Unsteady Aerodynamic Loads Research Articles

Aeroelasticity of an aircraft wing with nonlinear energy sink

In this paper, the effectiveness of nonlinear energy sinks on enhancing aeroelastic stability and post-instability response of aircraft wings is investigated. The wing has two degrees of freedom in bending and torsion, and is modelled using an extended Euler-Bernoulli beam theory with hardening nonlinearity. A Nonlinear Energy Sink (NES) absorber is embedded inside the wing distributed along the wing span. The wing attached unsteady aerodynamic loads are simulated using the Wagner's indicial lift model. The structural dynamics of the wing are derived using Extended Hamilton's Principle and it is discretised using Galerkin's method. The NES mass is connected to the wing spar through a linear damper and nonlinear spring with a cubic stiffness nonlinearity. The coupled aeroelastic equations are then transformed to state space. Then, integrated numerically to resolve the bending and torsional response of the wing to study the impact of spanwise and chordwise positions of the embedded NES on flutter suppression and instability response enhancement. The results demonstrate that the NES is most efficient and is most sensitive to changes in the stiffness when placed at the wingtip. For a given chordwise location, it is found that there is a range of flow speeds over which the NES is most effective and reducing the chordwise offset lowers the speed of the peak efficiency range and moves it closer to the flutter speed. In addition, increasing the stiffness coefficient of the NES improves the efficiency of the device in the immediate post-flutter region. Two near optimum NES devices are proposed with a mass ratios of 1% (located at the wingtip) and 2.5% (located at 75% span). Both of these improve the flutter speed by 5%, and reduce the post-flutter response by 64.5% and 59.2%, respectively.

Investigation of wind turbine unsteady aerodynamics and trailing-edge noise characteristics under wake steering

In wake steering strategy, the shaft of an upstream wind turbine is yawed to deflect the wake and decrease the wake-swept area of the downstream wind turbine rotor. This intentional yaw misalignment increases the output power of the downstream wind turbine at the expense of some loss of upstream wind turbine power, consequently increasing the total wind farm power. However, the asymmetric non-uniform inflow into the downstream wind turbine due to the deflected wake causes unsteady aerodynamic loads and affects the wind turbine noise characteristics. In this study, the unsteady vortex lattice method coupled with the curled wake model is used to predict the unsteady aerodynamics of a downstream wind turbine in wake steering. Based on the unsteady aerodynamic results, the trailing-edge noise characteristics are predicted by a semi-empirical method. The impact of wake steering on trailing-edge noise level and amplitude modulation is evaluated. The results show that the asymmetric non-uniform inflow due to wake steering increases the amplitude modulation of the downstream wind turbine.

Numerical study on transonic shock wave buffeting of airfoil

Abstract Modern transportation aircraft typically cruise at transonic speeds. However, under a specific combination of incoming flow Mach numbers and angles of attack, periodic self-excited oscillations of shock waves can lead to unsteady aerodynamic loads, causing sustained vibrations in the aircraft, which is known as transonic shock wave buffeting. Buffeting loads significantly impact the fatigue life of the aircraft’s structural materials and its handling performance. In severe cases, it causes structural damage or even leads to flight safety incidents, so we should pay more attention to transonic shock wave buffeting when focusing on aeronautical engineering. This paper employs computational fluid dynamics technology for calculations to solve the Navier-Stokes equations, using the SST k-ω turbulence model to numerically simulate the steady flow field, and further employing the detached eddy simulation (DES) method to study and analyze the buffeting initiation mechanism and flow field characteristics of the NACA0012 airfoil’s transonic unsteady flow. By applying the DES method, the results demonstrate an accurate prediction of the buffeting onset boundary of the airfoil compared to wind tunnel experimental data. The research findings on the initiation mechanism and load characteristics of transonic buffeting provide a theoretical basis for optimizing the aerodynamic performance of aircraft during transonic flight and offer guidance for engineering issues such as buffeting load mitigation.

