Large-eddy simulation of sonic coaxial jets with different total pressure ratios of the inner to outer nozzle

Shi, Haitao; Liu, Nansheng; Wang, Pei; Lu, Xi‐Yun

doi:10.1016/j.compfluid.2018.06.001

Cited by 7 publications

(2 citation statements)

References 57 publications

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“…The shock wave passes through the jet core region, reaching the outer shear layer of the airflow and reflecting to form an expansion wave [29,30]. As the airflow propagates downstream, the expansion and shock waves alternate, which leads to alternating low and high air pressure [31,32]. Due to the dissipative effect of the shock wave, the jet velocity decreases, and the shock wave structure gradually weakens and disappears.…”

Section: Analysis Of Noise Generationmentioning

confidence: 99%

Minimum Quantity Lubrication Jet Noise: Passive Control

Hu,

Yu,

et al. 2023

Micromachines

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Jet noise is a common problem in minimum quantity lubrication (MQL) technology. This should be given great attention because of its serious impacts on the physical and mental health of the operators. In this study, a micro-grooved nozzle is proposed based on the noise reduction concept of biological micro-grooves. The flow field and acoustic characteristics of an original nozzle and a micro-grooved nozzle were investigated numerically to help better understand the noise reduction mechanism. The reasons for noise generation and the effects of the length (L), width (W) and depth (δ) of the micro-grooves on noise reduction were analyzed. It was found that jet noise is generated by the large-scale vortex ring structure and the pressure fluctuations caused by its motion. The overall sound pressure level (OASPL) decreased with the increases in W and δ, and increased with the increase in L. Among of them, δ has the greatest effect on noise reduction. The maximum noise reduction achieved was 6.66 dB, as verified by the OASPL test. Finally, the noise reduction mechanism was discussed in terms of the flow field, vorticity and the frequency characteristics. Micro-grooves can enhance the mixing of airflow inside the nozzle and accelerate the process of large-scale vortices breaking into smaller-scale vortices. It also reduces the sound pressure level (SPL) of middle frequencies, as well as the SPL of high frequencies on specific angles.

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Section: Analysis Of Noise Generationmentioning

confidence: 99%

Minimum Quantity Lubrication Jet Noise: Passive Control

Hu,

Yu,

et al. 2023

Micromachines

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show abstract

“…Lovaraju and Rathakrishnan (2011) found that mixing was inhibited in CFJ with LT of 2.65 mm and VR of 0.4. The flow characteristics and structures of a sonic CFJ depend mainly on the total pressure ratio (Shi et al, 2018). Complicated interactions of the shear layers occur in the near field.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

Krishnan

Raja

et al. 2020

AEAT

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Purpose This study aims to analyze co-flowing jets (CFJs) with constant velocity ratio (VR) and varying primary nozzle lip thickness (LT) to find a critical LT in CFJs below which mixing enhances and beyond which mixing inhibits. Design/methodology/approach CFJs were characterized with a constant VR and varying LTs. A single free jet with a diameter equal to that of a primary nozzle of the CFJ was used for characteristic comparison. Numerical simulation is carried out and is validated with the experimental results. Findings The results show that within a critical limit, the mixing enhanced with an increase in LT. This was signified by a reduction in potential core length (PCL). Beyond this limit, mixing inhibited leading to the elongation of PCL. This limit was controlled by parameters such as LT and constant VR. A new region termed as influential wake zone is identified. Practical implications In this study, the VR is maintained constant and bypass ratio (BR) was varied from low value to very high values. Presently, subsonic commercial turbo fan operates under low to ultra-high BR. Hence the present study becomes vital to the current scenario. Originality/value To the best of the authors’ knowledge, this is the first effort to find the critical value of LT for a constant VR for compressible co-flow jets. The CFJs with constant VR and varying LT have not been studied in the past. The present study focuses on finding a critical LT below which mixing enhances and above which mixing inhibits.

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First-mode-induced nonlinear breakdown in a hypersonic boundary layer

Nair

Gaitonde

2019

Computers & Fluids

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Large-eddy simulation of sonic coaxial jets with different total pressure ratios of the inner to outer nozzle

Cited by 7 publications

References 57 publications

Minimum Quantity Lubrication Jet Noise: Passive Control

Minimum Quantity Lubrication Jet Noise: Passive Control

Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

First-mode-induced nonlinear breakdown in a hypersonic boundary layer

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