Experimental and Numerical Investigation of Partial Admission of a Radial Turbocharger Turbine for Improved Off-Design Operation

2015 ◽  
Author(s):  
Mirko Ilievski ◽  
Frederic Heidinger ◽  
Christopher Fuhrer ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
...  
Keyword(s):  
Admission Rate ◽  
Separate Flow ◽  
Expansion Ratio ◽  
Turbine Stage ◽  
Test Rig ◽  
Flow Channels ◽  
Exhaust Duct ◽  
Partial Admission ◽  
Admission System ◽  
Stator Design

A new partial admission concept for turbocharger turbine operation at off-design is designed and investigated numerically and experimentally in a turbocharger test rig. This new concept is called MEDUSA (Multiple Exhaust Duct with Source Adjustment) and is based on a partial admission turbine system consisting of several separate flow channels that connect the cylinder of the engine and individual nozzle segments of the turbine. The turbine flow is adjusted by the chosen admission rate according to the available exhaust enthalpy. In the present study, a reference turbocharger has been equipped with a four segment partial admission system instead of its conventional Waste-Gate scroll. The numerical results indicate similar loss mechanisms compared to an axial turbine stage, when partial admission is applied. Based on a stator design optimization, a design was chosen for manufacturing and testing on the turbocharger test rig. Despite the fact that the turbocharger efficiency at partial admission for the MEDUSA-system drops, a higher turbine expansion ratio can be achieved to obtain the same compressor operating point. These results indicate an enhanced use of the available exhaust enthalpy at part-load conditions, thus improving the turbocharger performance at low end torque engine speeds.

A New Partial Admission Method for Turbocharger Turbine Control at Off-Design

2013 ◽  
Author(s):  
Sebastian Challand ◽  
Eckart Dirschauer ◽  
Mirko Ilievski ◽  
Michael Casey ◽  
Markus Schatz
Keyword(s):  
Patent Application ◽  
Spark Ignition ◽  
Separate Flow ◽  
European Patent ◽  
Spark Ignition Engines ◽  
Flow Channels ◽  
Exhaust Duct ◽  
Partial Admission ◽  
Axial Turbines ◽  
The Individual

A new method for turbocharger control in automotive applications is presented. It is called MEDUSA (Multiple Exhaust DUct with Source Adjustment, European patent application number: 21326 - EP) and is a partial admission system consisting of several separate flow channels that connect the exhaust duct of the engine and individual nozzle segments of the turbine. By opening or closing the individual flow channels using external valves, the turbine flow can be adjusted, hence allowing the whole turbocharger to be controlled. Due to the use of external valves, the system is considerably more robust than other variable geometry systems based on variable inlet guide vanes and thus becomes suitable for application to spark-ignition motors at high temperature. The paper presents a theoretical assessment of this innovative control system, based on one dimensional considerations and CFD simulations. The CFD-calculations of the MEDUSA-system are compared to those of a turbocharger turbine controlled with a variable inlet nozzle. The results indicate that the performance and operating range of the new system is comparable, or even better, than the currently used variable nozzle systems, especially at low load conditions. This indicates that further experimental work is justified as it could become considerably more effective than the typical waste gate systems used in spark ignition engines and provides a new solution for the turbocharger control in these applications. So far, only radial turbines have been considered for application of this method but it could also be used for mixed-flow or axial turbines.

Modeling Partial Admission in Control Stages of Small Steam Turbines With CFD

2018 ◽  
Author(s):  
Juri Bellucci ◽  
Filippo Rubechini ◽  
Andrea Arnone
Keyword(s):  
Steam Turbine ◽  
Three Dimensional ◽  
Admission Rate ◽  
Point Of View ◽  
Test Case ◽  
Steam Turbines ◽  
Turbine Stage ◽  
Performance Curves ◽  
Partial Admission ◽  
The Impact

