Optimization of Herringbone Grooved Thrust Air Bearings for Maximum Load Capacity

Many studies in herringbone grooved thrust bearings are focused on searching for the optimal groove parameters to improve the load capacity, but few of them adopting different grooves in different sections. In this study, a novel optimization method of herringbone grooved thrust air bearings is proposed for maximum load capacity by seeking the optimal groove parameters in each section of the bearing independently. An example of an optimized thrust air bearing is presented, and its performance is compared with a non-optimized bearing and a conventionally optimized bearing without dividing grooves into sections. The resultant herringbone grooves are found to have different parameters in the inner and outer sections, which is uncommon in existing grooves. Numerical results show that the novel bearing has a higher load capacity than the non-optimized reference bearing and conventionally optimized bearing. The study shows that the new design can increase load capacity by 30.77%, verified by experiments.

Theoretical Study on Static Performance of Herringbone Grooved Aerodynamics Foil Bearing

In this paper, the mathematical model of herringbone grooved aerodynamic foil bearings is established, and the finite difference method is used to obtain the discretized form of Reynolds equation. The static characteristics of bearings, such as film pressure, film temperature, are obtained by solving the Reynolds equation and energy equation. The bearing load capacity and friction power consumption are obtained by calculating the film thickness and film pressure distribution in the bearing gap. The influence of the bearing operational parameters, such as eccentricity and rotation speed, and the bearing structural parameters, such as groove width, groove depth ratio, groove number and helix angle, on the bearing load capacity and friction power consumption of bearings are analyzed. The methods of improving bearing load capacity and reducing friction power consumption are obtained. Simultaneously, by comparing the bearing load capacity and friction power consumption of herringbone grooved gas foil bearings and gas foil bearings (GFBs) without herringbone grooves, the influence of herringbone grooves on the bearing performance is obtained.

Temperature rise of journal bearing of the high-speed circular arc gear pump

A “circular arc–involute–circular arc” circular arc gear pump was developed based on a gear meshing principle and coordinate transformation as well as an accurate calculation model of the radial force. The dependence of the radial force on the meshing angle was investigated. The temperature rise of journal bearings in the pump was evaluated for bearings with and without herringbone grooves. Furthermore, the influence of the rotational speed and outlet pressure on this rise was assessed. The results revealed using herringbone groove on the inner wall of bearing was effective in reducing the temperature increase. Therefore, the use of grooves represents a suitable method of reducing the temperature rise in the journal bearings of a high-speed gear pump.

Investigation on influences of herringbone grooves for the aerostatic journal bearings applied to ultra-high-speed spindles

Aerostatic bearings are the core parts of ultra-high-speed spindles with maximum running speed greater than 100,000 r/min. In this paper, the influences of herringbone grooves on the performance of aerostatic journal bearings are studied to design spindles with the features of higher precision and higher speed. Parametric studies and sensitivity analyses are executed in terms of the improved finite element method, which is specially developed to solve the compressible Reynolds equation for herringbone grooved air bearings. The calculated results indicate that herringbone grooves significantly improve the performance of aerostatic journal bearings under the conditions of ultra-high speeds and low supply pressures. Groove parameters are nonlinear dependent, and groove depth and length are the dominant influential factors for the load capacity at speed of 200,000 r/min. Experiments are designed and conducted to verify the improved finite element method, which show that the improved finite element method can be used to analyze the influences of herringbone grooves on aerostatic journal bearings and also manifest that suitable herringbone groove geometrical parameters can obviously decrease spindle radial runouts at ultra-high speeds.

Theoretical Solutions for Dynamic Characteristics of Liquid Annular Seals with Herringbone Grooves on the Stator Based on Bulk-Flow Theory

Liquid annular seals are primarily used to control the leakage in high-speed turbomachinery, especially in nuclear and petrochemical pumps. In this paper, a theoretical analysis method for dynamic characteristics of liquid seals with herringbone grooves on the stator is proposed based on bulk-flow theory. Steady-state velocities and leakage rates within the upstream and downstream spiral parts and the middle plain part taking account of the pumping effects are figured out first with the inertia term of the fluid within the whole seal. Then, the dynamic characteristics of the whole seal are solved based on Childs’ finite-length solutions and verified by comparing with experimental hydraulic forces. Moreover, characteristic coefficients and instability parameters of the herringbone-grooved teeth-on-stator (TOS) seals and teeth-on-rotor (TOR) seals of the same size under different pressure differences are predicted and compared in detail. The influences of the lengths of constituent parts on the dynamic characteristics and instability parameters of the model seals are theoretically investigated. The results show that the stability of the TOS seal is much better than that of the TOR seal under most operating conditions. And the lengths of the middle plain part significantly affect the dynamic characteristics and the stability parameter.

Dynamic analysis of liquid annular seals with herringbone grooves on the rotor based on the perturbation method

Annular seals have significant effects on the hydraulic and rotordynamic performances of turbomachinery. In this paper, an analysis method for calculating the leakage flow rates and dynamic characteristics of liquid annular seals with herringbone grooves on the rotor is proposed and verified. Leakage flow rates and dynamic characteristics of the model seals under different operating conditions are theoretically analysed and compared with those of plain and spiral-grooved seals of the same size. In addition, the influence of geometric parameters such as spiral angle and the lengths of the constituent parts on the sealing and rotordynamic coefficients of seals with herringbone grooves are also discussed. The results show that seals with herringbone grooves have better sealing performance, while providing better support actions and damping characteristics than the other two seal types under the same operating conditions. The seal geometric parameters including spiral angle, the lengths of the constituent parts and the clearance value have a significant influence on the dynamic characteristics of seals with herringbone grooves.

Thermohydrodynamic analysis on herringbone-grooved mechanical face seals with a quasi-3D model

A quasi-3D thermohydrodynamic model was introduced to analyze the seal performance of a herringbone-grooved mechanical face seal. In the model, the heat conduction equations of the seal rings and the energy equation of the lubrication film were solved simultaneously by the streamline upwind/Petrov–Galerkin finite element method. The Reynolds equation and the temperature equations were iteratively solved to obtain the liquid film pressure and the temperature distribution. A parameterized study was conducted to analyze the influence of the herringbone grooves’ geometry on the opening force, leakage rate, friction coefficient, and temperature rise. The results show that the hydrodynamic analysis overestimates the opening force because the viscous heat reduces the dynamic viscosity. The longer and narrower inner spiral groove gives the smaller leakage rate and the longer outer spiral groove with a smaller spiral angle shows the larger opening force.