scholarly journals Analysis of Simulated Axial-Flow Turbomachine Wakes for Estimation of Frequency-Response Requirements for Fast-Response Pressure Probes

1974 ◽  
Author(s):  
G. H. Junkhan
Keyword(s):  
Frequency Response ◽  
Axial Flow ◽  
Fast Response ◽  
Maximum Pressure ◽  
Pressure Time ◽  
Total Head ◽  
Blade Row ◽  
Probe Frequency ◽  
Response Pressure ◽  
Electronic Filters

Various types of fast-response pressure probes are currently used in turbomachines. One application of these probes is for the measurement of time varying total pressures downstream of an aixal-flow machine rotor. In this paper, the frequency-response requirements for a probe placed in such a stream are estimated using a simulated wake pressure-time function. The analysis indicates that the minimum required response depends mainly on the maximum pressure difference from wake to free stream, the blade passing frequency and the blade row geometry. One of the assumptions made in the analysis is that a fast-response probe with a short total head tube in front of the transducer behaves approximately as a second-order dynamic system. Experimental results are given to illustrate probe behavior both in frequency-response tests and behind an axial-flow rotor. Improved probe frequency response using electronic filters is also illustrated.

An Experimental Investigation of the Flow Through an Axial-Flow Pump

1995 ◽  
Vol 117 (3) ◽  
pp. 485-490 ◽  
Author(s):  
W. C. Zierke ◽  
W. A. Straka ◽  
P. D. Taylor
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Axial Flow ◽  
Fast Response ◽  
Complex Flow ◽  
Penn State ◽  
Response Pressure ◽  
Axial Flow Pump ◽  
Scale Experiment ◽  
High Reynolds

The high Reynolds number pump (HIREP) facility at ARL Penn State has been used to perform a low-speed, large-scale experiment of the incompressible flow of water through a two-blade-row turbomachine. The objectives of this experiment were to provide a database for comparison with three-dimensional, turbulent flow computations, to evaluate engineering models, and to improve our physical understanding of many of the phenomena involved in this complex flow field. This summary paper briefly describes the experimental facility, as well as the experimental techniques—such as flow visualization, static-pressure measurements, laser Doppler velocimetry, and both slow- and fast-response pressure probes. Then, proceeding from the inlet to the exit of the pump, the paper presents highlights of experimental measurements and data analysis, giving examples of measured physical phenomena such as endwall boundary layers, separation regions, wakes, and secondary vortical structures. In conclusion, this paper provides a synopsis of a well-controlled, larger scope experiment that should prove helpful to those who wish to use the database.

scholarly journals Surge Pressure Effect on Crude Oil Export Pipelines to Petroleum Ports

2014 ◽  
Vol 5 (1) ◽  
pp. 245-259
Author(s):  
Dr.Mohammad Nasir Hussain ◽  
Huda Khalil Ibrahim ◽  
Ahmed kareem Hasan ◽  
Ahmed Abdul Jaleel Haddar
Keyword(s):  
Crude Oil ◽  
Fast Response ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Transient Pressure ◽  
Strict Adherence ◽  
Speed Reduction ◽  
Oil Export ◽  
Transient Pressure Analysis ◽  
Response Pressure

Pressure surges in pipelines are created by a change in momentum of the moving stream (e.g. valve closure). The occurrence of pressure surges should be determined by transient pressure analysis .Surge pressures are particularly critical for pipelines transporting liquid fluids, because of the high density and lower compressibility compared to gaseous fluids. Although damping of  the pressure wave initiated at the point of blockage occurs as it travels upstream, surge may in some cases result in the highest pipeline pressure at a location well upstream of the point of origin. This may occur in particular for liquid pipelines in hilly terrain. Methods of preventing the generation of unacceptably high surge pressures including valve closure speed reduction or special fast-response pressure relief systems close to the point of surge initiation. If not sufficient, strict adherence to well formulated operating procedures should be implemented.    In our research we presented the factors that may contribute in the happening of surge phenomenon and with the use of computer calculations and experimental work we gave some solutions to  prevent it. Depending on Joukowsky equation we noticed that for crude oil that each time when decreasing the valve opening the pressure will increase .in experimental part we also made tests on gas oil by using  a system in petroleum research and development center the results showed that as the valve closed the pressure increase where we get maximum pressure of 42 psi.

scholarly journals Interaction of Rim Seal and Annulus Flows in an Axial Flow Turbine

