LES-DQMOM based Studies on Reacting and Non-reacting Jets in Supersonic Crossflow

Large Eddy Simulation based Studies of Reacting and Non-reacting Transverse Jets

in Supersonic Crossflow

Shaun Kim a,b Pratik Donde a Venkat Raman a

Kuo-Cheng Lin c Campbell Carter d

50th AIAA Aerospace Science Meeting January 10th, 2012Nashville, Tennessee

AcknowledgementsTexas Advanced Computing Center

Department of Aerospace Engineering and Engineering MechanicsThe University of Texas at Austin

a b c d

American Institute of Aeronautics and Astronautics

2

fq = dynamic pressure, 2

21

fff MpJ U = density

R = gas constant W = shear stress Re = Reynolds number T� = momentum thickness Subscripts LE = leading edge a = computational cell ref = reference, namely, user-defined incoming

free-stream conditions bc = boundary condition t = total g = gas specific w = wall int = interior tf = transformed

I. Introduction

ETS issuing perpendicularly into a free-stream have been the subject of research for more than 60 years.1 Much of the research has been focused on vertical/short take off and landing, applications where the free-stream is

either quiescent or can be regarded as incompressible. However, some studies have focused on supersonic free-streams. Such normal jets issuing into a supersonic free-stream have been suggested as viable means for aerodynamic vehicular control. Of interest in aerodynamic control is the surface pressure affects of the jet, often referred to as jet interaction or JI. However, a jet issuing perpendicularly into a supersonic flow results in a complex flowfield that makes it difficult to quantify its effect on forces and moments. In the past, some researchers2-4 have suggested that the jet can be properly represented by a solid cylinder of given transverse length in inviscid flow, but data have shown that this is not a realistic representation. Such a model does not include plume expansion into the free-stream, plume overexpansion downstream or the horseshoe vortex surrounding the jet around the jet exit. Subsequently, Champigny and Lacau5 gave a detailed explanation of the flow phenomena present in a jet in supersonic cross-flow. Their flow structure model is shown in Fig. 1.

Figure 1. Champigny and Lacau flow structure model.5

The Champigny–Lacau model has found widespread acceptance currently. Amongst the flow features is a single upstream separation zone created from a bow shock interaction with the approaching boundary layer. This shock/boundary layer interaction also generates a O shock, or separation shock. As the jet exits, it initially expands into the crossflow, but turns downstream because of this interaction and a shock forms around the jet, typically referred to as the barrel shock. The barrel shock is terminated with a Mach disk and wake vortices are generated as the plume moves downstream. A secondary shock is formed aft of the jet plume with the so-called horseshoe vortices moving downstream along the surface. The Champigny–Lacau model describes the horseshoe vortex as originating from the boundary layer separation upstream of the jet between the O-shock region. The present study examines this near field mean flow structure and their effects on forces and moments.

J

Champigny-Lacau

354 S. Kawai and S. K. Lele

Figure 1. Schematics of the transverse injection of an under-expanded jet into a supersoniccrossflow (Ben-Yakar et al. 2006; Gruber, Nejad, Chen & Dutton 1995).

turing flows with complex shocks and contact surfaces and the 3-D broadband turbulenteddying motions present in high Reynolds number flows.

In the present study, an under-expanded sonic jet injected into a supersonic crossflowis numerically simulated by using a high-order low dispersive and dissipative compactdi!erence scheme (Lele 1992) and spatial filtering (Gaitonde & Visbal 2000) to properlycapture the physics of the supersonic turbulent mixing. Recently developed discontinuity-capturing schemes of high-wavenumber biased artificial viscosity (Cook & Cabot 2004,2005) and di!usivity (Fiorina & Lele 2007) are simplified and extended to curvilinearand stretched grid framework (Kawai & Lele 2007) to perform the simulation. The mainobjective of this paper is to develop further insights into the 3-D complex flow physics ofthe supersonic jet mixing. Comparisons between the LES results and the experimentaldata (Santiago & Dutton 1997) are also performed for validation.

2. Mathematical models

2.1. Numerical methodsSpatially filtered Navier-Stokes equations, including the terms of artificial viscosity givenby Cook & Cabot (2004, 2005) and di!usivity by Fiorina & Lele (2007) for an ideal non-reactive gas, are employed for numerical simulations. In addition, one transport equationfor a passive scalar ! is also solved in order to distinguish the jet and crossflow fluidsand clearly understand the mixing:

"#!

