Effect Of Oil Temperature Research Articles

Tribological Performance of Soft Magnetic Composite Materials for Gas Turbine Applications

Abstract Soft magnetic composites (SMCs) have gained attention in the last years of their usage in more compact and powerful electromechanical systems. These materials are used to combine the application of metallic material to the capability of generating (without external supply) a magnetic field. Automotive and aerospace technologies push the applications of these original materials to even higher power and mechanical stress to reduce the number of components, the size, and, in turn, the weight of complex systems. Considering gas turbine application, SMCs were formerly developed for bearings, but in the last decades, the new era of gas turbine electrification (e.g., hybrid-electric fly) has determined the need for mechanical improvement of such materials. At the same time, the reliability of soft magnetic material has to be discovered to avoid failure and reduce the maintenance schedule. In the present work, tribological behaviors of SMCs were investigated by standard wear tests. Two different types of SMSc were prepared through the powder metallurgy technique. Tests were conducted by a tribometer using a ball-on-disk configuration in lubricated condition. The effect of oil temperature and applied load were investigated. In addition, an extensive post-mortem analysis was conducted on the worn surface to recognize the mechanisms responsible for the deterioration of the materials. The results showed the effects of the oil viscosity on the useful operating life of the SMCs. Removal mechanisms depend on the load conditions, and the proper selection of the oil characteristics and load was assessed.

Research on internal flow field analysis and power loss modeling of the expansion seal ring

Expansion seal rings are widely used in automobile transmission systems, and their sealing performance plays a vital role in the pressure stability and transmission efficiency of the transmission system. However, investigations into revealing the internal flow mechanism of the expansion seal ring and predicting the power loss of the expansion seal ring are still insufficient. In this study, a two-way fluid–structure interaction model consisting of the shaft, oil sleeve, and expansion seal ring was established. The flow and structural physical fields under a series of operating conditions were simulated, and the effects of oil temperature, rotational speed, and seal pressure differential on leakage rate, deformation, power loss, and contact pressure were analyzed. Further, a power loss prediction model was developed by multiple linear regression method. The results demonstrate that in the internal flow field, the oil flow into and out of the groove is characterized by backward step flow and jet flow, respectively. In the structural field, the maximum deformation and the maximum contact pressure of the main sealing surface appear at the notch of the expansion seal ring, and the seal pressure differential has the most significant influence on it. The relative error between the predicted value of the developed model and experimental values is within 9%, which meets the industrial requirements. This work facilitates scholars to understand the internal flow mechanism and deformation process of expanding seal rings and provides a method to predict sealing ring power loss.

Study on dynamic characteristics variation mechanism of wet-clutches during the filling phase considering temperature and rotational speed of the oil

A deep insight into the complex dynamic characteristics of wet-clutches can help to improve control accuracy of the filling phase in the clutch-to-clutch shift process of an automatic transmission (AT). Existing research focuses on ideal operating conditions, where the effects of oil temperature and its rotational speed are rarely considered. To deeply understand the variation mechanism of dynamic characteristics of the wet-clutch, this paper proposes an accurate model by accounting for oil temperature and rotational speed. In this model, the centrifugal force, elastic resistance, and axial friction are respectively included based on the theory of fluid dynamics. The effects of oil temperature on key parameters of the model are then described by using an exponential function. The comparison between the simulation and experimental results shows that the proposed model has a comparatively better performance compared to the experiment and conventional model. Based on the model, the influences of these factors on the dynamics of the wet-clutch during the filling phase are analyzed, and the influence laws are obtained.

Accurate transmission performance evaluation of servo-mechanisms for robots

The Servo-Mechanisms (SMs) mounted in industrial robots joints are a major source of positioning accuracy errors . To improve robots precision performance, researchers have been focusing on the development of novel SMs design and control strategies, which need extensive experimental analyses to tune their parameters. In this context, the scope of this paper is double: first, to present the novel experimental apparatus and methods designed to improve the accuracy of the transmission performance evaluation of high dynamics SMs and, secondly, to report and discuss the achieved experimental results. In the first part, a description of the test rig tuning operations is given, primarily focusing on the signals synchronization and on the elimination of the measuring errors caused by the mechanical transmission elasticity and the servomotor torque ripples. Then, control strategies for compensating the torque ripples and input speed errors are defined. It is shown that speed oscillations can be reduced of ≈ 70 % when rotating the servomotor up to 2000 rpm, improving the measurement quality of the reducer performance. In the second part, a set of experiments is carried out to assess the combined effect of input speed and lubricant temperature on the reducer behavior. The system sensitivity to the variation of the input parameters is confirmed by the dynamic lost motion curves, whose mean value equals 16 . 8 ″ and 35 . 4 ″ when the reducer is operated at its minimum and maximum friction load respectively. At last, the extrapolated harmonic content is used to build a simple mathematical model of the reducer transmission error. • Methods employed to assess the performance of modern servo-mechanisms are reported. • Practical guidelines for improving the measurements quality are proposed. • The effect of oil temperature and input speed on the reducer is assessed. • A model of the reducer transmission error is derived from the measured data.