This work aims at investigating the impact of partial admission on a steam turbine stage, focusing on the aerodynamic performance and the mechanical behavior. The partialized stage of a small steam turbine was chosen as test case. A block of nozzles was glued in a single “thick nozzle” in order to mimic the effect of a partial admission arc. Numerical analyses in full and in partial admission cases were carried out by means of three-dimensional, viscous, unsteady simulations. Several cases were tested by varying the admission rate, that is the length of the partial arc, and the number of active sectors of the wheel. The goal was to study the effect of partial admission conditions on the stage operation, and, in particular on the shape of stage performance curves as well as on the forces acting on bucket row. First of all, a comparison between the flow field of the full and the partial admission case is presented, in order to point out the main aspects related to the presence of a partial arc. Then, from an aerodynamic point of view, a detailed discussion of the modifications of unsteady rows interaction (potential, shock/wake), and how these ones propagate downstream, is provided. The attention is focused on the phenomena experienced in the filling/emptying region, which represent an important source of aerodynamic losses. The results try to deepen the understanding in the loss mechanisms involved in this type of stage. Finally, some mechanical aspects are addressed, and the effects on bucket loading and on aeromechanical forcing are investigated.

Transonic Turbine Stage Heat Transfer Investigation in Presence of Strong Shocks

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
A. de la Loma ◽  
G. Paniagua ◽  
D. Verrastro ◽  
P. Adami
Keyword(s):  
Heat Transfer ◽  
Rotor Blade ◽  
Shock Interaction ◽  
Turbine Stage ◽  
Test Rig ◽  
Unsteady Heat Transfer ◽  
Tube Test ◽  
Stator Blade ◽  
Transonic Turbine ◽  
Layered Thin Film

This paper reports the external convective heat transfer distribution of a modern single-stage transonic turbine together with the physical interpretation of the different shock interaction mechanisms. The measurements have been performed in the compression tube test rig of the von Karman Institute using single- and double-layered thin film gauges. The three pressure ratios tested are representative of those encountered in actual aeroengines, with M2,is ranging from 1.07 to 1.25 and a Reynolds number of about 106. Three different rotor blade heights (15%, 50%, and 85%) and the stator blade at midspan have been investigated. The measurements highlight the destabilizing effect of the vane left-running shock on the rotor boundary layer. The stator unsteady heat transfer is dominated by the fluctuating right-running vane trailing edge shock at the blade passing frequency.

108 A study of loss generation mechanisms in a partial admission supersonic turbine stage by unsteady CFD analysis

2014 ◽  
Vol 2014.49 (0) ◽  
pp. 17-18
Author(s):  
Yuki TOKUYAMA ◽  
Ken-ichi FUNAZAKI ◽  
Hiromasa KATO ◽  
Noriyuki HIMIYA ◽  
Mitsuru SHIMAGAKI ◽  
...  
Keyword(s):  
Cfd Analysis ◽  
Turbine Stage ◽  
Partial Admission ◽  
Generation Mechanisms

scholarly journals Design and Testing of a 10KW Steam Turbine for Steam Turbochargers

1985 ◽  
Author(s):  
M. Rautenberg ◽  
M. Malobabic ◽  
A. Mobarak ◽  
M. Abdel Kader
Keyword(s):  
Waste Heat ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Exhaust Gas ◽  
Test Rig ◽  
Pelton Turbine ◽  
Partial Admission ◽  
Turbine Design ◽  
Design And Testing

A Clausius-Rankine-cycle has been proposed to recover waste heat from a piston engine. This waste heat is then used to supercharge the cylinders by means of a steam turbocharger. The advantage of using this steam turbocharger system is to avoid the losses due to the engine back pressure which accompany the use of the conventional exhaust gas turbocharger. The mass flow rate of turbines for steam turbochargers in the range from 1 to 10 kW is about 0.03 to 0.08 kg/s. This implies a special turbine design, characterised by partial admission and supersonic flow, which unfortunately leads to low turbine efficiencies. A small Pelton turbine for steam has been designed and produced. The turbine is connected to the radial compressor of a conventional exhaust gas turbocharger which works, in this case, as a brake to dissipate the generated turbine power. A special test rig has been built to carry out the experimental investigations on the proposed Pelton turbine. The test rig is supplied with superheated steam from the University’s power plant. Two different rotors for this Pelton turbine have been tested under the same operating conditions (rotor 2 see Fig. 1). Some experimental test results of a special Pelton turbine are presented and discussed in this report.

