Pitch Oscillations Research Articles

Validation of vibration reduction in barge-type floating offshore wind turbines with oscillating water columns through experimental and numerical analyses

Floating offshore wind turbines (FOWTs) are highly susceptible to vibrations caused by wind and sea wave oscillations, necessitating effective vibration reduction strategies to ensure stability and optimal performance. This study investigates the effectiveness of a barge-type FOWT integrated with oscillating water columns (OWCs) in reducing oscillations, particularly in rotational modes. A hybrid FOWT-OWCs system was designed, and its vibration mitigation capabilities were assessed through both numerical simulations and experimental tests. The numerical approach focused on controlling airflow in the OWCs, while the experimental tests validated these results under similar conditions. A strong agreement between the simulations and experiments was observed, particularly in reducing platform pitch oscillations, even under irregular wave conditions. The open OWC-based platform outperformed the closed design, reducing pitch angle oscillations from 17.51° to 14.38° for waves with a 10-s dominant frequency. Benchmark tests confirmed this trend, with the open moonpool-based platform achieving a reduction from 18.41° to 12.23°. These findings demonstrate the potential of OWCs to improve the stability and performance of FOWTs, with experimental validation providing confidence in the numerical predictions.

Experimental Study of Airfoil Aerodynamic Behavior under Oscillating Motion in Ground Effect

When a flying vehicle approaches a water or land surface, it induces changes in the fluid flow field pattern known as the "ground effect." This research analyzes the ground effect phenomenon, exploring its impact on aerodynamic coefficients and flow patterns around the NACA0012 airfoil in an incompressible subsonic regime under static and dynamic conditions with pitch movements. Numerical simulations and experimental testing in an incompressible subsonic wind tunnel were deployed. The flow field solution is derived from the Navier-Stokes equations, incorporating the Transition SST turbulence model. Initially, the impact of the ground effect phenomenon was investigated at varying distances from the surface in the static state. Subsequently, the airfoil underwent a sinusoidal pitching oscillation at each distance with a specified frequency and amplitude. This allowed for examining its aerodynamic characteristics over time. The static analysis results reveal alterations in the curve's behavior and pressure distribution on the airfoil surface at close distances to the surface. This is attributed to the ground effect phenomenon, which reduces lift force to a certain height and then increases. Dynamic analysis further demonstrates changes in lift coefficient oscillation amplitude. It also exhibits a minimum and maximum lift point phase difference as the airfoil approaches the surface.

Design of Input Signal for System Identification of a Generic Fighter Configuration

This article investigates the design of time-accurate input signals in the angle-of-attack and pitch rate space to identify the aerodynamic characteristics of a generic triple-delta wing configuration at subsonic speeds. Regression models were created from the time history of signal simulations in DoD HPCMP CREATETM-AV/Kestrel software. The input signals included chirp, Schroeder, pseudorandom binary sequence (PRBS), random, and sinusoidal signals. Although similar in structure, the coefficients of these regression models were estimated based on the specific input signals. The signals covered a wide range of angle-of-attack and pitch rate space, resulting in varying regression coefficients for each signal. After creating and validating the models, they were used to predict static aerodynamic data at a wide range of angles of attack but with zero pitch rate. Next, slope coefficients and dynamic derivatives in the pitch direction were estimated from each signal. These predictions were compared with each other as well as with the ONERA wind tunnel data and some CFD calculations from the DLR TAU code provided by the NATO Science and Technology Organization research task group AVT-351. Subsequently, the models were used to predict different pitch oscillations at various mean angles of attack with given amplitudes and frequencies. Again, the model predictions were compared with wind tunnel data. Final predictions involved responses to new signals from different models. A feed-forward neural network was then used to model pressure coefficients on the upper surface of the vehicle at different spanwise sections for each signal and the validated models were used to predict pressure data at different angles of attack. Overall, the models predict similar integrated forces and moments, with the main discrepancies appearing at higher angles of attack. All models failed to predict the stall behavior observed in the measurements and CFD data. Regarding the pressure data, the PRBS signal provided the best accuracy among all the models.

