scholarly journals Turbocharger Radial Turbine Response to Pulse Amplitude

2021 ◽  
pp. 1-15
Author(s):  
Roberto Mosca ◽  
Shyang M. Lim ◽  
Mihai Mihaescu
Keyword(s):  
Heat Transfer ◽  
Viscous Friction ◽  
Pulse Amplitude ◽  
Operating Conditions ◽  
System Response ◽  
Flow Conditions ◽  
Temporal Gradient ◽  
Beneficial Effects ◽  
Turbine Performance ◽  
Radial Turbine

Abstract Under on-engine operating conditions, a turbocharger turbine is subject to a pulsating flow and, consequently, experiences deviations from the performance measured in gas-stand flow conditions. Furthermore, due to the high exhaust gases temperatures, heat transfer further deteriorates the turbine performance. The complex interaction of the aerothermodynamic mechanisms occurring inside the hot-side, and consequently the turbine behavior, is largely affected by the shape of the pulse, which can be parameterized through three parameters: pulse amplitude, frequency, and temporal gradient. This paper investigates the hot-side system response to the pulse amplitude via Detached Eddy Simulations (DES) of a turbocharger radial turbine system including exhaust manifold. Firstly, the computational model is validated against experimental data obtained in gas-stand flow conditions. Then, two different mass flow pulses, characterized by a pulse amplitude difference of 5%, are compared. An exergy-based post-processing approach shows the beneficial effects of increasing the pulse amplitude. An improvement of the turbine power by 1.3%, despite the increment of the heat transfer and total internal irreversibilities by 5.8% and 3.4\%, respectively, is reported. As a result of the higher maximum speeds, internal losses by viscous friction are responsible for the growth of the total internal irreversibilities as pulse amplitude increases.

Turbocharger Radial Turbine Response to Pulse Amplitude

2021 ◽  
Author(s):  
Roberto Mosca ◽  
Shyang Maw Lim ◽  
Mihai Mihaescu
Keyword(s):  
Heat Transfer ◽  
Continuous Flow ◽  
Viscous Friction ◽  
Pulse Amplitude ◽  
Operating Conditions ◽  
System Response ◽  
Maximum Speed ◽  
Detached Eddy Simulation ◽  
Beneficial Effects ◽  
Eddy Simulation

Abstract Under on-engine operating conditions, a turbocharger turbine is subject to a pulsating flow and, consequently, experiences deviations from the performance measured under continuous flow. Furthermore, due to the high exhaust gas temperatures, heat transfer further deteriorates the turbine performance. The complex interaction of the aerothermodynamic mechanisms occurring inside the hot-side, and consequently the turbine behavior, is largely affected by the shape of the pulse, which can be parameterized through three parameters: pulse amplitude, frequency, and temporal gradient. This paper investigates the hot-side system response to the pulse amplitude via a Detached Eddy Simulation (DES) approach of a radial turbocharger turbine system including exhaust manifold. Firstly, the computational model is validated against experimental data obtained under gas stand continuous flow conditions. Then, two different mass flow pulses, characterized by a pulse amplitude difference of ≈ 5%, are compared. An exergy-based post-processing approach shows the beneficial effects of increasing pulse amplitude. An improvement of the turbine power by 1.3%, despite the increment of the heat transfer and total internal irreversibilities by 5.8% and 3.4%, respectively, is reported. As a result of the higher maximum speed, internal losses by viscous friction are responsible for the growth of the total internal irreversibilities as pulse amplitude increases.

scholarly journals Influence of Pulse Characteristics On Turbocharger Radial Turbine

2021 ◽  
Author(s):  
Roberto Mosca ◽  
ShyangM. Lim ◽  
Mihai Mihaescu
Keyword(s):  
Mass Flow ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Operating Conditions ◽  
System Response ◽  
Primary Parameter ◽  
Temporal Gradient ◽  
Reciprocating Engine ◽  
Turbine Performance ◽  
Pulse Characteristics

