A novel pulse-adaption flow control method for a turbocharger turbine: Elastically restrained guide vane

2020 ◽  
Vol 234 (13) ◽  
pp. 2581-2594
Author(s):  
Zhihui Wang ◽  
Chaochen Ma ◽  
Hang Zhang ◽  
Fei Zhu
Keyword(s):  
Control Method ◽  
Combustion Engine ◽  
Aerodynamic Force ◽  
Guide Vane ◽  
Regulation Mechanism ◽  
Variable Geometry ◽  
Flow Angle ◽  
Variable Geometry Turbocharger ◽  
Turbine Inlet ◽  
Elastically Restrained

A turbocharger is a key enabler for energy conservation in an internal combustion engine. The turbine in a turbocharger is fed by highly pulsating gas flow due to the reciprocating engine, resulting in significant deterioration of the turbocharger performance. To solve this problem, a novel pulse-optimized regulation mechanism named ‘elastically restrained guide vane’ for a novel variable geometry turbocharger is proposed in this paper. The new mechanism regulates the instantaneous flow angle at turbine inlet due to guide vane's self-adaptive rotation under interactions of the elastic force by elastically restrained guide vane and the aerodynamic force from flowing gas, which is different from the traditional variable geometry turbocharger that is achieved by an active control system (e.g. actuator). To investigate the effectiveness of the novel method, a double-passage computational fluid dynamics model is built in ANSYS CFX software combined with a fluid-structure interaction method. The results demonstrate that the pulse-adaptive regulation method can effectively adjust the nozzle opening according to the different pulsating pressures at turbine inlet. Subsequently, based on the calibrated models, the numerical simulation concentrates on the potential gain in turbine eventual power output and the exhaust energy recover as well as the corresponding effects on efficiency as a result of operating the turbocharger in its elastically restrained guide vane mode compared to its operation as a conventional variable geometry turbocharger.

A novel variable geometry turbine achieved by elastically restrained nozzle guide vanes

2020 ◽  
Vol 234 (9) ◽  
pp. 2312-2329
Author(s):  
Zhihui Wang ◽  
Chaochen Ma ◽  
Zhi Huang ◽  
Liyong Huang ◽  
Xiang Liu ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Engine Speed ◽  
Guide Vane ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Variable Geometry ◽  
Brake Specific Fuel Consumption ◽  
The Novel ◽  
Variable Geometry Turbocharger ◽  
Elastically Restrained

Variable geometry turbocharging is one of the most significant matching methods between turbocharger and engine, and has been proven to provide air boost for entire engine speed range as well as to reduce turbo-lag. An elastically constrained device designed for a novel variable geometry turbocharger was presented in this paper. The design of the device is based on the nozzle vane’s self-adaptation under interactions of the elastic force by elastically restrained guide vane and the aerodynamic force from flowing gas. The vane rotation mechanism of the novel variable geometry turbocharger is different from regular commercial variable geometry turbocharger systems, which is achieved by an active control system (e.g. actuator). To predict the aerodynamic performance of the novel variable geometry turbocharger, the flow field of the turbine was simulated using transient computational fluid dynamics software combined with a fluid–structure interaction method. The results show that the function of elastically constrained device has similar effectiveness as the traditional variable geometry turbocharger. In addition, the efficiency of the novel variable geometry turbocharger is improved at most operating conditions. Furthermore, a turbocharged diesel engine was created using the AVL BOOST software to evaluate the benefits of the new variable geometry turbocharger. The proposed novel variable geometry turbocharger can effectively improve the engine performance at mid-high speeds, such that the maximum decrease of brake-specific fuel consumption reaches 17.91% under 100% load and 3600 r/min engine condition. However, the engine power and brake-specific fuel consumption decrease significantly at low engine speed conditions, and the decrease is more than 26% under 1000 r/min.

A Numerical Investigation on a New Pulse-Optimized Flow Control Method for Turbocharger Turbine Performance Improvement Under Pulsating Conditions

2015 ◽  
Author(s):  
K. Cao ◽  
M. Yang ◽  
R. F. Martinez-Botas
Keyword(s):  
Flow Control ◽  
Performance Improvement ◽  
Control Method ◽  
Combustion Engine ◽  
Flow Angle ◽  
Model Calculations ◽  
Reciprocating Engine ◽  
Turbine Performance ◽  
Low Mass ◽  
Stage Efficiency

A turbocharger turbine in an internal combustion engine is fed with continuously pulsating flow due to nature of the exhaust flow of a reciprocating engine. It is generally acknowledged that the performance of the turbine deteriorates due to this pulsation. In order to address the problem, a novel pulse-optimized flow control method is introduced in this paper, which involves a specially-designed nozzle ring upstream of the radial or mixed flow turbine. Unlike a traditional turbocharger, in which the nozzle ring is stationary, the nozzle ring is rotating. The inception of this new flow control method is based on the fact that the variable magnitude of the unsteady exhaust flow can be converted into the variation of the flow angle by means of the rotating nozzle ring. The new method is then validated by a steady-state, single passage numerical model. Calculations with different nozzle rotating speeds under both high and low mass flow rate conditions were executed and the results demonstrated significant improvements in both stage efficiency and power output. The results predicted that the new pulse-optimized flow control method was able to enhance the turbocharger performance to a great extent by means of addressing the potential energy within the highly dynamic exhaust flows.

