INVESTIGATION OF TORQUE GENERATION CAPABILITY OF MIXED FLOW TURBINE UNDER STEADY STATE CONDITIONS

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
M. A. S. Izaiddin ◽  
A. F. Mustaffa ◽  
M. H. Padzillah
Keyword(s):  
Mass Flow ◽  
Leading Edge ◽  
Maximum Efficiency ◽  
Blade Surface ◽  
Mixed Flow ◽  
Factors Affecting ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Torque Generation ◽  
Edge Surface

A mixed flow turbine is a type of turbine that is used mostly in turbocharger engine for vehicle. The ability of this turbine in obtain maximum efficiency on a wider operating range makes it more favorable compared to axial turbine and radial turbine. In this project, one of the factors affecting turbine performance which is torque has been studied using simulation. The simulation is then being run by varying the mass flow supply to the turbine. In this simulation, torque generation has been identified and plot on the entire blade surface. This torque generation capability is then been compared between 0.25 kg/s, 0.45 kg/s and 0.65 kg/s mass flow. From the simulation, the torque generated is founded to fluctuate along the turbine blade surface. Besides, the torque generated at the leading edge and trailing edge surface are negative. The magnitude of torque generated increases, as the mass flow increased. At the mid span of the blade, torque generated at 0.25 kg/s, 0.45 kg/s and 0.65 kg/s is -3.73 X 10-3Nm, 4.33 X 10-3Nm, and 11.8 X 10-3Nm respectively.

Numerical Simulation of Cavitating Flow in Mixed Flow Pump With Closed Type Impeller

2009 ◽  
Author(s):  
Katsutoshi Kobayashi ◽  
Yoshimasa Chiba
Keyword(s):  
Leading Edge ◽  
Suction Side ◽  
Experimental Results ◽  
Absolute Pressure ◽  
Pressure Side ◽  
Blade Surface ◽  
Mixed Flow ◽  
Closed Type ◽  
The Absolute ◽  
Flow Pump

LES (Large Eddy Simulation) with a cavitation model was performed to calculate an unsteady flow for a mixed flow pump with a closed type impeller. First, the comparison between the numerical and experimental results was done to evaluate a computational accuracy. Second, the torque acting on the blade was calculated by simulation to investigate how the cavitation caused the fluctuation of torque. The absolute pressure around the leading edge on the suction side of blade surface had positive impulsive peaks in both the numerical and experimental results. The simulation showed that those peaks were caused by the cavitaion which contracted and vanished around the leading edge. The absolute pressure was predicted by simulation with −10% error. The absolute pressure around the trailing edge on the suction side of blade surface had no impulsive peaks in both the numerical and experimental results, because the absolute pressure was 100 times higher than the saturated vapor pressure. The simulation results showed that the cavitation was generated around the throat, then contracted and finally vanished. The simulated pump had five throats and cavitation behaviors such as contraction and vanishing around five throats were different from each other. For instance, the cavitations around those five throats were not vanished at the same time. When the cavitation was contracted and finally vanished, the absolute pressure on the blade surface was increased. When the cavitation was contracted around the throat located on the pressure side of blade surface, the pressure became high on the pressure side of blade surface. It caused the 1.4 times higher impulsive peak in the torque than the averaged value. On the other hand, when the cavitation was contracted around the throat located on the suction side of blade surface, the pressure became high on the suction side of blade surface. It caused the 0.4 times lower impulsive peak in the torque than the averaged value. The cavitation around the throat caused the large fluctuation in torque acting on the blade.

The Effect of Leading Edge Curvature on a Mixed Flow Turbine Performance Under Pulsating Flow Conditions

2009 ◽  
Author(s):  
Li Chen ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Shuyong Zhang
Keyword(s):  
Incidence Angle ◽  
Leading Edge ◽  
Simulation Models ◽  
Pulsating Flow ◽  
Flow Conditions ◽  
Mixed Flow ◽  
Turbine Performance ◽  
Unsteady Simulation ◽  
Overall Performance ◽  
Inlet Angle

Turbines used in turbochargers matched to reciprocating engines are under natural pulsating flow conditions, and the turbine which has a good performance under steady design condition normally cannot get the same performance in the whole engine actual working circle. Under the pulsating conditions, the incidence angle will change tremendously, thus leads to undesirable flowfield in the turbine. It is shown in some published literature that varying turbine blade inlet angle can achieve better performance characteristics. In this paper, leading edge curvature is introduced to an original mixed flow turbine, while steady and unsteady simulation models of the mixed flow turbine are built to investigate the aerodynamic performance of the original and modified turbine. Flowfield analysis shows that the leading edge curvature can make the flow less sensitive to the incidence change, and average instantaneous efficiency under pulsating flow conditions is improved, while a better overall performance of the turbine is achieved.

