Aerodynamic Performance Analysis Research Articles

An adjustable vane-shaped nozzle-based modulated pre-swirl system for gas turbine aero-engine: Structure parameters and aerodynamic performance analysis

The pre-swirl system of an aero engine provides cooling air with suitable temperature and pressure for turbine blades, rarely contributing to thrust. However, the traditional pre-swirl system with a fixed geometry leads to significant wastage of cooling air during part-load conditions, such as subsonic cruising, resulting in a decrease in engine performance. Unlike the existing approach, which uses valves to close a part of the pipeline, a novel modulated pre-swirl system based on the adjustment of the vane-shaped nozzle is proposed to overcome the flow nonuniformity in the circumferential air supply. The effects of the number of pre-swirl nozzles and receiver hole parameters (number, length, and structure) on the system performance are discussed in design and subsonic cruising conditions. The results demonstrate that increasing the number of pre-swirl nozzles significantly improved the flow adjustment efficiency and performance of the modulated pre-swirl system. A larger number and shorter length of receiver holes resulted in a higher system temperature drop in both design and subsonic cruising conditions. With regard to the configurations of the receiver holes, the vane-shaped receiver hole exhibited optimal aerodynamic performance. Compared to the baseline case, the system with Np = 60, NRec = 60, lRec = 3 mm, and vane-shaped receiver hole showed a 27.6 % and 26.7 % improvement in the temperature drop efficiency in the design and subsonic cruising conditions, respectively.

Analysis of Aerodynamic Performance and Application of Flettner Rotor

Analysis of Aerodynamic Performance and Application of Flettner Rotor

Comparative Analysis of Aerodynamic and Structural Performance of Aircraft Wings Using Boron Aluminum Metal Matrix Composites and Aluminum Alloys: A CFD and FSI Approach

Comparative Analysis of Aerodynamic and Structural Performance of Aircraft Wings Using Boron Aluminum Metal Matrix Composites and Aluminum Alloys: A CFD and FSI Approach

Numerical analysis of aerodynamic performance of the Ram Air Turbine in an aircraft

A rotor design of a Ram Air Turbine (RAT) for a commercial aircraft was created taking three sections with different airfoils along the blade; those sections were assessed to evaluate their performance at different critical velocities (41, 81 and 251 m/s) and choose the best profile configuration generating a new proposal to increase the glide ratio by reducing the drag, which is helpful in emergency cases. The Blade Element Momentum (BEM) theory and Computational Fluid Dynamics (CFD) were used to analyze an initial design, then validating these results with the open software QBlade. For the BEM theory a program was created for the design and performance of the RAT adding the Viterna methodology for airfoil analysis. 16 designs were proposed by strategically interchanging wing profiles in different blade sections. These designs were analyzed by CFD, using the complete rotor and the SSTk−ω turbulence model. An optimal geometry was found, presenting a significant drag reduction of 25% generating an increase in the glide ratio and improving aircraft control in addition to maintaining the power generation above the desired values; therefore, it recommends using different airfoils for each section of a RAT's rotor blade.

Aerodynamic modeling and performance analysis of model predictive controller for fixed wing vertical takeoff and landing unmanned aerial vehicle

This research focuses mainly on the aerodynamic modelling and performance analysis of a model predictive controller for a hybrid fixed-wing vertical takeoff and landing of unmanned aerial vehicle. The aerodynamics, which comprises several aerodynamic characteristics including the lift, drag, and thrust coefficients, is modelled using Newton’s second law of motion. The force and moment equations were obtained, and they were then converted into matrix and state equation form, together with the transformation matrices. The essential equations with six degrees of freedom (6 DoF) and 12 state matrices including the control input and manipulating variables were obtained. The proposed model predictive controller (MPC) was designed using the optimal model predictive controller design parameters, such as a sampling time of 0.1, a prediction horizon of 15, a control horizon of 3 and additional controller settings. With a settling period of 3 s, an overshoot of 0.5865, and a steady state inaccuracy of 0.00785, the MATLAB simulation demonstrates that the system variables, including roll, pitch, and yaw, are stabilized. This MPC control is more effective in anticipating and optimizing the UAV than other control strategies. Eventually, the controller’s simulation on MATLAB Simulink demonstrates the controller’s ability to stabilize and control the system in a real-time application. Autonomous vertical takeoff and landing operations depend heavily on the mathematical model and architecture of the flight controller. Among the uses are inspection, monitoring, and rescue.

