Theoretical, simulation and experimental investigation of 1D hybrid pressure distribution for internal gear motors and pumps

Trong Hoa Pham,Dinh Tu Nguyen,Jürgen Weber 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

Internal gear motor and pump is the typical rotating machine which operates in hybrid regime of lubrication. Calculation of the pressure distribution in the oil-lubrication film is the fundamental issue for determination of the upper and lower speed limit as well as analysis of the stability phenomenon of internal gear motor and pump. However, the simultaneously existence problem of hydrodynamic and hydrostatic pressure in case of hybrid regime is a challenge for calculation. This paper introduces an approach for calculation of 1D hybrid pressure distribution. The Reynolds equation with appropriate boundary condition is solved to obtain 2D hydrodynamic pressure distribution by using the finite difference method (FDM). The resistance network model (RNM) is used to predict the 1D hydrostatic pressure profile. Based on the hydrostatic and hydrodynamic pressure, the 1D total pressure profile can be retrieved. The CFD simulation has been performed to obtain the hydrostatic pressure profile and then compare to the hydrostatic pressure distribution by using RNM. A test rig has been designed to measure the oil-film pressure at five different points over the circumferential direction. Results pointed out that the numerical calculation agree well with the experimental results, particularly at high values of the working pressure.

Dynamically loaded the ring gear in the internal gear motor/pump: Mobility method solution

Trong Hoa Pham,Lutz Müller,Jürgen Weber 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

To get an insight into the dynamic behavior of the dynamically loaded internal gear motor/pump, the crucial analysis problem is prediction of the ring gear motion (orbit) inside the housing under arbitrary loads. The aim of this paper is to study the start-up (zero load) and the dynamically-loaded behavior of the ring gear in the internal gear motor/pump. The theoretical mobility method is used to predict the ring gear movement during its start-up and dynamically-loaded cases. A test rig was designed and built to validate the simulation results. The theoretical and experimental results have a reasonable agreement. The results also point out that the strong vibration of the ring gear will occur when the initial eccentricity of the ring gear is large. Moreover, the orbit, the pressure distribution, and thermal behavior of the fluid film are also analyzed.

Theoretical and experimental analysis of the effect of misaligned ring gear on performance of internal gear motors/pumps

Hoa Trong Pham,Jürgen Weber 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.9

Misalignment is an undesired phenomenon for all types of rotating machines because it decreases their performance and the lifespan. For the internal gear motor/pump, there are many elements that can cause misalignment; e.g. manufacturing or assembly errors, asymmetric load. Consequences of the misaligned ring gear leads to the metal-to-metal contact between the ring gear and the housing. An analytical and experimental study concerning the effect of misalignment on the performance of the internal motor/pump are presented in this paper. A new mathematical model has been governed to determine the eccentricity, the position angle, the minimum oil film as well as the misalignment angle around x- and y-axes. A test rig has been designed to evaluate experimentally the effects of operating parameters on the misaligned angle. The experimental results point out that the minimum oil film thickness can be reduced up to 18 % due to misalignment. This leads to the solid contact at one of two ring gear sides whereas at the mid-plane the minimum film thickness is not fallen below the permissible film thickness. Hence, for more accurate prediction of the performance and the lifespan of internal gear motor/pump, the effect of misalignment must be considered in calculation at the early design stage. After experiments, the inspection of the test motor was performed to prove the accuracy of the calculation.

Numerical and experimental analysis of hybrid lubrication regime for internal gear motor and pump

Trong Hoa Pham,Jürgen Weber,Lutz Müller,Dinh Tu Nguyen 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

This paper addresses the simultaneously existence problem of both hydrodynamic and hydrostatic pressure components in the oil lubrication film in case of internal gear motor and pump. Reynolds equation with concerning hybrid parameter is developed to calculate the hybrid pressure profile. Finite difference method with appropriate boundary condition is then used to solve the Reynolds equation to obtain 2D hybrid pressure distribution. The percentage of hydrodynamic and hydrostatic components corresponding to the change of the working pressure and rotating speed are analyzed. Experimental setup is then designed and built to verify the individual effect of hydrodynamic and hydrostatic action on the performance of the internal gear motor and pump under different working conditions. The numerical and experimental results pointed out that the eccentricity ratio optimal for good hybrid force is from 0.46 to 0.75. The hydrodynamic action increases with the increase of the rotating speed whilst the hydrostatic action increases with the increase of operating pressure. As the rotating speed at maximum value and working pressure at minimum value, the proportion percentage of hydrodynamic component gets the largest value. Whilst the hydrostatic component has the largest proportion percentage at minimum rotating speed and maximum working pressure.