"t+ ! · (#u!) "!(($! + #D!)!!) = 0, (2.1)

where $! is the artificial di!usivity.The governing equations are solved in generalized curvilinear coordinates, where spa-

tial derivatives for convective terms, viscous terms, metrics and Jacobian are evaluatedby a sixth-order compact di!erence scheme (Lele 1992). An eighth-order low-pass spa-tial compact filtering scheme (Gaitonde & Visbal 2000) is applied on the conservativevariables once every time step to ensure numerical stability. The filtering scheme has afree parameter %f which satisfies the inequality "0.5 < %f # 0.5. In this range, as %f

is increased, a shorter range of frequencies is a!ected and less suppression is realized.In the present study, %f is set to 0.495 in order to avoid numerically damping resolvedscales.

Motivation

• Combustion inside hypersonic engine requires mixing optimization due to short residence time

• Jet in supersonic crossflow exhibits complex flow features; shock-turbulence interactions, 3D vortical structures

• Supersonic combustion modeling is crucial to predict chemical reaction characteristics

JetCrossflow

Outline

• Jet in supersonic crossflow (JISC)

• Numerical methodology

- Compressible flow solver

- Direct quadrature method of moments (DQMOM)

• Result and discussions

- Non-reacting jet in supersonic crossflow

- Reacting jet in supersonic crossflow

Jet in Supersonic Crossflow

• Jet/crossflow interaction creates complex 3D vortical structures

• Shock-turbulence interaction

• Highly unsteady flow field


2


21

fff MpJ U = density



I. Introduction





J

Champigny-Lacau







"#!

"t+ ! · (#u!) "!(($! + #D!)!!) = 0, (2.1)




UTCOMP : Compressible Flow Solver

• Large-eddy simulation (LES) captures unsteady flow motion in turbulence with large length scale

• Flow in subfilter scale needs closure

- Dynamic Smagorinsky model is used for closing convective terms

• High numerical scheme : 5th order WENO

• MPI based parallelization

Direct quadrature method of moments

• Joint PDF of thermochemical composition variables is evolved using DQMOM method

• Developed for supersonic combustion by Koo et al. (Proceedings of the Combustion Institutes, 2011)

configuration is shown in Fig. 1. In the simula-tions, the wall surrounding the annular jet is notsimulated. The hydrogen fuel is injected throughthe central jet at a Mach number of 2 while viti-ated air issues through the annulus with a Machnumber of 1.9. Detailed boundary conditions areprovided in Table 1.

The turbulent inflow conditions are generatedby simulating a periodic pipe flow with Reynoldsnumber and diameter identical to that of thehydrogen jet. After reaching statistical stationa-rity, planes of velocity, pressure, and energy fieldsare stored in a file. This time-dependent inflowdata is then used in the actual supersonic flow sim-ulation. The coflow is initialized using mean tur-bulent boundary layer correlations. Thecomputational domain spans 41D in the axialdirection and 12D in the radial direction. Theequations are solved in fully cylindrical coordinatesystem. The computational grid consists of1024! 128! 32 grid points. The simulations takeroughly 12 hours on 256 processors.

Boundary conditions have to be specified forthe weights and weighted abscissas as well. Theweights are chosen as discussed in the previoussection. The abscissas are set such that the initialsubfilter variance of all species and enthalpy is3% of the mean value. This only ensures that theDQMOM approach generates a non-zero subfiltervariance. As mentioned in the previous section,these choices did not impact the simulation results.Three di!erent simulations are reported: (1) LES-DQMOM with 2 peaks, (2) LES-DQMOM with3 peaks, and (3) LES with no subgrid closure forcombustion.

Figure 2 shows instantaneous temperature andOH contours from the 2-peak DQMOM simula-tion. The boundary layer in the coflow producesa high temperature ignition source that initiatesthe combustion process. The vitiated coflow sus-tains the reactions as the hydrogen jet movesdownstream. Due to the large density and velocitydi!erence between the jets, the central jet does notfully breakdown inside the domain considered.The OH contours show that the reactions becomemore dominant as the jet moves downstream butthe reaction zone is confined to the thin shearlayer formed between the fuel and coflow jets.

Figure 3 shows the pitot pressure probe mea-surements from the experiments compared withthe simulation results. At x/D = 13.8, all the sim-ulations predict the pressure drop through theshear layer quite well. But the pressure in the cen-tral jet drops faster in the simulations comparedto the experiment. Similar results were found atother locations. A comparison of reactant massfractions (Fig. 4) shows that near the centerline,the LES-DQMOM simulations predict higher fuelmass fraction compared with LES calculations.But overall, the results from the di!erent simula-tions look similar.