Improving the performance of a condensing heat exchanger for biomass combustion at household scale

A computational CFD model representing the behavior of a condensing heat exchanger used in domestic heating and hot water applications has been presented and validated, obtaining a flow output gas temperature error of 7%. An analysis of the heat exchanger internal aerodynamic performance revealed the need for geometry enhancements which involved increasing the number of combustion gas passages, reducing the cannon diameter, and incorporating turbulence generators.The geometric modifications produced a significant increase in variables of interest for the performance of the equipment when compared to the baseline case. The improvement is quantified as the 68% increase in turbulent intensity, 57% increase in velocity, doubling of flue gas residence time and 96% increase in total heat transfer rate.The design that contains turbulence generators presents the best performance, obtaining the highest heat transfer rate equal to 3.5 kW, which produces a decrease in the flue gas temperature equal to 62% and an increase in the water outlet temperature equal to 53% compared to the base case. In contrast, the prototype without turbulence generators showed a relatively lower performance in terms of heat transfer, but with a 9 times lower pressure drop.

Aerodynamic performance and flow field losses analysis: A study on nozzle governing turbine with varied regulated nozzle stator installation angle

During the energy release process in compressed air energy storage (CAES) system, the air storage pressure gradually diminishes. To optimize turbine performance in this scenario, a judicious air distribution method becomes imperative. This study adopts single nozzle governing method and elucidates the variation in aerodynamic characteristics under rated output work conditions by manipulating regulated nozzle stator installation angle (RNSIA) and total inlet pressure under varying base pressure. When the RNSIA ranges from −10° to 4° under the base pressure of 10.0 MPa, the maximum specific work increment is 13.2 % and efficiency increment is 14.3 % compared with throttle governing. Meanwhile, the maximum specific work increment is 4.0 % and efficiency increment is 2.9 % compared with designed RNSIA. The proportion of throttle entropy increase to the system progressively rises from 5 % to 40 %, mirroring the trend in system entropy increase. To maintain output work requirements, it's advisable to appropriately decrease the RNSIA to boost inlet pressure of the regulated nozzle and mitigate throttling losses. Additionally, the reduction in the RNSIA within a certain range prolongs the duration of the energy release process in the CAES system, which effectively enhances the round-trip efficiency of the CAES system.

Aerodynamic performance analysis on various wheel configurations of commercial vehicle

Aerodynamic performance analysis on various wheel configurations of commercial vehicle

Aerodynamic Performance and Numerical Analysis of the Coaxial Contra-Rotating Propeller Lift System in eVTOL Vehicles

Electric vertical takeoff and landing (eVTOL) vehicles possess high payload transportation capabilities and compact design features. The traditional method of increasing propeller size to cope with high payload is no longer applicable. Therefore, this study proposes the use of coaxial counter-rotating propellers as the lift system for eVTOL vehicles, consisting of two coaxially mounted, counter-rotating bi-blade propellers. However, if the lift of a single rotating propeller is linearly increased without considering the lift loss caused by the downwash airflow generated by the upper propeller and the torque effect of the lift system, it will significantly impact performance optimization and safety in the eVTOL vehicles design process. To address this issue, this study employed the Moving Reference Frame (MRF) method within Computational Fluid Dynamics (CFD) technology to simulate the lift system, conducting a detailed analysis of the impact of the upper propeller’s downwash flow on the aerodynamic performance of the lower propeller. In addition, the aerodynamic performance indicators of coaxial counter-rotating propellers were quantitatively analyzed under different speed conditions. The results indicated significant lift losses within the coaxial contra-rotating propeller system, which were particularly notable in the lift loss of the lower propeller. Moreover, the total torque decreased by more than 93.8%, and the torque was not completely offset; there was still a small torsional effect in the coaxial counter-rotating propellers. The virtual testing method of this study not only saves a significant amount of time and money but also serves as a vital reference in the design process of eVTOL vehicles.