Efficient Stator Design for Automotive Engine Cooling Fan Systems

2002 ◽  
Author(s):  
F. Bakir ◽  
S. Moreau
Keyword(s):  
Efficiency Improvement ◽  
Test Rig ◽  
Automotive Engine ◽  
Engine Cooling ◽  
Cooling Fan ◽  
Stator Design ◽  
Radial Equilibrium

This paper deals with stator efficiency improvement meant for automotive engine cooling fan systems. Four stators designed for a Valeo 380 mm rotor were manufactured and tested on a newly designed Valeo-Lemfi test rig. The following points are presented: • Overall performances of the 380 mm rotor. • Overall performances of the 380 mm rotor combined with a short chord stator. Inefficiency of such a design is shown: Slight deflection carried out by the stator is the cause of the slight gain of efficiency. • Overall performances of the 380 mm rotor combined to three long chord stators: this study confirms the gain of efficiency foreseen previously with the simplified radial equilibrium code VENTAX. • Steady velocities measured 33 mm downstream the various stage configurations: These measurements obtained by using a 5-holes probe show high deflection carried out by the long chord stators.

Performance Characteristics of a Turbo Expander Applied to the Expansion Process at a HFC134a Air-Conditioner

2007 ◽  
Author(s):  
Soo-Yong Cho ◽  
Chong-Hyun Cho ◽  
Chaesil Kim
Keyword(s):  
Output Power ◽  
Pressure Ratio ◽  
Admission Rate ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Air Conditioner ◽  
Performance Difference ◽  
Expansion Process ◽  
Partial Admission ◽  
Turbo Expander

An experimental study is conducted on a small turbo expander which can be applied to the expansion process in place of an expansion valve in a regenerator or air-conditioner to recover energy from the throttling process. The operating gas is HFC134a and the maximum cooling capacity of the air-conditioner used in this experiment is 32.7kW. Four different axial-type rotors in the turbo expander are tested to find not only the performance difference on the rotor with/without the shroud but also the performance characteristics of the turbo expander when the partial admission rate is increased by changing the annular passage area of the rotor. Two rotors among four are shrouded on the tip of rotor; the first has a mean diameter of 71.85mm and the second 70.46mm. The remaining two rotors are tested after removing the shroud. These axial-type rotors operate in the supersonic flow generated at the supersonic nozzle, and the partial admission rate is 1.70% or 2.37% depending on the rotor size. In the experiment, pressure and temperature are measured at ten different locations in the experimental apparatus. In addition to these measurements, output power at the turbo expander is measured through a generator installed on a rotor shaft with the rotational speed. Performance data of the turbo expander are obtained at many part load operations by adjusting the output power of the generator. Experimental results show that the optimal velocity ratio decreases when the pressure ratio is decreased, and peak efficiencies, which are obtained at locally maximized efficiency depending on the operating condition, vary linearly against the subcooling temperature or the pressure ratio. A maximum 15.8% total-to-static efficiency is obtained when the pressure ratio and the partial admission ratio are 2.66 and 1.70%, respectively. When the partial admission rate is increased by reducing the annular passage area of the rotor without changing the nozzle area, the performance difference is negligible. Comparing with the total-to-static efficiencies obtained at a rotor with/without the shroud, the efficiencies obtained with the shroud are improved by nearly 3.7% for all operating conditions.

A Study of Flow Behaviour in Radial and Mixed Flow Turbines With Variable Nozzle Vanes for a Turbocharger

2019 ◽  
Author(s):  
Ramesh Kannan ◽  
Bhamidi Prasad ◽  
Sridhara Koppa
Keyword(s):  
Radial Flow ◽  
Expansion Ratio ◽  
Flow Behaviour ◽  
Meridional Plane ◽  
Turbine Stage ◽  
Mixed Flow ◽  
Turbine Wheel ◽  
Flow Through ◽  
Loss Coefficients ◽  
Rotor Loss

