Effect of Solid Particles on Turbine Performance

1976 ◽  
Vol 98 (1) ◽  
pp. 47-52 ◽  
Author(s):  
W. Tabakoff ◽  
W. Hosny ◽  
A. Hamed
Keyword(s):  
Pressure Distribution ◽  
Gas Flow ◽  
Theoretical Method ◽  
Solid Particles ◽  
Injection System ◽  
Particle Injection ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Experimental Pressure ◽  
Good Agreement

A theoretical method was developed for predicting the pressure distribution over a blade in cascade for a compressible flow with solid particles. Experimental results were obtained from a cascade wind tunnel equipped with a solid particle injection system. Good agreement was noted between the theoretical and experimental pressure distribution. The change in pressure due to the particles gives reduction in the force on the blades. The presence of solid particles in air-breathing engine gas flow changes the turbine performance. The overall turbine efficiency decreases as a result of the introduction of solid particles. The performance experiment was performed on a two-stage velocity-compounded turbine.

The Relationship Between Breach Development and the Depressurization Transient During Axial Rupture of a Gas-Pressurized Steel Pipe

1982 ◽  
Vol 104 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. R. Baum
Keyword(s):  
Rarefaction Wave ◽  
Gas Flow ◽  
Theoretical Models ◽  
Observation Point ◽  
Steel Pipe ◽  
Growth Data ◽  
Flow Through ◽  
The Relationship ◽  
Experimental Pressure ◽  
Good Agreement

Theoretical models are developed to predict the depressurization generated by a propagating axial rupture in a gas-pressurized steel pipe. The pressure transient is composed of a relatively slow depressurization within the rarefaction wave which propagates through the undisturbed gas ahead of the developing breach and a rapid depressurization within the breach zone. The models combine a simplified one-dimensional treatment of the gas flow local to the breach with experimental breach area growth data. An instantaneous steady flow through the developing breach is assumed to determine the boundary condition for the rarefaction wave. The breach zone depressurization is assumed to be dominated by the transverse wave action initiated by the arrival of the breach at the observation point. In both cases the predicted transients are in good agreement with experimental pressure histories.

scholarly journals Numerical modeling of disperse material evaporation in axisymmetric thermal plasma reactor

2003 ◽  
Vol 7 (1) ◽  
pp. 63-99 ◽  
Author(s):  
Predrag Stefanovic ◽  
Dejan Cvetinovic ◽  
Goran Zivkovic ◽  
Simeon Oka ◽  
Pavle Pavlovic
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Thermal Plasma ◽  
Gas Flow ◽  
Disperse Material ◽  
Plasma Reactor ◽  
Solid Particles ◽  
Reactor Wall ◽  
Particle Injection ◽  
Injection Angle

A numerical 3D Euler-Lagrangian stochastic-deterministic (LSD) model of two-phase flow laden with solid particles was developed. The model includes the relevant physical effects, namely phase interaction, panicle dispersion by turbulence, lift forces, particle-particle collisions, particle-wall collisions, heat and mass transfer between phases, melting and evaporation of particles, vapour diffusion in the gas flow. It was applied to simulate the processes in thermal plasma reactors, designed for the production of the ceramic powders. Paper presents results of extensive numerical simulation provided (a) to determine critical mechanism of interphase heat and mass transfer in plasma flows, (b) to show relative influence of some plasma reactor parameters on solid precursor evaporation efficiency: 1 - inlet plasma temperature, 2 - inlet plasma velocity, 3 - particle initial diameter, 4 - particle injection angle a, and 5 - reactor wall temperature, (c) to analyze the possibilities for high evaporation efficiency of different starting solid precursors (Si, Al, Ti, and B2O3 powder), and (d) to compare different plasma reactor configurations in conjunction with disperse material evaporation efficiency.

scholarly journals Numerical Investigation: Effect of Stator Vanes on Turbocharger Turbine Performance

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Ganesh Yadagiri Rapolu ◽  
Siddharth Swaminathan Balachandar ◽  
Keerthi Vallarasu Kamaraj
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Guide Vane ◽  
Operating Conditions ◽  
Lower Efficiency ◽  
Flow Angle ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Stator Vane ◽  
Geometric Changes