Numerical study of dynamic stall effects on VR‐12 airfoil with pitch oscillation and accelerated inflow

AbstractThis study investigates the effects of positive horizontal acceleration of the freestream velocity on a pitch‐oscillating VR‐12 airfoil using computational fluid dynamics. The shear stress transport k–ω model, coupled with a low‐Reynolds number correction, was employed for Re <105 during dynamic stall. The flow equations were solved in two‐dimensional, incompressible form using the finite volume method. The study examined various parameters, including positive acceleration values of the inflow and the angle of attack of the airfoil, to determine their impact on lift and drag coefficients, as well as the ratio. Additionally, the maximum lift coefficient was analyzed under different inflow and airfoil motion conditions. The results indicate that aerodynamic force coefficients and the ratio are influenced by both the attack angle and the acceleration of the inflow. Furthermore, inflow acceleration affects the onset of dynamic stall conditions. Generally, inflow acceleration modifies the lift coefficient of the airfoil during the upstroke, while having minimal effect on the drag coefficient, except near dynamic stall points. The findings also suggest that, for a specific airfoil, the sequence of factors with the greatest influence on lift force generation before static stall occurs is as follows: asymmetric airfoil oscillation, symmetrical airfoil oscillation, accelerated inflow, constant velocity inflow, and static airfoil.

General framework for unsteady aerodynamic prediction of airfoils based on deep transfer learning

Analyzing the unsteady aerodynamic performance of airfoils under dynamic stall using computational fluid dynamics (CFD) is computationally intensive. Although deep learning models can quickly predict aerodynamic parameters, their generalization capability on a small-scale dataset is often poor. This paper presents a novel deep transfer learning (TL) framework that combines model-based and instance-based transfer methods, termed synergistic instance-model TL. This framework facilitates rapid predictions of unsteady aerodynamic performance for various airfoils and pitch oscillations from the small-scale dataset. The framework integrates the accelerated training speed of model-based methods with the dynamic dataset expansion benefits of instance-based approaches. Initially, a pre-trained Wasserstein-deep convolutional generative adversarial network (W-DCGAN) is developed, combining a convolutional neural network with a generative adversarial network to predict aerodynamic hysteresis loops for the SC1095 airfoil in the source domain. The framework then fine-tunes the pre-trained model and incorporates weighted source domain dataset into the small-scale target domain dataset, producing the transferred model W-DCGAN-TL. This approach significantly reduces prediction inaccuracies compared to model-based and non-TL methods when applied to the small-scale dataset. The framework's flexibility allows the use of pre-trained models and datasets from related aerodynamic problems to address issues with insufficient data. Consequently, it is expected to reduce the dependency on extensive datasets, enhance design efficiency, and minimize resource requirements.

The flow control mechanism of trailing-edge Gurney flap on a 50°-swept delta wing in forced pitching

The flow control effect of the trailing-edge Gurney flap (TG) on the dynamic lift characteristics for a 50°-swept delta wing during large-amplitude pitching oscillations at various reduced frequencies (k = 0.072, 0.144, 0.287, and 0.575) was investigated via force, particle image velocity, and dye visualization measurements in a water channel facility. Numerical simulations were carried out to further understand the flow control mechanism of the TG in low and high reduced frequency cases (k = 0.072 and 0.575). It was found that as the reduced frequency increases, the lift increments brought by the TG are magnified and abated during the upstroke and downstroke processes, respectively. The breakdown of the leading-edge vortex (LEV) on the upper surface of the wing is promoted by the TG during the early stage of the pitching cycle. The lift enhancement being benefited by the TG is mainly contributed by the recovery of lower surface pressure along the trailing edge due to the blockage effect of TG, which also stimulates the spanwise flow and strengthens the LEV upon the upper surface. The significant lift increment contribution of the upper surface during the upstroke process can be maintained to higher angle of attack as the reduced frequency increases.

Large-eddy simulation of vortex interaction in pitching-fixed tandem airfoils

In this study, the interaction of vortices generated from an oscillating airfoil with a hindfoil placed downstream of the oscillating forefoil at low-Reynolds-number flow was investigated numerically. The forefoil entered a deep dynamic stall induced by large-amplitude pitching oscillation. The dynamic stall process is characterized by unsteady separation and the formation of a strong clockwise vortex. A wall-resolved large-eddy simulation approach was applied to compute the flowfield. The numerical measurements were performed for an incompressible flow at a Reynolds number of Re = 30 000 based on chord length with a pitching reduced frequency of K= 0.5, and amplitude of A = 14.1° over Selig–Donovan 7003 airfoils. A single-airfoil case was validated against numerical and experimental measurements. In the present study, we investigated the flowfield and aerodynamic coefficients resulting from the deep dynamic stall of the pitching forefoil and the vortex interaction in tandem-airfoil configuration related to micro-air vehicle applications by employing large-eddy simulation approach. Large-eddy simulation was also compared to two-dimensional unsteady Reynolds-averaged Navier–Stokes simulation to determine the accuracy and validity of the low-fidelity approach in prediction of deep dynamic stall and vortex interaction at low-Reynolds-number flow.

