Numerical and Experimental Investigation of Pulsating Flow Effect on a Nozzled and Nozzleless Mixed Flow Turbine for an Automotive Turbocharger

2014 ◽  
Author(s):  
M. H. Padzillah ◽  
M. Yang ◽  
W. Zhuge ◽  
R. F. Martinez-Botas
Keyword(s):  
Pressure Ratio ◽  
Turbine Blades ◽  
Computational Cost ◽  
Operating Conditions ◽  
Pulsating Flow ◽  
Angle Distribution ◽  
Operating Pressure ◽  
Flow Conditions ◽  
Flow Angle ◽  
Turbine Speed

To achieve better flow guidance into the turbine blades, nozzle vanes were added as an integral part of the stator design. However, the full investigation that directly addresses the comparison between the two turbine arrangements under pulsating flow conditions is still not available in literature. This work represents the first attempt to observe differences, particularly in the circumferential flow angle distribution between both volute arrangements under steady and pulsating flow operating conditions. Experimentally validated Computational Fluid Dynamics (CFD) simulations have been conducted in order to achieve this aim. As the experimental data within the Turbocharger Group at Imperial College are extensive, the simulation procedures are optimized to achieve the best compromise between the computational cost and prediction accuracy. A single operating pressure ratio is selected for the steady and pulsating environment in order to provide consistent comparison for both volute arrangements. The simulation results presented in this work are conducted at the turbine speed of 48000rpm and 60Hz flow frequency for the pulsating flow simulations. The results indicated that there are significant differences in the flow angle behavior for both volutes regardless of the flow conditions (steady or unsteady). It is also found that the differences in flow angle distribution between increasing and decreasing pressure instances during pulsating flow operation is more prominent in the nozzleless volute than its nozzled counterpart.

Compressible Flowfield Characteristics of Butterfly Valves

1989 ◽  
Vol 111 (4) ◽  
pp. 400-407 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Flow Separation ◽  
Pressure Ratio ◽  
Disk Surface ◽  
Surface Flow ◽  
Operating Conditions ◽  
Local Geometry ◽  
Operating Pressure ◽  
Butterfly Valve ◽  
Pressure Distributions ◽  
Flow Separation And Reattachment

The results of an experimental investigation into the flowfield characteristics of butterfly valves under compressible flow operating conditions are reported. The experimental results include Schlieren and surface flow visualizations and flowfield static pressure distributions. Two valve disk shapes have been studied in a planar, two-dimensional test section: a generic biconvex circular arc profile and the midplane cross-section of a prototype butterfly valve. The valve disk angle and operating pressure ratio have also been varied in these experiments. The results demonstrate that under certain conditions of operation the butterfly valve flowfield can be extremely complex with oblique shock waves, expansion fans, and regions of flow separation and reattachment. In addition, the sensitivity of the valve disk surface pressure distributions to the local geometry near the leading and trailing edges and the relation of the aerodynamic torque to flow separation and reattachment on the disk are shown.

Performance of Radial Flow Turbines Under Pulsating Flow Conditions

1976 ◽  
Vol 98 (1) ◽  
pp. 53-59 ◽  
Author(s):  
H. Kosuge ◽  
N. Yamanaka ◽  
I. Ariga ◽  
I. Watanabe
Keyword(s):  
Steady Flow ◽  
Pressure Pulse ◽  
Radial Flow ◽  
Pressure Ratio ◽  
Pulse Frequency ◽  
Pulsating Flow ◽  
Frequency Range ◽  
Flow Conditions ◽  
Transient Pressure ◽  
Empirical Parameter

Investigations of the pulsating flow performances of an inward radial flow turbine were performed. The quasi-steady flow performances predicted from the measured transient pressure ratio and from steady flow performance data were compared with the measured mean performances under pulsating flow conditions over the pulse frequency range of 30 Hz–70 Hz. The validity of this quasi-steady flow assumption was treated more generally than by the hitherto employed method by adopting a new empirical parameter which indicates both the pressure pulse shape and the amplitude of pressure fluctuation, in addition to the pulse frequency.

