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Generally, the experimental aerodynamics is related to wind tunnel experiments. The wind tunnel design topic is very old but the development in computational fluid dynamics led to improvement in the wind tunnel design. This paper describes the design and optimization of low speed wind tunnel using CFD techniques. The new optimum wind tunnel will replace the old one featuring poor air quality and small area with lower wind speed at the test section. A computational domain was generated and adopted using ANSYS mesh generator and the solution domain was analysed by simulation technique using FLUENT CFD code in ANSYS Workbench package. The pressure drop calculations comparison between analytical, computational and experimental is included for different sections in the wind tunnel. The contraction cone was optimized using the response surface technique. The results identified that the pressure drop and turbulence level are modified as compared to the old wind tunnel.

The distinctive tubercles on the leading edge of humpback whale flippers have potential applications in the design of aviation wings. These knobby structures are hypothesized to enhance aerodynamic performance, particularly in low-speed, high-lift conditions, by reducing drag and increasing lift. This study investigates the feasibility of incorporating whale-inspired tubercles into aircraft wing designs to improve flight performance. Through a combination of computational fluid dynamics (CFD) simulations and wind tunnel experiments, the aerodynamic properties of tubercle-equipped wings are compared to those of conventional smooth-wing designs. The findings demonstrate that tubercles contribute to more stable airflow, delay flow separation, and increase lift-to-drag (L/D) ratios. These improvements have significant implications for enhancing aircraft performance and fuel efficiency, particularly during critical phases such as takeoff and landing, potentially leading to the development of more efficient and environmentally sustainable aviation technologies.

Developing wind tunnel models is time consuming, labor intensive, and expensive. Rapid prototyping for wind tunnel tests is an effective, faster, and cheaper method to obtain aerodynamic performance results while considerably reducing acquisition time and cost for the models. Generally, the rapid prototyping models suffer from insufficient stiffness or strength to withstand the loads generated during a wind tunnel test. In the present study, a rapid prototype model reinforced with metallic inserts was produced to experimentally investigate the aerodynamic characteristics of an uncrewed aerial vehicle with various wingtip deflections. The fused deposition modeling process was used to make the outer mold, whereas the metallic parts were produced using laser cutting and the computer numerical control machining process. Then, the model was evaluated both experimentally and numerically. The test campaign presented in this work was conducted in the de Havilland low-speed wind tunnel facility at the University of Glasgow. For better characterization of flow patterns dominated by leading edge vortices, numerical simulations were run using OpenFOAM 8.0 and validated with experimental data. The experimental data obtained from the hybrid rapid-prototyped model agreed well with the numerical results. This demonstrates the efficacy of hybrid rapid-prototyped models in providing reliable results for initial baseline aerodynamic database development within a short period and at a reduced cost for wind tunnel tests.

The design of an aircraft’s internal structure, and therefore the appropriate choice of material type, is a direct function of the performed tasks and the magnitude and type of the acting loads. The design of a durable aircraft structure with appropriate stiffness and lightness requires knowledge of the loads that will be applied to the structure. Therefore, this paper presents the results of an aerodynamic experimental test and numerical analysis of a newly designed jet-propelled aerial target. The experimental tests were carried out in a low-speed wind tunnel for a wide range of angles of attack and sideslips. Moreover, they were performed for various configurations of the airplane model. In addition, the results of the experimental test were supplemented with the results of the numerical analysis performed using computational fluid dynamics methods. During numerical analysis, specialized software based on solving partial differential equations using the Finite Volumes Method was used. This article presents the methodology of the conducted research. The results of the aerodynamic analysis are presented in the form of diagrams showing the aerodynamic force and moment components as a function of the angle of attack and sideslip. In addition, qualitative results of the flow around the plane have been presented. The results obtained prove that the adopted methods are sufficient to solve these types of problem. The aerial system was positively verified during the qualification tests of the system at the Polish Air Force training range and finally received the type certificate.