Gust response alleviation of the aircraft wing aeroelastic systems in supersonic flows using nonlinear energy sink

In order to reduce the gust response level of the aircraft wing aeroelastic systems in supersonic flows, the nonlinear energy sink (NES) is introduced into the aeroelastic system, and the effect of the nonlinear energy sink on the aeroelastic gust response is studied. The gust response dynamic model without and with NES is established by Lagrange equation, considering the cubic nonlinear characteristics of both plunge and pitch stiffness. The piston theory model as well as the '1-cos' model are employed to describe the unsteady aerodynamic load and the gust velocity, respectively. Besides, the comparison study of the gust response amplitude and energy characteristics of the wing aeroelastic systems with and without NES are analyzed. For systems with NES, the amplitude of gust dynamic response decreases rapidly, while vibration can be transmitted to the NES mechanism and causing its vibration. From an energy perspective, about 72.15 % of the original vibration energy has been transferred into NES, and further consumed through its damping. The influence of NES parameters, such as frequency ratio, mass ratio, damping ratio, and installation position on gust response, is discussed. Numerical simulations demonstrate that: as the frequency ratio, damping ratio and mass ratio increase, the dynamic response amplitude of the aeroelastic system decays faster, and the energy transferred from the wing system also increases. In addition, an optimal relative distance for the installation of NES can be found with best gust alleviation effect. The influence of nonlinear energy sink on the targeted transfer of vibration energy in aeroelastic systems are analyzed under different working conditions. The NES shows great gust alleviation effect and good robustness under different flight speeds, gust intensities, and gust lengths.

Semi-analytical solutions for steady-state bending-bending coupled forced vibrations of a rotating wind turbine blade by means of Green's functions

Wind power has received significant attention in recent years as a renewable energy source. Wind turbine blades, characterized by their long lengths, are prone to damage as a result of aeroelastic instability. This paper aims to derive semi-analytical solutions for steady-state forced vibrations of rotating wind turbine blades, considering the coupling of bending, bending, and unsteady aerodynamic loads. The novelty of this work lies in the use of the Green's function method to solve differential dynamic equations with variable coefficients, which are induced by aerodynamic forces. To model a wind turbine blade, the Euler-Bernoulli beam model is employed, and Greenberg's expressions are taken into consideration. Governing equations for coupled vibrations of the blade are then determined. In order to solve the governing equations, displacement solutions are decomposed into quasi-static displacements and dynamic displacements. The Laplace transformation and Green's function methods are utilized to obtain fundamental solutions of the governing equations. Subsequently, employing the principle of superposition, Fredholm integral equations for steady-state forced vibration of a rotating wind turbine blade are derived. To spatially discretize Fredholm integral equations, compound trapezoid formulae and central finite difference approximations are employed. This discretization process leads to the formation of a system of algebraic equations. Semi-analytical solutions for coupled forced vibrations of the rotating wind turbine blade are obtained by solving the algebraic equations. In the numerical solution part, validation of proposed solutions are verified by comparing them with numerical and finite element solutions in the literature. Influences of some important physical parameters, such as the rotating velocity, the setting angle, the cone angle, the inflow ratio, and damping, on vibration responses of blades are discussed.

Towards extending the aircraft flight envelope by mitigating transonic airfoil buffet

In the age of globalization, commercial aviation plays a central role in maintaining our international connectivity by providing fast air transport services for passengers and freight. However, the upper limit of the aircraft flight envelope, i.e., its operational limit in the high-speed (transonic) regime, is usually fixed by the occurrence of transonic aeroelastic effects. These harmful structural vibrations are associated with an aerodynamic instability called transonic buffet. It refers to shock wave oscillations occurring on the aircraft wings, which induce unsteady aerodynamic loads acting on the wing structure. Since the structural response can cause severe structural damage endangering flight safety, the aviation industry is highly interested in suppressing transonic buffet to extend the flight envelope to higher aircraft speeds. In this contribution, we demonstrate experimentally that the application of porous trailing edges substantially attenuates the buffet phenomenon. Since porous trailing edges have the additional benefit of reducing acoustic aircraft emissions, they could prospectively provide faster air transport with reduced noise emissions.