Aerodynamic Design and Performance Analysis of Mars Ascent Vehicles

The mid-lift-to-drag ratio vehicle possesses larger dimensions and enhanced aerodynamic characteristics compared to the conventional sphere-cone reentry vehicle, suggesting its suitability for crewed missions to Mars. This research employs Computational Fluid Dynamics (CFD) simulations to investigate the influence of varying geometries on the aerodynamic properties of mid-lift-to-drag ratio vehicles. The aerodynamic analysis of four distinct configurations demonstrates that a bow shock wave forms on the windward side, leading to a reduction in flow velocity and subsequent increases in pressure and temperature after the shock wave. The simulation results for the four configurations in both laminar and turbulent flow conditions, specifically using the Shear-Stress Transport (SST) model, reveal that turbulence results in higher aerodynamic heating compared to laminar flow. Moreover, the aerodynamic heating is greater at a 40° angle of attack than at 30°. In this study, the transition phenomena of four geometric configurations are examined using the k-ω-γ transition model. The findings indicate a pronounced transition to turbulence on the windward side of the Ellipsled 2.00-0.25 and Hammerhead-Nominal configurations under conditions of high Reynolds numbers, transitioning from laminar to turbulent flow. The investigation into the aerodynamic characteristics of mid-lift-to-drag ratio vehicles holds substantial importance for ensuring the safety and success of Martian reentry missions, highlighting the critical nature of aerodynamic behavior in the context of space exploration.

A Comparative Analysis of Aerodynamic Performance: Straight Fin and Curved Fin Rockets using Computational Fluid Dynamics (CFD)

This investigation seeks to discern the aerodynamic differentials between rockets featuring straight fins and those with curved fins, focusing on the drag coefficient (cd), lift coefficient (cl), and moment coefficient (cm). Employing the computational fluid dynamics (CFD) methodology within ANSYS Fluent software, the research endeavors to provide comprehensive insights. The rockets under scrutiny share a common cylindrical body configuration, boasting a 70 mm diameter, a conical nose, and four symmetrically positioned fins along the lower body. The CFD analyses encompass subsonic Mach 0.6 and supersonic Mach 1.2 scenarios, with the angle of attack systematically varying from 0° to 25° at 5° intervals for each velocity setting. The outcomes of the simulations reveal notable trends: both cd and cl exhibit an upward trajectory, while cm experiences a decrement with escalating angles of attack and velocities. The culmination of Ansys CFD simulations for both rocket configurations unequivocally indicates superior flight performance for the straight fin rocket. This discernment is grounded in the observed amplification of drag and lift coefficients, coupled with the concomitant reduction in the moment coefficient, thus elucidating the nuanced aerodynamic distinctions between straight fin and curved fin rockets across varying flight conditions.

Numerical Simulation of the Transient Flow around the Combined Morphing Leading-Edge and Trailing-Edge Airfoil.