Effect of Inlet Swirl on the Model Leading Edge of Turbine Vane

2013 ◽  
Author(s):  
Hong Yin ◽  
Yanmin Qin ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Film Cooling ◽  
Swirling Flow ◽  
Leading Edge ◽  
Operating Conditions ◽  
Test Model ◽  
Angle Distribution ◽  
Middle Section ◽  
Flow Angle ◽  
Stagnation Line ◽  
Film Cooling Effectiveness

Lean premixed combustion technology has been widely adopted in heavy duty and industrial gas turbine combustor. To enhance mixing and stabilize the flame, the large recirculation zone is built up by introducing strong swirling flow, which causes non-uniform flow field and has effect on the first stage vane, especially the leading edge. This paper investigates the effect of swirling flow on the downstream vane film cooling. Test rig consists of a swirler nozzle (swirl number equals 0.45) and a model leading edge with three rows of film cooling holes. Five-hole probe and pressure sensitive paint measurements were carried out. The operating conditions range includes three blowing ratios, two density ratios of cooling flow and two distances between the swirler and the model leading edge. Numerical simulations were also conducted and compared with the accumulated experimental data. Results show that the stagnation line of the model leading edge under swirling inlet flow condition is obviously altered compared with uniform inflow. Dividing the test model into three sections, film cooling effectiveness distribution has distinct characteristics in each section. Both ends of the model are mainly influenced by the flow direction. However the middle section performs differently since the vortex core impingement directly disturbs the film cooling ejection. Furthermore, detailed computational analysis reveals the swirling flow character and that the combined effect of total pressure and flow angle distribution dominates the film cooling of middle section.

Evaluation of the Accuracy of Selected Syngas Chemical Mechanisms

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Fahad M. Alzahrani ◽  
Yinka S. Sanusi ◽  
Konstantina Vogiatzaki ◽  
Ahmed F. Ghoniem ◽  
Mohamed A. Habib ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Laminar Flame ◽  
Computational Cost ◽  
Operating Conditions ◽  
Average Error ◽  
Operating Pressure ◽  
Chemical Mechanisms ◽  
Flame Thickness ◽  
Reduced Mechanism ◽  
Significant Difference

The implementation of reduced syngas combustion mechanisms in numerical combustion studies has become inevitable in order to reduce the computational cost without compromising the predictions' accuracy. In this regard, the present study evaluates the predictive capabilities of selected detailed, reduced, and global syngas chemical mechanisms by comparing the numerical results with experimental laminar flame speed (LFS) values of lean premixed (LPM) syngas flames. The comparisons are carried out at varying equivalence ratios, syngas compositions, operating pressures, and preheat temperatures to represent a range of operating conditions of modern fuel flexible combustion systems. NOx emissions predicted by the detailed mechanism, GRI-Mech. 3.0, are also used to study the accuracy of the selected mechanisms under these operating conditions. Moreover, the selected mechanisms' accuracy in predicting the laminar flame thickness (LFT), species concentrations of the reactants, and OH profiles at different equivalence ratios and syngas compositions are investigated as well. The LFS is generally observed to increase with increasing equivalence ratio, hydrogen content in the syngas, and preheat temperature, while it is decreased with increasing operating pressure. This trend is followed by all mechanisms understudy. The global mechanisms of Watanabe–Otaka and Jones–Lindstedt for syngas are consistently observed to over-predict and under-predict the LFS up to an average of 60% and 80%, respectively. The reduced mechanism of Slavinskaya has an average error of less than 20%, which is comparable to the average error of the GRI-Mech. 3.0. It however over-predicts the flame thickness by up to 30% when compared to GRI-Mech. 3.0. The NO prediction by Li mechanism and the reduced mechanisms are observed to be within 10% prediction range of the GRI-Mech. 3.0 at intermediate equivalence ratio (φ=0.74) up to stoichiometry. Moving toward more lean conditions, there is significant difference between the GRI-Mech. 3.0 NO prediction and those of the reduced mechanisms due to relative importance of the prompt NOx at lower temperature compared to thermal NOx that is only accounted for by the GRI-Mech. 3.0.