Comparative study on lateral vibration characteristics of the head and tail cars of high-speed trains under unsteady aerodynamic loadings

With the increasing speed of high-speed trains, abnormal vibrations in the tail car pose a threat to its overall stability and running safety. In this study, the aerodynamic and multibody dynamics models for 3-car and 8-car trains are established. The flow field characteristics and dynamic performance around the head and tail cars under both steady and unsteady aerodynamic loadings at a speed of 400 km/h are compared. The results reveal that the surrounding flow field exhibits highly pronounced unsteady characteristics, directly leading to a significant impact of unsteady aerodynamic loadings on the train's dynamic response. Under unsteady loadings, the lateral stability indexes, displacement, velocity, and acceleration of the tail car are all worser compared to those of the head car. Additionally, the larger oscillation amplitudes and frequencies closer to the suspension modal frequencies under unsteady aerodynamic loadings contribute to more pronounced lateral displacements and accelerations, constituting a crucial factor in the observed ‘tail swing' phenomenon for the high-speed train.

On the aeroelastic bifurcation of a flexible panel subjected to cavity pressure and inviscid oblique shock

The aeroelasticity of a panel in the presence of a shock is a fundamental issue of great significance in the development of hypersonic vehicles. In practical engineering, cavity pressure emerges as a crucial factor that influences the nonlinear dynamical characteristics of the panel. This study focuses on the aeroelastic bifurcation of a flexible panel subjected to both cavity pressure and oblique shock. To this end, a computational method is devised, coupling a high-fidelity reduced-order model for unsteady aerodynamic loads with nonlinear structural equations. The solution is meticulously tracked by continuous calculations. The obtained results indicate that cavity pressure plays a pivotal role in determining the bifurcation and stability characteristics of the system. First, the system exhibits hysteresis behaviour in response to the ascending and descending dynamic pressures. The evolution of hysteresis behaviour originates from the phenomenon of cusp catastrophe. Second, variations in cavity pressure induce three types of bifurcation phenomena, exhibiting characteristics akin to supercritical Hopf bifurcation, subcritical Hopf bifurcation and saddle-node bifurcation of cycles. The system's response at the critical points of these bifurcations manifests as long-period asymptotic flutter or explosive flutter. Lastly, the evolution of the dynamical system among these three types of bifurcations is an important factor contributing to the discrepancies observed in certain research results. This study enhances the understanding of the nonlinear dynamical behaviour of panel aeroelasticity in complex practical environments and provides new explanations for the discrepancies observed in certain research results.

Constructing nonlinear data-driven models from pitching wing experiments using multisine excitation signals

Accurate modelling of unsteady nonlinear aerodynamic loads is crucial for the effective design and control of aerodynamic systems. Data-driven modelling approaches have emerged as powerful tools for capturing intricate system dynamics without prior knowledge of the underlying physical principles. This paper focuses on the construction of nonlinear data-driven models for pitching wing systems using multisine excitation signals and their relative merits compared to swept sine signals. The polynomial nonlinear state-space (PNLSS) modelling framework is used, which has been proven in the system identification community to offer flexibility and richness in representing diverse nonlinear phenomena. Data are gathered with a dedicated experimental wind tunnel setup. A NACA 0018 wing is made to oscillate in pitch according to a swept sine and a multisine with a frequency up to 2 Hz. The experiments are repeated to cover the attached flow, light stall, and deep stall regimes. PNLSS models are trained on multisines and benchmarked against models trained on swept sines to assess their comparative performance. Then, all models are successfully cross-validated using single sine data at different angles of attack. We conclude that one single data-driven model can accurately represent the lift force across different linear (attached flow) and nonlinear (light and deep stall) operating regimes.

