An Investigation Into the Effect of Clearance Aspect Ratio on the Performance of a Variable Geometry Vaned Diffuser for Automotive Turbocharger Application

2021 ◽  
Author(s):  
Lee Gibson ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Charles Stuart ◽  
Martin Schwitzke ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Variable Geometry ◽  
Vaned Diffuser

An Investigation Into the Effect of Clearance Aspect Ratio on the Performance of a Variable Geometry Vaned Diffuser for Automotive Turbocharger Application

2020 ◽  
Author(s):  
Lee Gibson ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Charles Stuart ◽  
Martin Schwitzke ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Width Ratio ◽  
Boost Pressure ◽  
Variable Geometry ◽  
Peak Efficiency ◽  
Vaned Diffuser ◽  
Vortical Structures ◽  
Compressor Performance ◽  
Compressor Map ◽  
Compressor Efficiency

Abstract The current state-of-the-art in radial compressor design for automotive turbocharger applications utilize impellers with a high trailing edge backsweep angle and a vaneless diffuser to provide a high boost pressure over a wide operating range. A unique feature of this type of design is that the peak efficiency island is typically located near the choke side of the compressor map. As such, the compressor efficiency is generally satisfactory when the engine is operating at high speed, such as the rated power condition. However, at low speeds the engine operating line is located close to the compressor surge line where the efficiency is generally modest. Thus, there is a need to improve the compressor efficiency at low engine speeds without compromising performance near the choke side of the map or the overall map width. Variable geometry devices have shown good potential to improve the compressor performance without a compromise in map width. In general, variability is achieved by moving walls or rotating vanes to best suit the flow conditions for a given mass flow rate. In order for this to be practically realised, a clearance or gap is required between the stationary and moving parts. This ultimately gives rise to leakage flows within the compressor stage and generally results in a lower achievable efficiency relative to the fixed geometry configuration. A study by the authors on an on/off type variable geometry vaned diffuser identified significant loss mechanisms due to the clearances required for the vanes to slide in to and out of the main flow path. Moreover, the endwall position of the clearance was found to have a marked impact on the compressor stability and peak efficiency. This paper assesses the effect of the clearance depth to width ratio (or aspect ratio) at different endwall positions with the aim of identifying an appropriate geometry and position to approach an optimised design. Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations were performed using ANSYS CFX at three operating speeds to obtain a broad sense of the effect of the clearance aspect ratio on the compressor performance. It was found that a high value of aspect ratio enabled the formation of large vortical structures in the vaned diffuser. The mixing between the core flow and the vortical structures resulted in significant losses in the vaned diffuser and affected the compressor map width differently depending on the endwall position.

Variable Geometry Gas Turbine Radial Compressors

1968 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Performance Testing ◽  
Single Stage ◽  
Variable Geometry ◽  
Pressure Regulation ◽  
Vaned Diffuser ◽  
Radial Compressor ◽  
Flow Variation

An examination of the various mechanical and aerodynamic methods of flow and pressure regulation through high-speed, single-stage radial compressors is presented. Performance testing of a small gas turbine radial compressor with a variable vaned diffuser system is described. Methods of combined geometry variation to obtain minimum reduction of efficiency with flow variation are suggested based upon theoretical matching studies.

Variable Geometry Compressors for Heavy Duty Truck Engine Turbochargers

2017 ◽  
Author(s):  
Michael Wöhr ◽  
Markus Müller ◽  
Johannes Leweux
Keyword(s):  
Fuel Economy ◽  
Performance Criteria ◽  
Parameter Study ◽  
Variable Geometry ◽  
Heavy Duty ◽  
Vaned Diffuser ◽  
Driving Range ◽  
Development Approach ◽  
The Cost ◽  
Compressor Efficiency

This paper presents the development approach, design and evaluation of three turbocharger compressors with variable geometry for heavy duty engines. The main goal is the improvement of fuel economy without sacrifices regarding any other performance criteria. In a first step, a vaned diffuser parameter study shows that efficiency improvements in the relevant operating areas are possible at the cost of reduced map width. Concluding from the results three variable geometries with varying complexity based on vaned diffusers are designed. Results from the hot gas test stand and engine test rig show that all systems are capable of increasing compressor efficiency and thus improving fuel economy in the main driving range of heavy duty engines. The most significant differences can be seen regarding the engine brake performance. Only one system meets all engine demands while improving fuel economy.

