Isolator Dynamics During Unstart of a Dual-Mode Scramjet

Riley, Logan P.; Gaitonde, Datta V.; Hagenmaier, Mark A.; Donbar, Jeffrey M.

doi:10.2514/1.b36888

Cited by 17 publications

(5 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Spalart-Allmaras, Menter SST, and realizable k-ε models all follow the Boussinesq approximation, which equates the turbulent Reynolds stresses to the mean flow strain rate linearly through an eddy viscosity coefficient. The cubic k-ε model adds in additional higher-order, nonlinear terms to the Boussinesq approximation to account for anisotropy in the normal Reynolds stresses and streamline curvature effects [11]. Because of the number of models used, the exact formulations as implemented in CFD++ are not reproduced here but can be found in Refs.…”

Section: Turbulence Modelsmentioning

confidence: 99%

“…Additionally, steady-state and transient CFD calculations in two and three dimensions were conducted by Hoeger [9] to characterize the effect of backpressure on the shock train development and unstart in a separate rectangular inlet/isolator configuration. Riley et al [10,11] and Yentsch and Gaitonde [12,13] studied inlet unstart and mode transition of dual-mode ramjets with fixed geometry using transient CFD solutions.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Computational Analysis of Unstart in Variable-Geometry Inlet

Reardon

Schetz

Lowe

2021

Journal of Propulsion and Power

View full text Add to dashboard Cite

Computational fluid dynamics was used to study the flow through a scaled, mixed-compression, high-speed inlet with a rotating cowl at Mach 4.0 conditions. First, steady Reynolds-averaged Navier-Stokes computations were undertaken with a range of popular turbulence models including the Spalart-Allmaras model, the realizable k-ε model, the cubic k-ε model, and the Menter shear stress transport (SST) model to assess the impact on the inlet operating state. It was found that two models, the Spalart-Allmaras model and the Menter SST model, predicted the inlet to become unstarted at a cowl angle where the experimental data indicated the inlet remained started. Next, steady-state flow structures were studied at three discrete cowl positions, identifying highly three-dimensional flow features including regions of separated flow and spanwise gradients that became stronger as the cowl opened. Finally, the study culminated with the development of the new transient model, which allowed for time-accurate investigation into the unstart, restart, and hysteresis. The evolution of the separation bubbles was shown to be a major factor in the hysteresis, causing the inlet to restart at an angle different from where it unstarted. The utility of unsteady Reynolds-averaged Navier-Stokes computations to capture the complex time-dependent details of such flows was demonstrated.

show abstract

Section: Turbulence Modelsmentioning

confidence: 99%

mentioning

confidence: 99%

Computational Analysis of Unstart in Variable-Geometry Inlet

Reardon

Schetz

Lowe

2021

Journal of Propulsion and Power

View full text Add to dashboard Cite

show abstract

“…These events cause pressure disturbances in the flow path, moving the shock train in the isolator and potentially causing engine unstart. The timescale of the shock train moving a whole isolator length toward the inlet can be on the order of milliseconds [5]. This small time scale makes it challenging, yet necessary, to control for such events.…”

Section: Introductionmentioning

confidence: 99%

Dual-mode scramjet control using optical emission sensors

Elkowitz,

Wanchek,

Rockwell

et al. 2024

Appl. Opt.

View full text Add to dashboard Cite

Closed-loop fueling control of a dual-mode scramjet was successfully demonstrated using optical emission spectroscopy as the sole sensor for controller feedback. The optical emission from species of interest (OH∗, CH∗, C2∗) was first characterized throughout the combustor. The relative emission intensity between species pairs was studied over a range of fueling conditions and imaging locations throughout a dual-mode scramjet combustor flow path. The pair of emissive species (C2∗/OH∗) and imaging location that were the most sensitive to changes in fueling condition were selected for use in the control system. Changes in optical transmission of the observation windows and the impact on fuel control were explored. To our knowledge, this paper is the first demonstration of fueling control of a dual-mode scramjet using only optical emission spectroscopy as feedback.

show abstract

“…Understanding the dynamical properties of the shock train is critical for detecting and preventing inlet unstart because of its devastating effects on the engine performance (Wagner et al 2009;Do et al 2011b;Valdivia et al 2014;Im & Do 2018). Recently, the shock train has attracted much attention due to its unsteady behaviours (Laurence et al 2013;Im et al 2016;Riley et al 2018;Hunt & Gamba 2019).…”

Section: Introductionmentioning

confidence: 99%