Aeroelastic tailoring of stiffened cantilever plate using composites and structural layouts: A parametric study

AbstractThis paper studies the aeroelasticity of a stiffened cantilever plate using composite material and novel structural layouts. A comprehensive parametric study is conducted to determine the influence of different design parameters on the aeroelastic boundaries. Design parameters include plate sweep angle, ply orientation, stringer cross-section and stringer sweep angle. Nastran is used to run the aeroelastic analysis, and the process is automated using ${\rm{Matla}}{{\rm{b}}^{}}$ . The structure of the plate is modelled using laminate elements whereas the stringers are modelled using the Euler-Bernoulli beam elements. The unsteady aerodynamic loads are modelled using doublet-lattice method (DLM) and the structural and aerodynamic meshes are connected using an infinite plate surface (IPS) spline. A mesh sensitivity analysis is conducted to ensure fine meshes for the aerodynamics and structure. The study’s findings demonstrate the benefits of employing forward swept (Fw) stringers since it increases flutter speed by almost 38% compared to the unswept stringers case and prevents divergence. Moreover, the static aeroelastic analysis illustrates that the utilisation of Fw swept stringers can reduce the average tip displacement and tip twist effectively. T-shaped stringers are recommended to stiffen the plate due to their lower impact on the total mass of the plate. In some configurations, the structural layout has a much higher effect on the aeroelastic instabilities when compared to the material effect (ply orientation). However, results suggest combining both for some cases to get balanced washin and washout effects.

Analyzing Unsteady Turbomachinery Flow Simulations With Mixing Entropy

Abstract The prediction of unsteady aerodynamic loads is a central problem during the design of turbomachinery. Over the last 20 years, harmonic balance methods have been shown to be highly efficient for this task. A CPU-cost optimal setup of a harmonic balance simulation, however, requires knowledge of relevant harmonics. In the case of a single blade row with a periodic disturbance this question amounts to the classical problem of harmonic convergence, a problem which is solely due to the nonlinearity of the unsteady flow physics. In contrast, for multi-stage configurations, the choice of harmonics is further complicated by the fact that the interactions of disturbances with blade rows may give rise to a vast spectrum of harmonics that possibly have important modal content, e.g., Tyler–Sofrin modes. The aim of this paper is to show that the mixing entropy attributed to circumferential modes of a given harmonic can serve as a disturbance metric on the basis of which a criterion could be derived whether a certain harmonic should be included or not. The idea is based on the observation that the entropy due to the temporal and circumferential mixing of the flow at a blade row interface may be decomposed, up to third-order terms, into independent contributions from different frequencies and mode orders. For a given harmonic balance (and steady) flow result, the mixing entropy attributed to modes that are simply mixed out, rather than resolved in the neighboring row, is shown to be a natural indicator of a potential inaccuracy. We present important features of the mixing entropy for unsteady disturbances, in particular a close relationship to sound power for acoustic modes. The problem of mode selection in a 1.5-stage compressor configuration serves as a practical example to illustrate our findings.

Modelling the unsteady lift of a pitching NACA 0018 aerofoil using state-space neural networks

The development of simple, low-order and accurate unsteady aerodynamic models represents a crucial challenge for the design optimisation and control of fluid dynamical systems. In this work, wind tunnel experiments of a pitching NACA 0018 aerofoil conducted at a Reynolds number $Re = 2.8 \times 10^5$ and at different free-stream turbulence intensities are used to identify data-driven nonlinear state-space models relating the time-varying angle of attack of the aerofoil to the lift coefficient. The proposed state-space neural network (SS-NN) modelling technique explores an innovative methodology, which brings the flexibility of artificial neural networks into a classical state-space representation and offers new insights into the construction of reduced-order unsteady aerodynamic models. The work demonstrates that this technique provides accurate predictions of the nonlinear unsteady aerodynamic loads of a pitching aerofoil for a wide variety of angle-of-attack ranges and frequencies of oscillation. Results are compared with a modified version of the Goman–Khrabrov dynamic stall model. It is shown that the SS-NN methodology outperforms the classical semi-empirical dynamic stall models in terms of accuracy, while retaining a fast evaluation time. Additionally, the proposed models are robust to noisy measurements and do not require any pre-processing of the data, thus involving only a limited user interaction. Overall, these features make the SS-NN technique an excellent candidate for the construction of accurate data-driven models from experimental fluid dynamics data, and pave the way for their adoption in applications entailing design optimisation and real-time control of systems involving lift.