An integrated approach to active flow control is proposed by finding both the drooping leading edge and the morphing trailing edge for flow management. This strategy aims to manage flow separation control by utilizing the synergistic effects of both control mechanisms, which we call the combined morphing leading edge and trailing edge (CoMpLETE) technique. This design is inspired by a bionic porpoise nose and the flap movements of the cetacean species. The motion of this mechanism achieves a continuous, wave-like, variable airfoil camber. The dynamic motion of the airfoil's upper and lower surface coordinates in response to unsteady conditions is achieved by combining the thickness-to-chord (t/c) distribution with the time-dependent camber line equation. A parameterization model was constructed to mimic the motion around the morphing airfoil at various deflection amplitudes at the stall angle of attack and morphing actuation start times. The mean properties and qualitative trends of the flow phenomena are captured by the transition SST (shear stress transport) model. The effectiveness of the dynamically morphing airfoil as a flow control approach is evaluated by obtaining flow field data, such as velocity streamlines, vorticity contours, and aerodynamic forces. Different cases are investigated for the CoMpLETE morphing airfoil, which evaluates the airfoil's parameters, such as its morphing location, deflection amplitude, and morphing starting time. The morphing airfoil's performance is analyzed to provide further insights into the dynamic lift and drag force variations at pre-defined deflection frequencies of 0.5 Hz, 1 Hz, and 2 Hz. The findings demonstrate that adjusting the airfoil camber reduces streamwise adverse pressure gradients, thus preventing significant flow separation. Although the trailing-edge deflection and its location along the chord influence the generation and separation of the leading-edge vortex (LEV), these results show that the combined effect of the morphing leading edge and trailing edge has the potential to mitigate flow separation. The morphing airfoil successfully contributes to the flow reattachment and significantly increases the maximum lift coefficient (cl,max)). This work also broadens its focus to investigate the aerodynamic effects of a dynamically morphing leading and trailing edge, which seamlessly transitions along the side edges. The aerodynamic performance analysis is investigated across varying morphing frequencies, amplitudes, and actuation times.

Aeroacoustic assessment of a rectilinear cascade with leading edge serrations: predictions and measurements

This study aims at evaluating previously designed leading edge serrations for the turbulence-cascade interaction noise reduction on a rectilinear cascade. Low and high-fidelity methodologies have been investigated and are compared to experimental data issued from a cascade test rig mounted in an anechoic wind tunnel. These methods include mean flow simulations for aerodynamic performance analysis, analytical models well suited to acoustic design, an Euler-based numerical method coupled with an integral method for the far-field acoustic prediction, and finally high-fidelity simulations based on the lattice Boltzmann method to take account for installation effects. The scopes and benefits of each methodology are discussed. Fast design methods and mid-fidelity numerical simulations provide satisfactory trends, but only high-fidelity simulations are able to accurately match acoustic spectra and sound power level reductions measured by microphone antenna.

Aerodynamic performance analysis of a floating wind turbine with coupled blade rotation and surge motion

The unsteady aerodynamic characteristics and interference effects of a floating wind turbine are significantly influenced by the six-degree-of-freedom (6DoF) motions. In this paper, the computational fluid dynamics (CFD) method using the overset grid technique and the improved delayed detached eddy simulation (IDDES) model was adopted to investigate the effects of harmonic enforced surge motions on the aerodynamic performance and wake characteristics of wind turbines. The aerodynamic load coefficients including the constant term, damping coefficients (surge velocity-induced), and additional mass coefficients (surge acceleration-induced), were fitted by using the least squares method at different surge frequencies and surge amplitudes. The blade pressure distributions and wake characteristics were analysed in detail. The Ω ~ R of the third-generation vortex identification method was applied to visualize vortex evolution. The numerical results are evaluated against the data obtained by wind tunnel experiments, indicating an acceptable relative error of 3.45 % for the power coefficient, C p , at the rated tip speed ratio (TSR). The higher frequency and greater amplitude surge motions lead to more dramatic fluctuations for the power coefficient than the axial load coefficient. The neglect of the additional mass coefficient only results in an acceptable error. Furthermore, the mean damping coefficient is on average approximately 3.5 times the mean constant term coefficient for C p , approximately 1.5 times for C z . In terms of the blade pressure distributions and wake characteristics, a higher comprehensive induced velocity, V c , is induced to expand the wider high-pressure area and shrink the low-pressure area at the pressure surface. Meanwhile, toroidal vortex ropes were induced by surge motion. Besides, the surge motion at high frequency and greater amplitude positively impacts enhancing wake deficit recovery.