Oil film lubrication state analysis of piston pair in piston pump based on coupling characteristics of the fluid thermal structure

The axial piston pump will be seriously damaged when the poor oil film lubrication. Therefore, considering the influence of hydraulic oil viscosity on oil film pressure and oil film temperature, oil film heat transfer to the piston and elastic deformation caused by piston thermal expansion, a fluid thermal structure coupling model of piston pair of axial piston pump was established. An experimental platform was built to measure the oil film characteristic data throughout the cycle, and the multi-physical field test, including temperature, pressure and thickness at multiple locations of the oil film of the piston pair was realized. The effects of oil temperature, spindle speed and load pressure on the lubrication of piston pair were studied and analyzed. The working condition parameter range corresponding to the significant reduction of oil film lubrication performance was obtained, which provides a basis for predicting the lubrication failure of the piston pump.

Numerical and Experimental Investigation of the Effect of Cavitation on Dual Clearance Squeeze Film Damper

A new dynamic model is developed for the dual clearance squeeze film damper (DCSFD) considering the effect of cavitation in this paper. The relationship between the eccentricities of the inner and outer films is achieved based on the equations of motion. The Reynolds equation and Rayleigh–Plesset equation are employed to describe the kinetic properties of DCSFD and the cavitation effect of film, respectively. Under the assumption of compressible fluid, the pressure distribution of DCSFD is finally obtained by the numerically iterative method. The film pressure distribution in the outer layer (including the positive and negative pressure zones) obtained from the experimental test agrees well with the numerical prediction, which verifies the validity of the proposed numerical model. In Section 5, the effects of oil temperature, inlet pressure, eccentricity, and whirling frequency on the cavitation in the film are investigated systematically and experimentally. The experimental results indicate that cavitation mainly affect the pressure in the negative pressure zone of the inner and outer film of DCSFD, but has little influence on the pressure in the positive pressure zone. The area of cavitation increased with eccentricity; when the inner eccentricity reached 0.1 or above, the area near the injection hole of film also generated a small zone of negative pressure. The numerical model and the experimental results in this paper are valuable for further research and engineering applications of DCSFD.

Numerical simulation on the oil capture performance of the oil scoop in the under-race lubrication system

The under-race lubrication system providing a moderate amount of oil to high-speed bearings is one of the key factors to ensure its good lubrication and cooling. To investigate the oil capture performance of the oil scoop, a complete numerical calculation model was established, and unsteady simulations of oil–gas two-phase flow inside the under-race lubrication system were carried out. The results indicate that the oil capture efficiency increases first and then decreases with increasing rotating speed at different oil jet velocities. The ratio of the rotating Reynolds number of the oil scoop to the Reynolds number of the oil jet corresponding to the maximum oil capture efficiency changes linearly with oil jet velocity. There are three variation trends of oil capture efficiency at different rotating speeds with the increase of oil jet velocity: monotonically decreasing, first increasing, and then decreasing and monotonically increasing. However, the amount of oil captured by the oil scoop increases monotonically under all operating conditions. The effect of oil temperature on oil capture efficiency is mainly due to the change of dynamic viscosity of the oil. The oil capture efficiency can be improved by appropriately increasing the oil temperature within a certain temperature range.

Analysis effects of oil viscosity and temperature on orbit of ring gear in internal gear motor and pump

Effect of oil temperature and viscosity on the ring gear orbit in the internal gear motor and pump is analyzed in this study. The mobility method is used to calculate the ring gear orbit. The mathematical model of oil viscosity and temperature is then integrated into the mobility method. The simulation results point out that the oil temperature and viscosity have great effect on the eccentricity, position angle and minimum oil film thickness. The metal - to - metal contact phenomenon occurs if internal gear motor and pump operates under high values of oil temperature or low values of oil viscosity conditions.