Study on the aerodynamic performances and the operational safety of the vehicle-bridge system under the crosswind

The train operates in special environments such as large bridges and elevated viaducts. The fluctuations of the aerodynamic loads of the high-speed train (HST) are more intense and the possibility of the train derailment and overturning will increase when the train is running on the bridge under the crosswind. Thus, it is of utmost importance to study both the aerodynamic characteristics and the running safety of the train in this situation. This study uses the IDDES method to investigate the aerodynamic characteristics of the train running on the double track bridge in both up and down train directions at different speeds. The differences in the impact of aerodynamic loads on the train’s dynamic response indicators are discussed using the wind-vehicle coupling dynamic response calculation method. Based on these researches, the operational safety of the train under different operating conditions is evaluated from both flow field and dynamic perspectives. The results show that large-scale vortices fall off from the nose of the train and form a larger vortex structure on the leeward side and when the train is running under the crosswind. Its aerodynamic loads fluctuate intensely with time due to the complex wake flow of the train. The dominant frequencies of the unsteady aerodynamic loads are mostly concentrated in the range of 0–5Hz, which is close to the natural modal frequencies of the train. This will lead to the overturning of the train due to vehicle resonance. The derailment coefficient and wheel load reduction rate of the train increase with the speed. Their peak values exceed the limit of 0.8 while the peak duration of the derailment coefficient is less than 0.05s, which means the state of the leeward wheel will recover from a short derailment. However, the duration of derailment increases with speed. Therefore, appropriate measures should be taken to prevent accidents when the train is running at higher speed on the bridge to guarantee the operational safety of the HST.

Adaptive Internal Model Control for a Flexible Wing With Unsteady Aerodynamic Loads.

This article proposes adaptive internal model controls for the collocated output regulation of a flexible wing, where distributed disturbances, boundary disturbances, and references are from an exactly unknown exosystem. Observer-based tracking error feedback controls are first designed to address the robust output regulation in case of a known exosystem matrix. If the exosystem has an unknown matrix, an adaptive observer is further proposed with the observer error system converging to zero exponentially. Then, we can obtain adaptive observer-based controls by combining adaptive observers and observer-based controls, which are able to regulate the tracking errors toward zero in case of the exactly unknown disturbances and references. The corresponding closed-loop system is proved to be internally asymptotically stable. A simulation example is further provided for adaptive internal model control of the wing system.

Study on Lateral Vibration of Tail Coach for High-Speed Train under Unsteady Aerodynamic Loads

As the speed of high-speed trains increases, the vehicle’s lateral stability steadily deteriorates. There have been observations of abnormal vibrations in the tail car, particularly on certain sections of the railway line. This study built a high-speed train aerodynamic simulation model for a three-car consist, and a multibody dynamics simulation model for an eight-car consist based on numerical simulations of train aerodynamics and multibody dynamics. It investigated both steady and unsteady aerodynamic loads, flow field characteristics, and the dynamic performance of vehicles under varied aerodynamic loads at 400 km/h. The results indicate that the aerodynamic loads generated during high-speed train operation exhibit highly unsteady characteristics. Steady aerodynamic loads have a relatively minor impact on the vehicle’s dynamic performance, whereas unsteady loads exert a more significant influence. Under unsteady aerodynamic forces, the tail car experiences severe lateral vibrations. The lateral stability index, displacement, velocity, and acceleration of the tail car under unsteady conditions were measured at 2.26, 7.54 mm, and 0.53 m/s2, respectively. These values represent increases of over 17.71%, 148.84%, and 111.24%, respectively, compared to the steady loads. Large oscillation amplitudes result in more significant lateral displacements and accelerations of the vehicle. This phenomenon is a crucial factor contributing to the “tail swing” effect observed in high-speed trains. This study emphasizes the importance of considering unsteady aerodynamic effects in assessing the lateral stability of high-speed trains and highlights the significance of mitigating the adverse impacts of such dynamic responses, particularly in the tail car.

