Evaluation of Unsteady Flow Phenomena Induced by the Tailgate Gap of a Production Car Using Simulations and Experiments

2017 ◽  
pp. 83-92 ◽  
Author(s):  
Georg Eitel-Amor ◽  
Sascha Riedl ◽  
Reiner Weidemann
Keyword(s):  
Unsteady Flow ◽  
Flow Phenomena

Unsteady Flow Phenomena in Turbomachines

1990 ◽  
Author(s):  
Edward M. Greitzer ◽  
Alan H. Epstein ◽  
Michael B. Giles ◽  
James E. McCune ◽  
Choon S. Tan
Keyword(s):  
Unsteady Flow ◽  
Flow Phenomena

Unsteady Flow Phenomena in Rotating Centrifugal Impeller Passages

1970 ◽  
Vol 92 (1) ◽  
pp. 65-71 ◽  
Author(s):  
E. Lennemann ◽  
J. H. G. Howard
Keyword(s):  
Unsteady Flow ◽  
Secondary Flow ◽  
Centrifugal Impeller ◽  
Bubble Flow ◽  
Hydrogen Bubble ◽  
Visualization Technique ◽  
Rotating Systems ◽  
Flow Phenomena ◽  
Relative Flow ◽  
Zero Flow

The phenomena of unsteady relative flow observed in a centrifugal impeller passage running at part capacity and zero flow are discussed. The mechanisms of passage stall for a shrouded and unshrouded impeller are investigated and a qualitative correlation is developed for the influence of secondary flow and inducer flow on the passage stall. The hydrogen bubble flow visualization technique is extended to higher velocities and rotating systems and provides the method for obtaining the experimental results.

The Present Challenge of Transonic Compressor Blade Design

2018 ◽  
Author(s):  
A. Hergt ◽  
J. Klinner ◽  
J. Wellner ◽  
C. Willert ◽  
S. Grund ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Shock Waves ◽  
Unsteady Flow ◽  
Flow Behavior ◽  
Flow Behaviour ◽  
Compressor Cascade ◽  
Transonic Compressor ◽  
Flow Phenomena ◽  
Transonic Cascade

The flow through a transonic compressor cascade shows a very complex structure due to the occuring shock waves. In addition, the interaction of these shock waves with the blade boundary layer inherently leads to a very unsteady flow behaviour. The aim of the current investigation is to quantify this behaviour and its influence on the cascade performance as well as to describe the occuring transonic flow phenomena in detail. Therefore, an extensive experimental investigation of the flow in a transonic compressor cascade has been conducted within the transonic cascade wind tunnel of DLR at Cologne. In this process, the flow phenomena were thoroughly examined for an inflow Mach number of 1.21. The experiments investigate both, the laminar as well as the turbulent shock wave boundary layer interaction within the blade passage and the resulting unsteady behaviour. The experiments show a fluctuation range of the passage shock wave of about 10 percent chord for both cases, which is directly linked with a change of the inflow angle and of the operating point of the cascade. Thereafter, RANS simulations have been performed aiming at the verification of the reproducibility of the experimentally examined flow behavior. Here it is observed that the dominant flow effects are not reproduced by a steady numerical simulation. Therefore, a further unsteady simulation has been carried out in order to capture the unsteady flow behaviour. The results from this simulation show that the fluctuation of the passage shock wave can be reproduced but not in the correct magnitude. This leads to a remaining weak point within the design process of transonic compressor blades, because the working range will be overpredicted. The resulting conclusion of the study is that the use of scale resolving methods such as LES or the application of DNS is necessary to correctly predict unsteadiness of the transonic cascade flow and its impact on the cascade performance.

scholarly journals Effect of Suction and Discharge Conditions on the Unsteady Flow Phenomena of Axial-Flow Reactor Coolant Pump

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1592
Author(s):  
Xin Chen ◽  
Shiyang Li ◽  
Dazhuan Wu ◽  
Shuai Yang ◽  
Peng Wu
Keyword(s):  
Unsteady Flow ◽  
Pressure Pulsation ◽  
Flow Reactor ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Uniform Flow ◽  
Coolant Pump ◽  
Reactor Coolant ◽  
Flow Phenomena ◽  
Rotating Impeller

In order to study the effects of the suction and discharge conditions on the hydraulic performance and unsteady flow phenomena of an axial-flow reactor coolant pump (RCP), three RCP models with different suction and discharge configurations are analyzed by computational fluid dynamics (CFD) method. The CFD results are validated by experimental data. The hydraulic performance of the three RCP models shows little difference. However, the unsteady flow phenomena of RCP are significantly affected by the variation of suction and discharge conditions. Compared with that of Model E-S (baseline, elbow-single nozzle), the pressure pulsation in rotating frame of Model S-S (straight pipe-single nozzle) and Model E-D (elbow-double nozzles) is weakened in different degrees and forms, due to the more uniform flow fields upstream and downstream of the impeller, respectively. It indicates that the generalized rotor-stator interaction (RSI) actually exists between the rotating impeller and all stationary components causing the circumferentially non-uniform flow. Furthermore, improving the circumferential uniformity of the flow upstream and downstream of impeller (suction and discharge flow) also contributes to reducing the radial dynamic fluid force acting on the impeller. Compared with those of Model E-S, the dynamic FX and FY of Model S-S are severely weakened, and those of Model E-D also gain a minor amplitude decrease at fBPF. In contrast, the general pressure pulsation in fixed frame is mainly related to the rotating impeller and barely affected by the suction and discharge conditions.