Computations of Film Cooling for the Leading Edge Region of a Turbine Blade Model

1995 ◽  
Author(s):  
Pingfan He ◽  
Martha Salcudean ◽  
Ian S. Gartshore
Keyword(s):  
Turbine Blade ◽  
Mass Flow ◽  
Film Cooling ◽  
Leading Edge ◽  
Relative Mass ◽  
Computational Domain ◽  
Blade Surface ◽  
Stagnation Line ◽  
Curved Blade ◽  
Blade Model

Computations of film cooling are presented based on the geometry of a UBC experimental turbine blade model. This model has a semi-circlar leading edge with four rows of laterally-inclined film cooling orifices positioned symmetrically about the stagnation line. The computational domain follows the physical domain and includes the curved blade surface as well as the coolant regions in the circular coolant orifices. The injection orifices are inclined spanwise at 30° to the blade surface. A multi-zone curvilinear grid is used to simulate the complex configuration. Grids are generated by a block-structured elliptic grid generation method which represents exactly the curved blade surface as well as the circular injection orifices. Computations over the cooled turbine blade model are carried out for overall mass flow ratios of 0.52 and 0.97. The relative mass flow ratios from each orifice are specified to match experimental values. Density ratios of coolant to free stream were taken to be unity (constant density). Comparison of predicted film cooling effectiveness with experimental data showed reasonable agreement.

scholarly journals Analysis of the Impact of Leading Edge Surface Degradation on Wind Turbine Performance

2015 ◽  
Author(s):  
Christopher M. Langel ◽  
Raymond Chow ◽  
Owen F. Hurley ◽  
Case (CP) P. Van Dam ◽  
David C. Maniaci ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Leading Edge ◽  
Surface Degradation ◽  
Turbine Performance ◽  
Edge Surface ◽  
The Impact

scholarly journals Evaluating the Use of Leaned Stator Vanes to Produce a Non-Uniform Flow Distribution Across the Inlet Span of a Mixed Flow Turbine Rotor

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Richard Morrison ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Thomas Leonard ◽  
Andre Starke
Keyword(s):  
Leading Edge ◽  
Operating Conditions ◽  
Operating Point ◽  
Mixed Flow ◽  
Design Performance ◽  
Turbine Performance ◽  
Percentage Points ◽  
Wide Range ◽  
Turbine Rotors ◽  
Operating Points

Abstract Current trends in the automotive industry have placed an increased emphasis on downsized turbocharged engines for passenger vehicles. The turbocharger is increasingly relied upon to improve power output across a wide range of engine operating conditions, placing a greater emphasis on turbocharger off-design performance. An off-design condition of significant importance is performance at low turbine velocity ratios, since it is relevant to engine transient response and also to efficient energy extraction from pressure pulses in the unsteady exhaust flow. An increased focus has been placed on equipping turbochargers with mixed flow turbine rotors instead of conventional radial flow turbine rotors to improve off-design performance and to reduce rotor inertia. A recognized feature of a mixed flow turbine is the spanwise variation of flow conditions across the blade leading edge. This is a consequence of the reduction in leading edge radius from shroud to hub, coupled with the increasing tangential velocity of the flow due to conserved angular momentum as the radius decreases. The result is increasingly positive incidence toward the hub side of the leading edge. The resulting region of highly positive incidence at the hub produces separation from the suction surface and generates significant loss within the rotor passage. The aim of this study was to determine if the losses in a mixed flow turbine (MFT) could be reduced by the use of leaned stator vanes, which deliberately created a significant spanwise variation of flow angle between hub and shroud at rotor inlet, to reduce the positive incidence at the hub. The turbine performance with a series of leaned vanes was compared against that of a straight vane using a validated computational fluid dynamics (CFD) model. It was found that increasing vane lean improved turbine performance at all operating points considered. An increase of 3.2 percentage points in stage total-to-static efficiency was achieved at a key off-design operating point. Experimental testing of a set of leaned vanes and the baseline vanes confirmed the advantage of the leaned vanes at all operating points, with an increase in measured efficiency of 2.6 percentage points at the key off-design condition. Unsteady CFD models confirmed the same level of improvement at this operating point. The CFD and experimental results confirmed that the losses in an MFT can be reduced by the use of leaned stator vanes to shape the flow at rotor inlet.