Analysis effects of oil viscosity and temperature on orbit of ring gear in internal gear motor and pump

Effect of oil temperature and viscosity on the ring gear orbit in the internal gear motor and pump is analyzed in this study. The mobility method is used to calculate the ring gear orbit. The mathematical model of oil viscosity and temperature is then integrated into the mobility method. The simulation results point out that the oil temperature and viscosity have great effect on the eccentricity, position angle and minimum oil film thickness. The metal - to - metal contact phenomenon occurs if internal gear motor and pump operates under high values of oil temperature or low values of oil viscosity conditions.

Effect of Oil Temperature on Load Capacity and Friction Power Loss in Point Contact Elasto-hydrodynamic Lubrication

This study presents a numerical analysis for point contact Elasto-hydrodynamic lubrication EHL. The oils used are (0W-30 and 10W-40) as lubricants. The pressure and film-thickness profiles for point contact EHL are evaluated. The aims of this study are to estimate the effect of oil’s temperature on friction force, coefficient of friction and load carrying capacity. By using FORTRAN program, the Forward-iterative method is used, to solve two dimensional (2D) EHL problem. The viscosity is updating in the solution by using Roeland’s model. After the convergence of pressure is done, the friction force, friction power losses, and friction coefficient are calculated. The temperature used ranges from (-20 to 120 oC). The results showed the film-thickness decreases with the increasing of temperature. Though the maximum pressure is not affected, only the pressure distribution and profile are changed, inlet pressure decreases and the pressure profile tends towards a hertzian (dry contact) one. The friction force and the coefficient of friction decrease with the increasing of temperature.

Influence of Oil Temperature on the Lip Seal’s Performance

In some application fields—for example, the automotive industry—lip seals operate over a wide temperature range. Under such conditions, oil temperature plays an important role in determining the efficacy of lip seals. In order to simulate the lip seal’s behavior with ambient temperature change, this article improved the traditional simulation approach by characterizing the rubber material property regarding temperature dependency in the model. The effect of oil temperature on the sealing performance of lip seals was investigated through numerical simulation and experiments. The static contact pressure, radial force, reverse pumping rate, and friction torque were calculated as a function of oil temperature. The simulation results were verified by bench testing.

Experimental study on the effect of high-molecular polymer as drag reducer on drag reduction rate of pipe flow

Three types of relatively high-molecular polymer were used to investigate drag reduction in single-phase flow through a horizontal, 12.7-mm pipe. Diesel oil and a mixture of diesel oil and model oil were employed as the oil phase. The effect of various factors on the drag reduction rate was investigated. These factors included the oil and drag reducer polymer type, polymer concentration, Reynolds number, temperature, and shear under turbulent flow (Reynolds number: 3000–12000). The experimental results indicated that the drag reduction rate increases initially (when the polymer concentration increases from 1 ppm to 4 ppm) and then stabilizes at some maximum value. The maximum rate occurred at the maximum concentration (i.e., 5 ppm) in the experiment considering the diameter of the pipeline. The experimental results also indicated that, for a given concentration of a given drag reducer, the drag reduction rate differs with the type of oil system. Similarly, for a given oil system with a given concentration, the reduction rate varied with the type of drag reducer. In addition, the Reynolds number and shear have a significant effect on the drag reduction rate, but the effect of oil temperature can be ignored.

Incipient cavitation detection in external gear pumps by means of vibro-acoustic measurements

Cavitation is a well-known phenomenon in hydraulic machines, although its influence on volumetric pumps has been rarely studied. For this reason, this work investigates cavitation in external gear machines by means of a dedicated experimental campaign. Four different pump prototypes have been designed and manufactured to perform this research, one of them specifically built up to not be affected by such a phenomenon. Cavitation is induced in the testing procedure by increasing the working speed, in order to better reproduce the development of the phenomenon in actual applications. Vibro-acoustic measurements performed by a hydrophone and a high-frequency accelerometer are put in comparison with measurements of inlet and outlet pressure ripple, in order to enlighten their capability to effectively provide an earlier detection of the phenomenon. Waterfall spectra are investigated and later Root Mean Square (RMS) values of the filtered signals are shown with respect to the cavitation number and compared with efficiency measurements. Results demonstrate that vibro-acoustic measurements associated to a dedicated signal processing procedure represent a powerful tool to detect cavitation inception in gear pumps. Effect of oil temperature is investigated, showing that it contributes in spreading the phenomenon on a wider speed range. Finally, the comparison between different pump prototypes enlightens the capability of the presented procedure to quantitatively estimate the intensity of the cavitation phenomenon.

