Method for calculating the sliding bearing of a piston engine and compressor

2021 ◽  
pp. 51-54
Author(s):  
Keyword(s):  
Piston Compressor ◽  
Piston Engine ◽  
Sliding Bearing ◽  
One Dimensional ◽  
Working Length ◽  
Bearing Load ◽  
Compressor Piston ◽  
Crankshaft Journal ◽  
Relative Eccentricity ◽  
Engine Friction

A one-dimensional model for calculating the sliding bearing of a piston engine and compressor is proposed. The results of approximation of the graphs by analytical dependences of the relative eccentricity on the bearing load coefficient for different values of the ratio of the working length of the bearing to the diameter of the crankshaft journal are presented in the form of exponential functions. Keywords: sliding bearing, heat balance, piston compressor, piston engine, friction [email protected]; [email protected]; [email protected]

scholarly journals Computer#aided design of the pump profile with epicycloidal gearing using MathCad tools

2020 ◽  
Vol 21 (1) ◽  
pp. 7-13
Author(s):  
Pablo Ramon Vallejo Maldonado ◽  
Viktorina A. Romanova ◽  
Messias De Jesus Augusto Campos
Keyword(s):  
Least Squares Method ◽  
Combustion Engine ◽  
Thermal Balance ◽  
Engine Oil ◽  
Thermal Calculation ◽  
Load Factor ◽  
Oil Viscosity ◽  
Sliding Bearing ◽  
Working Length ◽  
Relative Eccentricity

The article discusses a method for determining the relative eccentricity , used in calculating the thermal balance of an internal combustion engine sliding bearing. When performing this calculation, a number of temperature values are set in the bearing oil layer. For each set temperature, the engine oil viscosity value and the bearing load factor Ф are determined. To determine the relative eccentricity, graphical dependencies of the load factor on the relative eccentricity are used as input data. The thermal calculation of the sliding bearing showed that the accuracy of determining the relative eccentricity is of great importance. Their inaccurate definition leads to a failure of the thermal balance in the bearing. In addition, the method of determining the value of by the accepted value of the ratio of the working length of the bearing to the diameter of the connecting rod neck of the crankshaft (graphically) for this calculation is quite time-consuming. For this reason, the graphical method for determining has been replaced with an analytical one. Relative eccentricities were obtained using the least squares method. An algorithm has been developed for automated construction of transverse and longitudinal profiles of an oil pump with epicycloidal engagement.

Comparison of Piston Concept Design Solutions for Composite Cycle Engines Part II: Design Considerations

2021 ◽  
Author(s):  
Dimitrios Chatzianagnostou ◽  
Stephan Staudacher
Keyword(s):  
Gas Turbine ◽  
Design Space ◽  
Piston Compressor ◽  
Design System ◽  
Surface Load ◽  
Preliminary Design ◽  
Concept Design ◽  
Piston Engine ◽  
Engine Design ◽  
Cylinder Piston

Abstract Hecto pressure composite cycle engines with piston engines and piston compressors are potential alternatives to advanced gas turbine engines. The nondimensional groups limiting their design have been introduced and generally discussed in Part I [1]. Further discussion shows, that the ratio of effective power to piston surface characterizes the piston thermal surface load capability. The piston design and the piston cooling technology level limit its range of values. Reynolds number and the required ratio of advective to diffusive material transport limit the stroke-to-bore ratio. Torsional frequency sets a limit to crankshaft length and hence cylinder number. A rule based preliminary design system for composite cycle engines is presented. Its piston engine design part is validated against data of existing piston engines. It is used to explore the design space of piston components. The piston engine design space is limited by mechanical feasibility and the crankshaft overlap resulting in a minimum stroke-to-bore ratio. An empirical limitation on stroke-to-bore ratio is based on existing piston engine designs. It limits the design space further. Piston compressor design does not limit the piston engine design but is strongly linked to it. The preliminary design system is applied to a composite cycle engines of 22MW take-off shaft power, flying a 1000km mission. It features three 12-cylinder piston engines and three 20-cylinder piston compressors. Its specific fuel consumption and mission fuel burn are compared to an intercooled gas turbine with pressure gain combustion of similar technology readiness.

scholarly journals Simulation Research of Aircraft Piston Engine Rotax 912

2019 ◽  
Vol 252 ◽  
pp. 05007 ◽  
Author(s):  
Łukasz Grabowski ◽  
Ksenia Siadkowska ◽  
Krzysztof Skiba
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Basic Unit ◽  
Piston Engine ◽  
Engine Operation ◽  
Simulation Research ◽  
One Dimensional ◽  
Operation Process ◽  
Model Aircraft