Some Aspects of Wake-Wake Interactions Regarding Turbine Stator Clocking

2000 ◽  
Vol 123 (3) ◽  
pp. 526-533 ◽  
Author(s):  
Maik Tiedemann ◽  
Friedrich Kost
Keyword(s):  
Total Pressure ◽  
Guide Vane ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Turbine Stage ◽  
Flow Angle ◽  
Wake Interactions ◽  
Turbulence Data ◽  
Number Flow ◽  
Nozzle Guide

This investigation is aimed at an experimental determination of the unsteady flowfield downstream of a transonic high pressure turbine stage. The single stage measurements, which were part of a joined European project, were conducted in the windtunnel for rotating cascades of the DLR Go¨ttingen. Laser-2-focus (L2F) measurements were carried out in order to determine the Mach number, flow angle, and turbulence distributions. Furthermore, a fast response pitot probe was utilized to determine the total pressure distribution. The measurement position for both systems was 0.5 axial rotor chord downstream of the rotor trailing edge at midspan. While the measurement position remained fixed, the nozzle guide vane (NGV) was “clocked” to 12 positions covering one NGV pitch. The periodic fluctuations of the total pressure downstream of the turbine stage indicate that the NGV wake damps the total pressure fluctuations caused by the rotor wakes. Furthermore, the random fluctuations are significantly lower in the NGV wake affected region. Similar conclusions were drawn from the L2F turbulence data. Since the location of the interaction between NGV wake and rotor wake is determined by the NGV position, the described effects are potential causes for the benefits of “stator clocking” which have been observed by many researchers.

Experimental Studies of Leading Edge Contouring Influence on Secondary Losses in Transonic Turbines

2012 ◽  
Author(s):  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten Fransson ◽  
Boris I. Mamaev ◽  
Mats Annerfeldt
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Noticeable Effect ◽  
Flow Angle ◽  
Wide Range ◽  
Contour Plots

An experimental study of the hub leading edge contouring using fillets is performed in an annular sector cascade to observe the influence of secondary flows and aerodynamic losses. The investigated vane is a three dimensional gas turbine guide vane (geometrically similar) with a mid-span aspect ratio of 0.46. The measurements are carried out on the leading edge fillet and baseline cases using pneumatic probes. Significant precautions have been taken to increase the accuracy of the measurements. The investigations are performed for a wide range of operating exit Mach numbers from 0.5 to 0.9 at a design inlet flow angle of 90°. Data presented include the loading, fields of total pressures, exit flow angles, radial flow angles, as well as profile and secondary losses. The vane has a small profile loss of approximately 2.5% and secondary loss of about 1.1%. Contour plots of vorticity distributions and velocity vectors indicate there is a small influence of the vortex-structure in endwall regions when the leading edge fillet is used. Compared to the baseline case the loss for the filleted case is lower up to 13% of span and higher from 13% to 20% of the span for a reference condition with Mach no. of 0.9. For the filleted case, there is a small increase of turning up to 15% of the span and then a small decrease up to 35% of the span. Hence, there are no significant influences on the losses and turning for the filleted case. Results lead to the conclusion that one cannot expect a noticeable effect of leading edge contouring on the aerodynamic efficiency for the investigated 1st stage vane of a modern gas turbine.

Nonlinear DOB-based explicit NMPC for station-keeping of a multi-vectored propeller airship with thrust saturation

2018 ◽  
Vol 122 (1257) ◽  
pp. 1753-1774 ◽  
Author(s):  
Y. Wen ◽  
L. Chen ◽  
Y. Wang ◽  
D. Sun ◽  
D. Duan ◽  
...  
Keyword(s):  
Control Method ◽  
Aerodynamic Force ◽  
Wind Effect ◽  
Station Keeping ◽  
Globally Asymptotically Stable ◽  
Tracking Differentiator ◽  
Propulsion Force ◽  
Predictive Controller ◽  
Dynamics Models ◽  
The Relationship

ABSTRACTA nonlinear station-keeping control method for a multi-vectored propeller airship under unknown wind field with thrust saturation is developed, which is composed of three modules: nonlinear model predictive controller (NMPC), disturbance observer (DOB) and tracking differentiator (TD). The nonlinear kinematics and dynamics models are introduced, and the wind effect is considered by the wind-induced aerodynamic force. Based on both models, an explicit NMPC is designed. Then a nonlinear DOB is introduced to estimate the wind disturbance. A TD, showing the relationship between the maximum propulsion force and the maximum flight acceleration, is proposed to handle the thrusts’ amplitude saturation. Stability analysis shows that the closed-loop system is globally asymptotically stable. Simulations for a multi-vectored propeller airship are conducted to demonstrate the robustness and effectiveness of the proposed method.

