Aerodynamic interaction of turbines in a regulated two-stage turbocharging system

2021 ◽  
pp. 095440702110647
Author(s):  
Mingyang Yang ◽  
Lei Pan ◽  
Mengying Shu ◽  
Kangyao Deng ◽  
Zhanming Ding ◽  
...  
Keyword(s):  
Entropy Generation ◽  
Internal Combustion Engines ◽  
Swirling Flow ◽  
Flow Analysis ◽  
Low Pressure ◽  
Two Stage ◽  
Operational Conditions ◽  
Low Pressure Turbine ◽  
Bypass Valve ◽  
Turbocharging System

Two-stage turbocharging becomes prevailing in internal combustion engines due to its advantage of flexibility of boosting for the variation of operational conditions. Two turbochargers are closely coupled by engine manifolds in the system especially under the requirement of compactness. This paper studies the influence of the interaction of two turbines in a two-stage turbocharging system on the performance. Results show that the performance of low-pressure turbine is highly sensitive to the stage interaction. Specifically, compared with the cases without interaction, the efficiency of low-pressure turbine increases maximumly by 2.8% when the bypass valve is closed, but reduces drastically by 7.5% when the valve is open. Detailed flow analysis shows that the combined results of swirling flow from the high-pressure turbine and the Dean vortex caused by the manifold elbow result in the alleviation of entropy generation in the turbine rotor. However, when the bypass valve is open, interaction of the swirling flow with the injected bypass flow results in strong secondary flow in the volute and distorted inlet flow condition for the rotor, leading to the enhancement of entropy generation in low-pressure turbine. The study provides valuable insights into turbine performance in a two-stage turbocharging system, which can be used for the modeling and optimization of multi-stage turbocharging systems.

A Matching Method for Two-Stage Turbocharging System

2014 ◽  
Author(s):  
Yanbin Liu ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Shuyong Zhang ◽  
Junyue Zhang ◽  
...  
Keyword(s):  
Similarity Theory ◽  
Calculation Model ◽  
Two Stage ◽  
Ratio Distribution ◽  
Operational Conditions ◽  
Low Pressure Turbine ◽  
Flow Capacity ◽  
Characteristic Lines ◽  
Turbocharging System ◽  
Compressor Map

The turbine system of a two-stage turbocharger composed of high pressure turbine, low pressure turbine and by-pass valve decides distribution and utilization of exhaust gas energy and influence performance of two-stage turbocharger in whole operational conditions. Besides, characteristics of turbine is expressed by envelop line of characteristic lines in different speeds. So turbine can be conveniently selected compared with compressor with similarity theory. Therefore two-stage turbocharger matching begins from turbine system matching in the paper. In two-stage turbocharger, cooler efficiency, cooler loss and by-pass valve open besides turbochargers will influence turbocharging system performance and design of cooler and by-pass valve are important contents of turbocharging system matching. The paper matched inter cooler, by-pass valve open, compressors and turbines jointly. Calculation model for turbocharger matching was built, and turbine performance is get from reference turbine based on similarity theory; influence of compressor ratio distribution, cooler efficiency and pressure drop in cooler imposing on compressor work was analyzed; and influence of turbine flow capacity and by-pass valve imposing on output working in expanding process was studied; the method for matching of two-stage turbocharging system in whole operational condition is studied Matching analysis was made aiming at two-stage turbocharging system of a type of high power density diesel engine, and design for turbocharging system was finished. Matching result using the method is compared to matching result using traditional method. Analysis result proves that using the method matching points in different operational conditions are located in more reasonable zone of compressor MAP.