This paper reports the results of simulation works of Rotax 912 aircraft piston engine, which is a basic unit in most ultra-light aircrafts. The method for preparing the model aircraft engine operation process was presented. Simulation tests were carried out in the AVL Boost programme. The programme allows a full use of zero-dimensional and one-dimensional modelling. It also allows a comparison of other engine models. The developed model has enabled us to simulate the flow of air through the inlet pipes, carburettors, valves and combustion process. The preparation of the model required us to enter parameters that are not available in the manufacturer's catalogue, therefore, necessary measurements and analysis of the engine parts were carried out on a laboratory bench. The calculations in the AVL Boost programme were carried out in the conditions determined for the selected BMEP values with the objective of characterising the engine performance by determining its power, torque and fuel consumption.

Reducing Piston Mass in a Free Piston Engine Compressor by Exploiting the Inertance of a Liquid Piston

2009 ◽  
Author(s):  
Joel A. Willhite ◽  
Eric J. Barth
Keyword(s):  
Dynamic Model ◽  
Check Valve ◽  
Piston Compressor ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Viscous Losses ◽  
Engine Compressor ◽  
Simulation Results ◽  
Liquid Piston

A dynamic model of a free liquid piston that exploits piston geometry to produce a high inertance was developed for use in a free piston engine compressor. It is shown that for the size scale targeted, advantageous piston dynamics can be achieved with a reduced piston mass compared to a rigid piston design. It is also shown that the viscous losses associated with the liquid piston are negligible for the application discussed. The slow dynamics achieved by the liquid piston also allow for reduced valve sizes for the compressor, creating a more energy-dense device on a systems level. Other advantages gained by this design compared to prior work are discussed, including the elimination of a separated combustion chamber, smaller (integrated) pump check valve, and the capability of more balanced operation for a single-piston compressor. A dynamic model of the proposed high inertance liquid piston is presented and simulation results are discussed.

The High Inertance Free Piston Engine Compressor—Part I: Dynamic Modeling

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Joel A. Willhite ◽  
Chao Yong ◽  
Eric J. Barth
Keyword(s):  
Dynamic Model ◽  
Engine Performance ◽  
Piston Compressor ◽  
Model Parameters ◽  
Piston Engine ◽  
Free Piston ◽  
Air Supply ◽  
Free Piston Engine ◽  
Critical Model ◽  
Liquid Piston

Free piston engine compressors have recently been investigated for the purpose of providing a high pressure air supply for untethered, pneumatically actuated robotic systems. Given that free piston engine performance is highly dependent on the dynamic characteristics of the piston, this paper presents the idea of incorporating a liquid piston whose geometry can be manipulated to achieve the desired piston dynamics while maintaining the compactness and light weight necessary for applications in the power output range of 100 W. An inertance-based dynamic model of the liquid piston is developed and validated experimentally. The piston model is incorporated into a complete system dynamic model of a proposed high inertance free liquid piston compressor (HIFLPC). Critical model parameters for individual components and subsystems of a proposed HIFLPC prototype are experimentally characterized. Simulation results for the proposed prototype are shown and discussed.

Modeling and Numerical Investigations for Launching a Free-Flight Models Using Light-Gas Propulsion Technology

2013 ◽  
Vol 325-326 ◽  
pp. 148-151
Author(s):  
Xin Lu ◽  
Yan Huang Zhou ◽  
Yong Gang Yu
Keyword(s):  
Mathematical Model ◽  
Piston Compressor ◽  
Free Flight ◽  
Working Process ◽  
Piston Velocity ◽  
One Dimensional ◽  
Computing Model ◽  
Parameter Configuration ◽  
Structure Dimension ◽  
Loading Parameter

In this paper, using light-gas propulsion technology, a one-dimensional mathematical model is established and simulated numerically for working process of light-gas launching facility with a piston-compressor type. A 30mm/120mm light-gas launcher is taken for the primary computing model, and lots of data, such as the pressure on pump, the piston velocity, the diaphragm failure pressure, etc. are obtained by computing the model in given geometry parameters and loading conditions. According to the numerical results, it is concluded that the developed mathematical model can provide theoretical references for structure dimension design and loading parameter configuration of light-gas launcher.

