# The Optimization of the Geometry of the Centrifugal Fan at Different Design Points
## 1 Introduction
The researchers noted that the calculation time was greatly reduced at this stage, as the intervals that most satisfy the optimal values of the criteria were analyzed in the most detail. It was observed that the full efficiency increased by 3.1%, with a flow rate of 1.4 m\({}^{3}\)/min, when comparing the optimized profile impeller with the original one. The improvement in criteria was achieved by changing the leading and trailing angles of the profile string, and the greatest differences were observed at the trailing edge of the profile, which was highly convex. This paper analyzes a centrifugal fan by creating a set of impellers with different outlet channel angles. [PERSON] et al. [7] conducted an analysis of a centrifugal fan using computer flow simulations; the distribution of flow velocity, as well as the pressure and turbulence energy on the blade walls, was observed, and the obtained results were compared to find the optimal parameters value. According to the authors, the relevance of the study is related to the fact that in the field of impeller optimization, little attention is paid to the influence of the rear angle of the blade on the flow inside the fan casing. To efficiently analyze the influence of the change in the trailing angle of the blade on pressure pulsations, pulsation frequency domains were created. It was observed that the main pulsation at the monitored points was caused by the movement of the impeller blades, and the biggest irregularities were observed in the exit zone of the fan casing. The authors observed a tendency of decreasing pressure pulsation as the angle of the exit channel increased. A reduction in pulsations allowed for the minimization of the level of noise emitted by the device, and the smallest amplitude of pressure irregularities was observed when the angle of the exit channel was 29.5\({}^{\circ}\). There are many problems related to fans, such as ventilation problems because of air pollution, blade design, operating conditions and problems, fan reliability, wear and failure research, component problems, stability and control, vibration, flow separation, noise, manufacturing difficulty, etc. In this work, our research is focused on fans equipped with impellers that have forward-facing blades, as well as the optimization of the geometry of such centrifugal fans at different design points. From the point of view of design and optimization, there can be various research tasks. The shape optimization of a centrifugal fan with forward-curved blades using Navier-Stokes analysis was reported by [PERSON] and [PERSON] [8]. They found that efficiency is more sensitive to the location of the cutoff and the expansion angle of the scroll than the other design variables. The application of a numerical optimization technique to the design of a centrifugal fan with forward-curved blades was reported by [PERSON] and [PERSON] in [9]. They found the optimum design flow rate by using flow rate as one of the design variables and mentioned that the optimization process provides a reliable design of this kind of fan with reasonable computing time. Design optimization of a centrifugal fan with splitter blades was investigated by [PERSON] et al. [10]. They mentioned that the relative errors of the predictions of the objective functions of the response surface approximation surrogate model were less than 2.7 and 1.0% compared to the Reynolds-averaged Navier-Stokes calculations. A multi-objective optimization design and experimental investigation of centrifugal fan performance were reported by [PERSON] et al. [11]. They mentioned that the optimum combination of impeller structural parameters was obtained using a genetic algorithm. The optimization of a multi-blade centrifugal fan design for ventilation and air-conditioning system based on the disturbance CST function was reported by [PERSON] et al. in [6]. They developed a multi-objective, multi-blade centrifugal fan optimization design using the disturbance CST function.