Thermodynamic analysis of different oil flooded compression enhanced vapor injection cycles

Oil flooded compression has been found to be able to improve the energy efficiency of vapor injection cycle significantly by reducing the specific compression work. In order to optimize the coupling and study the thermodynamic characteristics, six coupled cycles were proposed and studied in heating conditions. A detailed analysis on each cycle using R32 working fluid was conducted. COP and heating capacity at various conditions were obtained and compared to the respective values of the vapor injection cycle. The respective COP improvement of oil flooded compression in the coupled cycles were investigated and compared to that of oil flooded compression in the single stage vapor compression cycle. The effects of oil temperature and regenerator efficiency on the cycles were also investigated and revealed. The results can provide theoretical guide to the design of a coupled cycle system.

Effect of Thermal Treatment on the Disinfection of Infectious Waste by Fry-Drying Method Using Vegetable Oil

Healthcare waste must be managed properly due to the hazards they impose on public health and the environment. In this study, an alternative method of treating infectious waste via thermal treatment using coconut oil was investigated in a laboratory-scale setup. The effects of oil temperature (121°C, 145°C and 170°C) and treatment time (10, 20 and 30 minutes) on bacterial growth and properties of simulated infectious wastes contaminated with Bacillus subtilis were determined. No bacterial growth was observed in the samples even at the seventh day after treatment using 145oC (20- and 30-minute treatment time) and 170°C (all treatment time). However, growth on enriched media occurred for the samples treated at 170°C, indicating possible spore germination. The treatment at 145°C and 30 minutes was effective in treating contaminated syringes and cloths. The contaminated meat samples underwent thermal degradation and had a maximum weight reduction of 74.1%, which was mainly due to moisture loss. The cloths, however, did not change in its appearance but syringes and other plastics melted and deformed. Thus, the thermal treatment was found to be a good disinfection method, causing severe damage to cells. The treated infectious waste materials can be disposed in landfills without potential recurrence of bacterial growth.

مدل سازی سینتیک افت رطوبت قطعات سیب زمینی پیش تیمار شده با اولتراسوند و مایکروویو در طی فرایند سرخ کردن عمیق

مدل سازی فرایند سرخ کردن در جهت آگاهی از روابط بین متغییرهای مختلف، می تواند گامی مناسب در جهت بهبود کیفیت محصول باشد. در این پژوهش، اثر پیش تیمار اولتراسوند تحت فرکانس های 28 و 40 کیلوهرتز به مدت 15 دقیقه و پیش تیمار مایکروویو با توان های 3 و 6 وات بر گرم به مدت 10 دقیقه بر میزان رطوبت سیب زمینی سرخ شده در درجه حرارت های 150، 170 و 190 درجه سانتی گراد به مدت 60، 120، 180 و 240 ثانیه مورد بررسی قرار گرفت. برازش داده های تجربی افت رطوبت نمونه ها در طی فرآیند سرخ کردن با استفاده از شش مدل تجربی پیشنهادی و قانون فیک انجام شد. نتایج نشان داد که هر دو پیش تیمار اولتراسوند و مایکروویو در کلیه سطوح مورد استفاده، میزان رطوبت نهایی نمونه ها را به طور معنی داری در سطح احتمال 5 درصد کاهش دادند. همچنین، با افزایش دما، میزان رطوبت نمونه های سیب زمینی به شکل غیرمعنی دار در سطح احتمال 5 درصد کاهش یافت. از طرف دیگر، با افزایش زمان فرایند، میزان رطوبت نمونه ها به طور معنی دار و بصورت نمایی کاهش پیدا کرد. همچنین، مدل های پیشنهادی در این پژوهش، با داشتن ضریب تبیین بالا (2R( و ریشه میانگین مربعات خطا (RMSE) پایین، به خوبی داده های تجربی را برازش نمودند. ضریب انتشار مؤثر رطوبت برای نمونه های مختلف در دامنه 8-10×57/3 الی 8-10×08/11 متر مربع بر ثانیه به دست آمد. اعمال پیش تیمارهای اولتراسوند و مایکروویو موجب افزایش ضریب انتشار مؤثر رطوبت و کاهش انرژی فعال سازی نمونه ها شدند.