Optimization and control strategy for wind turbine aerodynamic performance under uncertainties

Aerodynamic performance of wind turbine governs the overall energy efficiency, which has been an ever-lasting research focus in the field of wind power technology. Due to the coupling effect among the highly complex environmental and structural uncertainties, the practical aerodynamic performance may not be reliably predicted. To aggravate, this performance declines with time in service. It is of great significance to efficiently and reliably assess the impact of uncertain factors and reduce these influences on wind turbine aerodynamic performance. This paper establishes an uncertainty analysis and robustness optimization model of wind turbine aerodynamic performance considering wind speed and pitch angle error uncertainties. An approach combined the no-instrusive probabilistic collocation method is used, and the blade element momentum theory is applied to quantify influences of variable uncertainties on NREL 5 MW wind turbine aerodynamic performance. The optimization target is to reduce the sensitivity of wind turbine aerodynamic performance to uncertainties, as well as maintain capture power. The results show that the wind turbine aerodynamic and mechanical performance will be greatly affected with uncertain factors. By optimizing and adjusting wind turbine rotor speed and blade pitch angle, the wind turbine rotor power and thrust load variation can be reduced to 9.14% and 9.36%, respectively, which indeed reduces the uncertainty effects.

Current Trends and Innovations in Enhancing the Aerodynamic Performance of Small-Scale, Horizontal Axis Wind Turbines: A Review

Abstract Wind energy has proven to be one of the most promising resources to meet the challenges of rising clean energy demand and mitigate environmental pollution. The global new installation of wind turbines in 2022 was 77.6 GW, bringing the total installed capacity to 906 GW, documenting an astounding 9% growth in just one year (Lee and Zhao, 2023, Global Wind Report, GWEC. Global Wind Energy Council). Sizeable research continues to focus on improving wind energy conversion, safety, and capacity. However, funding allocations and research have not matched this sustained market growth observed over the last few decades. This is particularly the case for small-size wind turbines. We define small-scale wind turbines as those with an output power of 40 kW or less that can nonetheless be interconnected to provide larger power output. Thus, the paper focuses on small-scale horizontal-axis wind turbines (HAWT) with emphasis on current technology trends including data gathering, aerodynamic performance analysis of airfoils and rotors, as well as computational approaches. The paper also highlights the challenges associated with small-scale HAWTs thereby conjecturing about future research directions on the subject. The literature review suggests that small-scale HAWT wind turbines are suitable for harnessing energy in communities with limited resources where grid-supplied power is out of reach. The power coefficient of these turbines ranges from 0.2 to 0.45 which shows that it could greatly benefit from research, built on targeting these modest performance scales by using efficient airfoils, mixed airfoils, optimizing the blade geometry, shrouding the wind turbine rotor, using maximum power tracking control, etc. This review paper is an attempt to prioritize and layout strategies toward evaluating and enhancing the aerodynamic performance of small-scale HAWTs.

Design and Analysis of an Adaptive Dual-Drive Lift–Drag Composite Vertical-Axis Wind Turbine Generator

In this paper, based on the lift-type wind turbine, an adaptive double-drive lift–drag composite vertical-axis wind turbine is designed to improve the wind energy utilization rate. A drag blade was employed to rapidly accelerate the wind turbine, and the width of the blade was adaptively adjusted with the speed of the wind turbine to realize lift–drag conversion. The aerodynamic performance analysis using Fluent showed that the best performance is achieved with a blade curvature of 30° and a drag-type blade width ratio of 2/3. Physical experiments proved that a lift–drag composite vertical-axis wind turbine driven by dual blades can start when the incoming wind speed is 1.6 m/s, which is 23.8% lower than the existing lift-type wind turbine’s starting wind speed of 2.1 m/s. At the same time, when the wind speed reaches 8.8 m/s, the guide rail adaptive drag-type blades all contract and transform into lift-type wind turbine blades. The results show that the comprehensive wind energy utilization rate of the adaptive dual-drive lift–drag composite vertical-axis wind turbine was 5.98% higher than that of ordinary lift-type wind turbines and can be applied to wind power generation in high-wind-speed wind farms.

