Experimental investigation of high-speed twin jets

Moustafa, Gamal H.

doi:10.2514/3.12293

Cited by 36 publications

(17 citation statements)

References 5 publications

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“…Of course, the existence of the second jet may change the entrainment of the main jet; however, we assume the neighboring jet will not change the entrainment of the main jet that much, and the entrainment rate is uniform all over the jet in a specific radius. Replacing equation (8) in equation (5) gives…”

Section: Equation Of Centerline Locationmentioning

confidence: 97%

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A phenomenological model of two circular turbulent jets

Faghani

Rogak

2012

International Journal of Engine Research

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A semi-analytical model for the interaction of twin circular jets is developed, requiring the solution of a second-order differential equation for the momentum balance. This model ('Bending Model') can predict the trajectory and the attachment of two jets. Using Reichardt's hypothesis, the three-dimensional velocity field of dual-hole circular jets can be predicted. The model is used to predict the interaction of converging, diverging, parallel and non-equal jets. The results show encouraging agreement with k-e numerical simulations and experimental results from the literature. The position of the maximum velocity is predicted to within 5%, and the model can predict the velocity field as well as the k-e model. The current model can be useful in phenomenological engine simulation of multi-hole injectors.

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Section: Equation Of Centerline Locationmentioning

confidence: 97%

“…The mean features of the high-speed twin jets were found to be quite similar to those of low-speed incompressible jets. 8 Few studies of non-parallel twin circular jets have been reported. Elangovan et al 9 studied experimentally the interaction of two converging high-speed circular jets.…”

Section: Introductionmentioning

confidence: 99%

A phenomenological model of two circular turbulent jets

Faghani

Rogak

2012

International Journal of Engine Research

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“…5 The third region called the combined region signifies the completion of the merging process and here the two plumes gradually mimic the behavior of a single-jet. 4 As a result, the cross-sectional profiles become nearly circular with maximum velocity region shifting from the center of the individual jets to the symmetry plane between the jets. 3 The coupling between the jets produces several interesting phenomena.…”

Section: Introductionmentioning

confidence: 98%

“…The distance of the merging point from the nozzle exit is a function of the jet lateral spacing and the exit Mach number. 4 Depending on these parameters, the length of the converging region can vary between 5D to 15D. 4 In this region, the interaction between the jets causes the shear-layers to bend towards each other.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of a Twinjet Configuration with and without Flow Control

Goparaju

Gaitonde

Bhaumik

2015

22nd AIAA Computational Fluid Dynamics Conference

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Jet noise has been an active area of research owing to public health concerns and aviation regulations. This problem is further amplified with the use of multiple engines placed in closed proximity to each other. In addition to significantly altered farfield noise as compared to a single-jet, previous experimental results show high levels of dynamic pressure fluctuations in the inter-nozzle region which can cause structural damage. In this work, Large Eddy Simulations are performed to study the dynamics of a supersonic twinjet configuration, with and without flow control. Results indicate that relative to single-jet configuration, twinjets show decrease in column lengths due to significant modifications in shear-layer properties. The simulations also corroborate previous experimental observations of very high levels of dynamic pressure fluctuations in the inter-nozzle region relative to a single-jet configuration for identical flow parameters. The phenomenon of noise shielding along the plane containing the two jets has been reported for all the twinjet cases explored in this work and trends of sound pressure levels obtained at various polar angles indicate an increased efficiency of shielding at lower polar angles. The sensitivity of the dynamic pressure fluctuations on the nozzle-exit boundary layer thickness is also characterized. Simulations are also performed to mimic the effects of Localized Arc Filament Plasma Actuators at different excitation frequencies (St=0.3 and 0.9) actuated in an axisymmetric fashion (m=0). Close to the nozzle exit, toroidal structures formed as a result of control result in significant increase in jet spreading leading to the formation of a recirculation region along the symmetry plane, relative to the uncontrolled case. This excitation scheme increased the levels of dynamic pressure fluctuations closer to the nozzle exit in the inter-nozzle region. In contrast, the near field shows significant reduction in pressure fluctuations, especially for the higher Strouhal number case.

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Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

Liu

Xiang

et al. 2020

steel research int.

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Scarfing applications cause severe noise pollution in metallurgical engineering. To determine the noise characteristics generated by parallel multiple impinging jets in the slab scarfing process, a physical experiment is performed, and a 3D mathematical model is established. Mutual attraction of the parallel multiple jets is recorded, and its influence on the acoustic properties is revealed. The effects of impact height, impact angle, and Reynolds number on the multi‐jet impingement are analyzed. The results indicate that the parallel multiple jets combine in pairs in the upstream. The multi‐jet impingement increases the magnitude of dipole acoustic source, and the noise directivity presents two peaks above the impacted surface. As the impact height increases, the noise intensity first increases to later decrease, and the noise propagation is deflected along the axial direction. As the impact angle decreases, the noise intensity gradually increases, and the spectrum shifts toward higher frequencies. The jet Reynolds number only affects the noise intensity, but has little influence on the spectrum and directivity. The results of this research may provide a theoretical basis for the formulation of guidelines to reduce noise pollution in slab scarfing processes.

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Experimental investigation of high-speed twin jets

Cited by 36 publications

References 5 publications

A phenomenological model of two circular turbulent jets

A phenomenological model of two circular turbulent jets

Investigation of a Twinjet Configuration with and without Flow Control

Experimental and Numerical Analysis on Noise Characteristics of Parallel Multiple Jets Obliquely Impinging on a Flat Surface in the Steel Slab Scarfing

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