One-Dimensional Model and Numerical Simulation of Two-Stage Light-Gas Launching Facility

2011 ◽  
Vol 66-68 ◽  
pp. 477-482
Author(s):  
Xin Lu ◽  
Yong Gang Yu ◽  
Yan Huang Zhou
Keyword(s):  
Mathematical Model ◽  
Structural Design ◽  
Piston Compressor ◽  
Two Stage ◽  
Numerical Accuracy ◽  
Piston Velocity ◽  
One Dimensional ◽  
First Order ◽  
Computing Model ◽  
Gas Chamber

In this paper, a one-dimensional mathematical model is established and simulated numerically for the interior ballistic cycle of two-stage light-gas launching facility with a piston-compressor type. A 35mm/130mm light-gas launcher is taken for the primary computing model, and lots of data, such as the pressure on light-gas chamber, the piston velocity, the diaphragm failure pressure, etc. are obtained by computing the model using the numerical difference scheme with the second order of numerical accuracy in space and the first order in time. On the basis of the results of analyzing these data systematically, some advices on enhancing the launching performance of light-gas launcher are put forward. The numerical results show that the developed mathematical model gives the correct trend and can provide useful calculated parameters for the structural design of the components of two-stage light-gas launcher.

Modelling of Micro Textured Bearings With Mass-Conserving Cavitation: A Two Dimensional Problem

2008 ◽  
Author(s):  
Mark T. Fowell ◽  
Andrew V. Olver ◽  
Hugh A. Spikes ◽  
Ian G. Pegg
Keyword(s):  
Two Dimensions ◽  
Current Paper ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
Lubrication Mechanism ◽  
Complete Understanding ◽  
Sliding Bearing ◽  
One Dimensional ◽  
Slider Bearings

There has recently been much interest in the micro-texturing of slider bearings, where many tiny micro-pockets are incorporated into one of the bearing surfaces. Proponents of this technology have reported that the application of micro-texture to sliding bearing surfaces can result in up to 40% reduction in friction, when the two bearing surfaces have low or zero convergence ratio, i.e. are near parallel [1]. The authors have shown previously, through a series of one dimensional analyses, that the ability of such bearings to generate load support can be explained by a lubrication mechanism termed “Inlet Suction” [2, 3]. In the current paper, these one dimensional analyses are extended to two dimensions with the inclusion of a mass-conserving cavitation algorithm based on Elrod [4]. This allows for a more complete understanding of “Inlet Suction” in real bearing geometries.

Optimization of the Axial Porosity Distribution of Porous Inserts in a Liquid-Piston Gas Compressor Using a One-Dimensional Formulation

2013 ◽  
Author(s):  
Chao Zhang ◽  
Terrence W. Simon ◽  
Perry Y. Li
Keyword(s):  
Porous Media ◽  
Piston Compressor ◽  
High Porosity ◽  
Porosity Distribution ◽  
One Dimensional ◽  
Piston Speed ◽  
Work Input ◽  
The One ◽  
Liquid Piston ◽  
D Model

A One-Dimensional (One-D) numerical model to calculate transient temperature distributions in a liquid-piston compressor with porous inserts is presented. The liquid-piston compressor is used for Compressed Air Energy Storage (CAES), and the inserted porous media serve the purpose of reducing temperature rise during compression. The One-D model considers heat transfer by convection in both the fluids (gas and liquid) and convective heat exchange with the solid. The Volume of Fluid (VOF) method is used in the model to deal with the moving liquid-gas interface. Solutions of the One-D model are validated against full CFD solutions of the same problem but within a two-dimensional computation domain, and against another study given in the literature. The model is used to optimize the porosity distribution, in the axial direction, of the porous insert. The objective is to minimize the compression work input for a given piston speed and a given overall pressure compression ratio. The model equations are discretized and solved by a finite difference method. The optimization method is based on sensitivity calculations in an iterative procedure. The sensitivity is the partial derivative of compression work with respect to the porosity value at each optimization node. In each optimization round, the One-D model is solved as many times as there are optimization nodes, and each time the porosity value at a single optimization node is changed by a small amount. From these calculations, the sensitivity of changing the porosity distribution to the total work input (objective) is obtained. Based on this, the porosity distribution is updated in the direction that favors the objective. Then, the optimization procedure marches to the next round and the same calculations are completed iteratively until an optimum solution is reached. The optimization shows that porous media with high porosity should be used in the lower part of the chamber and porous media with low porosity should be used in the upper part of the chamber. An optimal distribution of porosity over the chamber is obtained.

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