To understand further the impact of the subfil-ter closure, the e!ect of the mixing model is stud-ied. The rate of mixing depends on the coe"cientC/ that appears in the definition of the mixing timescale (Eq. (5)). Figure 5 shows the time-averagedabsolute di!erence between the abscissas normal-ized by the mean scalar values. When the mixingcoe"cient is doubled in value, the peaks are pulledtowards the mean, which is reflected in the lowernormalized value. This plot also shows that thereis significant variation in the abscissas with themaximum OH variation being around four timesthe mean value. Since these fluctuations occur inthe shear layer, it is likely that at any given time,the weight associated with one of the peaks ismuch higher than the other peaks. This will reducethe impact of the temperature di!erence between

Jet

Coflow,Annular jet

D (jet diameter) = 0.009525m

Lip thickness = 0.0015m

Outer diameter of annular jet= 0.0653m

Fig. 1. Flow configuration for the supersonic reactingjet test case [32].

Table 1Inflow conditions for a supersonic hydrogen jet.

Jet Coflow

Mach No. 2.0 1.9Temperature (K) 251 1495Velocity (m/s) 2432 1510Pressure (MPa) 0.1 0.1Y H2 1.0 0Y O2 0 0.241Y N2 0 0.478Y H2O 0 0.281

Fig. 2. Instantaneous plots of (top) temperature and(bottom) OH mass fraction from the 2-peak DQMOMsimulation. The plots show only a part of the compu-tational domain.

H. Koo et al. / Proceedings of the Combustion Institute 33 (2011) 2203–2210 2207

to the jet-wake stabilization mode. Figure 8 showsthe instantaneous temperature for the two cases.In the high inflow temperature case, the tempera-ture in the cavity is higher than the low inflow tem-perature case. Also a flame region is seen near thelower wall downstream of the cavity. This second-ary flame region is absent in the low inflow temper-ature case. This study clearly demonstrates thatthe DQMOM approach can predict these subtlechanges in reaction structure in a supersonic flowconfiguration.

4. Conclusions

The DQMOM approach has been developedfor supersonic combustion and validated usingtwo relevant test cases. The test cases illustratethe easy adaptability of the DQMOM approachin cylindrical coordinate system as well signifi-cantly complex flow configurations. Since thisapproach uses typical numerical schemes usedfor solving scalar transport equations, no geomet-rical limit is imposed. Comparisons with experi-ments demonstrate the predictive capability ofthe DQMOM-based PDF approach. The 2-peak

and 3-peak DQMOM simulations showed noappreciable di!erence indicating that this level ofapproximation is su"cient for the test problemsconsidered. It is worth noting that even the 3-peakDQMOM method is roughly 20–30 times lessexpensive than a comparable Lagrangian methodfor solving the PDF transport equation.

Acknowledgements

This work was funded by NASA throughNRA NNX08AB41A with Dr. Andrew Norrisas the technical monitor. The authors acknowl-edge computer time allocated by the Texas Ad-vanced Computing Center at UT Austin.

References

[1] H. Pitsch, Annu. Rev. Fluid Mech. 38 (2006) 453–482.

[2] V. Raman, H. Pitsch, Combust. Flame 142 (4)(2005) 329–347.

[3] A. Kempf, R.P. Lindstedt, J. Janicka, Combust.Flame 144 (1–2) (2006) 170–189.

[4] Seventh International Workshop on Measurementand Computation of Turbulent Non-premixedFlames.

[5] S. Menon, W.H. Jou, Combust. Sci. Technol. 73(1991) 53–72.

[6] V. Sankaran, S. Menon, Proc. Combust. Inst. 30 (2)(2005) 2835–2842.

[7] N. Peters, Turbulent Combustion, Cambridge Uni-versity Press, 2000.

[8] S.B. Pope, Combust. Sci. Technol. 25 (1981) 159–174.

[9] S.B. Pope, Prog. Energy Combust. Sci. 11 (1985)119.

[10] S.B. Pope, Turbulent Flows, Cambridge UniversityPress, 2000.

[11] S.B. Pope, Proceedings of the 23rd Symposium(International) on Combustion, The CombustionInstitute, Pittsburgh, 1990, pp. 591–612.

