Experimental investigation of flow dynamics of oscillating jet emitted in confined and non-confined backward-facing step geometries

Mohammadshahi, Shabnam; Samsam-Khayani, Hadi; Deng, Zhiwen; Kim, Kyung Chun

doi:10.1016/j.euromechflu.2021.03.002

Cited by 5 publications

(2 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the current study, the extremely con ned geometry increased the friction between the jet and wall surface and thus increased the energy consumption, such that all dissipations were expected to be larger than those occurring in open space. More details on the effects of con ned structures on the ow and heat transfer characteristics of sweeping jets are available in Mohammadshahi et al (2020Mohammadshahi et al ( , 2021.…”

Section: At Phase Anglementioning

confidence: 99%

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Song,

Wang,

Qiu

et al. 2024

Exp Fluids

View full text Add to dashboard Cite

The present study optimized some novel uidic oscillator designs, measured their internal-external uid dynamics, and used modal analysis to reveal their underlying oscillation mechanisms. It also investigated the effects of structural parameters on their uid dynamics. The time-resolved internalexternal pressure elds of the oscillators were determined by using pressure-sensitive paint (PSP) measurement. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) were used for modal analysis and phase reconstruction. The time-averaged pressure-eld and phasereconstruction results reveal that recirculation bubbles inside the mixing chamber and the feedback ow have underpinned the mechanism of formation of internal and external continuous sweeping ows. The modal analysis results reveal the spatial modal structures and their time evolution, which dominated the internal-external ow pattern. The inlet-wedge width and feedback-channel inlet diameter were found to be the structural parameters affecting feedback ow and recirculation-bubble size, and thereby in uenced ow characteristics such as jet oscillation frequency and divergence angle. Different Coandă surfaces altered the recirculation bubbles and feedback ow of the mainstream, thereby in uencing the formation mechanism of the sweeping jet.

show abstract

Section: At Phase Anglementioning

confidence: 99%

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Song,

Wang,

Qiu

et al. 2024

Exp Fluids

View full text Add to dashboard Cite

show abstract

“…As one kind of effective AFC technology, the sweeping jet has been considered a more practical flow controller than other existing technologies [11], and it is widely applied in other different sceneries. For example, the dynamics of oscillating jet emitted in confined and non-confined backward-facing step geometries were investigated with TR-PIV to resolve the mechanism of flow separation and reattachment that occurs at a sharp corner, which will help the application of fluidic oscillators in heat transfer enhancement or cooling process [12]. In addition, an experimental study on the flow control capability of sweeping jet actuators in an aggressive offset S-shaped duct with a compressed incoming flow was conducted to suppress flow separation in the duct and flow distortion at the aerodynamic interface plane.…”

Section: Introductionmentioning

confidence: 99%

Active Flow Control of a Supercritical Airfoil and Flap with Sweeping Jets

Luo,

Li,

Cheng

et al. 2023

Applied Sciences

View full text Add to dashboard Cite

To provide sufficient lift during takeoff and landing, large aircraft are equipped with complicated high-lift devices. The use of simple flaps coupled with active flow control (AFC) can achieve lift improvement while reducing mechanical structure and weight. The present study focuses on verifying the feasibility and effectiveness of simple flaps combined with sweeping jet flow control. An experimental study on the AFC of flaps, using sweeping jets, was carried out using a NASA SC(2)-0410 supercritical airfoil wind-tunnel model at Re = 2.0 × 105 (with velocity V = 10 m/s). In the experiment, the wing angle of attack (α) ranged from 3 to 18°, and the flap deflection angle (δ) ranged from 0 to 30°; the aerodynamic characteristics and surface pressure characteristics of the wing at typical working conditions were analyzed. Using sweeping jets to control the flow on the flaps, the momentum coefficients (for three actuator groups) of the jet are 0.8%, 3.6%, and 8.2%, respectively, and the maximum lift coefficient was increased by approximately 33%. The influence of the sweeping jet flow rate on the aerodynamic performance of the airfoil is analyzed. There are two main reasons for the lift coefficient increase caused by sweeping jet flow: an extra suction peak near the flap and a suction peak increase near the leading edge area caused by induced flow.

show abstract

Experimental investigation on flow characteristics of compressible oscillating jet

2022

View full text Add to dashboard Cite

An experimental study was performed to investigate the characteristics of a self-sustained oscillating jet emitted from a double feedback channel fluidic oscillator under high pressure inlet conditions. The working fluid was N2 gas from a portable liquid nitrogen tank. The pressure, temperature, and flow rate were measured, and z-type schlieren visualization was performed to study the high-frequency oscillating jet at nozzle pressure ratios (NPRs) of 4–16. A proper orthogonal decomposition (POD) technique was performed on schlieren images, and a Fast Fourier transform was performed on time coefficients of POD modes to calculate the frequency of oscillations. The results show that for the examined NPRs, the frequency of the oscillating jet is independent of the pressure and flow rate, which contrasts with previous studies. However, the flow behavior varies when changing the NPR. The frequency did not increase with increasing supply pressure. In order to find the main reason for the fixed frequency, a second-order mass spring system was assumed. An equation is also proposed for obtaining the resonance frequency of the double feedback fluidic oscillator.

show abstract

Experimental investigation of flow dynamics of oscillating jet emitted in confined and non-confined backward-facing step geometries

Cited by 5 publications

References 27 publications

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Flow mechanism study and geometrical parameters analysis of fluidic oscillators based on pressure-sensitive paint measurements and modal analysis

Active Flow Control of a Supercritical Airfoil and Flap with Sweeping Jets

Experimental investigation on flow characteristics of compressible oscillating jet

Contact Info

Product

Resources

About