Multi-Objective Optimization Design of Dynamic Performance of Hydrofoil with Gurney Flap

The horizontal axis tidal turbine, as a crucial device for capturing tidal energy, has gained significant attention because it has better energy efficiency performance. Enhancing the performance of foils, a vital part of tidal turbine blades, can significantly improve tidal turbine performance. Among numerous methods to enhance the foil performance, the Gurney flap has gained significant attention due to its avoidance of complex structural design. Currently, there is limited research on optimizing the design of Gurney flaps while considering the dynamic performance of foils. In this study, the S809 foil with a blade cross-section was selected as the research subject, a multi-objective optimization design platform was created by integrating a multi-objective optimization algorithm with Computational Fluid Dy-namics (CFD) numerical simulation techniques. The objective of this platform is to enhance the dynamic performance of the hydrofoil by optimizing the geometric structure of the Gurney flap. The improvement of dynamic lift and the size of the dynamic stall hysteresis loop are used as objective variables in this study to evaluate the hydrofoil’s dynamic performance. The optimal Latin hypercube design method is used in the optimization process to choose sample locations, and the Kriging approximation model is used to determine the relationship between the design variables and the objective variables. Meanwhile, the Non-Dominated Sorting Genetic Algorithm-II (NSGA-II) is used to create a multi-objective optimization platform for solving the optimization problem, and the optimized results are validated using CFD. Comparative validation results show that quantifying the dynamic performance during hydrofoil pitching oscillation and using the optimal Latin hypercube design method and Kriging approximation model for optimizing the Gurney flap structure is rational and accurate. This study explores the mechanism of the Gurney flap through in-depth CFD numerical simulations and finds that the Gurney flap affects the flow characteristics at the hydrofoil’s trailing edge, thereby influencing the performance. It increases the pressure difference between the pressure and suction surfaces, thus enhancing the hydrofoil’s lift. Finally, this article provides three recommended parameters to improve the dynamic performance of the hydrofoil. This research can serve as a reference for the application of Gurney flaps in tidal turbine blade design.

Numerical prediction of aerodynamic loads acting on a blade section-model oscillating in stall

For blades operating close to stall angle of attack, one of the potential instabilities is known as stall flutter. It is a dynamic instability in torsion for which the mechanism of energy transfer relies on a dynamic stall process where the flow separates partially or completely during each cycle of oscillation. It leads to dynamic loops in lift, drag and moment that affect the aerodynamic performance of the blade, create unsteady stresses in the blades and can lead to fatigue damage. In the present study, dynamic loops of a NACA 634421 airfoil in forced pitch oscillations have been simulated with the FastS CFD solver based on a URANS modelling approach and compared to benchmark experiments as well as results obtained with the ONERA semi-empirical dynamic stall model using a unique set of dynamic parameters that best fit the experimental dynamic loops. The dynamic tests have been conducted for a mean angle of attack of 13.5°, an amplitude of oscillation of 8° and three reduced frequencies k 1 = 0.0183, k 2 = 0.0785 and k 3 = 0.183. This study has shown that the CFD FastS solver can satisfactorily reproduce the unsteady lift and moment coefficients experienced by a section model oscillating in stall.

Coexistence of passive vortex-induced vibrations and active pitch oscillation triggered by a square cylinder attached with a deformable splitter plate

To understand passive vortex-induced vibrations (VIV) coexisting with active structure motions, this paper numerically investigates the use of pure pitch oscillation to control a square cylinder mounted with a deformable splitter plate at the Reynolds number of 333. The oscillation is enforced with an amplitude of 3° and different frequencies from 0 to 6 Hz. Direct numerical simulations using a partitioned method with a semi-implicit coupling algorithm are performed. According to the trajectories of the splitter-plate tip displacement with respect to the lift or drag force coefficient, a specific lock-in regime determined by the frequency of the enforced pitch oscillation is identified. Further spectral analyses of the tip displacement and lift force show that the lock-in frequencies are equal to the enforced frequencies. Next to the lock-in regime, semi-lock-in regimes with narrow bandwidths are distinguished, exhibiting both lock-in and non-lock-in features. In the non-lock-in regimes, the frequencies of the most predominant peaks in the spectra are found near the natural frequency of the splitter plate of 3.236 Hz, and the frequencies of the two secondary peaks are distributed along the characteristic lines following the ratios of these frequencies to the enforced frequency, which are ±1. Thus, the interaction is dependent on the combined effects of the passive VIV and the actively enforced pitch oscillations. Moreover, the intersection points of the characteristic lines are located close to the upper and lower frequency limits of the lock-in regime, inferring the conditions for the lock-in onset.