2003 ◽  
Author(s):  
C. Cao ◽  
J. W. Chew ◽  
P. R. Millington ◽  
S. I. Hogg
Keyword(s):  
Axial Flow ◽  
Fast Response ◽  
Pressure Measurements ◽  
Cfd Models ◽  
Annulus Flow ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Axial Clearance ◽  
Response Pressure ◽  
Good Agreement

A combined computational fluid dynamics (CFD) and experimental study of interaction of main gas path and rim sealing flow is reported. The experiments were conducted on a two stage axial turbine and included pressure measurements for the cavity formed between the stage 2 rotor disc and the upstream diaphragm for two values of the diaphragm-to-rotor axial clearance. The pressure measurements indicate that ingestion of the highly swirling annulus flow leads to increased vortex strength within the cavity. This effect is particularly strong for the larger axial clearance. Results from a number of steady and unsteady CFD models have been compared to the measured results. Good agreement between measurement and calculation for time-averaged pressures was obtained using unsteady CFD models, which predicted previously unknown unsteady flow features. This led to fast response pressure transducer measurements being made on the rig, and these confirmed the CFD prediction.

Measurement and Analysis of Total-Pressure Unsteadiness Data From an Axial-Flow Compressor Stage

1982 ◽  
Vol 104 (2) ◽  
pp. 479-488 ◽  
Author(s):  
W. C. Zierke ◽  
T. H. Okiishi
Keyword(s):  
Energy Transfer ◽  
Total Pressure ◽  
Axial Flow ◽  
Fast Response ◽  
Pressure Probe ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Blade Row ◽  
Measurement And Analysis ◽  
Flow Compressor

A fast-response, total-pressure probe was used with a periodically sampling and averaging data acquisition system to study the unsteady total-pressure field in an axial-flow turbomachine. Periodically unsteady total-pressure data were used to demonstrate some of the ways in which turbomachine blade wake transport and interaction influences the energy transfer involved. Observed trends of periodic variations in local total-pressure values could be explained in terms of the details of energy transfer associated with the different kinds of fluid particles (freestream, wake segment, blade surface boundary layer, mixed) moving through a blade row.

scholarly journals Interaction of Rim Seal and Annulus Flows in an Axial Flow Turbine

2004 ◽  
Vol 126 (4) ◽  
pp. 786-793 ◽  
Author(s):  
C. Cao ◽  
J. W. Chew ◽  
P. R. Millington ◽  
S. I. Hogg
Keyword(s):  
Axial Flow ◽  
Fast Response ◽  
Pressure Measurements ◽  
Cfd Models ◽  
Flow Features ◽  
Rotor Disk ◽  
Computational Fluid Dynamics Cfd ◽  
Axial Clearance ◽  
Response Pressure ◽  
Good Agreement

A combined computational fluid dynamics (CFD) and experimental study of interaction of main gas path and rim sealing flow is reported. The experiments were conducted on a two stage axial turbine and included pressure measurements for the cavity formed between the stage 2 rotor disk and the upstream diaphragm for two values of the diaphragm-to-rotor axial clearance. The pressure measurements indicate that ingestion of the highly swirling annulus flow leads to increased vortex strength within the cavity. This effect is particularly strong for the larger axial clearance. Results from a number of steady and unsteady CFD models have been compared to the measured results. Good agreement between measurement and calculation for time-averaged pressures was obtained using unsteady CFD models, which predicted previously unknown unsteady flow features. This led to fast response pressure transducer measurements being made on the rig, and these confirmed the CFD prediction.

The Effect of the Operating Point on the Pressure Fluctuations at the Blade Passage Frequency in the Volute of a Centrifugal Pump

2002 ◽  
Vol 124 (3) ◽  
pp. 784-790 ◽  
Author(s):  
Jorge L. Parrondo-Gayo ◽  
Jose´ Gonza´lez-Pe´rez ◽  
Joaquı´n Ferna´ndez-Francos
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Strong Increase ◽  
Flow Rates ◽  
Blade Passage ◽  
Pressure Transducers ◽  
Leading Role ◽  
Dynamic Forces ◽  
Response Pressure

An experimental investigation is presented which analyzes the unsteady pressure distribution existing in the volute of a conventional centrifugal pump with a nondimensional specific speed of 0.48, for flow-rates from 0% to 160% of the best-efficiency point. For that purpose, pressure signals were obtained at 36 different locations along the volute casing by means of fast-response pressure transducers. Particular attention was paid to the pressure fluctuations at the blade passage frequency, regarding both amplitude and phase delay relative to the motion of the blades. Also, the experimental data obtained was used to adjust the parameters of a simple acoustic model for the volute of the pump. The results clearly show the leading role played by the tongue in the impeller-volute interaction and the strong increase in the magnitude of dynamic forces and dipole-like sound generation in off-design conditions.