With reduced turbo lag and better transient response, the introduction of VTG stator guide vanes improved turbocharger performance at all the engine operating conditions. The VTG system accelerates and maneuvers exhaust gas flow to the turbine. Favorable flow conditions at turbine inlet created by vane shape improve turbine performance. At lower engine speed, it is observed that the pressure drop across vane system influences overall efficiency. Whereas at higher speed, the pressure drop and guide vane exit flow angle are found to determine the turbine efficiency. Successful practical operation of VTG system also depends on its ability to smoothly open and close the vanes at different gas loads. Stator vane shape greatly influences the smooth operability/controllability of vane system. In the present work, 3 symmetric vanes with differentT/Cratios and 2 asymmetric vanes are analyzed. The effect of geometric changes is studied from overall turbine performance as well as VTG system performance perspective. It is observed that symmetric vanes cause higher pressure drop at lower speeds leading to lower efficiency irrespective of the vane width. It is also observed that the pressure drop characteristics and vane exit flow angle are better with the asymmetric vanes, whereas the controllability of symmetric vanes is found to be superior. Analysis methodology is presented for achieving the best compromise between performance and controllability by the modification of vane geometric parameters through CFD simulations.

A Theoretical Analysis of the Viscous Flow in a Narrowly Spaced Radial Diffuser

1957 ◽  
Vol 24 (1) ◽  
pp. 9-15
Author(s):  
Henry W. Woolard
Keyword(s):  
Turbulent Flow ◽  
Viscous Flow ◽  
Plane Surface ◽  
Flow Analysis ◽  
Theoretical Method ◽  
Radial Pressure ◽  
Pressure Distributions ◽  
Disk Valve ◽  
Experimental Pressure ◽  
Good Agreement

Abstract A theoretical method for calculating the radial pressure distribution for laminar viscous flow in a narrowly spaced radial diffuser having arbitrarily shaped walls deviating only moderately from a plane surface is developed. The analysis as it stands is also directly applicable to turbulent flow in the initial inlet region of a diffuser. Additional work is necessary to obtain a complete turbulent-flow analysis. Pressure distributions calculated by the laminar-flow theory show reasonably good agreement with the limited experimental pressure distributions available at the time of the analysis. Fairly good agreement also is obtained for the performance of a disk-valve element.

Analysis of the Contact Deformation of a Radial Tire with Camber Angle

1995 ◽  
Vol 23 (1) ◽  
pp. 26-51 ◽  
Author(s):  
S. Kagami ◽  
T. Akasaka ◽  
H. Shiobara ◽  
A. Hasegawa
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Contact Region ◽  
Contact Deformation ◽  
Contact Pressure Distribution ◽  
Radial Tire ◽  
Ring Model ◽  
Camber Angle ◽  
Contact Free ◽  
Good Agreement

Abstract The contact deformation of a radial tire with a camber angle, has been an important problem closely related to the cornering characteristics of radial tires. The analysis of this problem has been considered to be so difficult mathematically in describing the asymmetric deformation of a radial tire contacting with the roadway, that few papers have been published. In this paper, we present an analytical approach to this problem by using a spring bedded ring model consisting of sidewall spring systems in the radial, the lateral, and the circumferential directions and a spring bed of the tread rubber, together with a ring strip of the composite belt. Analytical solutions for each belt deformation in the contact and the contact-free regions are connected by appropriate boundary conditions at both ends. Galerkin's method is used for solving the additional deflection function defined in the contact region. This function plays an important role in determining the contact pressure distribution. Numerical calculations and experiments are conducted for a radial tire of 175SR14. Good agreement between the predicted and the measured results was obtained for two dimensional contact pressure distribution and the camber thrust characterized by the camber angle.

A Compact Model for Spherical Rough Contacts

2004 ◽  
Author(s):  
M. Bahrami ◽  
M. M. Yovanovich ◽  
J. R. Culham
Keyword(s):  
Pressure Distribution ◽  
Entire Range ◽  
Present Model ◽  
Numerical Solutions ◽  
Contact Radius ◽  
Bulk Deformation ◽  
Dimensional Parameters ◽  
Maximum Contact ◽  
Good Agreement ◽  
Key Parameter

The contact of rough spheres is of high interest in many tribological, thermal, and electrical fundamental analyses. Implementing the existing models is complex and requires iterative numerical solutions. In this paper a new model is presented and a general pressure distribution is proposed that encompasses the entire range of spherical rough contacts including the Hertzian limit. It is shown that the non-dimensional maximum contact pressure is the key parameter that controls the solution. Compact expressions are proposed for calculating the pressure distribution, radius of the contact area, elastic bulk deformation, and the compliance as functions of the governing non-dimensional parameters. The present model shows the same trends as those of the Greenwood and Tripp model. Correlations proposed for the contact radius and the compliance are compared with experimental data collected by others and good agreement is observed.