Hybrid method to analysis the dynamic behavior of the ring gear for the internal gear motors and pumps

Trong Hoa Pham 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

Prediction of the ring gear trajectory inside its housing is a fundamental issue for analysis of the dynamic behavior of the internal gear motors/pumps. However, it is not easy because of lots of phenomenon happening inside motors/pumps. The mobility method introduced by Booker proves that it can predict well the trajectory of the journal bearing by considering the effect of hydrodynamic lubrication regime of the oil film. Unlike journal bearings, the oil film in the internal gear motors/pumps is the combination of two simultaneous regimes; e.g., hydrodynamic and hydrostatic lubrication. This paper presents a hybrid method by adding the effect of hydrostatic lubrication into the original mobility method. A test rig is then designed and built up to validate the simulation results. The theoretical and experimental results have a reasonable agreement. Comparison the calculation and experimental results points out that the deviation of the eccentricity for mobility method is about 14.5 %. Meanwhile, the deviation for the hybrid method is about 3 %. Meaning that with hybrid mobility method increases the accuracy of calculation of the ring gear orbit.

Numerical Study of the Pressure Distribution in the Internal Gear Motor and Pump

Trong Hoa Pham 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2

In this paper, Finite Difference Method (FDM) is used to calculate the pressure distribution in lubricated oil film inside the internal gear motor and pump. The effects of geometric and working parameters on the pressure distribution is then analysed. The simulation results point out that the pressure distribution as well the maximal pressure in film thickness greatly depends on the position of oil supporting nuts. Based on the analysis of the pressure distribution, a new concept for oil supporting system for the internal gear motor/pump is proposed. The simulation results point out that the new concept of oil supporting system allows the IGMaP to avoid the negative effect of nut position on pressure distribution even when the internal gear motor and pump operates in 4 quadrants.

Stability of the Internal Gear Motor and Pump: Single-Valued and Interval Analysis Technique

Trong Hoa PHAM,Dinh Tu NGUYEN 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.2

The dynamic behavior of the internal gear motor and pump is significantly influenced by the stiffness and damping characteristics of the oil lubricating film. This study addresses the stability problem of the internal gear motor and pump. The single-valued analysis is firstly used to predict the stability of internal gear motor and pump under the effect of the oil film coefficients. However, the oil lubricating film characteristics change according to operating conditions. Moreover, the internal ring gear and housing parameters are known with a certain tolerance interval owing to the manufacturing inaccuracy and poor assembly process. Consequently, the geometric parameters of the internal gear motor and pump are given as a range of values rather than single-valued quantities. This leads to significantly changes in dynamic behavior as well as stability of the internal gear motor and pump. Therefore, the interval analysis technique must be used to analyze the stability of the internal gear motor and pump. The numerical simulation is performed to prove the applicability and importance of this method. With this approach, it allows designers to evaluate the stability of internal gear motor and pump as well as analyze the effect of geometric and operating parameters on stability status of the internal gear motor and pump at the early design stage. This is the basic to expand the stable operating area for internal gear motor and pump.

Impact of Community Attachment and Resident's Support on Destination Sustainability: Evidence from Spiritual and Community Destination in Vietnam

THAN, Trong Thuy,KIEU, Thi Phuong Hoa,PHAM, Thi Anh Duong,HOANG, Thi Cam Van,TRAN, Thi Hau,NGUYEN, Huu Doan,DAO, Trung Kien Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8

This study investigates the influence of community involvement on the destination sustainability for community destinations and spiritual destinations in Vietnam. Community involvement is measured by two constructs, which are community attachment and residents' support. A structural questionnaire consisting of 41 observation variables measured on a 5-point Likert scale was used to survey households who live in a spiritual destination in An Giang province and three community destinations in Lang Son province with the help of local tour guides and Youth Union. 168 out of 200 responses collected were valid for multivariate data analysis. The results of confirmatory factor analysis (CFA) and structural equation modeling (SEM) reveal three main findings. Firstly, community attachment has a direct effect on both perceived benefits and destination sustainability. Secondly, while residents' support has a direct effect on perceived benefits, it indirectly affects destination sustainability. Finally, community destinations have a higher level of sustainability than the spiritual destination. Based on those findings, this study proposed three suggestions for local authorities, policymakers, and residents to improve the sustainable development of their local tourism destinations, including (1) diversifying local tourism products, (2) encouraging the community participation in tourism development programs, and (3) increasing in the expected benefits in local tourism development policies.