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CFD Validation and Flow Control of RAE-M2129 S-Duct Diffuser Using CREATE^{TM}-AV Kestrel Simulation Tools

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## Abstract

**:**

## 1. Introduction

## 2. CFD Solver

## 3. Test Case

## 4. Computational Grids

## 5. Intake Performance

## 6. Results and Discussions

## 7. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## Nomenclature

a | acoustic speed, ms${}^{-1}$ |

c | vane chord, m |

CFD | Computational Fluid Dynamics |

$Cp$ | pressure coefficient, $(p-{p}_{\infty})/{q}_{\infty}$ |

CREATE | Computational Research and Engineering Acquisition Tools and Environments |

DC | Distortion Coefficient |

DDES | Delayed Detached Eddy Simulation |

F | thrust force, N |

h | vane height, m |

L | diffuser length, m |

M | Mach number, V/a |

$PR$ | pressure recovery, ${p}_{t}/{p}_{t0}$ |

p | static pressure, N/m${}^{2}$ |

${p}_{f}$ | averaged engine face static pressure, N/m${}^{2}$ |

${p}_{\infty}$ | free-stream static pressure, N/m${}^{2}$ |

${p}_{0f}$ | averaged engine face total pressure, N/m${}^{2}$ |

${p}_{0\infty}$ | free-stream total pressure, N/m${}^{2}$ |

q | dynamic pressure, N/m${}^{2}$ |

${q}_{\infty}$ | free-stream dynamic pressure, N/m${}^{2}$ |

R | Radius, m |

${R}_{t}$ | Radius at throat, m |

${R}_{f}$ | Radius at engine face, m |

RAE | Royal Aircraft Establishment |

SARC | Spalart–Allmaras with rotational and curvature correction |

RANS | Reynolds Averaged Navier Stokes |

t | time, s |

V | free-stream velocity, ms${}^{-1}$ |

VG | Vortex Generator |

x,y,z | grid coordinates, m |

${X}_{VG}$ | position of vortex generator vanes, m |

$y+$ | non-dimensional wall normal distance |

Subscripts | |

f | engine face |

t | throat |

∞ | free-stream |

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**Figure 1.**The sketch of the RAE M2129 geometry used in this work. The pressure rakes at the engine face are shown as well. They include 12 equally spaced arms with 30-degree intervals with six pitot pressure probes at each arm.

**Figure 2.**The RAE M2129 vortex generator locations and geometry parameters. These pictures were adapted from Ref. [12]. (

**a**) VG locations; (

**b**) Geometric parameters.

**Figure 3.**RAE M2129 geometries. NASA model was obtained from Bernhard Anderson. USAFA model was created from given intake data and offset and diameter changes equation with length.

**Figure 4.**USAFA baseline intake model with vortex generator plates and jets. (

**a**) USAFA baseline geometry and symmetry grid; (

**b**) Vortex generator plates; (

**c**) Jets.

**Figure 5.**Time step sensitivity study. All cases were run for 2.25 s. Predictions between time 2 to 2.25 s were time-averaged. NASA baseline grid with SARC–DDES turbulence model was used.

**Figure 6.**Experimental and simulated engine face pressure ratio. NASA grid was used with SARC-DDES turbulence model. CFD data are time-averaged from 2 to 2.5 s of simulation time. (

**a**) Pressure recovery range; (

**b**) Experimental data; (

**c**) CFD—Baseline.

**Figure 7.**Illustration of the DC60 calculation approach. In the left, a 60-degree segment is shown which is at zero circumferential angle. The sector rotates clockwise one degree at a time. In the right, DC60 values for the 60-degree segment at each angle are shown. These plots correspond to simulation times of 2 and 2.25 s.

**Figure 8.**M2129 DP78 wall pressure measurements and simulations using Kestrel and SARC–DDES turbulence model. Static pressure ratio, ${p}_{f}/{p}_{0\infty}$, is the ratio of averaged engine face static pressure to free-stream total pressure. NASA baseline grid was used. CFD data are time-averaged from 2 to 2.5 s of simulation time.

