ( $[n+1/2]f_{\textit{AFC}}$ ) at intermediate forcing amplitudes. Strongest amplitudes of the 2-D mode and delay of transition downstream of the time-averaged reattachment are observed for the intermediate forcing amplitudes, previously only observed in numerical simulations. Consistent with numerical results, further increase of the forcing amplitude leads to rapid breakdown to turbulence in the LSB. This suggests that the most effective exploitation of the K–H instability for transition delay is connected to an optimal (moderate) forcing amplitude.

  PublisherOA PDFDOI

• Interaction of Crossflow With a Laminar Separation Bubble

  2025-01-03

  articleSenior author

  Crossflow development and its impact on a Laminar Separation Bubble (LSB) was investigated experimentally on a NACA 64₃-618 airfoil at a sweep angle of Γ = 45° and a chordwise Reynolds number of Re_C = 600000. Discrete Roughness Elements (DREs) imposed a dominant spanwise wavelength and successfully amplified the stationary crossflow instability along the suction side of the airfoil. A Type III secondary instability was identified in strong stationary crossflow at AoA = -8°. The boundary layer is fully attached at these conditions and there is no LSB. For weak crossflow at AoA = 0°, three-dimensional structures were observed in the LSB forming in the adverse pressure gradient. Laminar-to-turbulent transition in the LSB remains dominated by the 2D Kelvin-Helmholtz instability in the separated shear layer. However, the spanwise coherent vortical structures, typical for unswept LSBs, are significantly distorted due to the impact of the crossflow and associated instabilities.

  PublisherDOI

• Three-Dimensional Nature of Low-Frequency Unsteadiness in a Turbulent Separation Bubble

  AIAA Journal · 2024-09-02 · 3 citations

  articleSenior author

  Three-dimensional behavior of low-frequency unsteadiness in the incompressible turbulent separation bubble (TSB) produced by a wall-mounted hump is investigated using time-resolved planar and stereoscopic particle image velocimetry measurements at several planes across the separated region. The aspect ratio (wind tunnel width/separation length, [Formula: see text]) provides nominally two-dimensional flow for more than half of the spanwise extent of the test section. Analysis in the streamwise/wall-normal plane along the center of the test section shows low-frequency ([Formula: see text]) large-scale motion of the separated region. The flowfield contains features of both geometry-induced and pressure-gradient-induced separation, but unsteady dynamics produce dominant frequencies closer to geometry-induced TSBs ([Formula: see text]) compared to purely pressure-gradient-induced TSBs ([Formula: see text]). Measurements along the spanwise direction and parallel to the initial shear layer development show strong evidence that the low-frequency motion is inherently three-dimensional, providing an additional dimension to the understanding of the flapping/breathing typically observed in planar streamwise/wall-normal measurements. Spectral proper orthogonal decomposition and low-order modeling identify spanwise undulations with wavelengths of the order of [Formula: see text] and frequencies of [Formula: see text]. The three-dimensional behavior causes a peak/valley formation along the span and a more localized expansion/contraction, leading to only small variations in the integral volume of the TSB.

  PublisherDOI

• Scaling and Transition Effects on Hollow-Cylinder/Flare SBLIs in Wind Tunnel Environments

  2024-01-04 · 4 citations

  articleOpen access

  A comprehensive investigation into the flow over a Hollow-Cylinder/Flare (HCF) has been conducted at Mach 5 with Re_L ≈ 11 × 10^5 and a flare deflection θ = 15 deg. Experiments of two similar models have been conducted in LT5 at the University of Arizona (Tucson, USA) and R2Ch at ONERA (Meudon, France). Despite similar non-dimensional scaling of the models, a considerable difference in reattachment behavior was observed from Infrared Thermography (IRT) measurements, indicating that the reattachment in LT5 was located approximately twice as far from the flare base as observed in R2Ch. This discrepancy has driven the investigation in an attempt to identify the cause of this difference. Simulations have been performed at the University of Arizona, ONERA, and the Technical University of Munich (Germany) in support of this study, targeting a range of potential factors that are relevant to the challenge, to quantify the various influences. Amongst the effects reviewed are: differences in the freestream Mach number (M_∞) modulating boundary layer development and the flare-induced inviscid pressure rise, differences in the wall temperature conditions (T_w/T_0) also affecting boundary layer development, 3D relief effects due to different normalized cylinder diameters (D/L), differences in the bluntnesses of the two nominally sharp configurations (r_nose/L), and the impact of freestream disturbances. The noise environment appears to play a significant role in scaling the Shock Boundary Layer Interaction (SBLI) by affecting the transition behavior along the separated shear layer and causing the bubble to grow/shrink to accommodate. Simulations show that the amplitude can be modulated to control the SBLI size, and produce a close match to the experimental results. However, the distribution of noise in the frequency spectra remains unclear. Experimental investigation of the respective noise environment between the two facilities showed that despite each tunnel exhibiting similar noise magnitudes (expressed as p′/p_∞) they differed considerably in the range of frequencies (by a factor of 6.5 when considering freestream Strouhal number), suggesting additional parameters are required when quantifying wind tunnel freestream noise conditions beyond its simple amplitude. This study was conducted as part of an international collaborative effort in support of NATO STO AVT-346 Research Task Group.

  PublisherOA PDFDOI

Frequent coauthors

• James A. Threadgill

  Environmental Education Exchange

  35 shared

• Mo Samimy

  The Ohio State University

  35 shared

• Hermann F. Fasel

  University of Arizona

  25 shared

• Marco Debiasi

  Defence Academy of the United Kingdom

  24 shared

• Ashish Singh

  Maulana Azad National Institute of Technology

  19 shared

• E. Caraballo

  Miami University

  16 shared

• Andreas Groß

  New Mexico State University

  11 shared

• David Borgmann

  University of Arizona

  11 shared