Optimized design of wind turbine airfoil aerodynamic performance and structural strength based on surrogate model

Though offshore wind turbines have great potential for applications in ocean energy harvesting, their subject to complex unsteady aerodynamic loads. To obtain wind turbine airfoils with both aerodynamic performance and structural strength, an airfoil optimization method was proposed by adding the torsion constant to the objective function under the premise of improving the lift-to-drag ratio. The optimization method characterizes the airfoil geometric profile by using Class/Shape function transformation (CST) parameterization. The airfoil aerodynamics and the structural properties were solved by the computational fluid dynamics (CFD) method and Matlab program, respectively. To reduce the number of CFD calculations, a Kriging surrogate model was established. The combination of an optimized Latin hypercube sampling method and expected improvement (EI) points infill criteria is to improve surrogate modeling efficiency. The NREL 5 MW wind turbine blade was used as the research object. The NACA64618 with 18% relative thickness, the DU91-W2-250 with 25% and the DU97-W-350 with 35% were optimized by assigning different weights to aerodynamic and structural objectives based on airfoil position in the blade. The results showed that the aerodynamic performance of the optimized airfoils was improved. Subsequently, the three optimized airfoils were replaced in the same positions of the blade for lay-up design. The blade structural properties were calculated by finite element method (FEM) and it found that the blade torsion angle was reduced, which indicated that adding structural objectives in the airfoil optimization could enhance the blade structural performance.

An active suspension system for enhancing running safety of high-speed trains under strong crosswind

The running safety of trains subjected to strong crosswinds has become a major concern for the high-speed railways passing through complicated mountain areas. This paper reports an active secondary suspension system to improve the operation stability and running safety of high-speed trains under strong crosswind. The goal of the active suspension system is to regulate the lateral, yaw, and roll motion attitudes of high-speed train carbody, in which a controller is designed by combining with a disturbance observer and the sliding mode control method. To further verify the proposed active suspension strategy, a crosswind-vehicle-track coupled dynamics model is established, where the unsteady aerodynamic loads and random track irregularity excitations are considered. The results show that the proposed active suspension system has the efficient potential to regulate the carbody motion attitudes and enhance the anti-rolling performance of high-speed trains. In comparison to a quasi-static control strategy of active suspension, the use of the proposed active suspension system has led to a significant reduction in both wheel-load reduction ratios and derailment risks of high-speed trains.

Wake interaction between two spar-type floating offshore wind turbines under different layouts

Limited by layout space and manufacturing costs, wake interaction in offshore wind farms is inevitable and can have adverse effects on the performance of downstream wind turbines. To gain a better understanding of the wake interaction between Floating Offshore Wind Turbines (FOWTs), this paper conducts coupled aero-hydrodynamic simulations for two spar-type FOWTs under different layouts. The Unsteady Actuator Line Model (UALM) is used to analyze the unsteady aerodynamic loads of the wind turbine, while the hydrodynamic responses of the floating support platform are obtained using the Computational Fluid Dynamics (CFD) method. To predict the aero-hydrodynamic performance of the FOWT under combined wind and waves, an in-house CFD code developed at Shanghai Jiao Tong University (SJTU), called FOWT-UALM-SJTU solver, is utilized. First, grid convergence test and time step sensitivity study are performed to determine appropriate simulation parameters. Subsequently, numerical simulations of two FOWTs under tandem and offset layouts are conducted to investigate the influence of wake interaction on the performance of downstream FOWT. The dynamic responses of the FWOT, including aerodynamic loads, platform motions, and wake characteristics, are analyzed in detail. From the simulation results and discussions, several conclusions are drawn. Both platform motions and wake interaction contribute to an increased variation range of inflow wind speed experienced by the downstream FOWT, thereby exacerbating the instability of its aerodynamic loads. Under the tandem layout, the platform motions of the upstream FOWT and the downstream FOWT exhibit opposite effects on the aerodynamic loads of the downstream FOWT. Moreover, platform motions increase turbulence intensity in the wake region, accelerating wake velocity recovery and widening the wake width.