[12] P. Givi, AIAA J. 44 (2006) 16–23.[13] P.J. Colucci, F.A. Jaberi, P. Givi, Phys. Fluids 10

(2) (1998) 499–515.[14] F.A. Jaberi, P.J. Colucci, S. James, P. Givi, S.B.

Pope, J. Fluid Mech. 401 (1999) 85–121.[15] V. Raman, H. Pitsch, Proc. Combust. Inst. 31 (2006)

1711–1719.[16] V. Raman, R.O. Fox, A.D. Harvey, D.H. West,

Ind. Eng. Chem. Res. 42 (2003) 2544–2557.[17] V. Raman, R.O. Fox, A.D. Harvey, Combust.

Flame 136 (2004) 327–350.[18] C. Dopazo, in: P.A. Libby, F.A. Williams (Eds.),

Turbulent Reacting Flows, Academic Press, NewYork, 1994, pp. 375–474.

[19] H. Mobus, P. Gerlinger, D. Bruggemann, Combust.Flame 124 (2001) 519–534.

[20] R. Mustata, L. Valino, C. Jimenez, W. Jones, S.Bondi, Combust. Flame 145 (1–2) (2006) 88–104.

[21] J. Villermaux, L. Falk, Chem. Eng. Sci. 49 (24B)(1994) 5127–5140.

[22] J. Janicka, W. Kolbe, W. Kollmann, J. Non-Equilibrium Thermodyn. 4 (1970) 47–66.

Fig. 8. Instantaneous snapshots of temperature for (top)high inlet temperature and (bottom) low inlet temper-ature cases.

Fig. 7. Instantaneous snapshots of OH mass fraction for(top) high inlet temperature and (bottom) low inlettemperature cases.

H. Koo et al. / Proceedings of the Combustion Institute 33 (2011) 2203–2210 2209

Supersonic reacting jet Supersonic cavity-stabilized flame

(DQMOM)

Results and Discussion

• Non-reacting Jet in Supersonic Crossflow

• Reacting Jet in Supersonic Crossflow

Non-reacting Jet in Supersonic Crossflow

JetC2H4M = 1.0ρ = 2.504 kg/m3

T = 287.5 Kp = 213.8 kPad = 4.8 mm

CrossflowAirM = 2.0ρ = 0.65 kg/m3

T = 167 Kp = 31 kPaδ = 6.4 mm

• Sonic jet in Mach 2 crossflow

• Momentum ratio = 1.52

• Compared with the experiment from Air Force Research Laboratory (AFRL) by Lin et al. (Journal of Propulsion and Power, 2010)

8d

31d

24d

Computational details

• 17 million grid cells over 31d x 8d x 24d computational domain

- 15y+ x 1.5y+ x 15y+ near wall

• Spatial discretization

- Flow : 5th order WENO | Scalar : 3rd order QUICK

• Crossflow simulated separated as boundary layer

• Periodic boundary condition in spanwise direction

• Computed with 480 processors for 36 hours

Density gradient magnitude

Ma

Flow Evolution of Non-reacting JISC

C2H4


Ma

Flow Evolution of Non-reacting JISC

C2H4

y/d

z/d

y/d

z/d

y/d

z/d

LES Experiment

y/d

z/d

x/d=5 x/d=25 x/d=5 x/d=25

Wall PSP

C2H4 on symmetric plane

C2H4 at x/d=5 and x/d=25

x/d x/d

x/dx/d

Comparison with the Experiment

Wall pressure distribution

Wall PSP

x/dx/dWall pressure distribution

LES Experiment

Wall PSP



x/d x/d

x/dx/d

y/d

z/d

y/d

z/d

y/d

z/d

y/d

z/d

x/d=5

x/d=25

x/d=5

x/d=25


y/d

z/d

y/d

z/d

y/d

z/d

LES Experiment

y/d

z/d

x/d=5 x/d=25 x/d=5 x/d=25

Wall PSP



x/d x/d

x/dx/d


Wall pressure distribution

Recirculation zones

Bow shock

Barrel shock

Mach diskExpansion fan

λ-shock

Reflected shock

• Most of jet fluid passes through windward side of barrel shock and Mach disk

Shock Structures in JISC

• Underexpanded jet in crossflow creates barrel shock and Mach disk

• Common shock structures are visible in the result

Shock Structures in JISC

Bow shock

Barrel shock

Mach diskExpansion fan

λ-shock

Reflected shock


2


21

fff MpJ U = density



I. Introduction





J

Champigny-Lacau







"#!