Effect of oil temperature on tribological behavior of a lubricated steel−steel contact

Tribological tests were conducted on an AISI A2 steel plate against an AISI 51200 steel ball lubricated by SAE 0W30 and PAO 4cSt base oils containing no additive package. Friction and wear behaviors were evaluated at room temperature (RT, 23°C) and a series of elevated temperatures (75, 100, 125 and 175°C). The steady-state friction coefficient appeared to be proportional to the oil temperature, probably because reduced oil viscosity at a higher temperature caused more surface asperity collisions. In contrast, wear results did not follow the trend: the wear rate surprisingly decreased when the oil temperature increased from RT to 75−100°C, and then turned around to increase along with the temperature at above 100°C. Evidentially, there are other significant factors than just the oil viscosity that influence the wear process upon the temperature change. Wear scar morphology examination and surface chemical analysis revealed an oxide-containing surface film on the wear scars and higher oxide content and larger film coverage seemed to reduce the wear rate. Therefore, the wear mechanism is proposed as a combined effect of mechanical material removal and protective surface film formation: the former largely depending on oil viscosity that is inversely proportional to the temperature and the latter involving surface and wear debris oxidation that is promoted by temperature elevation as well as the water content (up to 100°C) in the oil.

Research on Viscosity of Watered Fuel Oil Prepared by Mechanical Agitation

Viscosity of Watered fuel oil, which was prepared by a self-made mechanical micro-mixing device, was measured with rotation viscosimeter. The effects of oil temperature, agitation speed and water content on viscosity were investigated in this research. The experimental results showed that: viscosity of watered fuel oil decreases with the increasing of oil temperature between 60-80 °C and water contents in 2.0-8.0 %, but increases with the accelerating agitation speed at 1000-1300 r/min.

The effect of oil temperature and additive concentration on the wear of non-hydrogenated DLC coating

Diamond-like carbon (DLC) coatings are amorphous hard carbon films which offer excellent mechanical and tribological properties. Recently, these coatings have been applied to engine and powertrain components in passenger cars, including those under boundary lubricated conditions. Tribological performance of DLC coatings in oil lubricated conditions and their interaction with various lubricant additives are very complex due to the variety of DLC coatings and lubricants. In this study, the effects of oil temperature and additive concentration on the wear and friction performance of non-hydrogenated tetrahedral amorphous carbon (ta-C DLC) coating have been investigated. Tribological tests were conducted using a pin-on-disc tribotester with ta-C DLC coated steel pins sliding against non-coated steel discs. Tribological tests were also carried out between DLC coated pin against germanium disc in base oil for clarification of wear mechanism. The ta-C coating gave very low boundary friction with base oil at 50°C but the coating experienced limited durability with increased wear rate at higher temperature against steel disc. Organic friction modifier glycerol-mono-oleate was able to preserve low friction behavior of the coating at higher temperature with enhanced durability. The anti-wear additive Zinc Dialkyldithiophosphate (ZnDTP) provided excellent wear protection for the ta-C coating due to the formation of thick pad-like tribofilm on steel counterpart at all temperature ranges but rubbing in ZnDTP additivated oil lead to higher friction coefficient. The results obtained at high temperature show the significant and beneficial influence of oil additives on the wear performance of the coating. Based on the obtained results and analysis, the wear performance of non-hydrogenated DLC was found to have a clear dependence on the concentration of the lubricant additives, test temperature and counter material.

Theoretical Investigation of Friction Forces between Vane Tip and Cam-Ring in Oil Vane Pumps

Oil type used for oil vane pumps is an essential element affecting its performance. Trying to understand oil type effect and proper oil type selection will lead to significant enhancement of oil pump performance and increase its life time. In order to accomplish this task, a simple thermo-elasto-hydrodynamic lubrication (TEHL) model was used to calculate the friction forces between vane tip and cam-ring. Effect of oil temperature, vane relative speed, normal vane force, and oil film thickness were theoretically investigated for different oil types. Navier-Stokes and energy equations were numerically solved using finite difference technique. Viscosity and density distributions as a function of oil pressure and temperature were taken into consideration. Results show that proper oil type selection and its operating temperature are key parameters that significantly affecting the vane pump performance. The vane relative speed is quit important parameter affecting the coefficient of friction and should not be less than 5 m/s. increasing of lubricant film thickness is not necessarily enhances the friction coefficient between van tip and cam-ring. The study shows that the best type of oil for vane pump in some operating conditions is not necessarily the best choice for this pump in other operating conditions. It may be helpful for designers to select more than one oil type for the same pump according to its operating conditions.