Numerical Modeling to Investigate the Aerodynamics of a Boundary-Layer Ingested Transonic Fan

Boundary-layer ingested engines have the potential to offer significantly reduced fuel burn, but the fan stage must be designed to run efficiently with a distorted inflow. It must also be able to withstand unsteady aerodynamic loads resulting from a complex nonuniform flowfield. This paper applies different numerical methods for an improved understanding of the aerodynamic interaction between a transonic fan and inlet distortion. A single-stage transonic tail cone thruster fan was designed using both in-house and commercial tools operating in an inlet distortion flowfield. This paper demonstrates that the relevant metrics required to compute the aerodynamic performance of a fan stage in distorted conditions can be reasonably modeled with a few harmonics using the nonlinear harmonic method in a fraction of time in comparison to a full annulus time marching solution. The nonlinear harmonic method also reduces the computational domain, and hence reduces the solution runtime by an order of magnitude. However, it fails to accurately resolve the wake and potential field transfer across the blade rows due to a limited number of harmonics being applied. A detailed aerodynamic description of the unsteady inflow distortion, the interacting blade-row mechanisms, the flow redistribution upstream of the rotor, the distortion transfer across the different blade rows, and the corresponding aerodynamic losses can be analyzed accurately using only a full annulus time-marching method.

Numerical simulation of subsonic flow around oscillating airfoil based on the Navier–Stokes equations

ABSTRACT Unsteady Reynolds-averaged Navier–Stokes equations of an incompressible fluid are used to numerically simulate the flow around an oscillating airfoil. A comparison is made between two differential one-equation turbulence models SA and SALSA on the problems of subcritical and supercritical turbulent incompressible flow around an oscillating NACA 0015 airfoil. The numerical algorithm utilized for solving the governing equations is founded upon a three-layer implicit scheme, which exhibits second-order integration accuracy in time, third order of upwind approximation of convective terms, and second-order symmetric approximation of the diffusion terms. Pressure and velocity field coupling is achieved through the implementation of the artificial compressibility approach, which is employed for the computation of unsteady problems. The system of initial equations is numerically integrated using the control volume method. The resulting system of algebraic equations has been solved by the GMRES method with ILU(k) preconditioning. The obtained instantaneous streamlines, vorticity contours, and hysteresis curves of unsteady airfoil aerodynamic loads are analyzed for cases of weak ( α 0 = 4 ° ), developed ( α 0 = 11 ° ) and massive ( α 0 = 15 ° ) flow separation at Reynolds number Re = 1.95 × 10 6 . In the case of weak flow separation, the values of the lift coefficient obtained using the SA and SALSA models differ from the experimental data by 10% and 5%, respectively. With a developed separation, these values are already equal to 10–20% for the SA model and 6–8% for the SALSA model. The average values of the lift coefficient, which are obtained using the SA and SALSA models, in the case of massive flow separation, differ from the experimental data by 50–60% and 10–15%, respectively. Comparing the calculation results with both known experimental and calculated data demonstrates that in flows with developed and massive flow separation, which are characterized by unsteady effects in turbulence, the SALSA turbulence model performs better than other tested models. The aerodynamic coefficients obtained with the SALSA turbulence model are in 10–15% better agreement with experimental data than those obtained with other turbulence models.