In general, standard aerodynamic design is divided into two paths—numerical analysis and empirical tests. It is crucial to efficiently combine both approaches in order to entirely fulfill the requirements of the design process as well as the final product. An effective use of computational analysis is a challenge, however it can significantly improve understanding, exploring and confining the search for optimal product solutions. The article focuses on a rapid prototyping and testing procedure proposed and employed at the Institute of Turbomachinery, Lodz University of Technology (IMP TUL). This so called Fast Track approach combines preparation of numerical models of a wind turbine rotor, manufacturing of its geometry by means of a 3D printing method and testing it in an in-house wind tunnel. The idea is to perform the entire procedure in 24 h. The proposed process allows one to determine the most auspicious sets of rotor blades within a short time. Owing to this, it significantly reduces the amount of individual subsequent examinations. Having fixed the initial procedure, it is possible to expand research on the singled-out geometries. The abovementioned observations and the presented overview of the literature on uses of 3D printing in aerodynamic testing prove rapid prototyping as an innovative and widely-applicable method, significantly changing our approach to experimental aerodynamics.

Purpose: This paper aims to discuss the results of the performance study of wind turbine blades equipped with winglets. An investigation focusses on small wind turbines (SWTs), where the winglets are recalled as one of the most promising concepts in terms of turbine efficiency increase. Design/methodology/approach: To investigate a contribution of winglets to SWT aerodynamic efficiency, a wind tunnel experiment was performed at Lodz University of Technology. In parallel, computational fluid dynamics (CFD) simulations campaign was conducted with the ANSYS CFX software to investigate appearing flow structures in greater detail. Findings: The research indicates the potential behind the application of winglets in low Reynolds flow conditions, while the CFD study enables the identification of crucial regions influencing the flow structure in the most significant degree. Research limitations/implications: As the global effect on a whole rotor is a result of a small-scale geometrical feature, it is important to localise unveiled phenomena and the mechanisms behind their generation. Practical implications: Even the slightest efficiency improvement in a distributed generation installation can promote such a solution amongst energy prosumers and increase their independence from limited natural resources. Originality/value: The winglet-equipped blades of SWTs provide an opportunity to increase the device performance with relatively low cost and ease of implementation.

One of the main issues related to the design and development of small wind turbines (SWTs) is the low Reynolds number. Operation in the transitory regime makes the rotor aerodynamic analysis a challenging task. Project GUST (Generative Urban Small Turbine) realized currently at the Institute of Turbomachinery (Lodz University of Technology, Poland) is devoted to the development of SWT (D = 1.6 m) for low-Reynolds number (low wind speed) flow conditions. The emphasis is on the blade design, aiming at improving the rotor aerodynamic efficiency. The paper will highlight the rotor design process, based on contemporary methods of experiment-simulation integration approach and use of rapid manufacturing techniques. In-house wind tunnel measurements of a scaled model performance were executed. A numerical analysis using dedicated software (QBlade) was conducted in parallel. A comparison between the obtained results indicated that the chosen numerical tools are capable of providing a reliable output, even in complex, transitional flow conditions. Bearing in mind the above observations, QBlade was incorporated into the development process of a completely new blade geometry which would increase rotor performance. The selected design has indeed prove to show better power outcome in an additional experimental campaign.

Small wind turbines (SWTs) can be significantly sensitive to variances in the blade geometry shape when their operation in relatively low ranges of Reynolds numbers is considered. An SWT case study, where an existing wind turbine prototype was equipped with a redesigned blade set, to increase its aerodynamic efficiency, is presented. The geometry modification process was targeted at maximizing the turbine power coefficient in the presumed point of low Reynolds operation. The applied design and analysis methods included practical implementation of previously established “Fast Track” procedure for wind turbine development. A newly prepared blade geometry and a reference blade set were examined numerically and experimentally. Selected design and assessment processes were supposed to be low resource demanding, making them possibly highly applicable in renewable energy industry. Therefore, the numerical analysis of both geometries was based on BEM (blade element momentum theory) equations. The research was expanded by model validation in small-scale wind tunnel tests to provide detailed information on BEM data reliability in comparison to the results of the experiment. The small-scale analysis, performed in Reynolds numbers below 100,000, provided information sufficient for evaluation of the redesigned blade. Implementation of the geometry obtained throughout the proposed procedure increased the rotor’s maximum power coefficient by 10%.

Purpose: This paper aims to provide the results of investigations concerning an influence of the tyre with longitudinal grooves on the car body aerodynamics. It is considered as an important aspect affecting the vehicle aerodynamic drag. Design/methodology/approach: To investigate a contribution of grooved tyres to the overall vehicle drag, three wind tunnel experimental campaigns were performed (two by Peugeot Société Anonyme Peugeot Citroen, one at the Lodz University of Technology). In parallel, computational fluid dynamics (CFD) simulations were conducted with the ANSYS CFX software to enable formulation of wider conclusions. Findings: The research shows that optimised tread patterns can be derived on a single tyre via a CFD study in combination with a controlled experiment to deliver designs actively lowering the overall vehicle aerodynamic drag. Practical implications: A reduction in the aerodynamic drag is one of ways to decrease vehicle fuel consumption. Alternatively, it can be translated into an increase in the maximum travel velocity and the maximum distance driven (key factor in electric vehicles), as well as in a reduction of CO₂ emissions. Finally, it can improve the vehicle driving and steering stability. Originality/value: The tyre tread pattern analysis on isolated wheels provides an opportunity to cut costs of R&D and could be a step towards isolating aerodynamic properties of tyres, irrespective of the car body on which they are applied.