A High Performance Low Pressure Ratio Turbine for Engine Electric Turbocompounding

2011 ◽  
Author(s):  
Aman M. I. Mamat ◽  
Muhamad H. Padzillah ◽  
Alessandro Romagnoli ◽  
Ricardo F. Martinez-Botas
Keyword(s):  
High Performance ◽  
Gasoline Engine ◽  
Flow Direction ◽  
Pressure Ratio ◽  
Design Procedure ◽  
Low Pressure ◽  
Operating Conditions ◽  
Exhaust Gases ◽  
Electric Generator ◽  
Turbine Design

In order to enhance energy extraction from the exhaust gases of a highly boosted downsized engine, an electric turbo-compounding unit can be fitted downstream of the main turbocharger. The extra energy made available to the vehicle can be used to feed batteries which can supply energy to electric units like superchargers, start and stop systems or other electric units. The current research focuses on the design of a turbine for a 1.0 litre gasoline engine which aims to reduce the CO2 emissions of a “cost-effective, ultra-efficient gasoline engine in small and large family car segment”. A 1-D engine simulation showed that a 3% improvement in brake specific fuel consumption (BSFC) can be expected with the use of an electric turbocompounding. However, the low pressure available to the exhaust gases expanded in the main turbocharger and the constant rotational speed required by the electric motor, motivated to design a new turbine which gives a high performance at lower pressures. Accordingly, a new turbine design was developed to recover energy of discharged exhaust gases at low pressure ratios (1.05–1.3) and to drive a small electric generator with a maximum power output of 1.0 kW. The design operating conditions were fixed at 50,000 rpm with a pressure ratio of 1.1. Commercially available turbines are not suitable for this purpose due to the very low efficiencies experienced when operating in these pressure ranges. The low pressure turbine design was carried out through a conventional non-dimensional mixed-flow turbine design method. The design procedure started with the establishment of 2-D configurations and was followed by the 3-D radial fibre blade design. A vane-less turbine volute was designed based on the knowledge of the rotor inlet flow direction and the magnitude of the absolute speed. The overall dimensions of the volute design were defined by the area-to-radius ratios at each respective volute circumferential azimuth angle. Subsequently, a comprehensive steady-state turbine performance analysis was performed by mean of Computational Fluid Dynamics (CFD) and it was found that a maximum of 76% of total-static efficiency ηt-s can be achieved at design speed.

SINGLE PASSAGE CFD ANALYSIS FOR NON-RADIAL FIBRE ELEMENT OF LOW PRESSURE TURBINE

2015 ◽  
Vol 76 (5) ◽  
Author(s):  
Bin Ahmad ◽  
Abdul Fattah ◽  
Bin Mamat, A. M. I.
Keyword(s):  
Combustion Engine ◽  
Flow Direction ◽  
Mechanical Energy ◽  
Pressure Ratio ◽  
Velocity Ratio ◽  
Low Pressure ◽  
Field Analysis ◽  
Electric Generator ◽  
Low Pressure Turbine ◽  
Exhaust Energy

Low Pressure Turbine (LPT) is a mixed-flow low pressure turbine meant for extracting energy from the exhaust of internal combustion engine. It converts the expanded exhaust energy into mechanical energy to drive an electric generator. The current available design of the LPT is only able to recover the exhaust energy efficiently with a pressure ratio range of 1.04 to 1.30. However, the performance efficiency deteriorates significantly when the pressure ratio exceeds 1.25. In the previous studies, flow field analysis has shown that the entropy is largely generated at the exit due to bigger vorticity. This vorticity can be minimized by optimizing the exit flow direction. This can be done by adjusting the exit camberline which reduces the deflection angle of the flow. This will effect exit flow of the fluid; subsequently reduces the exit loss as stipulated in the 1-Dimensional analysis of the turbine. Results have shown that the overall efficiency of the turbine has been improved as much as 7% at pressure ratios of 1.20. Its swallowing capacity is not largely affected at this point and its velocity ratio has shifted slightly from its design point of 0.70 to 0.65.