Performance of a Mixed Flow Turbocharger Turbine Under Pulsating Flow Conditions

1995 ◽  
Author(s):  
C. Arcoumanis ◽  
I. Hakeem ◽  
L. Khezzar ◽  
R. F. Martinez-Botas ◽  
N. C. Baines
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Velocity Ratio ◽  
Pulsating Flow ◽  
Flow Conditions ◽  
Mixed Flow ◽  
Engine Exhaust ◽  
High Pressure Ratio ◽  
Design Speed ◽  
Swallowing Capacity

The performance of a high pressure ratio (P.R.=2.9) mixed flow turbine for an automotive turbocharger has been investigated and the results revealed its better performance relative to a radial-inflow geometry under both steady and pulsating flow conditions. The advantages offered by the constant blade angle rotor allow better turbocharger-engine matching and maximization of the energy extracted from the pulsating engine exhaust gases. In particular, the mixed inlet blade geometry resulted in high efficiency at high expansion ratios where the engine-exhaust pulse energy is maximum. The efficiency characteristics of the mixed flow turbine under steady conditions were found to be fairly uniform when plotted against the velocity ratio, with a peak efficiency at the design speed of 0.75. The unsteady performance as indicated by the mass-averaged total-to-static efficiency and the swallowing capacity exhibited a departure from the quasi-steady assumption which is analysed and discussed.

Investigation on Pulsating Flow Effect of a Turbocharger Turbine

2017 ◽  
Author(s):  
Zhanming Ding ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Hua Chen ◽  
Ricardo Martinez-Botas
Keyword(s):  
Internal Combustion Engines ◽  
Oscillatory Behavior ◽  
Operating Conditions ◽  
Pulsating Flow ◽  
Inlet Temperature ◽  
Relative Importance ◽  
Flow Conditions ◽  
Pulse Flow ◽  
Flow Effect ◽  
Unsteady Performance

Turbocharger turbines in internal combustion engines operate under highly pulsating flow conditions. The pulsating inflow has a complicated interaction with the turbine flow field and generates strong unsteadiness across the turbine stage, which produces oscillatory behavior and renders turbine performance distinct from that under steady conditions. However, the unsteady effect of the pulse flow is not considered when matching turbocharger turbines to engines due to the lack of effective simulation tools and unsteadiness criterion. In this paper, a one-dimensional (1D) unsteady turbine model is proposed which could consider the volute curvature and preserve circumferential non-uniformity at rotor inlet. A parametric investigation of the response of a turbocharger turbine to inlet pulses is conducted based on the 1D model. The effects of various pulse parameters such as the amplitude, load, and frequency on the unsteady performance loops are studied. The influence of turbine operating conditions as the average inlet temperature and rotating speed on turbine unsteady performance is assessed. A dimensionless unsteadiness criterion Λ is used to correlate the relative importance of turbine unsteadiness. Results show that Λ is an effective criterion to judge the relative importance of unsteadiness. The investigation demonstrates turbine behaviors under different pulsating flow conditions, and strengthens the understanding of pulsating flow effect on turbine unsteady performance.

Turning Mid Turbine Frame Behavior for Different HP Turbine Outflow Conditions

2011 ◽  
Author(s):  
Berardo Paradiso ◽  
Cornelia Santner ◽  
Josef Hubinka ◽  
Emil Go¨ttlich ◽  
Martin Hoeger
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Time Resolved ◽  
Flow Angle ◽  
The Mean ◽  
Eu Project ◽  
The Eu