**Figure 9.**Effects of turbulence model on engine face pressure ratio. Time-averaged solutions are shown for the NASA baseline grid. (

**a**) Pressure recovery range; (

**b**) Experimental data; (

**c**) CFD–SARC + DDES; (

**d**) CFD–SA; (

**e**) CFD–SARC; (

**f**) CFD–Menter SST; (

**g**) CFD–Menter SST + DDES.

**Figure 10.**Turbulence model effects on CFD predictions of wall static pressure. Time-averaged solutions are shown for the NASA baseline grid. Static pressure ratio (${p}_{f}/{p}_{0\infty}$) is the ratio of averaged engine face static pressure to free-stream total pressure.

**Figure 11.**Unsteadiness in solutions of M2129 intake. Dot markers show time-averaged static to free-stream total pressure value of the NASA baseline grid. Bar denotes maximum difference from averaged values. Static pressure ratio (${p}_{f}/{p}_{0\infty}$) is the ratio of averaged engine face static pressure to free-stream total pressure.

**Figure 12.**Isosurfaces of scale Q-criterion (iso value of 0.25) colored by pressure coefficient. NASA baseline grid was used. CFD data are time-averaged from 2 to 2.5 s of simulation time. (

**a**) SARC turbulence model; (

**b**) SARC + DDES turbulence model; (

**c**) SST turbulence model; (

**d**) SST + DDES turbulence model.

**Figure 13.**Streamlines colored by pressure coefficient. NASA baseline grid was used. CFD data are time-averaged from 2 to 2.5 s of simulation time. (

**a**) SARC turbulence model; (

**b**) SARC + DDES turbulence model; (

**c**) SST turbulence model; (

**d**) SST + DDES turbulence model.

**Figure 14.**Engine face and symmetry pressure ratio using USAFA grids and SARC-DDES turbulence models. CFD data are time-averaged from 2 to 2.5 s of simulation time. (

**a**) Baseline engine face; (

**b**) Baseline symmetry; (

**c**) Baseline + VG engine face; (

**d**) Baseline + VG symmetry; (

**e**) Baseline + Jets engine face; (

**f**) Baseline + Jets symmetry.

**Figure 15.**Wall pressure data for the baseline, baseline + vortex generators, and baseline + jets simulations. Static pressure ratio (${p}_{f}/{p}_{0\infty}$) is the ratio of averaged engine face static pressure to free-stream total pressure. USAFA grids and SARC-DDES turbulence models were used. CFD data are time-averaged from 2 to 2.5 s of simulation time.

**Figure 16.**Isosurfaces of scale Q-criterion (iso value of 0.25) and streamlines colored by pressure coefficient. USAFA grids and SARC-DDES turbulence models were used. CFD data are time-averaged from 2 to 2.5 s of simulation time. (

**a**) Baseline; (

**b**) Baseline + VG; (

**c**) Baseline + Jets.

**Figure 17.**Validation of CFD data. USAFA grids and SARC-DDES turbulence models were used. CFD data are time-averaged from 2 to 2.5 s of simulation time. (

**a**) Pressure Recovery; (

**b**) DC60.

Flow Conditions | Experimental Data |
---|---|

Free-stream Mach | 0.204 |

Free-stream total pressure | 105,139.5 Pa |

Free-stream total temperature | 293.7 K |

Angle of attack | 0 degree |

Sideslip angle | 0 degree |

Mass flow ratio | 1.9382 |

Grid | Description | Number of Cells (Millions) |
---|---|---|

Grid1 | Obtained from NASA; baseline intake | 31.2 |

Grid2 | generated at USAFA; baseline intake | 15 |

Grid3 | generated at USAFA; baseline intake + 22 vanes | 19.9 |

Grid4 | generated at USAFA; baseline intake + 22 jets | 62.3 |

**Table 3.**Validation data of the RAE-M2129 baseline intake. NASA grid was used with SARC–DDES turbulence model. CFD data are time-averaged from 2 to 2.5 s of simulation time.

