Article
Mechanics
Wei Xie, Zhenbing Luo, Lin Hou, Yan Zhou, Qiang Liu, Wenqiang Peng
Summary: This study investigates the performance of a plasma synthetic jet actuator with Laval-shaped and straight-shaped exits. It shows that the drag reduction effect of a PSJA with a Laval-shaped exit is significantly better than that of one with a straight-shaped exit under certain conditions, with the optimal drag reduction values achieved at different epsilon levels.
Article
Thermodynamics
Jiaming Sheng, Yun Wu, Haideng Zhang, Yizhou Wang, Mengxiao Tang
Summary: In this study, a numeri-al investigation was conducted to examine the flow control effects of a spanwise distributed pulsed arc discharge plasma actuation (PADPA) on supersonic compressor cascade flow. The results demonstrate that under low static pressure ratio condition, PADPA reduces shock wave loss, improves the ability of the boundary layer to resist adverse pressure gradients, and reduces separation zone. However, under high pressure ratio condition, PADPA has little effect on controlling the boundary layer and results in a slight increase in total pressure loss.
JOURNAL OF THERMAL SCIENCE
(2022)
Article
Mechanics
Yizhou Wang, Haideng Zhang, Yun Wu, Yinghong Li, Yujie Zhu
Summary: This paper investigates the flow control effects of nanosecond dielectric barrier discharge (NS-DBD) plasma actuation on the supersonic compressor cascade flow at low Reynolds numbers through large-eddy simulations. The study shows that NS-DBD plasma actuation induces a distorted flow structure (DFS) on both the blade pressure surface and suction surface. Despite being suppressed by shock waves on the blade pressure surface, the DFS still triggers instability in the shear layer. The study also finds that the DFS on the blade pressure surface suppresses shock-wave-induced large-scale flow separation and reduces the overall total pressure loss of the blade passage by 7.4%.
Article
Mechanics
Xiuxiu Chen, Zhengzhong Sun
Summary: This article investigates the energy transformation characteristics of the plasma synthetic jet actuator (PSJA) through theoretical, experimental, and numerical research. The results show that the size and formation time of the plasma kernel can be predicted and the peak pressure and temperature rise in the cavity can be calculated. The proportion of kinetic energy increases linearly with non-dimensional deposition energy, while potential energy has a reverse tendency with non-dimensional cavity volume and deposition energy.
Article
Mechanics
Zongnan Chen, Jiaao Hao, Chih-Yung Wen
Summary: The control performance of a pulsed nanosecond dielectric barrier discharge (NSDBD) plasma actuator on a supersonic compression corner was studied using experiments and numerical simulations. The results showed that the plasma actuator can effectively reduce the separation bubble length and suppress the separation region by modifying the flow structures, when appropriately applied in terms of voltage and location.
Article
Engineering, Aerospace
Hongyu Wang, Fu Min, Zhendong Xie, Feng Xie, Jie Li, Yanguang Yang
Summary: We propose a novel method of high-speed aerodynamic control using active energy injection of pulsed discharges. Experimental and numerical simulations demonstrate that the control principle based on shock wave manipulation by energy injection is effective in reducing the local Mach number and aerodynamic force. The simutation results show similar flow topologies and consistent variation tendency in the aerodynamic force to the experimental results.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Mechanics
Hongyu Wang, Weibo Hu, Feng Xie, Jie Li, Yao Jia, Yanguang Yang
Summary: This study investigates the control effects of a high-frequency pulsed discharge on a hypersonic separated flow induced by a 42° compression ramp. The results show that the discharge can reduce the separation area, especially at relatively low frequencies of 10 or 20 kHz. The flow mechanism induced by the discharge is found to be the enhancement of unstable eddies within the shear layer.
Article
Engineering, Aerospace
Mengxiao Tang, Yun Wu, Hongyu Wang
Summary: In this paper, experimental research is conducted to study the hypersonic shock-shock interaction control using plasma actuator array, aiming to explore a new surface thermal protection method for hypersonic aircraft. The results show that the plasma actuator array can effectively control the shock-shock interaction system, and increasing energy deposition has a positive impact on the control outcome.
