This study's object is the aerodynamic characteristics of the compressor diffusers in hydrogen-cooled turbogenerators. This paper reports a solution to the task of improving the efficiency of a cooling system discharge unit. This issue relates to enabling the necessary gas consumption while reducing the number of diffuser blades. The problem was solved by introducing a seal with improved technological control capabilities and step-by-step optimization of the diffuser flow part. Another issue is the thermal loads on the power components of the diffuser unit due to the action of circulating currents and temperature gradients. The problem was solved by introducing dielectric and non-magnetic elements into the structure, by additional finning and multi-component design for the diffuser strength circuits. The main result is the designed multi-component diffuser structure with a number of blades of 20 while enabling a head of Hst = 978 mm H2O. The adopted duct opening angle was 20°. Other necessary geometric parameters were determined. The introduction of a multilayer seal made it possible to reduce the gap between the impeller and the diffuser to 0.9 mm. The proposed design was tested on the bench at a manufacturing enterprise. The results of the study are attributed to the use of non-magnetic and dielectric materials (AISI 321 steel and fiberglass), as well as the introduction of additional strength decoupling elements. A special feature of the proposed method is the application of mathematical models based on the basic equations of gas dynamics, taking into account the composition principles of engineering alloys and synthetic materials. This could be achieved via a step-by-step optimization of the design. The proposed structure could be implemented when designing and modernizing hydrogen-cooled turbogenerators

Gas coolers are critical elements of turbogenerator cooling systems, which ensure the reliability and stability of the thermal mode of high-power electric machines. The aim of this research is to improve the accuracy of thermal calculations of gas coolers by combining analytical methods with numerical CFD-modeling (Computation Fluid Dynamics). The cooler’s total cooling capacity is approximately 3.8 MW, distributed across three identical sections.An analytical calculation of heat transfer for a hydrogen-water gas cooler with finned tubes was performed, using classical dependencies to determine the heat transfer coefficients and pressure losses. The results were verified using three-dimensional CFD-modeling of the hydrogen flow through the cooler using the standard k-ε (k-epsilon) turbulence model. The discrepancy between the results of analytical and numerical calculations is less than 10%. The temperature of the cooled hydrogen at the outlet meets the design requirements (+40 °C); however, areas of uneven temperature distribution were identified that require further design optimization. The study introduces, for the first time, a combined approach using analytical calculations and CFD by thoroughly evaluating the heat exchange between the cooling tube fins and hydrogen. This scientific solution enabled the simulation of hydrogen flow within the multi-stage cooler system. The proposed method has proven to be reliable and can be applied both at the design stage and for the analysis of upgraded cooling systems of turbogenerators.

The features of the calculation of the thermal state of the turbo generator brush-contact device are discussed in this paper. The author provides an algorithm for analytical calculation of the device, determines the expected temperatures of the elements provided that additional filters are installed in the ventilation duct. Using the finite element method, a three-dimensional calculation of the thermal state of the brush-contact device elements was performed. The obtained results confirm the possibility of improving the design of the brush-contact device by installing filtering elements in order to increase the reliability of the operation of this unit.

This study explores heat and mass transfer processes in the structural elements of an umbrella-type hydrogenerator, as well as the ventilation and cooling system in the active components of the hydrogenerator. A vertical synchronous air-cooled hydrogenerator with a rated capacity of 60 MW has been investigated. The task addressed relates to the cooling efficiency of generator components. Conventional analytical calculation methods do not make it possible to identify local overheating zones and pressure distribution in complex ventilation channels. Therefore, it becomes necessary to use numerical methods and algorithms to calculate and analyze the cooling efficiency of the generator’s active parts. The main result of this study is the designed structure of the guide channels (blades) of the rotor, which provides the required air flow rate of 45 m3/s. At the same time, the maximum values of the winding temperature do not exceed the permissible values for class F insulation. The CFD calculation detailed the action of the superchargers and showed the real pressure in the channels and the volume of air passing through each section of the generator. The error between the results from CFD modeling and analytical calculations is less than 3%. The results are attributed to the detailed reproduction of the geometry of the ventilation channels in the 3D model, which made it possible to determine the real aerodynamic resistance and cooling medium consumption. The proposed method uses the boundary conditions of the third kind for a comprehensive calculation of the conjugate heat and mass transfer. The proposed structure could be implemented in the design and modernization of air-cooled hydrogenerators.

Many factors affect the vibration of the hydraulic unit, including the natural oscillation frequencies of the structural elements, which in some cases may contribute to an increase in vibration because of the occurrence of resonance phenomena. In this work, the case of design optimization of the support assemblies of the shaft pipeline of the hydrogenerator-motor was considered, installed at HSPP during its reconstruction in order to improve vibration parameters. The effect of increasing the stiffness of the upper crosspiece and reducing the weight of the rotating parts on the value of the first and second critical rotation frequencies was analyzed. Based on the results of computations, operability of the proposed new reinforced structure of the upper crosspiece of the hydrogenerator-motor with increased rigidity was confirmed. Using this design could increase the first critical rotation frequency from 9 Hz (540 rpm) to 17.6 Hz (1056 rpm). This would lead to the avoidance of resonance phenomena caused by the proximity of the first critical rotation frequency of the rotor to the rated rotation frequency (600 rpm). The computations were performed in a three-dimensional setting in two stages for each of the considered design cases. At the first stage, the supporting elements rigidity of the shaft line of the hydrogenerator-motor were studied by determining the structural element elastic deformations when it was loaded by a transverse force. At the second stage, these determined stiffnesses of the support elements were used as input data for calculating the critical rotation frequencies of the hydraulic unit rotor