Blade Triggered Excitation of Periodically Unsteady Impinging Jets for Efficient Turbine Liner Segment Cooling

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Christian Scherhag ◽  
Jan Paul Geiermann ◽  
Fabian Wartzek ◽  
Heinz-Peter Schiffer
Keyword(s):  
Engine Speed ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Measurement Data ◽  
Pressure Oscillation ◽  
Impinging Jets ◽  
Rotor Blades ◽  
Cavity Pressure ◽  
Pressure Transducers ◽  
Computational Fluid Dynamics Cfd

In the present study, an application for efficient cooling of turbine liner segments employing pulsating impinging jets was investigated. A combined numerical and experimental study was conducted to evaluate the design of a case cavity device which utilizes the periodically unsteady pressure distribution caused by the rotor blades to excite a pulsating impinging jet. Through an opening between the main annulus and a case cavity, pressure pulses from the rotor blades propagated into this cavity and caused a strong pressure oscillation inside. The unsteady computational fluid dynamics (CFD) results were in good qualitative agreement with the measurement data obtained using high-frequency pressure transducers and hot wire anemometry. Furthermore, the numerical study revealed the formation of distinct toroidal vortex structures at the nozzle outlet as a result of the jet pulsation. Within the scope of the measurements, the influence of the operating point on the pressure propagation inside the cavity was investigated. The dependence of shape and amplitude of the pressure oscillation on engine speed and stage pressure ratio was found to be in accordance with an analytical consideration.

Blade Triggered Excitation of Periodically Unsteady Impinging Jets for Efficient Turbine Liner Segment Cooling

2015 ◽  
Author(s):  
Christian Scherhag ◽  
Jan Paul Geiermann ◽  
Fabian Wartzek ◽  
Heinz-Peter Schiffer
Keyword(s):  
High Frequency ◽  
Engine Speed ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Measurement Data ◽  
Pressure Oscillation ◽  
Impinging Jets ◽  
Rotor Blades ◽  
Cavity Pressure ◽  
Pressure Transducers

In the present study an application for efficient cooling of turbine liner segments employing pulsating impinging jets was investigated. A combined numerical and experimental study was conducted to evaluate the design of a case cavity device which utilizes the periodically unsteady pressure distribution caused by the rotor blades to excite a pulsating impinging jet. Through an opening between the main annulus and a case cavity, pressure pulses from the rotor blades propagated into this cavity and caused a strong pressure oscillation inside. The unsteady CFD results were in good qualititative agreement with the measurement data obtained using high frequency pressure transducers and hot wire anemometry. Furthermore, the numerical study revealed the formation of distinct toroidal vortex structures at the nozzle outlet as a result of the jet pulsation. Within the scope of the measurements the influence of the operating point on the pressure propagation inside the cavity was investigated. The dependence of shape and amplitude of the pressure oscillation on engine speed and stage pressure ratio was found to be in accordance with an analytical consideration.

A Numerical Study on the Effect of Bleed System on Starting Ability and Flow Performance of Rampressor Inlet

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Weijia Kang ◽  
Zhansheng Liu ◽  
Yu Wang ◽  
Yanyang Dong ◽  
Yong Sun
Keyword(s):  
Boundary Layer ◽  
Power Systems ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Work Condition ◽  
High Pressure Ratio ◽  
Compressor Rotor ◽  
Improvement Effect ◽  
Negative Effect ◽  
Computational Fluid Dynamics Cfd

A unique supersonic compressor rotor with high pressure ratio, termed the Rampressor, is presented by Ramgen Power Systems, Inc., (RPS). Based on the models of Rampressor inlet, the inlet flow field with bleed system is numerically studied. Validation of the employed computational fluid dynamics (CFD) scheme is provided through test cases. The effects of boundary layer bleed location and bleed amount on Rampressor rotor inlet start and flow performance are analyzed. The results indicate that the boundary layer bleed has a significant effect for start and flow performance of Rampressor inlet. Boundary layer bleed technique has been applied to eliminate the emerging flow separation zone for enhancing Rampressor rotor inlet performance and enlarging its stable working range. The starting ability and flow performance of Rampressor inlet are efficiently improved by bleeding system, but the improvement effect is different for Rampressor inlet with different bleed location. Along the position of bleeding system moves forward, the range of Rampressor inlet normal work rotation speed is enlarged. The flow performance of Rampressor inlet improves obviously with the increment of bleed flow rate, and exit stability of Rampressor inlet enhances. And in the same back pressure work condition of Rampressor inlet, bleed system has been shown to be effective that exit stability of Rampressor inlet ameliorates, but the loss of compressed air from the bleed system has a negative effect on overall Rampressor inlet efficiency.