Experimental and numerical analysis of power take-off control effects on the dynamic performance of a floating wind-wave combined system

The integration of wave energy converters (WEC) into floating offshore wind turbines (FOWT) is regarded as a promising approach for comprehensively harnessing deep-sea energy and reducing the levelized cost of energy. This study aims to investigate the WEC power take-off (PTO) control effects on the dynamic performance of a floating wind-wave combined system, wherein three heaving-type WECs are integrated into a semi-submersible FOWT. In particular, the hydraulic PTO is modelled as a Coulomb damping system to enable a more realistic analysis. The aero-hydro-servo-elastic-mooring coupled numerical simulations and 1:50 wave basin experimental data demonstrate good agreement. It is observed that wave power production varies significantly with different control settings, potentially reaching 24.0 % of the overall hybrid energy production with proper control parameters. Furthermore, platform pitch oscillation generally shows a decreasing trend with increasing damping forces under below-rated and rated conditions, while showing minimal influence when above-rated. Conversely, tower base damage equivalent load (DEL) tends to initially decrease and subsequently increase across all examined conditions. This consistent convexity indicates the potential use of DEL as a performance index for optimising PTO control. In summary, power increment, motion reduction, and load mitigation could be achieved concurrently with appropriate control design. For instance, an extra 0.48 MW wave power could be produced under the rated condition, while a 10.4 % reduction in tower base DEL and a 6.57 % mitigation in platform pitch oscillation could also be achieved at the same time.

Shock migration on an oscillating straked delta wing using an unsteady Euler solver

Many investigations, including flight tests, wind tunnel tests, and computational methods have attempted to determine the drivers of limit cycle oscillations (LCO) on the F-16 fighter aircraft. One area of interest has focused on shock-induced trailing-edge separation (SITES) as a driver of limit cycle oscillations. The investigation presented herein aims to expand the understanding of unsteady, nonlinear aerodynamics by studying the flow over a wing undergoing pitch oscillations using Euler computational fluid dynamics with a boundary layer coupling scheme capable of estimating viscous flow effects within the boundary layer. A straked NACA 64A204 delta wing model was used for this analysis. Parameters such as trim angle of attack, pitch amplitude, and Mach number were varied to create 71 unique test cases. Results demonstrate that the same single shock systems at low angles of attack and two shock systems at moderate to high angles of attack that were observed by Cunningham in his wind tunnel tests were also present in this investigation. Patterns of significant shock movement and disappearance were observed within the transonic flow region. Hysteresis of the pitching moment was also found to be present. These findings support the theories that shock movement and SITES may play significant roles in driving LCO.

Dynamic Responses of 8-DoF Vehicle with Active Suspension: Fuzzy-PID Control

The driving smoothness of vehicles is heavily influenced by their suspension system, and implementing active suspension control can effectively minimize the vibration movement of the vehicle and ensure a comfortable driving experience. An 8-DoF active suspension model of the full vehicle is established, and a fuzzy-PID controller is designed to autonomously regulate the parameters of the PID controller. Using the MATLAB/Simulink environment, a simulation model for suspension is created, and the vibration characteristics of passive, PID control, and fuzzy-PID control suspensions are compared with the help of the continuous crossing road hump model and C-level road model as road inputs. The results show that the utilization of fuzzy-PID control considerably diminishes the vertical, pitch, and roll oscillations of the suspension body and modifies the suspension dynamic deflection and tire dynamic load in contrast to the other two scenarios, thus enhancing ride comfort. Fuzzy-PID control led to a decrease of approximately 40% in acceleration, 25% in suspension workspace, and 30% in tire deflection compared to passive suspension. In addition, the reduction in acceleration is about 20%, the reduction in suspension workspace is approximately 10%, and the reduction in tire deflection is about 15% compared to the PID control suspension system.

