Behavior of Thermal Effects and Velocity-Slip on Performance of Externally Pressurized Porous Incompressible Gas Thrust Bearing

1979 ◽  
Vol 46 (2) ◽  
pp. 465-468 ◽  
Author(s):  
V. K. Kapur ◽  
J. S. Yadav
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Effects ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Velocity Slip ◽  
Experimental Results ◽  
Slip Condition ◽  
Static Stiffness

In the present analysis, the interactions of thermal effects and velocity slip on the performance of externally pressurized porous incompressible gas thrust bearing have been studied. Numerical results for load capacity, mass flow rate, and static stiffness have been obtained and their behavior is illustrated in figures. The results for slip as well as no-slip condition have also been compared with the experimental results of Gargiulo and Gilmour [7].

Magnetogasdynamic thrust bearing with an axial pinch

1969 ◽  
Vol 38 (4) ◽  
pp. 673-677 ◽  
Author(s):  
G. Ramanaiah
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Axial Current ◽  
Pinch Effect ◽  
Electrically Conducting ◽  
Compressible Lubricant

An analysis of a hydrostatic thrust bearing with electrically conducting compressible lubricant under an axial-current-induced pinch is presented. It is shown that the load capacity of the bearing can be increased by the pinch effect and the magnitude of the pinch effect depends on the mass flow rate. It is also shown that a load proportional to the square of the axial current can be sustained even when there is no flow or external pressurization.

scholarly journals Investigation into gas lubrication performance of porous gas bearing considering velocity slip boundary condition

Friction ◽  
2021 ◽  
Author(s):  
Xiangbo Zhang ◽  
Shuiting Ding ◽  
Farong Du ◽  
Fenzhu Ji ◽  
Zheng Xu ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Porous Layer ◽  
Mass Flow ◽  
Flow Rate ◽  
Load Capacity ◽  
Velocity Slip ◽  
Slip Boundary ◽  
Lubrication Performance ◽  
Gas Lubrication ◽  
Simulation Results

AbstractPorous gas bearings (PGBs) have a proactive application in aerospace and turbomachinery. This study investigates the gas lubrication performance of a PGB with the condition of velocity slip boundary (VSB) owing to the high Knudsen number in the gas film. The Darcy-Forchheimer laws and modified Navier-Stokes equations were adopted to describe the gas flow in the porous layer and gas film region, respectively. An improved bearing experimental platform was established to verify the accuracy of the derived theory and the reliability of the numerical analysis. The effects of various parameters on the pressure distribution, flow cycle, load capacity, mass flow rate, and velocity profile are demonstrated and discussed. The results show that the gas can flow in both directions, from the porous layer to the gas film region, or in reverse. The load capacity of the PGB increases with an increase in speed and inlet pressure and decreases with an increase in permeability. The mass flow rate increases as the inlet pressure and permeability increase. Furthermore, the simulation results using VSB are in agreement with the experimental results, with an average error of 3.4%, which indicates that the model using VSB achieves a high accuracy. The simulation results ignoring the VSB overrate the load capacity by 16.42% and undervalue the mass flow rate by 11.29%. This study may aid in understanding the gas lubrication mechanism in PGBs and the development of novel gas lubricants.

Design and Testing of a Can Combustor for a Small Gas Turbine Application

2013 ◽  
Author(s):  
K. V. L. Narayana Rao ◽  
N. Ravi Kumar ◽  
G. Ramesha ◽  
M. Devathathan
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Pressure Loss ◽  
High Energy ◽  
Experimental Results ◽  
High Mass ◽  
Test Facility ◽  
Design Requirements

Can type combustors are robust, with ease of design, manufacturing and testing. They are extensively used in industrial gas turbines and aero engines. This paper is mainly based on the work carried out in designing and testing a can type combustion chamber which is operated using JET-A1 fuel. Based on the design requirements, the combustor is designed, fabricated and tested. The experimental results are analysed and compared with the design requirements. The basic dimensions of the combustor, like casing diameter, liner diameter, liner length and liner hole distribution are estimated through a proprietary developed code. An axial flow air swirler with 8 vanes and vane angle of 45 degree is designed to create a re-circulation zone for stabilizing the flame. The Monarch 4.0 GPH fuel nozzle with a cone angle of 80 degree is used. The igniter used is a high energy igniter with ignition energy of 2J and 60 sparks per minute. The combustor is modelled, meshed and analysed using the commercially available ansys-cfx code. The geometry of the combustor is modified iteratively based on the CFD results to meet the design requirements such as pressure loss and pattern factor. The combustor is fabricated using Ni-75 sheet of 1 mm thickness. A small combustor test facility is established. The combustor rig is tested for 50 Hours. The experimental results showed a blow-out phenomenon while the mass flow rate through the combustor is increased beyond a limit. Further through CFD analysis one of the cause for early blow out is identified to be a high mass flow rate through the swirler. The swirler area is partially blocked and many configurations are analysed. The optimum configuration is selected based on the flame position in the primary zone. The change in swirler area is implemented in the test model and further testing is carried out. The experimental results showed that the blow-out limit of the combustor is increased to a good extent. Hence the effect of swirler flow rate on recirculation zone length and flame blow out is also studied and presented. The experimental results showed that the pressure loss and pattern factor are in agreement with the design requirements.