In order to further promote the digitalization extent of environmental test, ensure that the test chamber can more realistically simulate the actual environment, and improve the environmental adaptability of vehicle equipment in extreme environments, the three-dimensional CFD simulation method was used to calculate simulation test chamber of an armored vehicle in high-altitude environment in the form of low-speed return flow wind tunnel. There are movable suspension and flap in the entrance to the contraction section of the test chamber. The velocity field and temperature field were analyzed, the temperature distribution and heat transfer in the characteristic section of the test section under different flap deflection angles were compared and analyzed by selecting working conditions, and make the relationship among flow speed and flow rate and the temperature field of the test section clear.

In this study, we developed a compact low-speed wind tunnel. First, we computationally analysed the flow quality of different wall shapes for the contraction section, the most critical part of a wind tunnel, and selected the design exhibiting minimal boundary layer separation at simulated flow velocities of 2 and 8 km h −1 . Then, after constructing the wind tunnel, we experimentally evaluated its overall performance based on different parameters per the United States Environmental Protection Agency (U.S. EPA) guidelines (40 CFR 53.62). The air velocity and turbulence profiles were uniform, displaying ≤ 10% variation in the section we tested. Additionally, we measured the mass concentrations and size distributions of polydisperse dust particles, which were generated by a custom-made rotary dust feeder to ensure the homogeneity of the aerosol, inside the wind tunnel at air velocities of 2 and 8 km h −1 and found ≤ 10% deviation for the mean values across the test section relative to those for the central sampling point. We also assessed the effectiveness of the Well Impactor Ninety-Six (WINS) and Very Sharp Cut Cyclone (VSCC) in the wind tunnel at an air velocity of 8 km h −1 by determining the D 50 cutoffs, which, being 2.44 ± 0.05 µm and 2.54 ± 0.05 µm, respectively, fulfilled U.S. EPA’s criteria. Furthermore, we compared the performance of a low-cost sensor against that of a reference instrument in measuring PM 2.5 concentrations, and our results agreed with those from previous studies.

The implementation of morphing wing mechanisms shows significant potential for improving aircraft performance, as highlighted in the recent literature. The Clean Sky 2 AirGreen 2 European project team is currently performing ground and wind tunnel tests to validate improvements in morphing wing structures. The project aims to demonstrate the effectiveness of these morphing designs on a full-scale flying prototype. This article describes the design methodology and structural testing of a scaled morphing-flap structure, which can adapt to three different morphing modes for various flight conditions: low-speed (take-off and landing) and high-speed (cruise). A scale factor of 1:3 was selected for the wind tunnel test campaign. Due to challenges in scaling the embedded mechanisms and actuators necessary for shape-changing, a full geometrical scale of the real flap prototype was not feasible. Static analyses were performed using the finite element method to address critical load conditions determined through three-dimensional computational fluid dynamic (CFD) analysis. The finite element (FE) analysis was conducted and the results were compared with the empirical data from the structural test. Good correlations were found between the structural testing results and numerical predictions, including static deflections and elastic deformations under applied loads. This indicates that the modeling approaches used during the design and testing phases were highly successful. Based on simulations for the ultimate load conditions tested during the wind tunnel tests, the scaled flap prototype has been deemed suitable for further testing.

Purpose The flow topology for multi-disciplinary configuration (MULDICON) wing is very complicated and nonlinear at low to high angle of attack (AOA). This paper aims to provide the correlation between the unsteadiness and uncertainties of the flow topology and aerodynamic forces and moments above MULDICON WING at a medium to a higher AOA. Design/methodology/approach The experimental and computational fluid dynamics methods were used to investigate a generic MULDICON wing. During the experiment, the AOA were varied from α = 5° to 30°, whereas yaw angle varies between β = ±20° and Reynolds number between Re = 3.0 × 105 and Re = 4.50 × 105. During the experiments steady-state loading, dynamic loading and flow visualization wind tunnel methods were used. Findings The standard deviation quantified the unsteadiness and uncertainties of flow topology and predicted that they significantly affect the pitching moment (Cm) at medium to higher AOA. A strong correlation between flow topology and Cm was exhibited, and the experiment data was well validated by previous numerical work. The aerodynamic center was not fixed and shifted toward the wing apex when AOA is increasing. For a = 10°, the flow becomes more asymmetric. Power spectral densities plots quantify the flow separation (apex vortex, leading-edge vortex and vortex breakdown) over the MULDICON wing. Originality/value The application and comparison of steady-state and dynamic loading data to quantify the unsteadiness and uncertainties of flow topology above the MULDICON wing.