A New Approach to the Experimental Study of Turbomachinery Flow Phenomena

1977 ◽  
Vol 99 (1) ◽  
pp. 97-105 ◽  
Author(s):  
J. P. Gostelow
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Axial Flow ◽  
Centrifugal Pumps ◽  
New Approach ◽  
Static Pressure Distribution ◽  
Compressor Rotor ◽  
Flow Phenomena ◽  
On Line ◽  
Flow Compressor

Measurements of the unsteady flow field over a rotor and within its wake are needed in the development of most turbomachines. The technique advocated is that of data acquisition by on-line computer, using the periodic passing of a blade as a phase reference. The phase-lock averaging process is described as is its use in reducing the noise of raw data traces. Measurements of the unsteady flow over a cascade and of the resulting boundary layer behavior are presented. The approach was used in interpreting the unsteady flow field of an axial-flow compressor rotor and the static pressure distribution over the rotor tip. Finally the application to centrifugal pumps is discussed, enabling the designer to obtain information on the suction pressures and the extent of any separated region.

Endwall Effects at Two Tip Clearances in a Multistage Axial Flow Compressor With Controlled Diffusion Blading

1994 ◽  
Vol 116 (4) ◽  
pp. 635-645 ◽  
Author(s):  
M. A. Howard ◽  
P. C. Ivey ◽  
J. P. Barton ◽  
K. F. Young
Keyword(s):  
Unsteady Flow ◽  
Axial Flow ◽  
Tip Clearance ◽  
Exit Angle ◽  
Controlled Diffusion ◽  
The Third ◽  
Flow Phenomena ◽  
Multistage Compressor ◽  
Flow Compressor ◽  
Stage Efficiency

Effects of tip clearance, secondary flow, skew, and corner stall on the performance of a multistage compressor with controlled diffusion blading have been studied experimentally. Measurements between 1 and 99 percent annulus height were carried out in both the first and the third stages of a four-stage low-speed compressor with repeating-stage blading. Measurements were obtained at a datum rotor tip clearance and at a more aerodynamically desirable lower clearance. The consequences of the modified rotor tip clearance on both rotor and stator performance are examined in terms of loss coefficient and gas exit angle. Stator losses close to the casing are found to increase significantly when the clearance of an upstream rotor is increased. These increased stator losses cause 30 percent of the stage efficiency reduction that arises with increased rotor tip clearance. The deviation angles due to tip clearance from the multistage measurements are found to be similar to data from single-stage machines with conventional blading, which suggests that the unsteady flow phenomena associated with the multistage environment do not dominate the physics of the flow.

Unsteady Flow Phenomena in a Transonic Centrifugal Compressor at near-surge conditions

2016 ◽  
Vol 2016 (0) ◽  
pp. J0520202
Author(s):  
Atsuki OKAMOTO ◽  
Hiromitsu ARAI ◽  
Masato FURUKAWA ◽  
Satoshi GUNJISHIMA ◽  
Kazutoyo YAMADA
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Compressor ◽  
Transonic Centrifugal Compressor ◽  
Flow Phenomena

scholarly journals Investgation of Turbine stage performance and Unsteady flow phenomena with Injection flow from casing

2004 ◽  
Vol 2004 (0) ◽  
pp. 18
Author(s):  
Kenichi FUNAZAKI ◽  
Kazutoyo YAMADA ◽  
Masanori KONNO ◽  
Callos Felipe Ferreira Favaretto ◽  
Tadashi TAMURA
Keyword(s):  
Unsteady Flow ◽  
Turbine Stage ◽  
Injection Flow ◽  
Flow Phenomena ◽  
Stage Performance

The Present Challenge of Transonic Compressor Blade Design

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Alexander Hergt ◽  
J. Klinner ◽  
J. Wellner ◽  
C. Willert ◽  
S. Grund ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Shock Waves ◽  
Unsteady Flow ◽  
Flow Behavior ◽  
Complex Structure ◽  
Compressor Cascade ◽  
Transonic Compressor ◽  
Flow Phenomena ◽  
Transonic Cascade

The flow through a transonic compressor cascade shows a very complex structure due to the occurring shock waves. In addition, the interaction of these shock waves with the blade boundary layer inherently leads to a very unsteady flow behavior. The aim of the current investigation is to quantify this behavior and its influence on the cascade performance as well as to describe the occurring transonic flow phenomena in detail. Therefore, an extensive experimental investigation of the flow in a transonic compressor cascade has been conducted within the transonic cascade wind tunnel of DLR Institute of Propulsion Technology at Cologne. In this process, the flow phenomena were thoroughly examined for an inflow Mach number of 1.21. The experiments investigate both the laminar and the turbulent shock wave boundary layer interaction within the blade passage and the resulting unsteady behavior. The experiments show a fluctuation range of the passage shock wave of about 10% chord for both cases, which is directly linked with a change of the inflow angle and of the operating point of the cascade. Thereafter, Reynolds-averaged Navier–Stokes (RANS) simulations have been performed aiming at the verification of the reproducibility of the experimentally examined flow behavior. Here, it is observed that the dominant flow effects are not reproduced by a steady numerical simulation. Therefore, a further unsteady simulation has been carried out to capture the unsteady flow behavior. The results from this simulation show that the fluctuation of the passage shock wave can be reproduced but not in the correct magnitude. This leads to a remaining weak point within the design process of transonic compressor blades because the working range will be overpredicted. The resulting conclusion of this study is that the use of scale-resolving methods such as LES or the application of DNS is necessary to correctly predict unsteadiness of the transonic cascade flow and its impact on the cascade performance.

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