## 6 Conclusions  
The paper considers a double-row symmetric aerostatic radial bearing with an external combined throttling system and longitudinal microgrooves in the inter-row zone. It is hypothesized that the use of microgrooves will reduce the circumferential flows of compressed air, as a result of which the compliance should decrease and the bearing capacity should increase.  
To test the hypothesis, mathematical modeling, calculations, and a theoretical study of the stationary operating modes of the bearing were carried out on the assumption that when the journal moves, the axes of the shaft and sleeve remain parallel. A study of compliance for small eccentricities of the shaft in the vicinity of the central equilibrium position of the shaft and the bearing capacity for arbitrary eccentricities was carried out. Formulas were obtained for the numerical evaluation of compliance for bearings with a smooth bushing surface and with longitudinal microgrooves. Iterative finite-difference methods for determining the fields of the squared pressure were proposed, on the basis of which the load capacity of the bearings was calculated. Experimental verification of the theoretical characteristics of the bearing was carried out, which showed a satisfactory agreement of the compared data.  
The study of the compliance and load capacity of a microgroove bearing yielded impressive results. It is shown that the positive effect from the application of the improvement begins to manifest itself already at four microgrooves; at six microgrooves, it becomes significant, and at twelve or more microgrooves, circumferential flows in the bearing gap practically disappear; therefore, the load characteristics can be calculated on the basis of one-dimensional models of the longitudinal flow of air lubrication. The calculations have shown that with a length of \(L=1\), the maximum bearing capacity of a bearing with microgrooves is 1.5 times greater than that of a conventional bearing; for \(L\geq 1.5\), the bearing capacity doubles or more. The result obtained allows us to recommend the proposed improvement for practical use in order to increase the load capacity of radial aerostatic bearings significantly.  
It is also shown that the increase in the volume of compressed gas in the bearing gap due to the presence of microgrooves is only a few percent of a similar volume of a conventional bearing. On this basis, it was concluded that this circumstance cannot affect the deterioration of dynamic characteristics. It should be noted that bearings with combined external throttling systems have a large margin of stability, which guarantees the operability of bearings with microgrooves.  
Thus, the proposed double-row aerostatic radial bearing with longitudinal microgrooves in the inter-row zone can find practical application as a better replacement for conventional aerostatic bearings in order to reduce compliance and significantly increase the bearing load capacity.  
Conceptualization, V.K.; formal analysis, A.K.; investigation, S.S., O.G., I.P. and Y.P.; data curation, M.B. and L.S.; writing--original draft preparation, V.K.; writing--review and editing, A.K.; project administration, A.K. and O.G. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors declare no conflict of interest.