This work presents the results of the development of a vertical axis wind turbine composed of variable geometry, plane blades, applied in operations with low wind speeds. The new concept of vertical axis wind turbine with variable opening blades is presented as an innovative prototype where mechanical details are important for the natural control of the openings of the blades. Theoretical, numerical and experimental analyzes are performed in the turbine called DEC® with the aim of determining the aerodynamic characteristics. An analysis of the behavior of the DEC® turbine consists of a numerical study carried out to calculate or drag coefficient, considering a range of opening positions of the opening at each moment to determine the power coefficient. A second numerical approach is to analyze the moment caused by the interaction between all the turbine blades, in which the effects of energy dissipation caused by the flow mats are considered. Then, the theoretical, numerical results are validated by tests performed using a model in the open wind tunnel, where the prototype is subjected to different wind speeds while maintaining rotation control. Suggestions are made to improve the mechanical and aerodynamic design of the innovative prototype. Finally, the DEC® turbine is expected to serve as an inspiration for creating other mechanical forms of passive or active control to improve variable aerodynamics applied in low-speed conditions.

Purpose The main purpose of this paper is to investigate the effects of icing on unmanned aerial vehicles (UAVs) at low Reynolds numbers and to highlight the differences to icing on manned aircraft at high Reynolds numbers. This paper follows existing research on low Reynolds number effects on ice accretion. This study extends the focus to how variations of airspeed and chord length affect the ice accretions, and aerodynamic performance degradation is investigated. Design/methodology/approach A parametric study with independent variations of airspeed and chord lengths was conducted on a typical UAV airfoil (RG-15) using icing computational fluid dynamic methods. FENSAP-ICE was used to simulate ice shapes and aerodynamic performance penalties. Validation was performed with two experimental ice shapes obtained from a low-speed icing wind tunnel. Three meteorological conditions were chosen to represent the icing typologies of rime, glaze and mixed ice. A parameter study with different chord lengths and airspeeds was then conducted for rime, glaze and mixed icing conditions. Findings The simulation results showed that the effect of airspeed variation depended on the ice accretion regime. For rime, it led to a minor increase in ice accretion. For mixed and glaze, the impact on ice geometry and penalties was substantially larger. The variation of chord length had a substantial impact on relative ice thicknesses, ice area, ice limits and performance degradation, independent from the icing regime. Research limitations/implications The implications of this manuscript are relevant for highlighting the differences between icing on manned and unmanned aircraft. Unmanned aircraft are typically smaller and fly slower than manned aircraft. Although previous research has documented the influence of this on the ice accretions, this paper investigates the effect on aerodynamic performance degradation. The findings in this work show that UAVs are more sensitive to icing conditions compared to larger and faster manned aircraft. By consequence, icing conditions are more severe for UAVs. Practical implications Atmospheric in-flight icing is a severe risk for fixed-wing UAVs and significantly limits their operational envelope. As UAVs are typically smaller and operate at lower airspeeds compared to manned aircraft, it is important to understand how the differences in airspeed and size affect ice accretion and aerodynamic performance penalties. Originality/value Earlier work has described the effect of Reynolds number variations on the ice accretion characteristics for UAVs. This work is expanding on those findings by investigating the effect of airspeed and chord length on ice accretion shapes separately. In addition, this study also investigates how these parameters affect aerodynamic performance penalties (lift, drag and stall).