Paper 10: Pressure Losses in the Inlet and Outlet Casings of Axial Flow Turbines for Turbo-Chargers

1967 ◽  
Vol 182 (4) ◽  
pp. 71-79 ◽  
Author(s):  
C. W. Simpson ◽  
D. E. Y. Scarlett
Keyword(s):  
Axial Flow ◽  
Annular Nozzle ◽  
Design Studies ◽  
Pressure Losses ◽  
Pressure Loss Coefficient ◽  
Turbine Efficiency ◽  
Annular Section ◽  
Turbine Casing ◽  
Transition Piece ◽  
Experimental Pressure

During initial design studies for a new range of turbo-chargers it was apparent that a considerable gain of efficiency could be achieved by a reduction of turbine casing losses. In this paper the theoretical and experimental pressure losses obtained from rig tests on the inlet and outlet casings for old and new designs will be presented. The inlet casing tests were completed on an axial entry casing with transition from circular to semi-annular section. The effect of this transition piece on gas incidences is also shown for the semi-annular nozzle entry. Studies on the outlet casing as a transition from annular through radial to axial flow have been completed and will be presented as a pressure loss coefficient for various designs. The tests have been undertaken with both convex and flat plate radial diffusers, with or without swirl. Different outlet ducts were used to determine the effects on pressure losses in the casings, and the results are discussed. Finally, the gains in overall turbine efficiency obtained by adopting the beneficial results from these tests are considered.

An anti-crystallization design of selective catalytic reduction nozzle holder

2021 ◽  
pp. 095440702097084
Author(s):  
Dewen Liu ◽  
Kai Lu ◽  
Shusen Liu ◽  
Yan Wu ◽  
Shuzhan Bai
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Injection System ◽  
Test Results ◽  
Verification Methods ◽  
Crystallization Risk ◽  
Protective Cover ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Good Agreement

From the aspect of reducing the risk of crystallization on nozzle surface, a new design of nozzle protective cover was to solve the problem in selective catalytic reduction (SCR) urea injection system. The simulation calculation and experimental verification methods were used to compare different schemes. The results show that reducing the height of nozzle holder can reduce the vortex currents near nozzle surface and effectively reduce the risk of crystallization on the nozzle surface. It is proposed to install a protective cover in the nozzle holder under the scheme of reducing the height of nozzle holder, which can further eliminate the vortex. Simulation and test results demonstrate good agreement under the rated running condition. The scheme of adding a protective cover in the nozzle holder shows the least crystallization risk by computational fluid dynamics (CFD) method. The crystallization cycle test shows that, after the height of nozzle holder is reduced, the risk of crystallization on the nozzle surface is reduced correspondingly. The addition of a protective cover in the nozzle holder solves the problem of crystallization on the nozzle surface, which provides a new method for anti-crystallization design.

Theoretical Prediction of Motions of High-Speed Planing Boats in Waves

1978 ◽  
Vol 22 (03) ◽  
pp. 140-169
Author(s):  
Milton Martin
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Nonlinear Effects ◽  
Theoretical Method ◽  
Valuable Insight ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Response Amplitude Operators ◽  
Phase Angles ◽  
Good Agreement

A theoretical method is derived for predicting the linearized response characteristics of constant deadrise high-speed planing boats in head and following waves. Comparisons of the theoretical predictions of the pitch and heave response amplitude operators and phase angles with existing experimental data show reasonably good agreement for a wide variety of conditions of interest. It appears that nonlinear effects are more severe at a speed to length ratio of 6 than of, say, 4 or less, principally because of the reduction of the damping ratio of the boat with increasing speed, and the consequent increase in motions in the vicinity of the resonant encounter frequency. However, it is concluded that the linear theory can provide a simple and fast means of determining the effect of various parameters such as trim angle, deadrise, loading, and speed on the damping, natural frequency, and linearized response in waves, and that this can furnish valuable insight into the actual boat dynamics, even though the accurate predictions of large motions and peak accelerations would require a nonlinear analysis.

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