Abstract A mixed flow turbine with variable nozzle vanes is developed along with its radial counterpart for the wheel size of about 30 mm, suitable for turbocharger of 1.5 lit. engine capacity. In order to understand the flow behaviour inside the turbines, computational fluid dynamics studies are conducted for both the radial and mixed flow turbines. Flow through the turbine stage is discussed with velocity distribution in the meridional plane. In addition, the loss coefficients for the nozzle vanes and turbine wheel are estimated. At nozzle vanes opening of 50% mass flow parameter and for the turbine expansion ratio of 1.5, the flow velocities at the exit of the nozzle vanes are found to be about 120 to 170 m/s for the radial flow turbine and 150 to 180 m/s for the mixed flow turbine. Higher level of uniformity in flow is also observed for mixed flow turbine stage compared to the radial. The maximum Mach number is observed on the middle of the turbine wheel, and the same is less than unity for both the turbines. Both the nozzle and rotor loss coefficients for mixed flow turbine are lower than the values observed for the radial flow by about 6% and 15% respectively.

Analysis of Measured and Predicted Turbine Maps From Start-Up to Design Point

2020 ◽  
Author(s):  
Alberto Scotti del Greco ◽  
Sara Biagiotti ◽  
Vittorio Michelassi ◽  
Tomasz Jurek ◽  
Daniele Di Benedetto ◽  
...  
Keyword(s):  
Full Range ◽  
Velocity Ratio ◽  
Expansion Ratio ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Design Point ◽  
Start Up ◽  
Wide Range ◽  
Constant Shape ◽  
Ratio Versus

Abstract This paper describes a coupled experimental and CFD campaign conducted on a 1.5 intermediate turbine stage in the full range of operating conditions, from start-up to design point under variable expansion ratio and physical speed. The test maintains engine similitude conditions and allows direct comparison with CFD data to assess the predictions accuracy. The choice of variables to describe the speedlines is also addressed by using both measured and predicted data. A discussion on velocity ratio versus corrected speed illustrates the advantages of the former parameter the adoption of which produces constant shape curves in a very wide range of operating conditions. The comparison between measurements and predictions suggests that CFD, in conjunction with performance correlations, is a viable tool to predict speedlines in a fairly wide range of conditions, provided that geometrical and operational details are carefully matched.

Influence of Supersonic Nozzle Design Parameters on the Unsteady Stator-Rotor Interaction in Radial-Inflow Turbines for Organic Rankine Cycles

2021 ◽  
Author(s):  
Alessandro Cappiello ◽  
Raffaele Tuccillo
Keyword(s):  
Power Plants ◽  
Supersonic Nozzle ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Design Parameters ◽  
Large Expansion ◽  
Downstream Flow ◽  
Organic Fluids ◽  
Stator Design

Abstract Organic Rankine Cycle (ORC) technology represents an interesting option for improving the efficiency of existing power plants and industrial processes as well as exploiting renewable and renewable-equivalent energy sources. The use of Radial-Inflow Turbine (RIT) for ORC plant sizes below 100 kW is promising, although the application remains challenging. In fact, the single stage arrangement imposed by economic constraints and hence the large expansion ratio, together with the large molecular weight, which characterizes organic fluids, usually result in highly supersonic flows, so making the use of transonic stators often mandatory. Particularly, the influence of RIT stator design parameters on losses and the level of unsteadiness seen by the subsequent rotor is still scarcely addressed in published literature. Previous work by the authors investigated the effect of some stator design parameters on stator loss and downstream circumferential uniformity. The present work investigates the effect of the convergent-divergent stators design parameters and the resulting downstream flow field non-uniformity on the unsteady stator-rotor interaction and loss generation in ORC Radial-Inflow Turbines. To this end, two stator and rotor configurations which differ by the stator design parameters (i.e., discharge metal angle and number of vanes) have been tested by means of 3D unsteady CFD calculations accounting for real-gas properties. The results show that larger stator-rotor interaction is present for the case featuring higher vane count and lower outlet metal, which also features the largest fluctuations of power output and pressure force on blade, together with a substantially lower average total-to-static efficiency.

Sign in / Sign up

Export Citation Format

Share Document