Article
Thermodynamics
Deepak Prem Ramaswamy, Anne-Marie Schreyer
Summary: Experiments were conducted to study the influence of spanwise spacing between adjacent orifices of an air-jet vortex-generator (AJVG) array on their separation-control effectiveness. The results showed that the array with intermediate spacing achieved the best control effect, significantly reducing the length and area of separation. The array with the smallest spacing caused adverse vortex interactions and increased separation, while the array with the largest spacing only made local modifications in the separation region.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Mechanics
Alan H. Duong, Thomas C. Corke, Flint O. Thomas
Summary: Experiments using active flow control successfully reduced the viscous drag in turbulent boundary layers and decreased the wall-normal vorticity component, improving turbulence characteristics.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Chandrasekhar Medipati, S. Deivandren, R. N. Govardhan
Summary: Liquid jet injection into supersonic crossflow can result in unsteady flow and spray formations. This study experimentally investigates the self-induced fluctuations in flow and spray caused by liquid jet injection into supersonic crossflow. The results show significant variations in windward spray edge and penetration, which are influenced by fluctuations in mass flow rate and shocks.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Engineering, Aerospace
Marcin Kurowski, Ryszard Szwaba
Summary: This study presents the results of experimental and numerical investigations on synthetic jet actuators with different arrangements. The promising results show an increase in output velocity and vorticity in the context of separation control by the modified arrangement.
JOURNAL OF AEROSPACE ENGINEERING
(2022)
Article
Physics, Applied
Chuan-Biao Zhang, He-Sen Yang, Hua Liang, Shan-Guang Guo
Summary: An experimental investigation was conducted to study the control effects of the high-frequency streamwise pulsed arc discharge array (HS-PADA) on the double compression ramp shock wave/boundary layer interaction (DCR-SWBLI) at Mach 2.0. The results showed that the 20 kHz actuation was more effective in weakening the shock wave intensity compared to the 10 kHz actuation. The HS-PADA exhibited two different control effects: modifying the shock structure related to the separation zone and modifying the low-frequency unsteadiness of the shock wave, which may not be related to the separation zone. The first separation shock wave was more sensitive to the HS-PADA compared to the second. The control mechanism of the HS-PADA on DCR-SWBLI was extracted.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Engineering, Aerospace
S. Vaisakh, T. M. Muruganandam
Summary: An experimental study was conducted to understand the near flowfield of an over-expanded supersonic wall-jet. The study focused on capturing flow features using shadowgraphy, oil flow visualization, and infrared thermography, with a comparative analysis between the two methods. The research also looked at the ability of these methods to capture supersonic surface flow features and listed their merits and demerits.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Deepak Prem Ramaswamy, Anne-Marie Schreyer
Summary: Experimental analysis showed that adequate interaction between steady air-jet vortex generators is essential for effective control of shock-induced boundary-layer separation, with the most favorable control effect achieved at a jet spacing of 0.76 delta. The injection of jets resulted in strong corrugation of the separation zone, reducing its area and turbulent intensity. The increase in turbulent mixing confirmed the control effect between jet injection and separation shock, while flow farther away from the surface remained unaffected, reducing potential drag penalties.
Article
Engineering, Aerospace
Joshua D. Pickles, Venkateswaran Narayanaswamy
Article
Optics
Abinash Sahoo, Dominic Zelenak, Venkateswaran Narayanaswamy
Article
Optics
Abinash Sahoo, Dominic Zelenak, Venkateswaran Narayanaswamy
Article
Engineering, Aerospace
Maxim Freydin, Dani Levin, Earl H. Dowell, Santosh Vaibhav Varigonda, Venkateswaran Narayanaswamy
Article
Engineering, Aerospace
Joshua D. Pickles, Venkateswaran Narayanaswamy
Article
Mechanics
Michael D. Leonard, V. Narayanaswamy
Summary: Research was conducted on shock oscillations within a two-dimensional axisymmetric inlet model with a constant area isolator, showing low and high frequency broadband oscillations. It was found that downstream propagation of pressure fluctuations occurs primarily through convection of boundary layer structures, while upstream propagation is through acoustic waves.