Computer Simulation of Icing on NACA0015 Blade Airfoil for Vertical Axis Wind Turbine

2011 ◽  
Vol 84-85 ◽  
pp. 697-701
Author(s):  
Yan Li ◽  
Fang Feng ◽  
Sheng Mao Li ◽  
Wen Qiang Tian
Keyword(s):  
Wind Turbine ◽  
Cold Water ◽  
Leading Edge ◽  
Vertical Axis ◽  
Blade Surface ◽  
Vertical Axis Wind Turbine ◽  
Discrete Phase Model ◽  
Factors Affecting ◽  
Flow Discharge ◽  
Wind Speeds

In recent years, vertical axis wind turbine is widely used. However, when it is installed in cold regions icing and snow on blade surface will occur in winter. To simulate the situation of icing, computer simulations were carried out on a NACA0015 airfoil which is often used for vertical axis wind turbine. The computations were based on the N-S equation in 2D incompressible steady flow with using the DPM (Discrete Phase Model) to calculate icing. Under the different wind speeds and cold water discharges in cold air, the icing distributions on airfoil at 8 kinds of typical attack angles were calculated. The icing area on the leading edge and trailing edge of blade airfoil were also obtained. Based on these results, the factors affecting the icing on blade surface including wind speed, attack angle and cold water flow discharge were discussed. With the increasing of the flow discharge, the icing area ratio increases and ice accretions become more and more dense.

Numerical Computation of the Pulsatile Flow in a Turbocharger With Realistic Inflow Conditions From an Exhaust Manifold

2009 ◽  
Author(s):  
Fredrik Hellstrom ◽  
Laszlo Fuchs
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Mass Flow ◽  
Pulsatile Flow ◽  
Exhaust Manifold ◽  
Ic Engine ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Flow Components ◽  
Inflow Conditions

The combined effect of different secondary perturbations at the turbine inlet and the pulsatile flow on the turbine performance was assessed and quantified by using Large Eddy Simulation. The geometrical configuration consists of a 4-1 exhaust manifold and a radial turbine. At the inlet to each port of the manifold, engine realistic pulsatile mass flow and temperature fields are specified. The turbine used in this numerical study is a vaneless radial turbine with 9 blades, with a size that is typical for a turbocharger mounted on a 2.0 liters IC engine of passenger cars. The flow field is investigated and the generated vortices are visualized to enable a better insight into the unsteady flow field. Correlations between the turbine inflow conditions, such as mass flow rate, strength of secondary flow components, and the turbine performance have also been studied. The results show that the flow field entering the turbine is heavily disturbed with strong secondary flow components and disturbed axial velocity profile. Between the inlet to the turbine and the wheel, the strength of the secondary flow and the level of the disturbances of the axial flow decrease which gives large losses in this region. Even though the magnitude of the disturbances decrease, the flow entering the wheel will still be disturbed, resulting in a perturb inlet flow to the wheel which affects the shaft power output from the turbine.

Experiment Study of Simulated Effect of Rotor Stator Interaction: Effect of Axial Spacing and Rotor Blade Film Cooling Air Injection Ratio

2011 ◽  
Author(s):  
Murari Sridhar ◽  
B. V. S. S. S. Prasad ◽  
N. Sitaram
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Main Flow ◽  
Air Injection ◽  
Blade Surface ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

The effect of inlet wake and air injection on blade surface temperature distribution is experimentally determined in the present paper. A flat plate with smoothly curved leading edge and a symmetric beveled trailing edge is used to produce inlet wake. Experiments are performed on a seven-airfoil linear cascade in a low speed wind tunnel at the chord Reynolds number of 5.3×105. Three blades in the middle of the cascade are provided with multiple rows of air injection holes on both pressure surface and suction surface. The distance between the trailing edge of the wake plate and leading edge of the cascade blade is kept at three axial locations, i.e. 0.25, 0.35 and 0.5 (all measured in terms of percent blade chord), at seven transverse locations for each axial location. The detailed temperature distributions on the blade surface are measured using “T-Type” thermocouples connected to a data logger. The results are obtained in terms of film cooling effectiveness for a density ratio (between the hot fluid through air injection holes and cold main flow fluid) of 1.1 and injection mass flow rates of 1.1, 2.5, 3.0 and 5.0 percent of main flow. A significant change in the film cooling effectiveness is observed with increase in the injection mass flow rate and change in the axial spacing.

