# Structural Design and Optimization of Herringbone Grooved Journal Bearings Considering Turbulent
## 3 Results
### The Influence of Groove to Ridge Ratio on the Performance of HGJBs  
The HGJB groove to ridge ratio is the ratio of the groove width to the convex ridge width. The groove to ridge ratio will directly affect the stiffness of the bearing and the amount of lubricating oil. We kept other parameters unchanged, took the groove to ridge ratio as 0.5, 0.8, 1.0, 1.5, and 2.0; and analyzed the influence of the groove to ridge ratio on the performance of bearings with different structures, as shown in Figure 17.  
Figure 17: _Cont._  
Figure 17 shows that with the increase of the groove to land ratio, the bearing load capacity of the bearing gradually decreases, but the magnitude of the change is smaller relative to the influence of the number of grooves and the helix angle on the bearing load capacity. When the groove to ridge ratio is equal to 0 or infinite, the bearing surface of the bearing becomes a full table area or a full groove area, which is equivalent to an ordinary journal bearing, and the full groove area is equivalent to increasing the bearing clearance, making the bearing load capacity much smaller than the full table area. When the eccentricity is 0.5 and the groove to ridge ratio is 0.5, the bearing load capacity of the convergent HGJBs is nearly 1.6 times that of the constant-width HGJBs. The friction power decreases proportionally with the increase of the groove to ridge ratio. This is mainly because the larger the groove to ridge ratio, the larger the herringbone groove area, and the larger the overall oil film thickness, resulting in lower friction. The friction power of the convergent HGJBs is reduced by 2% every time the groove to ridge ratio increases by 0.5. With the gradual increase of the ridge to ridge ratio, the side leakage also increases and tends to a stable value, and the temperature rise gradually decreases and stabilizes. This is because increasing the groove to ridge ratio is equivalent to increasing the herringbone groove area, indirectly increasing the clearance between the bearing and the journal, and increasing the volume of stored lubricating oil; resulting in an increase in side leakage and a decrease in average temperature rise.  
As the ratio of groove to ridge increases, the area of the herringbone groove increases, and the dynamic pressure effect of the oil film gradually strengthens, and the stiffness coefficient increases significantly. The Figure 17 shows that after the groove to ridge ratio of the convergent HGJBs and the constant-width HGJBs is increased to a certain extent, the oil film stiffness coefficient remains basically unchanged. When the groove to ridge ratio  
Figure 17: The influence of groove-ridge ratio on the performance of HGJBs: (**a**) Dimensionless load capacity (**b**) Side leakage (**c**) Dimensionless friction power (**d**) Average temperature rise (**e**) Dimensionless principal stiffness (**f**) Dimensionless principal damping.  
is 2, the overall stiffness coefficient of the convergent HGJBs is only about 3% larger than when the groove to ridge ratio is 1.5. When the eccentricity is 0.5, the maximum stiffness coefficient of the convergent HGJBs is nearly twice that of the constant-width HGJBs. With the increase of the ridge to ridge ratio, the damping coefficient also shows an increasing trend. The groove to ridge ratio makes the difference between the maximum and minimum values of the convergent HGJBs much larger than that of the constant-width HGJBs. The influence of the groove to ridge ratio on the dynamic performance of the convergent HGJBs is more obvious than that of the constant-width HGJBs.  
Therefore, considering the bearing, stiffness, and rationality of design and processing, when the convergent HGJBs groove to ridge ratio is selected as 1, that is, when the groove width and the convex ridge width are equal, the balance between the bearing load capacity and the stiffness coefficient can be achieved. At the same time, when the groove to ridge ratio of the constant-width HGJBs is selected as 1, it is also more appropriate.