Numerical Analysis of Non-Radial Blading in a Low Speed and Low Pressure Turbine for Electric Turbocompounding Applications

2021 ◽  
Author(s):  
Eva Alvarez-Regueiro ◽  
Esperanza Barrera-Medrano ◽  
Ricardo Martinez-Botas ◽  
Srithar Rajoo
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Thermal Stresses ◽  
Waste Heat ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Blade Angle ◽  
Low Speed

Abstract This paper presents a CFD-based numerical analysis on the potential benefits of non-radial blading turbine for low speed-low pressure applications. Electric turbocompounding is a waste heat recovery technology consisting of a turbine coupled to a generator that transforms the energy left over in the engine exhaust gases, which is typically found at low pressure, into electricity. Turbines designed to operate at low specific speed are ideal for these applications since the peak efficiency occurs at lower pressure ratios than conventional high speed turbines. The baseline design consisted of a vaneless radial fibre turbine, operating at 1.2 pressure ratio and 28,000rpm. Experimental low temperature tests were carried out with the baseline radial blading turbine at nominal, lower and higher pressure ratio operating conditions to validate numerical simulations. The baseline turbine incidence angle effect was studied and positive inlet blade angle impact was assessed in the current paper. Four different turbine rotor designs of 20, 30, 40 and 50° of positive inlet blade angle are presented, with the aim to reduce the losses associated to positive incidence, specially at midspan. The volute domain was included in all CFD calculations to take into account the volute-rotor interactions. The results obtained from numerical simulations of the modified designs were compared with those from the baseline turbine rotor at design and off-design conditions. Total-to-static efficiency improved in all the non-radial blading designs at all operating points considered, by maximum of 1.5% at design conditions and 5% at off-design conditions, particularly at low pressure ratio. As non-radial fibre blading may be susceptible to high centrifugal and thermal stresses, a structural analysis was performed to assess the feasibility of each design. Most of non-radial blading designs showed acceptable levels of stress and deformation.

scholarly journals Sensitivity of Supersonic ORC Turbine Injector Designs to Fluctuating Operating Conditions

2015 ◽  
Author(s):  
Elio A. Bufi ◽  
Paola Cinnella ◽  
Xavier Merle
Keyword(s):  
Method Of Characteristics ◽  
Organic Rankine Cycle ◽  
Design Procedure ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Real Gas ◽  
Real Gas Effects ◽  
Nozzle Shape ◽  
Turbine Design ◽  
The Impact

The design of an efficient organic rankine cycle (ORC) expander needs to take properly into account strong real gas effects that may occur in given ranges of operating conditions, which can also be highly variable. In this work, we first design ORC turbine geometries by means of a fast 2-D design procedure based on the method of characteristics (MOC) for supersonic nozzles characterized by strong real gas effects. Thanks to a geometric post-processing procedure, the resulting nozzle shape is then adapted to generate an axial ORC blade vane geometry. Subsequently, the impact of uncertain operating conditions on turbine design is investigated by coupling the MOC algorithm with a Probabilistic Collocation Method (PCM) algorithm. Besides, the injector geometry generated at nominal operating conditions is simulated by means of an in-house CFD solver. The code is coupled to the PCM algorithm and a performance sensitivity analysis, in terms of adiabatic efficiency and power output, to variations of the operating conditions is carried out.

Compressor Design for Multi-Point Operating Conditions of Turbocharged Gasoline Engines

2010 ◽  
Author(s):  
Tao Chen ◽  
Yangjun Zhang ◽  
Xinqian Zheng ◽  
Weilin Zhuge
Keyword(s):  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Design Method ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Combustion Engines ◽  
Gasoline Engines ◽  
Compressor Design ◽  
Operating Points ◽  
Load Conditions

Turbocharger compressor design is a major challenge for performance improvement of turbocharged internal combustion engines. This paper presents a multi-point design methodology for turbocharger centrifugal compressors. In this approach, several design operating condition points of turbocharger compressor are considered according to total engine system requirements, instead of one single operating point for traditional design method. Different compressor geometric parameters are selected and investigated at multi-point operating conditions for the flow-solutions of different design objectives. The method has been applied with success to a small centrifugal compressor design of a turbocharged gasoline engine. The results show that the consideration of several operating points is essential to improve the aerodynamic behavior for the whole working range. The isentropic efficiency has been increased by more than 5% at part-load conditions while maintaining the pressure ratio and flow range at full-load conditions of the gasoline engine.

