Hot Streak Characterization in Serpentine Exhaust Nozzles

Crowe, Darrell S.

doi:10.2514/6.2016-4502

Cited by 13 publications

(4 citation statements)

References 3 publications

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“…Sun et al [24,25] investigated serpentine nozzles' flow field using numerical and experimental methods, and they concluded that the APG appeared near the upper wall, the bent structure of which could lead to hot streaks. Crowe et al [26,27] studied serpentine nozzles' flow mechanism, and they claimed that variations in their cross-section and curvature led to a streamwise vortex that could induce a hot streak on their walls. In summary, a curved pipeline leads to complex pressure gradients and strong swirls, which pose daunting challenges to the design of film cooling for serpentine nozzles.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Investigation of Film Cooling under the Effects of Different Adverse Pressure Gradients

Shi,

Hui,

Zhou

et al. 2024

Aerospace

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Film cooling needs to be applied to serpentine nozzles due to an increase in thermal load. Adverse pressure gradients (APGs) near the upper wall of such nozzles hinder the forward flow of the coolant, and they may even induce a recirculation zone that complicates the cooling of the film in serpentine nozzles under different APGs. In this study, the film cooling characteristics of a serpentine nozzle under various APGs are investigated through numerical simulations. The studied pressure gradients include strong, moderate, and weak APGs. The results show that the APG weakened the adhesion of the coolant to the surface, thereby reducing the film cooling effectiveness (FCE) and the convective heat transfer coefficient (CHTC). The stronger the APG, the greater its obstructive effect. However, the recirculation zone induced by the strong APG was composed of the coolant, and it adhered tightly to the wall, thereby significantly strengthening the FCE and CHTC. The CHTC under the moderate APG significantly increased due to the convergence of two jets ejected from different holes. For the four blowing ratios, the area-averaged FCE under the strong APG was 29.8% and 24.5% higher than that under the moderate and weak APGs, while the area-averaged ratios of the CHTC under the moderate APG were 1.6% and 16.7% higher than those under the strong and weak APGs. Therefore, more holes should be arranged on the film in the zones of moderate and weak APGs.

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Section: Introductionmentioning

confidence: 99%

A Numerical Investigation of Film Cooling under the Effects of Different Adverse Pressure Gradients

Shi,

Hui,

Zhou

et al. 2024

Aerospace

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“…The results indicated an initial deceleration of the flow due to the turning of streamlines caused by the nozzle curvature, as well as an acceleration of the core flow due to the geometric transition. Furthermore, the vortices induced by separation from the tailcone and the sidewall vortices have a significant impact on the temperature distribution of the nozzle [15,16]. This effect becomes particularly prominent in the instance of double serpentine nozzles, where regions with high temperature, often termed as hot streaks, tend to develop along the nozzle surface.…”

Section: Introductionmentioning

confidence: 99%

Multi-Objective Bayesian Optimization Design of Elliptical Double Serpentine Nozzle

Zhang,

Yang,

Wang

et al. 2023

Aerospace

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The use of traditional optimization methods in engineering design problems, specifically in aerodynamic and infrared stealth optimization for engine nozzles, requires a large number of objective function evaluations, therefore introducing a considerable challenge in terms of time constraints. In this paper, this limitation is addressed by using a sample-efficient multi-objective Bayesian optimization that takes Kriging as a surrogate model and Expected Hypervolume Improvement as the infill criterion. Using this approach, the probabilistic model is continuously established and updated, and the approximate Pareto front is obtained at a relatively small computational budget. The objective of this work is to evaluate the applicability of employing a multi-objective Bayesian optimization framework for the aerodynamic-infrared shape optimization of an elliptical double serpentine nozzle at 6 km flight condition, where the objective functions are evaluated by means of high-fidelity computational fluid dynamics and reversed Monte Carlo ray tracing simulations. We achieve good results in both infrared radiation signature reduction and aerodynamic performance improvement with a reasonable number of evaluations, indicating that the proposed method is effective and efficient for tackling the computationally intensive optimization challenges in the aircraft design.

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“…At present, the research on the S-bend nozzle is mainly based on the internal flow field characteristics and infrared radiation. The flow characteristics of the S-bend nozzle are complex, and the nozzle geometry has a strong correlation with the change of vorticity (Crowe and Martin, 2015, 2016). There is an interaction relationship among the design parameters such as the aspect ratio, inlet and outlet area ratio and offset length ratio of the first S-bend nozzle (Shi et al , 2016).…”

Section: Introductionmentioning

confidence: 99%

Research on jet noise characteristics of aeroengine double S-bend nozzles with different cross sections

Shao

Zheng

et al. 2022

HFF

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Purpose This study aims to improve the survivability and maneuverability of the fighter,and study the stealth performance of fighter in the jet noise of aeroengine, it is of great significance to study the jet noise characteristics of double S-bend nozzles. Design/methodology/approach The multiparameter coupling and super-ellipse design methods are used to design the cross section of double S-bend nozzle. Taking unsteady flow information as the equivalent sound source, the noise signal at the far-field monitoring points were calculated with Ffowcs Williams–Hawkings (FW–H) method, and then, the sound source characteristics of the double S-bend nozzle are analyzed. Findings The results show that the internal flow of the S-bend nozzle with rectangular section is smoothed and the aerodynamic performance is better than super-ellipse section, the shear layer length of rectangular section is longer, the thickness is smaller and the mixing ability is stronger. The sound pressure level of the two S-bend nozzles decreases with the increase of the monitoring angle, and the sound pressure on the horizontal plane is greater than the vertical plane. In the direction of 40°–120°, the jet noise of rectangular nozzle is smaller, and the multiparameter coupled rectangular cross section structure is more applicable. Practical implications It is beneficial to reduce the jet noise of the engine tail nozzle and improve the stealth performance of the aircraft. Originality/value There is very little research on the jet noise characteristics of the double S-bend nozzle. The multiparameter coupling and the super-ellipse method are used to design the nozzle flow section to study the aerodynamic performance and jet noise characteristics of the double S-bend nozzle and to improve the acoustic stealth characteristics of the aircraft.

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Hot Streak Characterization in Serpentine Exhaust Nozzles

Cited by 13 publications

References 3 publications

A Numerical Investigation of Film Cooling under the Effects of Different Adverse Pressure Gradients

A Numerical Investigation of Film Cooling under the Effects of Different Adverse Pressure Gradients

Multi-Objective Bayesian Optimization Design of Elliptical Double Serpentine Nozzle

Research on jet noise characteristics of aeroengine double S-bend nozzles with different cross sections

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