scholarly journals Static characteristics of hydrostatic thrust bearing considering the inertia effect on the region of supply hole

2018 ◽  
Vol 233 (1) ◽  
pp. 188-193
Author(s):  
Zhuxin Tian ◽  
Haiyin Cao ◽  
Yu Huang
Keyword(s):  
Flow Rate ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Experimental Results ◽  
Inertia Effect ◽  
Static Characteristics ◽  
Hole Radius ◽  
Inertia Parameter ◽  
Theoretical Results ◽  
Inertia Theory

In the previous studies on the hydrostatic thrust bearing, the differences between the theoretical results and experimental results are obvious when the inertia parameter S and the ratio of supply hole radius to bearing radius r0/ R become large enough. To explain the differences, in this study, the inertia effect on the region of supply hole is considered in discussing the static characteristics of hydrostatic thrust bearing, and then new expressions of pressure, load capacity, and flow rate are given. For the continuous parallel bearing, the results of this study agree well with experiments, thus there is no need for the extra modified inertia theory. For the step bearing with a large inertia parameter (e.g., S = 2), the results of this study agree with experiments on the recess region, and are closer to the experimental results than those of old method on the region of bearing land. So when the inertia parameter S and the ratio of supply hole radius to bearing radius r0/ R are large enough, the inertia effect on the region of supply hole cannot be ignored in discussing the static characteristics of hydrostatic thrust bearing.

scholarly journals The effect of cohesion on the discharge of a granular material through the orifice of a silo

2021 ◽  
Vol 249 ◽  
pp. 08014
Author(s):  
Adrien Gans ◽  
Pascale Aussillous ◽  
Blanche Dalloz ◽  
Maxime Nicolas
Keyword(s):  
Granular Material ◽  
Numerical Simulations ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Experimental Results ◽  
Numerical Investigations ◽  
Silo Discharge

We present the results of both experimental and numerical investigations of the silo discharge for a cohesive granular material. In our study, thanks to a cohesion-controlled granular material (CCGM) we propose to investigate the effect of the cohesive length lc, on the discharge of a silo for two different configurations, one axisymmetrical, and one quasi-2D rectangular silo. In both configurations, an adjustable bottom is used to control the size of the orifice. As observed for cohesionless granular material by previous studies, the mass flow rate and the density through an orifice are mostly controlled by the diameter of the orifice D. The experimental results of the quasi-2D silo are compared with continuum numerical simulations.

Condensation flow at the wet steam centrifugal turbine stage

2019 ◽  
Vol 234 (8) ◽  
pp. 1108-1121 ◽  
Author(s):  
Yaping Liu ◽  
Xuefei Du ◽  
Xuyang Shi ◽  
Diangui Huang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Three Dimensional ◽  
Velocity Slip ◽  
Aerodynamic Characteristics ◽  
Nucleation Theory ◽  
Wet Steam ◽  
Flow Angle ◽  
Shaft Power

This paper investigates spontaneous condensation of wet steam in a centrifugal turbine by means of three-dimensional computational fluid dynamics. The flow field and aerodynamic characteristics of the wet steam in the centrifugal turbine are compared and analyzed by using the equilibrium steam and nonequilibrium steam models, respectively, where the latter applies the classical droplet nucleation theory and neglects velocity slip between the liquid phase and the gaseous phase. The state parameters of wet steam are described here based on the IAPWS’97 formulation. It is concluded that under the design condition, the mass flow rate, wetness fraction, and flow angle of the wet steam centrifugal turbine in the nonequilibrium steam model all change compared with the equilibrium steam model, with values of 4.4%, 0.5%, and 10.57%, respectively. Then the performance variation of the wet steam centrifugal turbine is analyzed under different steam conditions and different outlet back-pressure conditions. The results show that the change law of the mass flow rate, shaft power, and wetness fraction in the centrifugal turbine are basically identical in both models, and the mass flow rate, shaft power, wheel efficiency, and entropy loss coefficient of the centrifugal turbine in the nonequilibrium steam model are all higher than those in the equilibrium steam model, whereas the outlet wetness fraction is lower than that in the equilibrium steam model.

scholarly journals Flow Investigation in a Small High Speed Impeller Passage Using Laser Anemometry

1990 ◽  
Author(s):  
N. A. Ahmed ◽  
R. L. Elder
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Three Dimensional ◽  
Experimental Results ◽  
Centrifugal Impeller ◽  
Laser Velocimetry ◽  
Laser Anemometry ◽  
Flow Investigation

The paper describes experimental results obtained using laser velocimetry in a small high speed centrifugal impeller. The formation of wakes and the effect of varying speed and mass flow rate on the flow within the impeller passages are presented. In addition, an indication of the three dimensional nature of the impeller flow is discussed (the three dimensional results being obtained using a novel Doppler anemometer).

