scholarly journals Influence of Forward Skew Blade Angle on Positive Slope Characteristics of Mixed Flow Pumps

2021 ◽  
Vol 1909 (1) ◽  
pp. 012076
Author(s):  
Akihiro Ikuta ◽  
Naruki Nitta ◽  
Kazuyoshi Miyagawa ◽  
Yasushi Shinozuka ◽  
Shigeyuki Tomimatsu
Keyword(s):  
Blade Angle ◽  
Positive Slope ◽  
Mixed Flow

scholarly journals Influence of forward rake and skew blade angle on positive slope characteristics of mixed flow pumps

2019 ◽  
Vol 240 ◽  
pp. 032045
Author(s):  
N Nitta ◽  
S Maeda ◽  
H Kanno ◽  
K Miyagawa ◽  
Y Shinozuka ◽  
...  
Keyword(s):  
Blade Angle ◽  
Positive Slope ◽  
Mixed Flow

scholarly journals Suppression of Mixed-Flow Pump Instability and Surge by the Active Alteration of Impeller Secondary Flows

1993 ◽  
Author(s):  
Akira Goto
Keyword(s):  
Flow Characteristic ◽  
Secondary Flows ◽  
Wake Flow ◽  
Streamwise Vorticity ◽  
Jet Injection ◽  
Positive Slope ◽  
Suction Surface ◽  
Mixed Flow ◽  
Pump System ◽  
Flow Pump

An active method for enhancing pump stability, featuring water jet injection at impeller inlet, was applied to a mixed-flow pump. The stall margin, between the design point and the positive slope region of the head-flow characteristic, was most effectively enlarged by injecting the jet in the counter-rotating direction of the impeller. The counter-rotating streamwise vorticity along the casing, generated by the velocity discontinuity due to the jet injection, altered the secondary flow pattern in the impeller by opposing the passage vortex and assisting the tip leakage vortex motion. The location of the wake flow was displaced away from the casing-suction surface corner of the impeller, thus avoiding the onset of the extensive corner separation, the cause of positive slope region of the head-flow characteristic. This method was also confirmed to be effective for stabilizing a pump system already in a state of surge.

Design and Performance Analysis of Mixed Flow Turbine Rotors With Extended Blade Chord

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Thomas Leonard ◽  
Stephen Spence ◽  
Dietmar Filsinger ◽  
Andre Starke
Keyword(s):  
Transient Response ◽  
Mechanical Performance ◽  
Cone Angle ◽  
Chord Length ◽  
Optimized Design ◽  
Blade Angle ◽  
Peak Efficiency ◽  
Mixed Flow ◽  
Blade Thickness ◽  
Turbine Rotors

Abstract Mixed flow turbines offer additional design freedom compared with conventional radial turbines. This is useful in the automotive turbocharger application to reduce rotor inertia, which can be very beneficial for the transient response of a highly boosted downsized passenger car powertrain. A previously published study from the authors analyzed a series of nine mixed flow turbine rotors with varying blade cone angle and inlet blade angle. This paper reports an extension of that study with two further mixed flow turbine rotors where the chord length of the rotor blade was extended. The aim of this work was to understand both the aerodynamic and mechanical impacts of varying the chord length, particularly for the turbocharger application where off-design performance and transient response are very important. The baseline mixed flow rotor for this study had a blade cone angle of 30 deg and an inlet blade angle of 30 deg. Two further variations were produced; one with the trailing edge (TE) extended in the downstream direction across the entire blade span. In the second variation, the chord was extended at the hub corner only, while the shroud corner of the TE remained unchanged, with the aim of achieving some aerodynamic improvement while meeting mechanical requirements. When the blade was extended at both the hub and shroud, the inertia and stress levels increased significantly and the blade eigenfrequencies reduced. There was a significant improvement in peak efficiency, but the mechanical performance was unfavourable. The improvement in peak efficiency was mainly due to better exhaust diffuser performance and, therefore, would not be realized in most turbocharger installations. The blade that was extended at only the hub corner incurred very little additional inertia, and the centrifugal stresses and blade eigenfrequencies were improved. Consequently, it was possible to reduce the blade thickness at the TE in order to achieve a more aerodynamically optimized design. In this case, the mechanical performance was acceptable and there were efficiency improvements of up to 1.1% points at off-design conditions, with no reduction in peak efficiency or maximum mass flowrate. Therefore, the blade that was extended only at the hub produced some improvement within acceptable mechanical limits. The flow field features were considered for the three rotor geometries to explain the changes in loss and efficiency across the operating range.

