However, at low TSR values (\(\lambda<1\)), which are critical for self-starting conditions, the four-bladed design demonstrated a 15-20% higher initial torque, which is essential for overcoming the self-starting issue [24]. Another aspect highlighted by [PERSON] et al. emphasizes that four-bladed rotors provide a more uniform torque distribution compared to three-bladed ones, reducing the amplitude of torque fluctuations by 30%. This significantly decreases vibrations and enhances the structural durability of the turbine, which is particularly important for turbulent flow conditions typical of urban environments where VAWTs are planned to be deployed [25]. [PERSON] et al. [26] studied the use of slotted guide flaps (SGF) on the NACA 0021 airfoil for VAWTs, finding that SGFs reduce vortex intensity and drag while improving the lift-to-drag ratio. At higher TSR values (TSR \(>\) 2.5), SGFs outperformed passive guide flaps (PGF), increasing rotor efficiency by 13.9% at a TSR of 2.62. Despite the importance of the conducted research, previous studies have focused on two- or three-bladed Darrieus wind turbines. In contrast, the present study focuses on a modified four-bladed Darrieus turbine, in which the blades are symmetrically distributed around the circumference and grouped into two rigidly connected pairs. This design contributes to improved torque stability and a more uniform distribution of aerodynamic loads, especially under turbulent wind conditions. Furthermore, the design is protected by a national patent of the Republic of Kazakhstan [27], authored by the participants of this study, highlighting its originality and practical significance. An additional feature of the configuration is the presence of two independent rotation shafts, each of which can be connected to a separate electric generator. This approach not only increases the overall system efficiency but also enables redundancy or flexible load distribution modes under variable wind conditions when, as in this paper, a four-bladed wind turbine model is considered. The design considered in this paper is a modified vertical-axis Darrieuswind turbine with four blades located symmetrically around the central axis (Figure 1) [27]. This installation consists of two independent pairs of blades rigidly fixed to each other by bearings. This allows us to consider the operation of one of the units separately, for example, the effect of the air flow on blades 1 and 4, which set the central shaft in motion. The main objective of the study is to select rotor parameters such as diameter and chord length that provide the best balance between power coefficient and aerodynamic losses. To achieve this goal, numerical modeling is used in the ANSYS 2022 R2 Fluent software environment, based on a non-stationary two-dimensional formulation with a turbulent SST k-\(\omega\) model that describes the flow near the walls and shear zones well. The calculated data are used to evaluate the efficiency of various configurations using the Taguchi method, which allows for identifying the optimal combination of parameters and determining the sensitivity of the characteristics to changes in geometry. This article presents a detailed analysis of the aerodynamic characteristics of the innovative design and an assessment of its performance based on numerical modeling. Namely, the determination of optimal geometric parameters that contribute to an increase in the power coefficient while reducing aerodynamic losses. A description of the methodology, basic equations, convergence criteria, and the Taguchi method are given in Section 2. The results of modeling 20 combinations of blade diameter and chord length, as well as an analysis of the distribution of velocity and pressure contours, are given in Section 3. Section 4 displays the main results of the analysis.