The Port Width and Position Determination for Pressure-Exchange Ejector

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Wenjing Zhao ◽  
Dapeng Hu ◽  
Peiqi Liu ◽  
Yuqiang Dai ◽  
Jiupeng Zou ◽  
...  
Keyword(s):  
High Pressure ◽  
Performance Optimization ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Operating Conditions ◽  
Maximum Deviation ◽  
Dimensionless Time ◽  
Pressure Flow ◽  
Outlet Pressure ◽  
Pressure Exchange

A pressure-exchange ejector transferring energy by compression and expansion waves has the potential for higher efficiency. The width and position of each port are essential in pressure-exchange ejector design. A dimensionless time τ expressing both port widths and the positions of port ends was introduced. A prototype was designed and the experimental system was set up. Many sets of experiment with different geometrical arrangements were conducted. The results suggest that the efficiency greatly changes with the geometrical arrangements. The efficiency is about 60% at proper port widths and positions, while at improper geometrical arrangements, the efficiency is much lower and the maximum deviation may reach about 20%. The proper dimensionless port widths and positions at different operating conditions are obtained. For a fixed overall pressure ratio, the widths of the high pressure flow inlet and middle pressure flow outlet increase as the outlet pressure increases and the low pressure flow inlet width is reduced with a larger outlet pressure. The middle pressure flow outlet (MO) opening end remains constant at different outlet pressures. The positions of the high pressure flow inlet (HI) closed end and the low pressure flow inlet (LI) open end increase with the elevation of outlet pressure, however, the distance between the HI closing end and the LI opening end is constant. The port widths and positions have a significant influence on the performance of the pressure-exchange ejector. The dimensionless data obtained are very valuable for pressure-exchange ejector design and performance optimization.

Design, Test and Analysis of a High-Pressure-Ratio Transonic Fan

2003 ◽  
Author(s):  
W. John Calvert ◽  
Paul R. Emmerson ◽  
Jon M. Moore
Keyword(s):  
High Performance ◽  
Mechanical Design ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Pressure Transducers ◽  
Technology Acquisition ◽  
Laser Anemometry ◽  
High Pressure Ratio ◽  
Response Pressure ◽  
Stage Matching

Aircraft gas turbine engines require compression systems with high performance and low weight and cost. There is therefore a continuing drive to increase compressor stage pressure ratios, particularly for military fans. To meet this need, a technology acquisition programme has been carried out by QinetiQ and Rolls-Royce. Firstly, the stage matching issues for an advanced two-stage military fan were investigated, including the effects of employing variable inlet guide vanes. From this, the requirements for the first stage together with key operating conditions for the blading were defined. The blade profiles were then designed to satisfy the range of aerodynamic conditions using a quasi-3D calculation system. A satisfactory compromise between the aerodynamic and mechanical design requirements was reached in which a blisk construction was employed for the rotor, machined from a single piece of titanium. The new stage was manufactured and tested successfully, and it achieved its target flow, pressure ratio and efficiency on the first build. Detailed measurements of the internal flows using laser anemometry and high response pressure transducers were taken. Finally, these data have been analysed and used to calibrate current 3D multi-row CFD methods.

Variable Inlet Guide Vane Effect on Centrifugal Compressor Performance in Wet Gas Flow

2016 ◽  
Author(s):  
Levi André B. Vigdal ◽  
Lars E. Bakken
Keyword(s):  
Centrifugal Compressor ◽  
Guide Vane ◽  
Flow Direction ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Compressor Stage ◽  
Guide Vanes ◽  
Wet Gas ◽  
Compressor Performance

The introduction of variable inlet guide vanes (VIGVs) upfront of a compressor stage affects performance and permits tuning for off-design conditions. This is of great interest for emerging technology related to subsea compression. Unprocessed gas from the wellhead will contain liquid condensate, which affects the operational condition of the compressor. To investigate the effect of guide vanes on volume flow and pressure ratio in a wet gas compressor, VIGVs are implemented upfront of a centrifugal compressor stage to control the inlet flow direction. The guide vane geometry and test rig setup have previous been presented. This paper documents how changing the VIGV setting affects compressor performance under dry and wet operating conditions. The reduced performance effect and operating range at increased liquid content are of specific interest. Also documented is the change in the VIGV effect relative to the setting angle.