A Numerical Study of Inlet Geometry for a Low Inertia Mixed Flow Turbocharger Turbine

2014 ◽  
Author(s):  
Thomas M. Leonard ◽  
Stephen Spence ◽  
Juliana Early ◽  
Dietmar Filsinger
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Velocity Ratio ◽  
Cone Angle ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Transient Performance ◽  
Blade Angle ◽  
Low Velocity ◽  
Mixed Flow

Mixed flow turbines can offer improvements over typical radial turbines used in automotive turbochargers, with regards to transient performance and low velocity ratio efficiency. Turbine rotor mass dominates the rotating inertia of the turbocharger, and any reductions of mass in the outer radii of the wheel, including the rotor back-disk, can significantly reduce this inertia and improve the acceleration of the assembly. Off-design, low velocity ratio conditions are typified by highly tangential flow at the rotor inlet and a non-zero inlet blade angle is preferred for such operating conditions. This is achievable in a Mixed Flow Turbine without increasing bending stresses within the rotor blade, which is beneficial in high speed and high inlet temperature turbine design. A range of mixed flow turbine rotors was designed with varying cone angle and inlet blade angle and each was assessed at a number of operating points. These rotors were based on an existing radial flow turbine, and both the hub and shroud contours and exducer geometry were maintained. The inertia of each rotor was also considered. The results indicated that there was a trade-off between efficiency and inertia for the rotors and certain designs may be beneficial for the transient performance of downsized, turbocharged engines.

Multi-objective optimization for mixed-flow pump with blade angle of impeller exit and diffuser inlet

2017 ◽  
Vol 31 (11) ◽  
pp. 5099-5106 ◽  
Author(s):  
Sung Kim ◽  
Ung-Been Jeong ◽  
Kyoung-Yong Lee ◽  
Jin-Hyuk Kim ◽  
Joon-Yong Yoon ◽  
...  
Keyword(s):  
Multi Objective Optimization ◽  
Blade Angle ◽  
Mixed Flow ◽  
Multi Objective ◽  
Flow Pump

scholarly journals Detailed Flow Measurements at the Exit of a Mixed Flow Turbine Under Steady Flow Conditions

1999 ◽  
Author(s):  
N. Karamanis ◽  
R. F. Martinez-Botas ◽  
C. C. Su
Keyword(s):  
Laser Doppler Velocimetry ◽  
Incidence Angle ◽  
Performance Tests ◽  
Doppler Velocimetry ◽  
Flow Conditions ◽  
Blade Angle ◽  
Mixed Flow ◽  
Flow Measurements ◽  
Flow Investigation ◽  
Improved Performance

A detailed flow investigation downstream of two mixed-flow turbocharger turbines has been carried out at 50% and 70% design speeds, equivalent to 29,400 and 41,300 rpm respectively. The measurement technique used was laser Doppler velocimetry (LDV). The measurements were performed at a plane 9.5 mm behind the rotor trailing edge, they were resolved in a blade-to-blade sense to fully examine the nature of the flow. The results confirmed the performance tests and indicated the improved performance of the rotor with a constant inlet blade angle relative to the rotor with a nominally constant incidence angle.

Clarification of Performance Curve Instability Mechanism Using Large Eddy Simulation of Internal Flow of a Mixed-Flow Pump

2015 ◽  
Author(s):  
Isao Hagiya ◽  
Chisachi Kato ◽  
Yoshinobu Yamade ◽  
Takahide Nagahara ◽  
Masashi Fukaya
Keyword(s):  
Flow Rate ◽  
Leading Edge ◽  
Low Flow ◽  
Performance Curve ◽  
Instability Mechanism ◽  
Positive Slope ◽  
Mixed Flow ◽  
Flow Rates ◽  
Direction Opposite ◽  
Flow Pump