JOURNAL OF FLUID MECHANICS
(2021)
Correction
Engineering, Aerospace
Maxim Freydin, Dani Levin, Earl H. Dowell, Santosh Vaibhav Varigonda, Venkateswaran Narayanaswamy
Article
Optics
Abinash Sahoo, Aravind Ramachandran, Venkateswaran Narayanaswamy, Kevin M. Lyons
Summary: This study demonstrates a Rayleigh scattering-based approach to measure mixture fraction in a turbulent ethylene MILD combustion zone, which shows low sensitivity to local temperature and composition. The results provide evidence that the distributed heat release does not significantly impact the turbulent processes of the flow-field.
Article
Engineering, Mechanical
S. V. Varigonda, V. Narayanaswamy
Summary: This paper introduces an approach to uncover the elastic mode contributions in the pressure dynamics over the panel surface in weakly coupled fluid-structure interactions. By averaging multiple power spectra, broadband fluctuations can be subdued while retaining the elastic mode contributions.
EXPERIMENTS IN FLUIDS
(2021)
Article
Engineering, Aerospace
Ethan Johnson, Chase Jenquin, Jonathan McCready, Venkat Narayanaswamy, Jack Edwards
Summary: This study experimentally investigates the performance of a stream-traced truncated-Busemann inlet and provides a thorough understanding of the intricate flowfield within the inlet at different operation conditions. The effects of external backpressure and facility on the inlet operation are explored.
Article
Engineering, Mechanical
Maxim Freydin, Earl H. Dowell, Santosh Vaibhav Varigonda, Venkateswaran Narayanaswamy
Summary: The aeroelastic response of a plate with supersonic freestream flow and a shallow cavity to turbulent pressure fluctuations is investigated computationally and experimentally. The study finds that the structural response is relatively small when the excitation is filtered by the plate dynamics. The measured pressure parameters show good agreement with the computed results, indicating consistency in a wide range of structural natural frequencies.
JOURNAL OF FLUIDS AND STRUCTURES
(2022)
Article
Optics
Abinash Sahoo, Venkateswaran Narayanaswamy, Kevin M. Lyons
Summary: This study demonstrates a new approach for direct quenching measurements at atmospheric conditions using nanosecond lasers. The quenching measurements are performed on a krypton-perturber system. A theoretical construct is presented to relate the absorption spectral parameters and integrated fluorescence signal to the quenching rate. The technique can measure relative quenching rates but can be converted to absolute values when the reference quenching rate is independently measured.
Article
Mechanics
Chase Jenquin, Ethan C. Johnson, Venkat Narayanaswamy
Summary: This study investigates the large-scale pulsations of shock-induced separation, which have a length scale significantly larger than the incoming boundary layer thickness. Two-dimensional highly resolved maps of the surface pressure field are obtained using fast-response pressure-sensitive paint fluorescence imaging. The measurements provide new insights into the dynamics and coupling of the shock-boundary layer interaction unit and validate the theoretical models. The results also reveal the influence of pressure perturbations at azimuthally offset locations on the dynamics of the separation bubble.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Engineering, Mechanical
S. V. Varigonda, V. Narayanaswamy
Summary: The study investigates the flow structure coupling caused by impinging shock boundary layer interactions (SBLI) flowfield over a rectangular panel. The impinging oblique shock is generated by an 8 shock generator in a Mach 2.5 flow. The weak coupling between the flowfield and structural response in this study does not change the mean separation size, but causes discrete elevations in the pressure fluctuations near different panel resonance mode frequencies.
JOURNAL OF FLUIDS AND STRUCTURES
(2023)
Article
Mechanics
James Walz, Venkat Narayanaswamy
Summary: This research demonstrates a new approach to reduce separation scales and mitigate skin friction drag in high-speed aerial vehicles using the native or programmable material properties of aerostructures. It is experimentally shown that appropriately chosen viscoelastic materials can simultaneously reduce the skin friction coefficient by 11% and mitigate the size of separated flows by up to 28%. This study opens up a new application space for soft/programmable materials in high-speed aerial vehicles.