Dynamics modeling and experiment validation for piezoelectric-transmission-wing system

Aiming at the challenge of predicting the dynamic behavior of the flapping wing in the piezoelectric-transmission-wing (PTW) wingbeat system, a lumped-parameter model coupling piezoelectric structural mechanics and flapping-wing aerodynamics is proposed to address the challenge caused by the fluid-structure interaction (FSI). Firstly, a model describing the piezoelectric mechanical response is established, which has the ability to better predict the mechanical response of the piezoelectric actuator under high electric field and low-frequency driving conditions. In order to verify the validity and accuracy, tip deflection, stiffness and blocking force experiments as well as data comparisons are performed to substantiate the findings. Secondly, a comprehensive and reasonable lumped-parameter dynamic model is constructed based on the analysis of the transmission mechanics based on pseudo-rigid-body theory and the improved aerodynamic modeling of the wing, along with the aforementioned piezoelectric mechanical modeling. Thirdly, simulation and dynamic response experiments of the wingbeat system are carried out. Results show that the simulation data are in good agreement with the experimental values, which indicates the accuracy of the model in predicting the dynamic behavior of the flapping wing powered by the piezoelectric actuator. Moreover, some interesting phenomena such as the pitch oscillation of the wing and the dependence of the flapping motion on the driving frequency have been demonstrated in the simulation and the wingbeat experiment, respectively. The research findings of this article offer three types of assistance: (1) providing a parameter design method for piezoelectric actuators to achieve the desired mechanical response; (2) predicting and explaining the dynamic behavior of the PTW wingbeat system; and (3) providing a theoretical foundation for the parameter design and optimization of the wing-actuator pairing in the flapping wing system.

Study of Self-Excited Pitch Oscillations of Conical-Spherical Body at Mach Number M = 1.75 and Two Moments of Inertia

Tests of a conical-spherical body in a supersonic wind tunnel were carried out on a free oscillation installation along the pitch angle at a Mach number M = 1.75 and two moments of inertia of the body relative to the axis of rotation. For a body with a large moment of inertia, self-oscillations with the amplitude of ca. 10 deg were obtained. For the first time, the phenomenon of degeneration of self-oscillations for a body with a smaller moment of inertia has been discovered. An attempt was made to model the phenomenon using an ordinary linear differential equation of the first order

Стабилизирующая активная подвеска вращающейся антенны аэростатной радиолокационной станции

The paper considers the problem of the precision accurate angular orientation and stabilization of the radar station rotating antenna suspended from the tethered balloon and exposed to external vibrational influences capable of leading to significant amplitudes of the low-frequency oscillations in roll and pitch (±15°) at the angular velocity of 10 s-1. Analysis of the known solutions to this problem demonstrated that they all were reduced to the aerostat stabilizers in the form of the tail assembly, as well as to using passive or active stabilizing suspensions. It was noted that gimbal or other suspension with formation of a physical pendulum was used in passive suspensions that were unable to meet modern requirements for accuracy of orientation and stabilization of the rotation axis of the aerostat radar antenna (no more than 6’). Additional use of the servo drives with the self-braking mechanical gears or introduction of the active suspension based on a tripod in combination with the pendulum suspension would inevitably lead to an increase in mass, energy consumption and cost. Possibility of solving this problem is shown on the example of a stabilizing active suspension constructed using the pneumatic automation system elements. A stabilizing active suspension for the rotating antenna of an aerostat radar station is proposed. The proposed suspension is universal and could be used in other areas, for example, in lifting and transport systems designed to work with the objects of increased hazard, as well as in precise installation works in the hard-to-reach locations, for example, with using helicopters or high-altitude cranes.

Shock Buffet and Associated Fluid–Structure Interactions of the Benchmark Supercritical Wing

This study focuses on the fluid–structure interactions of the Benchmark Supercritical Wing (BSCW) at buffet conditions (transonic flows and moderate angles of attack). It presents unsteady Reynolds-averaged Navier–Stokes simulations of the fixed BSCW, the BSCW undergoing prescribed pitch motion, and the BSCW suspended on springs in one and two degrees of freedom. The study’s objectives are to 1) establish the BSCW buffet properties and 2) investigate the aeroelastic and prescribed-motion responses of the wing at buffet conditions. The results indicate that the BSCW buffet is predominantly two-dimensional in terms of its characteristics, although it is greatly affected by the tip flow. The response to prescribed pitch motion and the aeroelastic response of the spring-suspended wing display similar phenomena, where the response in the buffet frequency is suppressed once the oscillation amplitude exceeds some threshold, and the structural and aerodynamic responses are solely at the structural frequency. At the studied conditions, the BSCW undergoes stall flutter, dominated by pitch oscillations, compared to a bending-torsion coalescence flutter at lower angles of attack. We conclude that the shock buffet does not drive the BSCW flutter instability. However, both the buffet and stall flutter develop at similar flow conditions of detached boundary layer behind a strong shock at transonic Mach numbers and moderate angles of attack.