We analyzed the internal flows of a test mixed-flow pump exhibiting performance curve instability at low flow rates by using LES to clarify the performance curve instability mechanism. The LES was conducted using the open source software FrontFlow/blue [1]. In particular, we investigated in detail the flows at the flow rates, where the head curve had a positive slope under low flow rate condition. We clarified that Euler’s head drop caused by a stall near the tip of the rotor-blades is a dominant factor at the instability of the test pump. At the bottom point of the positive slope of the head curve, stall regions covered all the rotor-blade passages on the tip side. The drop of the angular momentum in the impeller caused by the stall on the leading edge side exceeds the increment caused by the decrease in the flow rate on the trailing edge at the bottom point of the positive slope. At the middle point of the positive slope of the head curve we also found regions with low-velocities in some blade passages. Such regions, namely stall cells, rotated around the impeller for one revolution while the impeller rotated almost about 20 revolutions in the direction opposite to the impeller’s rotation. The region with low-velocity first appears at the trailing edge and expands toward the leading edge. The angle of attack of the neighbouring blade in the direction opposite to the rotation of the blade increases and that blade pitch begins to stall. When that blade pitch is fully stalled, it is no longer loaded and the positive pressure gradient in that blade pitch decreases. The blade pitch is most likely to accept the excess flow. It recovers from the stalled state.

Design and Test for High Specific Speed Mixed Flow Pump with Volute

2011 ◽  
Vol 354-355 ◽  
pp. 669-673
Author(s):  
Xian Fang Wu ◽  
Hou Lin Liu ◽  
Ming Gao Tan ◽  
Hong Hui Li
Keyword(s):  
Cross Sections ◽  
Flow Analysis ◽  
Maximum Efficiency ◽  
Blade Angle ◽  
Mixed Flow ◽  
Commercial Code ◽  
Hydraulic Design ◽  
Velocity Circulation ◽  
Specific Speed ◽  
Flow Pump

The characteristics and research actuality on mixed flow pumps are introduced simplely. A mixed flow pump with volute as diffusion part is designed and its specific speed is 556.8. The axial velocity circulation and blade angle variety with linearity distribution are used to deisign the impeller. The fixed diffeuser between impeller and volute is deigned by arc airfoil.The cross sections of volute are all asymmetry. The commercial code FLUENT is applied to simulate the inner flow in the mixed flow pump and its energy characteristics are predicted according to the simulation results. The inner flow analysis indicates that the flow in the pump is good and the characteristic prediction shows that the pump performance can meet the design demand. The experiment test of the pump are done. When the blade angle is about 0°, the maximum efficiency of the pump is up to 85.76% and the actual efficiency at design point is about 3% higher than demand efficiency. The study fruits can instruct the hydraulic design of higher specific speed mixed flow pump with volute as diffusion part.

Design of a Highly Loaded Mixed Flow Turbine

1992 ◽  
Vol 206 (2) ◽  
pp. 95-107 ◽  
Author(s):  
M Abidat ◽  
N C Baines ◽  
M R Firth
Keyword(s):  
Expansion Ratio ◽  
Expansion Velocity ◽  
Blade Angle ◽  
Peak Efficiency ◽  
Suction Surface ◽  
Mixed Flow ◽  
Static Efficiency ◽  
Radial Turbine ◽  
C Value ◽  
Turbine Design

The high boost pressures and fuel–air ratios required for the next generation of turbocharged diesel engines imply an increased turbine expansion ratio without an increase in the speed of rotation. This leads to a requirement for high peak efficiency at lower values of blade speed/isentropic expansion velocity U/C than are normal today. The objective of this project was to achieve this with a mixed flow rotor with a positive inlet blade angle. Two rotors were manufactured and tested: one a ‘constant blade angle’ design and the other a ‘constant incidence’ design. In practice both achieved a peak efficiency at a low U/C value, but the constant blade angle design, at 0.84 total to static efficiency, was significantly more efficient than the constant incidence design at 0.77. These efficiencies are highly competitive, compared to current radial turbine design. It is suggested that the reasons for this difference are a lack of understanding of the incidence and its effects on a mixed flow rotor, and a region of diffusion in the shroud-trailing edge corner of the suction surface, apparently worse for the constant incidence design.

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