A Matching Method for Two-Stage Turbocharging System

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Liu Yanbin ◽  
Zhuge Weilin ◽  
Zhang Yangjun ◽  
Zhang Shuyong ◽  
Zhang Junyue ◽  
...  
Keyword(s):  
Similarity Theory ◽  
Calculation Model ◽  
Two Stage ◽  
Ratio Distribution ◽  
Operational Conditions ◽  
Low Pressure Turbine ◽  
Flow Capacity ◽  
Characteristic Lines ◽  
Turbocharging System ◽  
Compressor Map

The turbine system of a two-stage turbocharger composed of high pressure turbine (HT), low pressure turbine (LT), and by-pass valve decides distribution and utilization of exhaust gas energy and influence performance of two-stage turbocharger in whole operational conditions. Besides, characteristics of turbine is expressed by envelop line of characteristic lines in different speeds. So turbine can be conveniently selected compared with compressor with similarity theory. Therefore, two-stage turbocharger matching begins from turbine system matching in the paper. In two-stage turbocharger, cooler efficiency, cooler loss, and by-pass valve open besides turbochargers will influence turbocharging system performance and design of cooler and by-pass valve are important contents of turbocharging system matching. The paper matched intercooler, by-pass valve open, compressors, and turbines jointly. Calculation model for turbocharger matching was built, and turbine performance is get from reference turbine based on similarity theory; influence of compressor ratio distribution, cooler efficiency, and pressure drop in cooler imposing on compressor work was analyzed; and influence of turbine flow capacity and by-pass valve imposing on output working in expanding process was studied; the method for matching of two-stage turbocharging system in whole operational condition is studied. Matching analysis was made aiming at two-stage turbocharging system of a type of high power density diesel engine, and design for turbocharging system was finished. Matching result using the method is compared to matching result using traditional method. Analysis result proves that using the method matching points in different operational conditions are located in more reasonable zone of compressor MAP.

Application of a miniaturized solid state electrolyte sensor for tracer gas measurements in a two-stage low pressure turbine

2017 ◽  
Vol 82 ◽  
pp. 367-374 ◽  
Author(s):  
Marcel Günter ◽  
Frank Hammer ◽  
Christian Koch ◽  
Klaus Kuhn ◽  
Martin G. Rose ◽  
...  
Keyword(s):  
Solid State ◽  
Low Pressure ◽  
Tracer Gas ◽  
Two Stage ◽  
Solid State Electrolyte ◽  
Low Pressure Turbine ◽  
Gas Measurements

scholarly journals Research on the Power Recovery of Diesel Engines with Regulated Two-Stage Turbocharging System at Different Altitudes

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Hualei Li ◽  
Lei Shi ◽  
Kangyao Deng
Keyword(s):  
Diesel Engines ◽  
Control Strategies ◽  
Pressure Recovery ◽  
Boost Pressure ◽  
Two Stage ◽  
Bypass Valve ◽  
Turbocharging System ◽  
Power Recovery ◽  
Valve Control ◽  
Different Altitudes

Recovering the boost pressure is very important in improving the dynamic performance of diesel engines at high altitudes. A regulated two-stage turbocharging system is an adequate solution for power recovery of diesel engines. In the present study, the change of boost pressure and engine power at different altitudes was investigated, and a regulated two-stage turbocharging system was constructed with an original turbocharger and a matched low pressure turbocharger. The valve control strategies for boost pressure recovery, which formed the basis of the power recovery method, are presented here. The simulation results showed that this system was effective in recovering the boost pressure at different speeds and various altitudes. The turbine bypass valve and compressor bypass valve had different modes to adapt to changes in operating conditions. The boost pressure recovery could not ensure power recovery over the entire operating range of the diesel engine, because of variation in overall turbocharger efficiency. The fuel-injection compensation method along with the valve control strategies for boost pressure recovery was able to reach the power recovery target.