Particle abrasion of lifting elbow in dilute pneumatic conveying

2020 ◽  
pp. 135065012095129
Author(s):  
Yun Ji ◽  
Songyong Liu ◽  
Dianrong Gao ◽  
Jianhua Zhao
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Design Method ◽  
Orthogonal Design ◽  
Industrial Applications ◽  
Experimental Results ◽  
Solid Mass ◽  
Airflow Velocity ◽  
Two Phase

Elbows are widely used in various industrial fields and are important for industrial applications. In this study, Eulerian coupling method was used to address the fluid-particle, and particle-particle interactions in a gas-solid two-phase flow while considering the effects of lifting angle, airflow velocity, and solid mass flow rate. The Hertz-Mindlin contact model and empirical Erosion/Corrosion Research Center erosion model were used to predict erosion in a lifting elbow, and the erosion ratio was used for validation with the experimental results. Experimental results indicated that the established model herein is accurate with different airflow velocities and lifting angles. The orthogonal design method was applied to the simulation scheme design, and range and variance analyses were used for the analysis of the results. Results indicated that the solid mass flow rate most affected elbow erosion comparing with lifting angles and airflow velocities. Additionally, the effect of the elbow lifting angle on the erosion mechanism was considered, and results indicated that the maximum erosion region is independent of the airflow velocity, lifting angle, and solid mass flow rate.

Assessment of Porous Type Gas Bearings: Measurements of Bearing Performance and Rotor Vibrations

2016 ◽  
Author(s):  
Luis San Andrés ◽  
Travis A. Cable ◽  
Yong Zheng ◽  
Oscar De Santiago ◽  
Drew Devitt
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Load Capacity ◽  
Gas Bearings ◽  
Rotor Spinning ◽  
Supply Pressure ◽  
Seizure Event ◽  
Flow Drag ◽  
Gas Bearing

Gas bearings are an attractive means of load support for rotating machinery due to their low mechanical power losses and dispensing of expensive lubrication systems. A subset of gas bearing technology, porous type gas bearings utilize a porous material as a means of feeding externally pressurized gas (typically air) to the bearing clearance region. When compared to typical orifice type hydrostatic bearings, porous bearings distribute pressurized gas more uniformly into the film clearance, thus resulting in a higher load capacity for similar flow rates [1]. The majority of the literature on porous type gas bearings focuses on the numerical evaluation of cylindrical bushings, yet experimental data on their performance is scant. As a follow up to Ref. [2], the paper presents an analysis of measurements of flow, drag torque and rotordynamic response of a large (100 mm OD, ∼275 N) rotor supported on two tilting pad (five-pad) porous journal bearings (specific load∼19 kPa). Measurements of air mass flow into the bearings, with and without the rotor in place, show that the film clearance offers little restriction. The mass flow rate is proportional to the supply pressure and lead to an estimated permeability coefficient. In operation with various levels of supply pressure and with the rotor spinning to 8 krpm (133 Hz, surface speed ∼42 m/s), several rotordynamic response tests (masses up to 6.9 gram) show the rotor amplitude of synchronous response is proportional to the mass imbalance; hence demonstrating the system is linear. Finally, rotor speed coast down tests from 8 krpm show that the bearings offer little drag friction; and increasing the supply pressure gives to lesser drag. The measurements verify the pair of gas bearings support effectively the rigid rotor with little expense in mass flow rate delivered to them. Most importantly, while operating at 10 krpm with a large added imbalance, the system survived a seizure event with little damage to the rotor and bearings, both restored to a near pristine condition after a simple cleaning procedure.

scholarly journals Theoretical and Experimental Investigation of a 34 Watt Radial-Inflow Steam Turbine With Partial-Admission

2020 ◽  
Author(s):  
Patrick H. Wagner ◽  
Jan Van herle ◽  
Jürg Schiffmann
Keyword(s):  
Steam Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Turbine Blades ◽  
Tip Clearance ◽  
Experimental Results ◽  
Partial Admission ◽  
Blade Tip

Abstract A micro steam turbine with a tip diameter of 15 mm was designed and experimentally characterized. At the nominal mass flow rate and total-to-total pressure ratio of 2.3 kg h−1 and 2, respectively, the turbine yields a power of 34 W and a total-to-static isentropic efficiency of 37%. The steam turbine is conceived as a radial-inflow, low-reaction (15%), and partial admission (21%) machine. Since the steam mass flow rate is limited by the heat provided of the system (solid oxide fuel cell), a low-reaction and high-power-density design is preferred. The partial-admission design allows for reduced losses: The turbine rotor and stator blades are prismatic, have a radial chord length of 1 mm and a height of 0.59 mm. Since the relative rotor blade tip clearance (0.24) is high, the blade tip leakage losses are significant. Considering a fixed steam supply, this design allows to increase the blade height, and thus reducing the losses. The steam turbine drives a fan, which operates at low Mach numbers. The rotor is supported on dynamic steam-lubricated bearings; the nominal rotational speed is 175 krpm. A numerical simulation of the steam turbine is in good agreement with the experimental results. Furthermore, a novel test rig setup, featuring extremely-thin thermocouples (ϕ0.15 mm) is investigated for an operation with ambient and hot air at 220 °C. Conventional zero and one-dimensional pre-design models correlate well to the experimental results, despite the small size of the turbine blades.

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