"t+ ! · (#u!) "!(($! + #D!)!!) = 0, (2.1)




Vortical Structures in JISC





Q-criterion vorticitywith contour of C2H4

C2H4 = 0.8


C2H4 = 0.8 Vortical structure


• Boundary layer thickening is seen in the shock-boundary layer interaction

• Jet/crossflow interaction creates vortical structures

• Interaction of vortical structures is closely related to efficient mixing in the near field



Long streak of streamwise vorticity


Long streak of streamwise vorticity

x/D=0

x/D=0x/D=0

x/d = 0

LES Experiment

x/d = 5

x/D=0

x/D=0x/D=0

x/d = 5

x/d = 3

x/d = 0


Results and Discussion

• Non-reacting Jet in Supersonic Crossflow

• Reacting Jet in Supersonic Crossflow

Reacting Jet in Supersonic Crossflow

JetC2H4M = 1.0ρ = 7.02 kg/m3

T = 263 Kp = 550 kPad = 2 mm

CrossflowAirM = 3.38ρ = 0.0846 kg/m3

T = 1290 Kp = 32.4 kPaδ = 0.75 mm

• Sonic jet in Mach 3.38 crossflow

• Momentum ratio = 1.4

• Compared with the experiment by Ben-Yakar et al. (Physics of Fluids, 2006)

10d

21d

24d

Computational details

• 15 million grid cells over 21d x 10d x 24d computational domain

- 60y+ x 2y+ x 60y+ near wall

• Periodic boundary in spanwise direction

• LES-DQMOM methodology for combustion modeling

- Reduced 13 species C2H4-air mechanism

• Computed with 820 processors for 72 hours

!I

I"

dn

dy. !4"

The index of refraction of a gas is expressed as a function ofdensity !#" and a constant characteristic of the gas !$",

n = 1 + $#

#s, !5"

where #s is the density at standard conditions !273 K andatmospheric pressure". The density ratio for a specific gas isequal to

#

#s=

pTs

psT. !6"

Substituting from Eqs. !5" and !6" gives

!I

I"

d

dy#$

#

#s$ "

d

dy#$

pTs

psT$ . !7"

Consequently, the flow visualization of large scale struc-tures based on schlieren is a result of the differences in thepressure, the temperature and the characteristic $ constant ofthe freestream fluid and the jet fluid. As the jet turns in thestreamwise direction the static pressure between the hotfreestream !%1300 K" and the cold jet !%300 K" approachesequilibrium. The schlieren contrast between unmixed jet andfreestream fluids can therefore be expressed in terms of

!I

I" #$

Ts

T$

%

! #$Ts

T$

j. !8"

By substituting the values of $ and T for each stream in Eq.!8", we found that the schlieren contrast between the ethylenejet and the freestream nitrogen !or air" should be &10 timeslarger than the hydrogen jet case !$H2

=0.000 138, $C2H4=0.000 720, $N2

=0.000 297". The loss of the visibility of theethylene jet shear layer structures can, therefore, be attrib-uted to the loss of the coherence of the vortical structures and

FIG. 9. The second example of an ethylene transversejet flowfield in a supersonic crossflow as observed fromeight time correlated schlieren images. Exposure timeof each image is 200 ns and interframing time is 1.2 &s.

026101-9 Transverse jets in supersonic crossflows Phys. Fluids 18, 026101 !2006"

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Shock Structures Comparison

• Shock structure is highly unsteady due to flapping motion at the windward side of the barrel shock

stream reattachment shock. The small instantaneous fluctua-tions of the bow shock are observed to average into asmoother and slightly thicker one.

The barrel shock and the Mach disk are, however, notvery clear even in the long exposure schlieren images, mostprobably due to the unsteadiness of the shear layer vorticalstructures. Only the Prandtl-Meyer expansion fan of the un-derexpanded jet is observable !the white region at the jetcore" indicating that the jet is indeed underexpanded. Wehave therefore attempted to estimate the location of the firstMach disk for our experiments by substituting an “effectiveback pressure” term in the Ashkenaz and Sherman18 correla-tion given in Eq. !2". The effective back pressure introducedin earlier work is a notion that permits an analogy betweenthe very complicated flowfield of an underexpanded jetemerging into a supersonic crossflow and that for the simplerand well-understood case of a jet exhausting into a quiescentmedium. Among those previous studies, Schetz and Billig10