Analysis of pulsating flow measurement of engine exhaust by a Pitot tube flowmeter

2005 ◽  
Vol 6 (1) ◽  
pp. 85-93 ◽  
Author(s):  
H Nakamura ◽  
I Asano ◽  
M Adachi ◽  
J Senda
Keyword(s):  
Fast Response ◽  
Differential Pressure ◽  
Pulsating Flow ◽  
Pitot Tube ◽  
Engine Exhaust ◽  
Idle Speed ◽  
Pressure Transducers ◽  
Vehicle Engine ◽  
Before And After ◽  
Response Pressure

The Pitot tube flowmetering technique has been used to measure pulsating flow from a vehicle engine exhaust. In general, flowmetering techniques that utilize differential pressure measurements based on Bernoulli's theory are likely to show erroneous readings when measuring an average flowrate of pulsating flow. The primary reason for this is the non-linear relationship between the differential pressure and the flowrate; i.e. the flowrate is proportional to the square root of the differential pressure. Therefore, an average of the differential pressure does not give an average of pulsating flow. In this study, fast response pressure transducers have been used to measure the pulsating pressure. Then the pulsating differential pressure is converted to the flowrate while keeping the pulsation unaveraged. An average flowrate is then calculated in the flowrate domain in order to maintain linearity before and after averaging. The peak amplitude of a pulsation measured here was about 1800 L/min at an average flowrate of 70 L/min when the engine ran at idle speed. This measurement has been confirmed by measuring the pulsation with a gas analyser. The results show a large amount of back and forth gas movement in the exhaust tube. This magnitude of pulsation can cause as much as five times higher erroneous results with the pressure domain averaging when compared to a flowrate domain averaging.

Unsteady Pressure Measurement on Oscillating Blade in Transonic Flow Using Fast-Response Pressure-Sensitive Paint

2017 ◽  
Author(s):  
Toshinori Watanabe ◽  
Toshihiko Azuma ◽  
Seiji Uzawa ◽  
Takehiro Himeno ◽  
Chihiro Inoue
Keyword(s):  
Surface Pressure ◽  
Transonic Flow ◽  
Aerodynamic Force ◽  
Fast Response ◽  
Pressure Sensitive Paint ◽  
Unsteady Pressure ◽  
Pressure Distributions ◽  
Pressure Sensitive ◽  
Unsteady Surface Pressure ◽  
Response Pressure

A fast-response pressure-sensitive paint (PSP) technique was applied to the measurement of unsteady surface pressure of an oscillating cascade blade in a transonic flow. A linear cascade was used, and its central blade was oscillated in a translational manner. The unsteady pressure distributions of the oscillating blade and two stationary neighbors were measured using the fast-response PSP technique, and the unsteady aerodynamic force on the blade was obtained by integrating the data obtained on the pressures. The measurements made with the PSP technique were compared with those obtained by conventional methods for the purpose of validation. From the results, the PSP technique was revealed to be capable of measuring the unsteady surface pressure, which is used for flutter analysis in transonic conditions.

The Effect of Vane Clocking on the Unsteady Flowfield in a One and a Half Stage Transonic Turbine

2007 ◽  
Author(s):  
O. Schennach ◽  
R. Pecnik ◽  
B. Paradiso ◽  
E. Go¨ttlich ◽  
A. Marn ◽  
...  
Keyword(s):  
Laser Doppler Velocimetry ◽  
Three Dimensional ◽  
Fast Response ◽  
Navier Stokes ◽  
Doppler Velocimetry ◽  
Pressure Transducers ◽  
Wake Interactions ◽  
Transonic Turbine ◽  
Response Pressure ◽  
Vane Clocking

The current paper presents the results of numerical and experimental clocking investigations performed in a high-pressure transonic turbine with a downstream vane row. The objective was a detailed analysis of shock and wake interactions in such a 1.5 stage machine while clocking the vanes. Therefore a transient 3D-Navier Stokes calculation was done for two clocking positions and the three dimensional results are compared with Laser-Doppler-Velocimetry measurements at midspan. Additionally the second vane was equipped with fast response pressure transducers to record the instantaneous surface pressure for 20 different clocking positions at midspan.

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