Mean Line Flow Model of Steady and Pulsating Flow of a Mixed-Flow Turbine Turbocharger

2010 ◽  
Author(s):  
Aman M. I. Bin Mamat ◽  
Ricardo F. Martinez-Botas
Keyword(s):  
Experimental Data ◽  
Steady Flow ◽  
Mass Flow ◽  
Flow Condition ◽  
Flow Parameter ◽  
Pulsating Flow ◽  
Mixed Flow ◽  
One Dimensional ◽  
Turbine Performance ◽  
Relative Standard

A one-dimensional investigation for a mixed-flow turbine turbocharger turbine is described in this paper. The main outcome of the research is to develop a validated procedure for turbine performance maps in both steady and pulsating flow. The approach is limited to a simple procedure that can be integrated in wave action codes and thus not requiring 2D or 3D calculations. The mass flow parameter map is used as an input for the investigation, thus requiring some knowledge of either from experiments or from mean line methods calculations. In this paper, the mass flow parameter is experimentally measured at the turbocharger facility in Imperial College. A realistic yet reduced-order model for turbine losses allows the prediction of the steady flow performance; the calibration of the model is performed at peak efficiency of the turbine for a given rotational speed. The loss model for steady flow is then extended for pulsating conditions and for presumed quasi-steady operation. Finally, the predicted turbine performance is compared with experimental data. The comparison between one-dimensional modeling and experimental data for steady flow condition has shown Relative Standard Deviation (RSD) range from 1.62% to 11.62%. Meanwhile, a good trend agreement has been achieved for pulsating flow condition.

scholarly journals Evaluating the Use of Leaned Stator Vanes to Produce a Non-Uniform Flow Distribution Across the Inlet Span of a Mixed Flow Turbine Rotor

2019 ◽  
Author(s):  
Richard Morrison ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Thomas Leonard ◽  
Andre Starke
Keyword(s):  
Leading Edge ◽  
Operating Conditions ◽  
Operating Point ◽  
Mixed Flow ◽  
Flow Angle ◽  
Turbine Performance ◽  
Percentage Points ◽  
Wide Range ◽  
Turbine Rotors ◽  
Operating Points

Abstract Current trends in the automotive industry have placed an increased emphasis on downsized turbocharged engines for passenger vehicles. The turbocharger is increasingly relied upon to improve power output across a wide range of engine operating conditions, placing a greater emphasis on turbocharger offdesign performance. An off-design condition of significant importance is performance at low turbine velocity ratios, since it is relevant to engine transient response and also to efficient energy extraction from pressure pulses in the unsteady exhaust flow. An increased focus has been placed on equipping turbochargers with mixed flow turbine rotors instead of conventional radial flow turbine rotors to improve off-design performance and to reduce rotor inertia. A recognized feature of a mixed flow turbine is the spanwise variation of flow conditions across the blade leading edge. This is a consequence of the reduction in leading edge radius from shroud to hub, coupled with the increasing tangential velocity of the flow due to conserved angular momentum as the radius decreases. The result is increasingly positive incidence towards the hub side of the leading edge. The resulting region of highly positive incidence at the hub produces separation from the suction surface and generates significant loss within the rotor passage. The aim of this study was to determine if the losses in a MFT could be reduced by the use of leaned stator vanes, which deliberately created a significant spanwise variation of flow angle between hub and shroud at rotor inlet, to reduce the positive incidence at the hub. The turbine performance with a series of leaned vanes was compared against that of a straight vane using a validated CFD model. It was found that increasing vane lean improved turbine performance at all operating points considered. An increase of 3.2 percentage points in stage total-to-static efficiency was achieved at a key off-design operating point. Experimental testing of a set of leaned vanes and the baseline vanes confirmed the advantage of the leaned vanes at all operating points, with an increase in measured efficiency of 2.6 percentage points at the key off-design condition. Unsteady CFD models confirmed the same level of improvement at this operating point. The CFD and experimental results confirmed that the losses in a MFT can be reduced by the use of leaned stator vanes to shape the flow at rotor inlet.

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