Numerical Predictions of Scarfing on Performance of S-Shaped Nozzle with Asymmetric Lobe

Du, Liwei; Liu, Youhong; Li, Teng

doi:10.2514/1.b35222

Cited by 14 publications

(3 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As already studied by many researchers [22][23] that the key mechanism concerning the outweighed mixing performance of the lobed mixer is two counter-rotating large-scale stream-wise vortexes downstream of the lobed trailing edge. Therefore, the reversed flow zone on the lobe suction surface induced by the swirling flow is suggested to interact with the stream-wise vortexes in the subsequent mixing flow field causing the stream-wise vortexes to deform and transfer.…”

Section: Influence Of Inlet Swirl On Mixed Flow Fieldmentioning

confidence: 99%

Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

Ding¹,

Liu²,

Du³

2019

Preprint

Self Cite

View full text Add to dashboard Cite

Influence of core flow inlet swirl angle on aerodynamic performances of an exhaust nozzle with scarfed lobed mixer was studied by the validated computational approach. The computational simulation was conducted by resolving the steady form of discretized three-dimensional Reynolds Averaged Navier-Stokes equations with the shear stress transport k-Ω turbulence model. Simulation results depict that swirling motions have ignorable influence on the flow field of the top part in the cross sections slightly downstream of the lobed trailing edge. Besides, for the flow field downstream of the L/D=0.1 cross section, the swirling motions are suggested to cause the clockwise stream-wise vortex to stretch into several smaller-scale vortexes. When the case with a bigger swirling angle is investigated, the induced smaller-scale vortexes are more strengthened by the swirling motions. Concerning the 15° swirling case, the loss caused by the destroyed vortex pattern and the benefit induced by the improved smaller-scale vortexes almost counteract with each other with respect to the thermal mixing efficiency. In the last studied cross section as compared with the baseline case, the case with a maximum swirling angle of 30° has increased 6.94% for the thermal mixing efficiency and decreased 0.42% for the total pressure recovery coefficient.

show abstract

Section: Influence Of Inlet Swirl On Mixed Flow Fieldmentioning

confidence: 99%

Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

Ding¹,

Liu²,

Du³

2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Jet mixing enhancement methods can be classified in two major categories: passive flow control and active flow control technologies. The passive flow control methods include solid tab, lobe nozzle, and chevron nozzle [5][6][7][8][9][10][11]. These techniques can effectively alter the primary jet shear layers, but the performance of the engine exhaust system will decrease with these off-design conditions.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Flow and Infrared Radiation Characteristics of Nozzles with Transverse Jets of Different Shapes

et al. 2022

View full text Add to dashboard Cite

The hot jet of an aero engine is one of the main radiation sources of infrared detectors in 3–5 microwave bands. Transverse jets were introduced into a hot jet to enhance mixing and reduce the infrared radiation characteristics. This proved to be a high-efficiency and low-resistance infrared suppression technology. The steady-state distribution of temperature data was simulated, which was needed in the thermal radiation calculation. The radiation characteristics were calculated based on the anti-Monte Carlo method in 3–5 microwave bands. The mechanics of enhanced mixing by a rectangular nozzle or transverse jets was investigated with the LES simulation. Compared with an axisymmetric nozzle, a rectangular nozzle induced abundant counter-rotating vortex pairs (CVP), hairpins, shears, and helical vortexes, which resulted in significant mixing enhancement and infrared radiation decrease of the hot jets. Further, circumferential transverse jets of different types were introduced downstream of the nozzle. These jets enhanced the mixing and reduced the infrared radiation in the 3–5 µm band. The mixing characteristics of these different schemes were studied in detail. Large-scale vortices formed on the windward portion of the hot jet boundary under the effect of the transverse jets, which caused strong CVP structures. They also resulted in hairpin vortexes, shear vortexes, and helical vortexes appearing earlier and occurring more frequently than with nozzles without transverse jets. The enhanced mixing caused by the transverse jets led to an increase in temperature decay and a decrease in infrared radiation in the 3–5 µm band. Further, transvers jets of different geometrical shapes (rectangular, cube, and circular schemes) achieved different mixing characteristics, and the rectangular transverse jets allowed the most significant mixing for the largest Q criterion value.

show abstract

“…It revealed initial deceleration of the flow due to the turning of the streamlines caused by the nozzle curvature and the acceleration of the core flow due to geometric transition. Du et al [9] numerically conducted the predictions of a lobed jet mixing flow within an S-shaped nozzle. Due to the use of the S-shaped nozzle, a sharp decrease in total pressure recovery coefficient, as well as a reduced thermal mixing efficiency, was shown.…”

Section: Introductionmentioning

confidence: 99%

Parametric Design Method and Performance Analysis of Double S-Shaped Nozzles

Shan

Zhou

Tan

et al. 2019

International Journal of Aerospace Engineering

View full text Add to dashboard Cite

A parametric design method, which was based on super-elliptical transition and self-adaption infrared radiation shield for the double S-shaped nozzle, was introduced. The complete shielding of high-temperature components in the S-shaped nozzle was realized. Model experiments and numerical simulations were performed to investigate the effects of offset ratio S/D, the ratio of length to diameter L/D, and the aspect ratio W/H on the aerodynamics and infrared radiation. The results showed that the total pressure recovery and thrust coefficients were improved initially, but dropped rapidly with the increase in offset ratios with the range of investigated parameters. There existed an optimal offset ratio for the aerodynamic performances. Considering the weight penalty, the length of nozzles should only be increased properly to achieve better aerodynamic performances. Both friction and viscous losses caused by large streamwise vortices dominated the aerodynamic performances of nozzles. The nozzle with the aspect ratio of W/H=5.0 was recommended for achieving optimal aerodynamics. The increase in aspect and offset ratios could effectively suppress plume radiation, which was, however, not sensitive to overall radiation. Compared to circular nozzles, double S-shaped nozzles reduced overall infrared radiation by over 50%, which proves significant stealth ability. A balance between aerodynamic performances and infrared radiation suppression could be reached for double S-shaped nozzles.

show abstract

Numerical Predictions of Scarfing on Performance of S-Shaped Nozzle with Asymmetric Lobe

Cited by 14 publications

References 22 publications

Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

Numerical Investigation of the Flow and Infrared Radiation Characteristics of Nozzles with Transverse Jets of Different Shapes

Parametric Design Method and Performance Analysis of Double S-Shaped Nozzles

Contact Info

Product

Resources

About