Forced Response in Axial Turbines Under the Influence of Partial Admission

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Jens Fridh ◽  
Björn Laumert ◽  
Torsten Fransson
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Forced Response ◽  
Rotor Blades ◽  
Response Analysis ◽  
Validation Data ◽  
Pressure Transducers ◽  
Control Stage ◽  
Engine Order ◽  
Partial Admission

High cycle fatigue (HCF) due to unforeseen excitation frequencies, underestimated force magnitudes, or a combination of both causes control-stage failures for steam turbine stakeholders. This paper provides an extended design criteria toolbox, as well as validation data, for control-stage design based on experimental data to reduce HCF incidents in partial-admission turbines. The upstream rotor in a two-stage air test turbine is instrumented with pressure transducers and strain gauges. Admission degrees extend from 28.6% to 100%, as one or two admission arcs are simulated by blocking segmental arcs immediately upstream of the first stator vanes with aerodynamically shaped filling blocks. Sweeps across a speed range of 50%–105% of design speed are performed at a constant turbine pressure ratio during simultaneous high-speed acquisition. A forced-response analysis is performed and results presented in Campbell diagrams. Partial admission creates a large number of low-engine-order forced responses because of the blockage, pumping, loading, and unloading processes. Combinations of the number of rotor blades and low-engine-order excitations are the principal sources of forced-response vibrations for the turbine studied here. Altering the stator and/or rotor pitches changes the excitation pattern. We observed that a relationship between the circumferential lengths of the admitted and nonadmitted arcs dictates the excitation forces and may serve as a design parameter.

Forced Response in Axial Turbines Under the Influence of Partial Admission

2012 ◽  
Author(s):  
Jens Fridh ◽  
Björn Laumert ◽  
Torsten Fransson
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Forced Response ◽  
Rotor Blades ◽  
Response Analysis ◽  
Validation Data ◽  
Pressure Transducers ◽  
Control Stage ◽  
Engine Order ◽  
Partial Admission

High cycle fatigue (HCF) due to unforeseen excitation frequencies or due to under predicted force magnitudes, or a combination of both causes control stage failures for steam turbine stakeholders. The objectives of this paper is to provide an extended design criteria toolbox and validation data for control stage design based on experimental data, with the aim to decrease HCF incidents for partial admission turbines. The upstream rotor in a two stage air test turbine is instrumented with pressure transducers and strain gauges. Admission degrees stretching from 28.6% to 100% as one or two admission arcs are simulated by blocking segmental arcs immediately upstream of first stator vanes by aerodynamically shaped filling blocks. Sweeps across a speed range from 50 to 105% of design speed are performed at constant turbine pressure ratio during simultaneous high speed acquisition. A forced response analysis is performed and results presented in Campbell diagrams. Partial admission creates a large number of low engine order forced responses because of the blockage, pumping, loading and unloading processes. Combinations of the number of rotor blades and low engine order excitations are the principal sources of forced response vibrations for the turbine studied herein. Altering the stator and/or rotor pitches will change the excitation pattern. A relation between the circumferential lengths of the admitted and non-admitted arcs that dictates the excitation forces is observed that may serve as a design parameter.

Evaluation of Erosion Equations in Submerged Impinging Jets

2020 ◽  
Author(s):  
Qiuchen Wang ◽  
Qiyu Huang ◽  
Xu Sun ◽  
Jun Zhang ◽  
Soroor Karimi ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Numerical Study ◽  
Exclusion Process ◽  
Impinging Jets ◽  
Slurry Erosion ◽  
Carrier Fluid ◽  
Erosion Models ◽  
Computational Fluid Dynamics Cfd ◽  
Sand Particles ◽  
Pipeline Safety

Abstract During petroleum production, small sand particles can be entrained with the transported carrier fluid despite of any sand exclusion process and these sand particles can erode inner walls of pipelines. Therefore, the ability to accurately predict erosion rate caused by particles in oil and water is important to pipeline safety. There are erosion equations available in the literature to predict this phenomenon. However, most of the widely used erosion equations are derived by analyzing gas-solid erosion process, which were later validated and shown to be less accurate in predicting slurry erosion. Modified slurry erosion equations are then proposed to improve the prediction accuracy, while overpredictions occur when particle sizes vary. In this study, the available mechanistic and empirical equations are evaluated by experimental and numerical study. Computational Fluid Dynamics (CFD) is used to simulate the fluid flow and track particles to obtain impact information. Erosion equations then connect the particles’ impact information with erosion rate. The slurry erosion experiments are conducted using quartz silica particles with similar shapes and different sizes ranging from 25 micrometers to 600 micrometers in oil and water as carrier fluids. Finally, the erosion models are evaluated by comparing predicted erosion profile with experimental data.