The design of turbine frames with turning vanes, known as turning mid-turbine frames (TMTF), becomes of great importance for high by-pass ratio engines with counter-rotating turbines. To achieve a more efficient low-pressure turbine the overall diffusion and radial offset should be increased. One goal of the EU project DREAM is to analyse the flow through a TMTF and a downstream arranged counter rotating LP rotor. The investigation of these complex interrelationships has been performed in the unique two-spool continuously operating transonic test turbine facility at Graz University of Technology. The test setup consists of an unshrouded HP stage, the TMTF and a shrouded LP rotor. The shafts of both turbines are mechanically independent, so the test rig allows a realistic two shaft turbine operation. The TMTF flow field is highly complex. It is a turbulent and unsteady flow dominated by strong secondary flows and vortex-interactions. The upstream transonic high pressure turbine stage produces a complex inflow with high levels of turbulence, stationary and rotating wakes and vortical structures. Therefore the application of advanced measurement techniques is necessary. To describe the HP-TMTF interaction time-resolved pressure measurements have applied within the project. The TMTF was instrumented with 10 fast response pressure transducers; static pressure tap recordings on the strut and on the TMTF end-walls have been also applied. Five hole probe, total pressure and total temperature rakes have been additionally acquired in the planes just in front of the struts and downstream to evaluate the performance of the TMTF. The results of these conventional techniques are presented in this work and they represent the necessary starting point for the evaluation and the description of the flow field. The idea is to start the study analysing the mean quantities and the overall performance of the two stages for different conditions and to leave the analysis of the time-resolved results for further investigation. Detailed investigations will start from the data presented in this paper; indeed, the use of unsteady measurement techniques is time consuming and cannot be performed for such a large amount of flow conditions, radial planes and HP vane - TMTF relative positions. Three operating conditions for different clocking positions have been considered. The variation of the operating conditions has been achieved by varying the HP shaft velocity and pressure ratio, with a consequence change of pressure ratio in the LP rotor. For this analysis the LP shaft velocity was kept constant. The TMTF performance variations will be analysed in terms of total pressure loss coefficient and exit flow angle; the mean interaction between the structures coming from the HP stage and the struts will represent the interpretation key to explain these variations. This work is part of the EU project DREAM (ValiDation of Radical Engine Architecture SysteMs, contract No. ACP7-GA-2008-211861).

scholarly journals INVESTIGATION OF JET ENGINE INTAKE DISTORTIONS CAUSED BY CROSSWIND CONDITIONS

2020 ◽  
Vol 4 ◽  
pp. 48-62
Author(s):  
Lennart Harjes ◽  
Christoph Bode ◽  
Jonas Grubert ◽  
Philip Frantzheld ◽  
Patrick Koch ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Boundary Conditions ◽  
Operating Conditions ◽  
Test Facility ◽  
Hysteresis Phenomenon ◽  
Angle Distribution ◽  
Flow Angle ◽  
Jet Engine ◽  
Validation Experiment

The Propulsion Test Facility of the TU Braunschweig is capable of investigating future jet engine intakes and fan aerodynamics to a high level of detail. A goal of this facility is the examination of coupled fan-intake-interactions which is not possible in any existing test bench around the world. Before doing research on these interactions, it is important to undergo proper studies of isolated aspirated intakes and fans under varying operating conditions (design and off-design). Therefore comparable result of the well-known LARA nacelle to existing experimental and numerical data has been generated for a first validation purpose. Therefore, comparable studies have been conducted with the LARA nacelle, to that of experimental and numerical investigations performed in the early 1990s at the ONERA F1 wind tunnel (mention reference), in order to generate results for validation. The first results of the validation experiment show differences in peak Mach number between the ONERA F1 and PTF experimental data for identical boundary conditions based on Mach number and crosswind. To investigate this further, a comprehensive numerical study has been carried out. It was inferred that the discrepancy was mainly caused by the Reynolds number effect within the PTF environment and its sensitivity to the inlet flow angle distribution with regard to angle of attack for crosswind. Within the validation test campaign, the experimental investigations showed a separation and reattachment hysteresis, which was identified when crosswind as well as nacelle mass flow had been increased or decreased to set up the different operating points. This phenomenon has still no established theoretical basis for understanding the aerodynamic behaviour. Overall, the applicability of conventional RANS models is shown. Additionally, the sensitivity to the aforementioned boundary conditions and the numerical reproducibility of the hysteresis phenomenon are discussed and compared to new experimental data in detail.

