Fast method for computation of the static pressure field in stenotic geometries by PC MRI

2003 ◽  
Author(s):  
Abbas N. Moghaddam ◽  
Nasser Fatouraee ◽  
Eric T. Choi ◽  
Amir A. Amini
Keyword(s):  
Static Pressure ◽  
Pressure Field ◽  
Fast Method

Development of a Lifetime Pressure Sensitive Paint Procedure for High-Pressure Vane Testing

2021 ◽  
Author(s):  
Papa Aye N. Aye-Addo ◽  
Guillermo Paniagua ◽  
David G. Cuadrado ◽  
Lakshya Bhatnagar ◽  
Antonio Castillo Sauca ◽  
...  
Keyword(s):  
High Pressure ◽  
Test Section ◽  
Static Pressure ◽  
Pressure Field ◽  
Optical Measurements ◽  
Wall Region ◽  
Pressure Amplitude ◽  
Pressure Sensitive Paint ◽  
Suction Surface ◽  
Pressure Sensitive

Abstract Optical measurements based on fast response Pressure Sensitive Paint (PSP) provide enhanced spatial resolution of the pressure field. This paper presents laser lifetime PSP at 20 kHz, with precise calibrations, and results from a demonstration in an annular vane cascade. The laser lifetime PSP methodology is first evaluated in a linear wind tunnel with a converging-diverging nozzle followed by a wavy surface. This test section is fully optically accessible with maximum modularity. A data reduction procedure is proposed for the PSP calibration, and optimal pixel binning is selected to reduce the uncertainty. In the annular test section, laser lifetime PSP was used to measure the time-averaged static pressure field on a section of the suction surface of a high-pressure turbine vane. Tests were performed at engine representative conditions in the Purdue Big Rig for Annular Stationary Turbine Analysis module at the Purdue Experimental Turbine Aerothermal Lab. The 2-D pressure results showed a gradual increase of pressure in the spanwise and flow directions, corroborated with local static pressure taps and computational results. The variation in PSP thickness was measured as a contribution to the uncertainty. The discrete Fourier transform of the unsteady pressure signal showed increased frequency content in wind-on conditions compared to wind-off conditions at the mid-span and 30% span. Compared to the mid-span region, the hub end wall region had an increase in frequencies and pressure amplitude. This result was anticipated given the expected presence of secondary flow structures in the near hub region.

Numerical Study of Pressure Loss in Ceramic Bed of Thermal Flow Reversal Reactor

2013 ◽  
Vol 655-657 ◽  
pp. 149-153
Author(s):  
Zhen Qiang Gao ◽  
Rui Xiang Liu ◽  
Yong Qi Liu
Keyword(s):  
Pressure Loss ◽  
Static Pressure ◽  
Pressure Field ◽  
Numerical Study ◽  
Volume Flow Rate ◽  
Flow Reversal ◽  
Thermal Flow ◽  
Dimensional Model ◽  
Model Fluid ◽  
Main Factors

This paper describes the use of a commercial CFD code, FLUENT, to model fluid flow in thermal flow reversal reactor (TFRR) for lean methane oxidation. A two dimensional model is used. Pressure loss in ceramic bed of TFRR was focused on, and the effects of main factors are presented. The results show that the contours of static pressure in ceramic bed are slightly inclined due to the gradually variation distribution of velocity; the pressure field in distributing header is more uniform than that of collecting header; the ratio of header’s height to ceramic length influences the pressure loss most and with the increase of the ratio the pressure loss of TFRR decreased dramatically; the pressure loss increased with the increase of volume flow rate. The structure of headers is the most important factor which affects the pressure loss of TFRR.