Variable Geometry Compressors for Heavy Duty Truck Engine Turbochargers

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Michael Wöhr ◽  
Markus Müller ◽  
Johannes Leweux
Keyword(s):  
Fuel Economy ◽  
Performance Criteria ◽  
Parameter Study ◽  
Variable Geometry ◽  
Heavy Duty ◽  
Vaned Diffuser ◽  
Driving Range ◽  
Development Approach ◽  
The Cost ◽  
Compressor Efficiency

This paper presents the development approach, design, and evaluation of three turbocharger compressors with variable geometry for heavy duty engines. The main goal is the improvement of fuel economy without sacrifices regarding any other performance criteria. In a first step, a vaned diffuser parameter study shows that efficiency improvements in the relevant operating areas are possible at the cost of reduced map width. Concluding from the results, three variable geometries with varying complexity based on vaned diffusers are designed. Results from the hot gas test stand and engine test rig show that all systems are capable of increasing compressor efficiency and thus improving fuel economy in the main driving range of heavy duty engines. The most significant differences can be seen regarding the engine brake performance. Only one system meets all engine demands while improving fuel economy.

Modification of MnS inclusion by tellurium in 38MnVS6 micro-alloyed steel

2020 ◽  
Vol 117 (6) ◽  
pp. 615
Author(s):  
Ping Shen ◽  
Lei Zhou ◽  
Qiankun Yang ◽  
Zhiqi Zeng ◽  
Kenan Ai ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Aspect Ratio ◽  
Strong Influence ◽  
Experimental Results ◽  
Alloyed Steel ◽  
Equivalent Diameter ◽  
Small Aspect Ratio ◽  
Steel Quality ◽  
Eds Analysis ◽  
Micro Alloyed Steel

In 38MnVS6 steel, the morphology of sulfide inclusion has a strong influence on the fatigue life and machinability of the steel. In most cases, the MnS inclusions show strip morphology after rolling, which significantly affects the steel quality. Usually, the MnS inclusion with a spherical morphology is the best morphology for the steel quality. In the present work, tellurium was applied to 38MnVS6 micro-alloyed steel to control the MnS inclusion. Trace tellurium was added into 38MnVS6 steel and the effect of Te on the morphology, composition, size and distribution of MnS inclusions were investigated. Experimental results show that with the increase of Te content, the equivalent diameter and the aspect ratio of inclusion decrease strikingly, and the number of inclusions with small aspect ratio increases. The inclusions are dissociated and spherized. The SEM-EDS analysis indicates that the trace Te mainly dissolves in MnS inclusion. Once the MnS is saturated with Te, MnTe starts to generate and wraps MnS. The critical Te/S value for the formation of MnTe in the 38MnV6 steel is determined to be approximately 0.075. With the increase of Te/S ratio, the aspect ratio of MnS inclusion decreases and gradually reaches a constant level. The Te/S value in the 38MnVS6 steel corresponding to the change of aspect ratio from decreasing to constant ranges from 0.096 to 0.255. This is most likely to be caused by the saturation of Te in the MnS inclusion. After adding Te in the steel, rod-like MnS inclusion is modified to small inclusion and the smaller the MnS inclusion, the lower the aspect ratio.

PENINGKATAN KEMAMPUAN GURU BAHASA INDONESIA DALAM MENYUSUN RENCANA PROGRAM PEMBELAJARAN (RPP) SDN 015 PAGARAN TAPAH DARUSSALAM MELALUI METODE PEMBERIAN TUGAS

2017 ◽  
Vol 5 (3) ◽  
pp. 713
Author(s):  
Mukhlis '
Keyword(s):  
Aspect Ratio ◽  
Duty Cycle ◽  
Lesson Plans ◽  
Learning Program ◽  
School Subjects ◽  
Bahasa Indonesia

Based on the observation of some teachers found the symptoms as follows: the lack of abilityof Indonesian teachers in designing learning program (RPP), the learning device is only usedas a supplement and not to the needs of teaching, most teachers again if asked the lessonanswered not have or has not been made. The purpose of this research is to improve theability of Indonesian teachers in designing learning program (RPP) at SDN 015 PagaranTapah Darussalam through the method of administration tasks. This type of research is actionresearch school. Subjects in this study were teachers Indonesian as many as 12 people. Basedon the analysis and discussion can be concluded that the method of administration tasks canimprove the ability of Indonesian teachers in making learning device in SDN 015 PagaranTapah Darussalam through the method of administration tasks. Under these conditions, thelevel of acceptance of teachers increased. The aspect ratio capability Indonesian teachers inpreparing lesson plans through the provision of duty cycle I and II of the increase from 56%and the second cycle to 79%.

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