Effect of a volute on the unsteady flow in the vane diffuser of a centrifugal compressor

2016 ◽  
Vol 230 (8) ◽  
pp. 773-791 ◽  
Author(s):  
Gong W Qi ◽  
X Hong Zhang
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
High Mass ◽  
Flow Conditions ◽  
Asymmetric Component ◽  
Unsteady Loading ◽  
Vane Diffuser

A volute is the only circumferential asymmetric component in a centrifugal compressor, and thus, it should account for the circumferential asymmetry of the flow in a vane diffuser. This study performs a transient numerical analysis to investigate the effect of a volute on the flow in the vane diffuser of a centrifugal compressor under three operating conditions (near-stall, middle, and high mass flow). We compare numerical and experimental performance of the compressor, including polytropic efficiency, total pressure ratio, and unsteady pressure on a diffuser vane. The numerical scheme is proven valid owing to the fact that the numerical and experimental results considerably agree well with each other. Under middle and high mass flow conditions, the time-averaged static pressure recovery and the total pressure loss coefficients for all the diffuser passages indicate that the performance of the passages near and upstream of the volute tongue is affected negatively by the volute, whereas that of the passages downstream of the volute tongue is less affected. Under near-stall condition, the performance of all the passages is disturbed, and the diffuser passage marked as DP 3 demonstrates the worst performance. Investigation on the time-averaged aerodynamic forces, loading, and pressure on the vanes yields results that are consistent with those of the investigation on the performance of the passages. The harmonics with 0.5 fb and fb, which are included in the unsteady loading and pressure on the pressure and suction sides of the vanes, are dominant, where fb is the impeller main and splitter blades passing frequency. Their amplitude values increase as mass flow deviates from the middle mass flow condition. Under middle and high mass flow conditions, the harmonic with 0.5 fb is affected more negatively because of the larger amplitude on the vanes near and upstream of the volute tongue than those downstream, whereas the harmonic with fb is less affected by the volute. Under the near-stall condition, the transient vorticity fields along with the harmonics of 0.5 fb and fb are investigated to evaluate the performance of the diffuser passages. DP 3, which is located at approximately 90° downstream of the volute tongue, suffers the strongest flow deterioration and is inferred to stall first. Further researches for designing more matching diffuser/volute combination will be performed by referring this study.

Aeroelasticity at Reversed Flow Conditions: Part 3—Reduction of Surge Loads by Means of Intentional Mistuning

2012 ◽  
Author(s):  
Harald Schoenenborn ◽  
Mirja de Vries
Keyword(s):  
Pressure Ratio ◽  
Pressure Rise ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Reversed Flow ◽  
Blow Down ◽  
Flow Angle ◽  
Multi Stage ◽  
Compressor Surge ◽  
Very High

Compressor surge consists of four phases: (i) pressure rise, (ii) flow breakdown, (iii) blow-down and (iv) flow recovery. During the blow-down phase reversed flow conditions exist, where a blade may accumulate hundreds of vibration cycles, depending on the surge volume and the vibration frequency. High vibration amplitudes and blade damages were observed in the past. In part 1 (GT2011-45034) a compressor cascade was analyzed experimentally and analytically at steady reversed flow conditions. It has been shown that (i) the steady flow field can be predicted well by CFD analysis, (ii) the overall damping coefficient calculated by unsteady CFD compares reasonably well with measurements and (iii) a blade may become unstable at certain reversed flow conditions. In part 2 (GT2011-45035) the analytical procedures used in part 1 were applied to the front part of a multi-stage HPC for reversed flow conditions. It was found that surge loads consist in reality of two physically different phenomena: (i) the pressure wave during the flow breakdown leading to rather low blade stresses and (ii) flutter during the blow-down phase which may lead to very high blade stresses and damages during surge for some stages. As it is well known that intentional mistuning is a way to mitigate flutter, intentional mistuning is investigated in part 3 of the paper at reversed flow conditions. At first, a CFD study of a single airfoil is presented showing the dependency of aerodynamic damping upon flow angle and pressure ratio over the airfoil at reversed flow conditions, including intentional mistuning studies. Secondly, an investigation is presented which shows experimentally and analytically that surge stresses can be reduced significantly by the use of intentional mistuning. In a multi-stage compressor test rig, one rotor stage, which experienced very high stresses during surge, was subjected to a cutback on every second blade, leading to significantly reduced surge stresses. Analytically, an aeroelastic eigenvalue analysis showed the same behavior.

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