Experimental Investigation of Flow Induced Rotor Oscillations in a Centrifugal Sewage Water Pump

Volume 3 ◽  
2004 ◽  
Author(s):  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen ◽  
Oliver Schneider
Keyword(s):  
Experimental Investigation ◽  
Static Pressure ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Sewage Water ◽  
Water Pump ◽  
Flow Rates ◽  
Pump Rotor ◽  
Pump Shaft ◽  
Impeller Geometry

Most of the pumps for sewage transport have a special impeller geometry in order to avoid operational disturbances by clogging. The almost exclusively used single stage machines particularly are equipped with single-blade impellers. With this impeller geometry a strongly uneven pressure field along the perimeter of the pump casing can be expected. The resulting periodically unsteady flow forces affect the impeller and produce strong radial deflections of the pump shaft. In this contribution the experimental investigation of the dynamic behavior of the pump rotor as a consequence of the transient hydrodynamic forces is described. To verify the calculated rotor oscillations measurements were performed at several rotating speeds and at different volume flow rates. The pump which before has been investigated numerical was equipped with several sensors. The deflections of the pump rotor were measured with two proximity sensors. The measurement of the vibration accelerations at the pump casing showed the effects of the transient hydrodynamic stimulation forces. Measurements of the static pressure in the casing allowed a correlation between the rotor oscillations and the pressure fluctuations produced by the single-blade impeller.

Dynamics and motion of a gas bubble in a viscoplastic medium under acoustic excitation

2019 ◽  
Vol 865 ◽  
pp. 381-413 ◽  
Author(s):  
G. Karapetsas ◽  
D. Photeinos ◽  
Y. Dimakopoulos ◽  
J. Tsamopoulos
Keyword(s):  
Effective Viscosity ◽  
Acoustic Pressure ◽  
Static Pressure ◽  
Pressure Field ◽  
Spherical Shape ◽  
Lagrangian Formalism ◽  
Acoustic Excitation ◽  
Bubble Motion ◽  
Viscoplastic Material ◽  
Simplified Approach

We investigate the dynamics of the buoyancy-driven rise of a bubble inside a viscoplastic material when it is subjected to an acoustic pressure field. To this end, we develop a simplified model based on the Lagrangian formalism assuming a pulsating bubble with a spherical shape. Moreover, to account for the effects of a deformable bubble, we also perform detailed two-dimensional axisymmetric simulations. Qualitative agreement is found between the simplified approach and the detailed numerical simulations. Our results reveal that the acoustic excitation enhances the mobility of the bubble, by increasing the size of the yielded region that surrounds the bubble, thereby decreasing the effective viscosity of the liquid and accelerating the motion of the bubble. This effect is significantly more pronounced at the resonance frequency, and it is shown that bubble motion takes place even for Bingham numbers (Bn) that can be orders of magnitude higher than the critical Bn for bubble entrapment in the case of a static pressure field.

Mechanism of the Interaction of a Ramped Bleed Slot With the Primary Flow

2005 ◽  
Author(s):  
B. A. Leishman ◽  
N. A. Cumpsty
Keyword(s):  
Static Pressure ◽  
Pressure Field ◽  
Computational Study ◽  
Large Fraction ◽  
Rear Surface ◽  
Stagnation Pressure ◽  
Stream Velocity ◽  
Compressor Cascade ◽  
Primary Flow ◽  
Blade Passage

An experimental and computational study of the ramped bleed slot in a compressor cascade is presented. The geometry is a circumferential slot downstream of the stator blade trailing edge, with endwall ramps inside the blade passage, and the paper builds on work previously reported for different bleed off-take geometries [1, 2]. The strong interaction between any bleed slot and the primary flow through the cascade can be strong, thereby causing the levels of loss and blockage in the primary flow leaving the blade passage to be increased at some bleed flow rates. Radial flow into the bleed slot is highly non-uniform because the blade-to-blade pressure field causes flow to enter the bleed slot preferentially where the static pressure is high, and to spill out into the primary flow where the static pressure is low. The mechanism for the ramped bleed slot is different from that described in the earlier papers for other geometries. For the ramped bleed slot a static pressure field, with large variations of static pressure in the circumferential direction, is set up in the slot because the endwall flow entering the slot has higher stagnation pressure downstream of the pressure surface than downstream of the suction surface of the upstream blades. The flow entering the slot with high stagnation pressure is brought to rest in a stagnation point on the downstream surface of the slot, and the consequent variation in static pressure on the rear surface sets tangential and radial components of velocity which are a large fraction of the free-stream velocity. As well as demonstrating the mechanism for the flow behaviour, the paper presents results of experiments and calculations to demonstrate the behaviour and gives guidance for the design of bleed slots by stressing the fundamental features of the flow.