suggested peb=0.8p!!, where p!! is the freestream pressurebehind a normal shock wave. Later, Billig et al.20 developeda correlation to predict the height of the Mach disk, y1, as-suming that the effective back pressure is equal to two thirdsof the freestream stagnation pressure behind a normal shockpeb=2/3ptot,!!. More recently Everett et al.21 measured thepressure distribution around a sonic jet injected transverselyinto a Mach 1.6 freestream using a pressure-sensitive-painttechnique. Their averaged surface pressure resulted in peb#0.35p!! !for J"1.5" which differs greatly from the earlierwork. This discrepancy was attributed to the larger jet-to-momentum flux ratios, J used earlier. We have adopted theback pressure values of Everett !peb#0.35p!!", since thevalue of J in our experiments is small. Using Eq. !2", theMach disk height for the current experiments was estimatedto be around y1$1.7·dj which compares well with the jetbending location !see discussion below".

The freestream conditions behind the hydrogen bowshock could be estimated by measuring the average bowshock position. Figure 6 presents two plots; the first showsthe measured bow shock position and its angle !#", while thesecond plot shows the bow shock-induced freestream veloc-ity !U2" and its turning angle !$". Calculations are performedassuming a calorically perfect gas. In the region of 10 jet

diameters studied in this work, the bow shock starts almost at90° and weakens downstream as it angle decays continu-ously down to 20°–25°. Further downstream, the bow shockis expected to reach its minimum strength or a Mach wavewith an angle of 17.2° !M!=3.38". The induced velocity ofthe freestream behind the bow shock is subsonic upstream ofthe location of the critical bow shock angle !#cr%67.6° ",defined as the maximum angle for an oblique shock to beattached to a wedge. It is interesting to see that the bowshock reaches this angle around 1.8–1.9 jet diameters abovethe wall at the expected height of the upper side of the Machdisk. Since the Mach disk occurs at a rather high Mach num-ber on the jet centerline, the jet loses most of its momentum!owing to the rise on the static pressure across the Machdisk" and the subsequent trajectory of the jet turns nearlyparallel to the freestream direction. Consequently, beyondthe critical angle, the bow shock curves sharply downstreamand the shock-induced freestream velocity becomes super-sonic varying from approximately 1050 m/s to 2260 m/s at9.5 jet diameters downstream !note that the freestream veloc-

FIG. 5. An example schlieren image with 3 %s exposure time for hydrogeninjection case. While the unsteady features !coherent structures" are aver-aged to zero, some of the weak shocks such as upstream separation shockwave and downstream recompression wave are emphasized.

FIG. 6. !a" Bow shock position and its angle at the centerline of the jet asmeasured from the long exposure schlieren image shown in Fig. 5. !b" Thefreestream velocity behind the bow shock and the flow turning angle basedon the measured bow shock shape. For the calculations a calorically perfectgas has been assumed.

026101-6 Ben-Yakar, Mungal, and Hanson Phys. Fluids 18, 026101 !2006"

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LES Experiment

Instantaneous

Time-averaged

Flow Evolution of Reacting JISC

Mixture Fraction

Temperature (K)


Mixture Fraction

Temperature (K)


0.5 flow residence time

Mixture Fraction

Temperature (K)

OH

t1 t2





• Mixing depends on much larger coherent motions

• Low Reynolds number in crossflow cause the mixing process to be “tearing up” rather than effective turbulent mixing

• Difference in flow configuration between non-reacting and reacting jet

• Reacting case had thinner boundary layer thickness (shock tunnel)

Non-reacting ReactingJ 1.52 1.4 ± 0.1

Rejet ~420,000 ~480,000Reδ ~190,000 ~3,000δ 1.33 D 0.375 D

Ujet 325 m/s 315 m/s

Flow Configuration

Time-averaged Mixing Properties

• Entrainment heavily depends on large coherent motion

• Inefficient mixing quality in the near field (mixture fraction RMS ~ 0.5)

• Flow residence time much smaller than ignition time delay

Conclusions

• LES captures unsteady motion of jet in supersonic crossflow accurately

• Flow structures in JISC were studied

• LES-DQMOM methodology was used to study supersonic combustion with multivariate ethylene-air reaction mechanism

• Reacting case did not have enough near field mixing

• No flame stabilization was found in the reacting case

Large Eddy Simulation based Studies of Reacting and Non-reacting Transverse Jets

in Supersonic CrossflowShaun Kim a,b Pratik Donde a Venkat Raman a

Kuo-Cheng Lin c Campbell Carter d

a b c d

Questions

Technology

LES-DQMOM based Studies on Reacting and Non-reacting Jets in Supersonic Crossflow