Wind tunnel testing of a Formula Student vehicle for checking CFD simulation trends

The aerodynamic performance analysis of Formula Student racecars has been mostly done by teams with CFD tools, for time and cost savings, that often lack proper validation. To address this, the FST Lisboa team performed a detailed wind tunnel (WT) test campaign, using a one-third scale model, under different configurations, including variable ride heights, bullhorn appendix, and rear wing flap settings, also replicated in CFD. The simulations used RANS with the SST k-omega turbulence model, with a 13.7 million polyhedral mesh for the test chamber region domain. Both experimental and numerical errors were estimated from the instrumentation and mesh convergence analysis, respectively. Comparisons were made between WT and CFD both in terms of local flow, using tufts for flow visualization, and global flow, using lift, drag, and pitching moment coefficients. Overall, the numerical streamlines agreed very well with the orientations of the tufts in experiments, but some discrepancies were found in regions of cross-flow and high-frequency unsteadiness, mainly caused by limitations of the visualization technique. The gamma transition model in CFD was abandoned as it could not replicate the WT observations. In terms of aerodynamic coefficients, a strong correlation was found between WT and CFD. The parametric studies revealed that the simulations captured the experimental sensitivity to each car setting parameter studied but the uncertainties did not enable a full quantitative evaluation of the aerodynamic performance. The drag reduction system significantly impacted the aerodynamic balance of the racecar, while the current bullhorn design proved to be ineffective. The ride height increase led to higher downforce, mostly due to the higher pitch angle of the vehicle, with negligible variation of the aerodynamic balance. This work validated the team CFD studies, building confidence in that trends estimated in numerical parametric studies are likely to be translated to the real prototype performance.

Numerical Investigation of Aerodynamic Performance and Structural Analysis of a 3D J-Shaped Based Small-Scale Vertical Axis Wind Turbine

Small vertical axis wind turbines (VAWTs) are often considered suitable for use in urban areas due to their compact design. However, they are also well known to offer poor performance at low wind speeds, which is a common situation in such environments. An optimised 3D J-shaped VAWT was designed from standard NACA 0015 blades and analysed numerically through computational fluid dynamics (CFD). A finite element analysis (FEA) was also carried out to ensure the model’s structural integrity. Optimal results were obtained with aluminium alloy hollow blades and stainless-steel struts with X-shaped beams, with internal ribs. Numerical results showed that the J-shaped VAWT achieved an 18.34% higher moment coefficient compared to a NACA 0015-based VAWT, indicating better self-starting abilities.

Correlation analysis of lift fan lip feature geometry and aerodynamic performance

In hover, the lip of a lift fan plays a crucial role, contributing to nearly half of the lift for the VTOL aircraft power plant. Thus, investigating the geometric parameters that influence lip performance is of significant importance. In this study, four types of lift fan lips were designed, tailored to meet specific application requirements. Numerical analysis, validated through experimental data, was employed to examine the flow field and the geometric factors that lead to variations in lip performance. Based on the findings, the relationship between lip geometric parameters and aerodynamic performance was thoroughly investigated and confirmed. The results demonstrate that, at a rotational speed of 10 000 r/min, the non-dimensional lift and non-dimensional mass flow of the lemniscate lip exhibit improvements of 33% and 9.5%, respectively, compared to lips designed based on NACA65. Among the various lip configurations, it is found that the performance parameters of the lip are optimal when the slope of the inner surface equaled twice the slope of the lemniscate. On the other hand, when the slope deviated from this optimal value, whether greater or lesser, a reduction in lip performance was observed. Specifically, at a rotational speed of 10 000 r/min, the lip designed based on a lemniscate slope could increase the total lift of the lift fan by 5.6% when compared to the lemniscate lip.