Influence of Rim Seal Purge Flow on the Performance of an Endwall-Profiled Axial Turbine

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
P. Schuepbach ◽  
R. S. Abhari ◽  
M. G. Rose ◽  
J. Gier
Keyword(s):  
Static Pressure ◽  
Pressure Field ◽  
Leading Edge ◽  
Streamwise Vortex ◽  
Suction Side ◽  
Total Efficiency ◽  
Time Resolved ◽  
Axial Turbine ◽  
Baseline Case ◽  
Purge Flow

Nonaxisymmetric endwall profiling is a promising method to reduce secondary losses in axial turbines. However, in high-pressure turbines, a small amount of air is ejected at the hub rim seal to prevent the ingestion of hot gases into the cavity between the stator and the rotor disk. This rim seal purge flow has a strong influence on the development of the hub secondary flow structures. This paper presents time-resolved experimental and computational data for a one-and-1/2-stage high work axial turbine, showing the influence of purge flow on the performance of two different nonaxisymmetric endwalls and the axisymmetric baseline case. The experimental total-to-total efficiency assessment reveals that the nonaxisymmetric endwalls lose some of their benefit relative to the baseline case when purge is increased. The first endwall design loses 50% of the efficiency improvement seen with low suction, while the second endwall design exhibits a 34% deterioration. The time-resolved computations show that the rotor dominates the static pressure field at the rim seal exit when purge flow is present. Therefore, the purge flow establishes itself as jets emerging at the blade suction side corner. The jet strength is modulated by the first vane pressure field. The jets introduce circumferential vorticity as they enter the annulus. As the injected fluid is turned around the rotor leading edge, a streamwise vortex component is created. The dominating leakage vortex has the same sense of rotation as the rotor hub passage vortex. The first endwall design causes the strongest circumferential variation in the rim seal exit static pressure field. Therefore, the jets are stronger with this geometry and introduce more vorticity than the other two cases. As a consequence the experimental data at the rotor exit shows the greatest unsteadiness within the rotor hub passage with the first endwall design.

scholarly journals Reconstructing Compressor Non-Uniform Circumferential Flow Field From Spatially Undersampled Data: Part 2 — Practical Application for Experiments

2020 ◽  
Author(s):  
Fangyuan Lou ◽  
Douglas R. Matthews ◽  
Nicholas J. Kormanik ◽  
Nicole L. Key
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Field ◽  
Leading Edge ◽  
Pressure Profile ◽  
Sampled Data ◽  
Mean Values ◽  
Novel Method

Abstract In the previous part of the paper, a novel method to reconstruct the compressor non-uniform circumferential flow field using spatially under-sampled data points is developed. In this part of the paper, the method is applied to two compressor research articles to further demonstrate the potential of the novel method in resolving the important flow features associated with these circumferential non-uniformities. In the first experiment, the static pressure field at the leading edge of a vaned diffuser in a high-speed centrifugal compressor is reconstructed using pressure readings from nine static pressure taps placed on the hub of the diffuser. The magnitude and phase information for the first three dominant wavelets are characterized. Additionally, the method shows significant advantages over the traditional averaging methods for calculating repeatable mean values of the static pressure. While using the multi-wavelet approximation method, the errors in the mean static pressure with one dropout measurement are 70% less than the pitchwise-averaging method. In the second experiment, the full-annulus total pressure field downstream of Stator 2 in a three-stage axial compressor is reconstructed from a small segment of data representing 20% coverage of the annulus. Results show very good agreement between the reconstructed total pressure profile and the experiment at a variety of spanwise locations from near hub to near shroud. The features associated with blade-row interactions accounting for passage-to-passage variations are resolved in the reconstructed total pressure profile.

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