Clocking in Low-Pressure Turbines

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Kathryn R. Evans ◽  
John P. Longley
Keyword(s):  
Leading Edge ◽  
Low Pressure ◽  
Two Stage ◽  
Low Speed ◽  
Low Pressure Turbine ◽  
Lost Work ◽  
Blade Row ◽  
Stage 1

The effect of stator clocking has been experimentally and computationally investigated using a low-speed, two-stage, low-pressure turbine (LPT) which was specifically designed to maximize the clocking potential by aligning the stator 1 wake segments with the stator 2 leading edge along the span. It was verified that the wake segments are aligned to within 10% of stator pitch across the span. The measured clocking effect on the work extraction is 0.12% and on efficiency is 0.08%. Although the effect of clocking is small, it is repeatable, periodic across four stator pitches and consistent between independent measurements. Furthermore, factors to consider for a reliable clocking investigation are discussed. The measurements revealed that the majority of the clocking effect on the work extraction occurs in stage 2 and it originates at stator 2 exit. This indicates that the flow is being processed differently within stator 2. There is also an effect on the stage 1 work. In each blade row, the measured clocking effect on the lost work is similar across the span. The computations with meshed cavities do not capture any clocking effects in stage 1. This indicates that an unsteady viscid phenomenon within rotor 1 is not captured by the fully turbulent calculation, e.g., unsteady transition. However, the computations do capture the measured clocking effect on the stage 2 work extraction. It is hypothesized that the clocking effect on stator 2 flow turning is dominated by a steady, inviscid process.

scholarly journals Transient Simulation of the Six-Inlet, Two-Stage Radial Turbine under Pulse-Flow Conditions

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2043
Author(s):  
Dariusz Kozak ◽  
Paweł Mazuro
Keyword(s):  
Internal Combustion Engines ◽  
Three Dimensional ◽  
Green Energy ◽  
Pollutant Emission ◽  
Flow Conditions ◽  
Two Stage ◽  
Pulse Flow ◽  
Emission Reductions ◽  
Exhaust Gases ◽  
Turbocharging System

In recent years, the automotive sector has been focused on emission reductions using hybrid and electric vehicles. This was mainly caused by political trends promoting “green energy”. However, that does not mean that internal combustion engines (ICEs) should be forgotten. The ICE has still the potential of recovering energy from exhaust gases. One of the promising ways to recover energy is turbocharging. Over the years engine manufacturers have designed very efficient turbocharger systems which have greatly increased the overall engine efficiency. This led to pollutant emission reductions. This paper presents the results of the three-dimensional (3-D) numerical simulations of the two-stage, six-inlet turbocharging system under the influence of unsteady, pulsed-flow conditions. The calculations were carried out for three turbine speeds. The most interesting results of this study were the separation of exhaust gases coming from the six-exhaust pipes and the performance of both stages under pulse-flow conditions. The two-stage turbocharging system was compared against the single-stage turbocharging system and the results showed that the newly designed two-stage turbine system properly separated the exhaust gases of the adjacent exhaust pipes.

Clocking in Low-Pressure Turbines

2016 ◽  
Author(s):  
K. R. Evans ◽  
J. P. Longley
Keyword(s):  
Leading Edge ◽  
Low Pressure ◽  
Two Stage ◽  
Low Speed ◽  
Low Pressure Turbine ◽  
Lost Work ◽  
Blade Row ◽  
Stage 1

The effect of stator clocking has been experimentally and computationally investigated using a low-speed, two-stage, Low-Pressure Turbine which was specifically designed to maximise the clocking potential by aligning the Stator 1 wake segments with the Stator 2 leading edge along the span. It was verified that the wake segments are aligned to within 10% of stator pitch across the span. The measured clocking effect on the work extraction is 0.12% and on efficiency is 0.08%. Although the effect of clocking is small, it is repeatable, periodic across four stator pitches and consistent between independent measurements. Furthermore, factors to consider for a reliable clocking investigation are discussed. The measurements revealed that the majority of the clocking effect on the work extraction occurs in Stage 2 and it originates at Stator 2 exit. This indicates that the flow is being processed differently within Stator 2. There is also an effect on the Stage 1 work. In each blade row the measured clocking effect on the lost work is similar across the span. The computations with meshed cavities do not capture any clocking effects in Stage 1. This indicates that an unsteady viscid phenomenon within Rotor 1 is not captured by the fully turbulent calculation e.g. unsteady transition. However, the computations do capture the measured clocking effect on the Stage 2 work extraction. It is hypothesised that the clocking effect on Stator 2 flow turning is dominated by a steady, inviscid process.

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