Experimental Study on Porpoising of a High-Speed Planing Trimaran

Porpoising is defined as unstable coupled heave and pitch motions. In this study, seven test conditions with various longitudinal locations of the center of gravity and the moment of inertia were designed to study the porpoising phenomenon of a tunnel-type planing trimaran. After comparing the lower speed limit for porpoising, this study revealed that moving the center of gravity forward could increase the lower speed limit of porpoising, but it could also increase the amplitude of heave and pitch. Furthermore, the reduction of the moment of inertia of the planing hulls could effectively reduce the oscillation amplitude of planing trimaran porpoising and improve the longitudinal stability of planing trimarans. In this test, condition A5 had a 15% reduction in the inertia moment compared to A3, but the amplitude of the pitch oscillation in porpoising decreased by 60%. Unlike conventional trimaran towing tests, this experiment studied the effect of speed on porpoising after exceeding the lower speed limit for porpoising and found that with an increase in speed, the amplitude of porpoising first increased, then decreased, and then increased again. This study defines the speed at which the amplitude of porpoising increases for the second time as the second critical speed of porpoising. The porpoising generated by a planing trimaran after reaching the second critical speed is defined as the second porpoising. Finally, the limitations of the conventional longitudinal stability limit curve method to predict the porpoising of a planing trimaran are discussed.

Experimental Study on Dynamic Stall of Airfoil in Rotor Reverse Flow Region

The large reverse flow region of the rotor with a high advance ratio is an important factor that affects the performance improvement of helicopters. This paper examines the dynamic stall of the airfoil in the reverse flow region of the rotor to develop a set of dynamic pressure measurement systems for the airfoil in the reverse low region. The pitch oscillation experiment of the NACA0018 airfoil in and out of the rotor reverse flow region has been carried out, and the influence of the airfoil motion parameters on dynamic stalls has been studied. The results show that the airfoil is more likely to stall in the reverse flow region under static conditions and that stall is invariant to the Reynolds number. After a stall occurs, the lift coefficient decreases more slowly with the increase of the angle of attack (about 10% of that in the forward flow state). Under the dynamic environment, in a pitching cycle, the quarter chord moment coefficient of the airfoil alternates between positive and negative frequently during reverse-blowing. The pitching oscillation in the reverse flow region is more sensitive to the changes in airfoil parameters than that under normal flow, and there is a marked difference. The alternating moment of the airfoil in the reverse flow region is significant: the greater the pitching amplitude, the greater the alternating moment. In the reverse-blowing state, with the increase in reduced frequency, the dynamic stall angle of attack increases more significantly.

Dependence of wake structure evolution on the frequency of a pitching wing: A numerical investigation using LES

The flapping kinematics have revealed a new paradigm of locomotion which is highly maneuverable and efficient compared to traditional propulsion systems. This work numerically investigates a three-dimensional wing undergoing pitching oscillations using Large eddy simulation (LES). The wake structure is presented using the [Formula: see text]-function, and the influence of pitching frequency on the structure of the wake is discussed. The vortices appear to travel as interconnected vortex rings in the bifurcated wake and are completely different from the two-dimensional investigations. The increase in pitching frequency [Formula: see text] generates the interlinking structures between the two limbs of the bifurcated wake. The interlinking between the two limbs increases with [Formula: see text] and will get disrupted at sufficiently high [Formula: see text]. The increase in [Formula: see text] increased the force generated by the pitching wing, and the periodic dynamics between the force coefficients slowly transformed to quasi-periodic dynamics. The transition to quasi-periodic dynamics has not reduced the force generation of the pitching wing. The disruption of interlinking structures between the two limbs enhanced the lift generated by the pitching wing. The present investigation shows that the wake vortex structure strongly depends on [Formula: see text]. The generation of a jet in the wake is visible in the mean velocity profile indicating the thrust developed by the wing. The formation of multiple peak profiles indicated the formation of multiple jets, which resulted in enhanced thrust production. The Reynolds stress field generated from the velocity fluctuations appears to be influenced by both the pitching oscillations and vortex interactions. This study can guide the selection of better kinematic parameters to enhance the propulsive performance.