Engine Face Station | Experimental Data | CFD Data (Rake) | CFD Data (Face) | Error (Rake), $\mathit{\epsilon}$ % |
---|---|---|---|---|

${p}_{0f}/{p}_{0\infty}$ | 0.9744 | 0.9776 | 0.9752 | −0.328 |

Mach No. | 0.4193 | 0.4329 | 0.4329 | −3.243 |

${p}_{f}/{p}_{0\infty}$ | 0.8522 | 0.8737 | 0.8497 | −2.523 |

DC60 | 0.3130 | 0.2945 | 0.3294 | 5.910 |

**Table 4.**Turbulence modeling effects on the RAE-M2129 baseline predictions. NASA grid was used. CFD data are time-averaged from 2 to 2.5 s of simulation time.

${\mathit{p}}_{0\mathit{f}}/{\mathit{p}}_{0\mathit{\infty}}$ | Mach No. | ${\mathit{p}}_{\mathit{f}}/{\mathit{p}}_{0\mathit{\infty}}$ | DC60 | |
---|---|---|---|---|

Experiments | 0.9744 (-) | 0.4193 (-) | 0.8522 (-) | 0.3130 (-) |

CFD–SARC + DDES | 0.9776 (−0.3280%) | 0.4329 (−3.243%) | 0.8737 (−2.523%) | 0.2945 (5.910%) |

CFD–SA | 0.9809 (−0.6671%) | 0.4245 (−1.2402%) | 0.8780 (−3.0275%) | 0.2233 (28.65%) |

CFD–SARC | 0.9805 (−0.6260%) | 0.4291 (−2.3372%) | 0.8778 (−3.004%) | 0.2370 (24.28%) |

CFD–Menter SST | 0.9790 (−0.4721%) | 0.4296 (−2.4565%) | 0.8770 (−2.9101%) | 0.2899 (7.38%) |

CFD–Menter SST + DDES | 0.9778 (−0.3489%) | 0.4380 (−4.4598%) | 0.88715 (−4.1011%) | 0.2880 (7.98%) |

**Table 5.**Flow control predictions of the RAE-M2129 intake. USAFA grids were used with SARC-DDES turbulence model. CFD data are time-averaged from 2 to 2.5 s of simulation time.

Configuration | ${\mathit{p}}_{0\mathit{f}}/{\mathit{p}}_{0\mathit{\infty}}$ | Mach No. | ${\mathit{p}}_{\mathit{f}}/{\mathit{p}}_{0\mathit{\infty}}$ | DC60 |
---|---|---|---|---|

Baseline | 0.97089 (-) | 0.4275 (-) | 0.8500 (-) | 0.4215 (-) |

Baseline + Vortex generators | 0.97255 (0.171%) | 0.4333 (1.357%) | 0.8512 (0.1412%) | 0.1361 (−67.7%) |

Baseline + jets | 0.98187 (1.131%) | 0.4198 (−1.80%) | 0.8675 (2.058%) | 0.0881 (−79.1%) |

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Aref, P.; Ghoreyshi, M.; Jirasek, A.; Satchell, M.J. CFD Validation and Flow Control of RAE-M2129 S-Duct Diffuser Using CREATE^{TM}-AV Kestrel Simulation Tools. *Aerospace* **2018**, *5*, 31.
https://doi.org/10.3390/aerospace5010031

**AMA Style**

Aref P, Ghoreyshi M, Jirasek A, Satchell MJ. CFD Validation and Flow Control of RAE-M2129 S-Duct Diffuser Using CREATE^{TM}-AV Kestrel Simulation Tools. *Aerospace*. 2018; 5(1):31.
https://doi.org/10.3390/aerospace5010031

**Chicago/Turabian Style**

Aref, Pooneh, Mehdi Ghoreyshi, Adam Jirasek, and Matthew J. Satchell. 2018. "CFD Validation and Flow Control of RAE-M2129 S-Duct Diffuser Using CREATE^{TM}-AV Kestrel Simulation Tools" *Aerospace* 5, no. 1: 31.
https://doi.org/10.3390/aerospace5010031