Load Characteristics of Steel and Concrete Tubular Members Under Jet Fire: An Experimental and Numerical Study

2010 ◽  
Author(s):  
Jeong Hyo Park ◽  
Bong Ju Kim ◽  
Jung Kwan Seo ◽  
Jae Sung Jeong ◽  
Byung Keun Oh ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Numerical Study ◽  
Fire Load ◽  
Adiabatic Wall ◽  
Fire Engineering ◽  
Ansys Cfx ◽  
Design Values ◽  
Computational Fluid Dynamics Cfd ◽  
Load Characteristics ◽  
Set Up

The aim of this study was to evaluate the load characteristics of steel and concrete tubular members under jet fire, with the motivation to investigate the jet fire load characteristics in FPSO topsides. This paper is part of Phase II of the joint industry project on explosion and fire engineering of FPSOs (EFEF JIP) [1]. To obtain reliable load values, jet fire tests were carried out in parallel with a numerical study. Computational fluid dynamics (CFD) simulation was used to set up an adiabatic wall boundary condition for the jet fire to model the heat transfer mechanism. A concrete tubular member was tested under the assumption that there is no conduction effect from jet fire. A steel tubular member was tested and considered to transfer heat through conduction, convection, and radiation. The temperature distribution, or heat load, was analyzed at specific locations on each type of member. ANSYS CFX [2] and Kameleon FireEx [3] codes were used to obtain similar fire action in the numerical and experimental methods. The results of this study will provide a useful database to determine design values related to jet fire.

Numerical Study of Plane and Round Impinging Jets using RANS Models

2008 ◽  
Vol 54 (3) ◽  
pp. 213-237 ◽  
Author(s):  
J. E. Jaramillo ◽  
C. D. Pérez-Segarra ◽  
I. Rodriguez ◽  
A. Oliva
Keyword(s):  
Numerical Study ◽  
Impinging Jets ◽  
Rans Models

Effect of Vaned Diffuser on a Modified Turbocharger Centrifugal Compressor Performance

2014 ◽  
Vol 663 ◽  
pp. 347-353
Author(s):  
Layth H. Jawad ◽  
Shahrir Abdullah ◽  
Zulkifli R. ◽  
Wan Mohd Faizal Wan Mahmood
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Width Ratio ◽  
Outlet Section ◽  
Suction Surface ◽  
Vaned Diffuser ◽  
Minimum Width

A numerical study that was made in a three-dimensional flow, carried out in a modified centrifugal compressor, having vaned diffuser stage, used as an automotive turbo charger. In order to study the influence of vaned diffuser meridional outlet section with a different width ratio of the modified centrifugal compressor. Moreover, the performance of the centrifugal compressor was dependent on the proper matching between the compressor impeller along the vaned diffuser. The aerodynamic characteristics were compared under different meridional width ratio. In addition, the velocity vectors in diffuser flow passages, and the secondary flow in cross-section near the outlet of diffuser were analysed in detail under different meridional width ratio. Another aim of this research was to study and simulate the effect of vaned diffuser on the performance of a centrifugal compressor. The simulation was undertaken using commercial software so-called ANSYS CFX, to predict numerically the performance charachteristics. The results were generated from CFD and were analysed for better understanding of the fluid flow through centrifugal compressor stage and as a result of the minimum width ratio the flow in diffuser passage tends to be uniformity. Moreover, the backflow and vortex near the pressure surface disappear, and the vortex and detachment near the suction surface decrease. Conclusively, it was observed that the efficiency was increased and both the total pressure ratio and static pressure for minimum width ratio are increased.

Development of an Anti-Interference Swirl Meter Based on Numerical Simulation of Hydrodynamic Vibration

2000 ◽  
Author(s):  
Xin Fu ◽  
Huayong Yang
Keyword(s):  
High Reliability ◽  
Fluid Dynamic ◽  
Pressure Oscillation ◽  
Measuring Error ◽  
Dynamic Features ◽  
Pressure Transducers ◽  
Vortex Precession ◽  
Eccentric Motion ◽  
Piezoelectric Pressure Sensor ◽  
Good Medium

Abstract Having the advantages of no motion elements, high reliability, undemanding maintenance and good medium flexibility, the swirl meter has been widely used to measure the gas, liquid and steam in chemical, petroleum as well as processing industries. For the current one-piezoelectric-pressure-sensor swirl meter, however, the measuring error caused by the interference pressure oscillation limits its application in the system where pressure is unsteady, or a noisemaker is nearby. In this paper, the fluid dynamic features inside the channel of the swirl meter are studied numerically and by experiment. The time dependent vortex motions as well as the hydrodynamic vibrations within the channel of the swirl meter are simulated using the CFD approaches of the RNG k-ε model. The computed flow fields indicate that the eccentric motion of vortexes initiates an axisymmetric pressure oscillation within the vortex precession area of the swirl meter. The frequency of the oscillation shifts linearly with volume flow rates. Both the calculated and the measured results prove that the hydrodynamic vibrations on the arbitrary axisymmetric points are equal in amplitude and frequency but with a 180 degree phase difference. By installing differential pressure transducers on such the axisymmetric points, the signals of the vortex pressure oscillations are enhanced, while the interferential signals are suppressed, enabling the anti-interference performance and low-flowrate sensibility of the swirmeter to be effectively improved.

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