Performance Study of a 1 MW Gas Turbine Using Variable Geometry Compressor and Turbine Blade Cooling

2010 ◽  
Author(s):  
Cleverson Bringhenti ◽  
Jesuino Takachi Tomita ◽  
Joa˜o Roberto Barbosa
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Turbine Blades ◽  
Axial Flow ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Variable Geometry ◽  
Performance Study ◽  
Turbine Blade Cooling ◽  
Blade Cooling

This work presents the performance study of a 1 MW gas turbine including the effects of blade cooling and compressor variable geometry. The axial flow compressor, with Variable Inlet Guide Vane (VIGV), was designed for this application and its performance maps synthesized using own high technological contents computer programs. The performance study was performed using a specially developed computer program, which is able to numerically simulate gas turbine engines performance with high confidence, in all possible operating conditions. The effects of turbine blades cooling were calculated for different turbine inlet temperatures (TIT) and the influence of the amount of compressor-bled cooling air was studied, aiming at efficiency maximization, for a specified blade life and cooling technology. Details of compressor maps generation, cycle analysis and blade cooling are discussed.

A methodology for loss and performance assessment of a variable geometry turbocharger turbine through a new meanline FORTRAN program

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahmed Ketata ◽  
Zied Driss
Keyword(s):  
Rotational Speed ◽  
Internal Combustion Engines ◽  
Maximum Efficiency ◽  
Variable Geometry ◽  
Mixed Flow ◽  
Content Type ◽  
Variable Geometry Turbocharger ◽  
Nozzle Vane ◽  
Wide Range ◽  
Vane Angle

PurposeVariable geometry turbine (VGT), a key component of modern internal combustion engines (ICE) turbochargers, is increasingly used for better efficiency and reduced exhaust gas emissions. The aim of this study is the development of a new meanline FORTRAN code for accurate performance and loss assessment of VGTs under a wider operating range. This code is a useful alternative tool for engineers for fast design of VGT systems where higher efficiency and minimum loss are being required.Design/methodology/approachThe proposed meanline code was applied to a variable geometry mixed flow turbine at different nozzle vane angles and under a wide range of rotational speed and the expansion ratio. The numerical methodology was validated through a comparison of the predicted performance to test data. The maps of the mass flow rate as well as the efficiency of the VGT system are discussed for different nozzle vane angles under a wide range of rotational speed. Based on the developed model, a breakdown loss analysis was carried out showing a significant effect of the nozzle vane angle on the loss distribution.FindingsResults indicated that the nozzle angle of 70° has led to the maximum efficiency compared to the other investigated nozzle vane angles ranging from 30° up to 80°. The results showed that the passage loss was significantly reduced as the nozzle vane angle increases from 30° up to 70°.Originality/valueThis paper outlines a new meanline approach for variable geometry turbocharger turbines. The developed code presents the novelty of including the effect of the vane radii variation, due to the pivoting mechanism of the nozzle ring. The developed code can be generalized to either radial or mixed flow turbines with or without a VGT system.

Behavior of a Variable Geometry Turbine Wheel to High Cycle Fatigue

2020 ◽  
Author(s):  
Calogero Avola ◽  
Alberto Racca ◽  
Angelo Montanino ◽  
Carnell E. Williams ◽  
Alfonso Renella ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Combustion Engine ◽  
Turbine Blades ◽  
Variable Geometry ◽  
Cycle Fatigue ◽  
Turbine Stage ◽  
Turbine Wheel ◽  
Variable Geometry Turbine ◽  
Turbine Design ◽  
Mechanical Optimization

Abstract Maximization of the turbocharger efficiency is fundamental to the reduction of the internal combustion engine back-pressure. Specifically, in turbochargers with a variable geometry turbine (VGT), energy losses can be induced by the aerodynamic profile of both the nozzle vanes and the turbine blades. Although appropriate considerations on material limits and structural performance of the turbine wheel are monitored in the design and aero-mechanical optimization phases, in these stages, fatigue phenomena might be ignored. Fatigue occurrence in VGT wheels can be categorized into low and high cycle behaviors. The former would be induced by the change in turbine rotational speed in time, while the latter would be caused by the interaction between the aerodynamic excitation and blades resonating modes. In this paper, an optimized turbine stage, including unique nozzle vanes design and turbine blades profile, has been assessed for high cycle fatigue (HCF) behavior. To estimate the robustness of the turbine wheel under several powertrain operations, a procedure to evaluate HCF behavior has been developed. Specifically, the HCF procedure tries to identify the possible resonances between the turbine blades frequency of vibrations and the excitation order induced by the number of variable vanes. Moreover, the method evaluates the turbine design robustness by checking the stress levels in the component against the limits imposed by the Goodman law of the material selected for the turbine wheel. In conclusion, both the VGT design and the HCF approach are experimentally assessed.

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