An Investigation On the Discharge Coefficient of Compound Orifices in Rotating Disks

2021 ◽  
Author(s):  
Jiaxi Yan ◽  
Junkui Mao ◽  
Song Wei ◽  
Zhaolin Sun ◽  
Ranran Tian
Keyword(s):  
Discharge Coefficient ◽  
Positive Impact ◽  
Incidence Angle ◽  
Flow Direction ◽  
Pressure Ratio ◽  
Static Condition ◽  
Operating Conditions ◽  
Confined Space ◽  
Empirical Formulas ◽  
Significant Difference

Abstract In the modern multi-shaft gas turbine engines, orifice is an important throttling element and the discharge coefficient of rotating orifices may vary considerably depending on the operating conditions, the geometry and surrounding environment. The influences of the rotating number and the pressure ratio on the rotating orifices flow characteristics are investigated in the present study. Besides, the effects of confined space, wall inclination angle (a) and the angle between the axis of orifice and the disk wall normal (ß) are also analyzed statistically. It is found that the rotating number has a significant effect on the discharge coefficient. As the rotating number increases from 0 to 0.6, the discharge coefficient reduces by about 47.88%. When rotating number is 0.74 and pressure ratio is 1.10, the discharge coefficient can be improved by 16.88% with a changes from 90° to 180°. The parameter, ß, affects discharge coefficient slightly in rotating condition. However, the maximum discharge coefficient is achieved with ß=0° in the static condition. The results also show that, a confined space weakens the effect of rotation, and changes the air flow direction in the inlet chamber, which also has a positive impact on the discharge coefficient. In the current research, it is found that there is a significant difference between the traditional empirical formulas used in the literature and the fitting result. By modifying the incidence angle and taking account of the influence of the angle of inclination, the maximum error was reduced from 56.79% to 3.16%

scholarly journals Experimental study on the effect of high-pressure and low-pressure exhaust gas recirculation on gasoline engine and turbocharger

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880960 ◽  
Author(s):  
Xianqing Shen ◽  
Kai Shen ◽  
Zhendong Zhang
Keyword(s):  
High Pressure ◽  
Fuel Consumption ◽  
Gasoline Engine ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Partial Load ◽  
Recirculation System ◽  
Gas Recirculation

The effects of high-pressure and low-pressure exhaust gas recirculation on engine and turbocharger performance were investigated in a turbocharged gasoline direct injection engine. Some performances, such as engine combustion, fuel consumption, intake and exhaust, and turbocharger operating conditions, were compared at wide open throttle and partial load with the high-pressure and low-pressure exhaust gas recirculation systems. The reasons for these changes are analyzed. The results showed EGR system of gasoline engine could optimize the cylinder combustion, reduce pumping mean effective pressure and lower fuel consumption. Low-pressure exhaust gas recirculation system has higher thermal efficiency than high-pressure exhaust gas recirculation, especially on partial load condition. The main reasons are as follows: more exhaust energy is used by the turbocharger with low-pressure exhaust gas recirculation system, and the lower exhaust gas temperature of engine would optimize the combustion in cylinder.

The Application of a Computer-Aided Design Technique to the Conceptual Design of Turbochargers: Part A — Centrifugal Compressor Design and Turbine Matching

1996 ◽  
Author(s):  
A. Whitfield ◽  
Abu Hasan Abdullah
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Computer Aided Design ◽  
Pressure Ratio ◽  
Design Procedure ◽  
Compressor Design ◽  
Design Options ◽  
Turbine Design

In many turbomachinery applications a compressor is directly driven by a turbine; for turbocharger applications a centrifugal compressor is usually adopted which is generally driven by a radial flow turbine, although mixed flow or axial flow turbines are occasionally required. A non-dimensional design procedure is developed to provide the basic dimensions and blade angles of centrifugal compressor impellers, whilst accounting for the turbine conditions as assessed through the matching requirements. The design of the turbine is then considered further in Part B. The procedure can be applied for any desired compressor pressure ratio and target efficiency to develop an initial non-dimensional skeleton design. No other parameters are required from the initial specification and the design is developed non-dimensionally without recourse to empirical loss models and the associated uncertainties as the target efficiency must be specified. The procedure provides graphical information with respect to the impeller discharge conditions and inlet conditions from which the designer must select the most appropriate design. The screen graphics interface enables the designer to search across the design options; as this search is carried out numerical data are displayed and continuously up-dated to provide immediate information on which an infnrmed assessment can be based. In addition to the compressor design options which are provided the matching conditions for the drive turbine provides information, such as specific speed, non-dimensional mass flow rate and pressure ratio, relevant to the turbine design. Judgements with respect to the design options for the compressor can then be made with the consequences for the associated turbine design clearly in view. The non-dimensional design can be translated into an absolute design through the specification of the required mass flow rate and the inlet stagnation pressure and temperature.

Sign in / Sign up

Export Citation Format

Share Document