Abstract Due to the reciprocating engine, a pulsating flow occurs in the turbine turbocharger, which experiences conditions far from the continuous flow scenario. In this work, the effects of the characteristics of the mass flow pulse, parameterized through amplitude, frequency and temporal gradient, are decoupled and studied via unsteady Computational Fluid Dynamics calculations under on-engine operating conditions. Firstly, the model is validated based on comparisons with experimental data in steady flow conditions. Then, the effect of each parameter on exergy budget is assessed by considering a +/-10% variation with respect to a baseline pulse. The other factors defining the operating conditions (e.g. mass flow, shaft speed and inflow exergy) are kept the same as the baseline. The adopted approach enables to completely isolate the effects of each parameter in contrast with previous literature studies. Based on the results observed, pulse amplitude is identified as the primary parameter affecting the hot-side system response in terms of turbine performance, heat transfer and entropy generation, while frequency and temporal gradient show a smaller influence compared to it. As the pulse amplitude increases, the turbine work is reported to improve up to 9.4%. Smaller variations are observed for the frequency and temporal gradient analysis. With a 10% increase of the pulse frequency the turbine work is registered to improve by 5.0%, while the same percentage reduction of the temporal gradient leads to an increase of turbine work equal to 3.6%.

A Direct Performance Comparison of Vaned and Vaneless Stators for Radial Turbines

2006 ◽  
Vol 129 (1) ◽  
pp. 53-61 ◽  
Author(s):  
S. W. T. Spence ◽  
R. S. E. Rosborough ◽  
D. Artt ◽  
G. McCullough
Keyword(s):  
Performance Comparison ◽  
Performance Model ◽  
Operating Conditions ◽  
One Dimensional ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Surface Finishes ◽  
The Impact ◽  
Radial Turbines ◽  
Extensive Performance

An extensive performance investigation has been conducted on a radial turbine with three different vaneless volutes and three corresponding vaned stators. Previously published comparisons have been based on turbines with unmatched flow rates, meaning that the impact of stator losses was not isolated from rotor and exit losses. Each vaned stator configuration tested in this investigation matched the flow rate of the corresponding vaneless volute to within 1%. The volutes and the vaned stators were all machined in order to achieve high quality and comparable surface finishes. At all operating conditions, the vaneless volutes were shown to deliver a significant efficiency advantage over the vaned stators. However, the vaneless volute turbines did not demonstrate any greater tolerance for off-design operating conditions than the vaned stator configurations. Full performance data are presented for the six different turbine configurations tested and a one-dimensional turbine performance model is evaluated as a means of predicting and extrapolating turbine performance.

Influence of Upstream Exhaust Manifold on Pulsatile Turbocharger Turbine Performance

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Shyang Maw Lim ◽  
Anders Dahlkild ◽  
Mihai Mihaescu
Keyword(s):  
Heat Transfer ◽  
Pulsatile Flow ◽  
Exhaust Manifold ◽  
Detached Eddy Simulation ◽  
Flow Conditions ◽  
Blow Down ◽  
Flow Angle ◽  
Eddy Simulation ◽  
Turbine Performance ◽  
Geometry Configuration

This research was primary motivated by limited efforts to understand the effects of secondary flow and flow unsteadiness on the heat transfer and the performance of a turbocharger turbine subjected to pulsatile flow. In this study, we aimed to investigate the influence of exhaust manifold on the flow physics and the performance of its downstream components, including the effects on heat transfer, under engine-like pulsatile flow conditions. Based on the predicted results by detached eddy simulation (DES), qualitative and quantitative flow fields analyses in the scroll and the rotor's inlet were performed, in addition to the quantification of turbine performance by using the flow exergy methodology. With the specified geometry configuration and exhaust valve strategy, our study showed that (1) the exhaust manifold influences the flow field and the heat transfer in the scroll significantly and (2) although the exhaust gas blow-down disturbs the relative flow angle at rotor inlet, the consequence on the turbine power is relatively small.

Understanding the Twin Scroll Turbine: Flow Similarity

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Nils Brinkert ◽  
Siegfried Sumser ◽  
Siegfried Weber ◽  
Klaus Fieweger ◽  
Achmed Schulz ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Velocity Ratio ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Flow Conditions ◽  
Hot Gas ◽  
Turbine Performance ◽  
Turbine Inlet ◽  
Gas Measurements ◽  
Flow Similarity

The current study investigates the flow conditions of a twin scroll asymmetric turbine. This is motivated by the operating conditions of the turbine at a heavy-duty reciprocating internal combustion engine with exhaust gas recirculation. The flow conditions of the turbine at the engine can be described best with the turbine scroll interaction map. Standard hot gas measurements of a turbocharger turbine are presented and discussed. Due to the strong interaction of the turbine scrolls, further hot gas measurements are performed at partial admission conditions. The turbine inlet conditions are analyzed experimentally, in order to characterize the turbine performance. The turbine scroll pressure ratio is varied, leading to unequal twin turbine admission conditions. The flow behavior is analyzed regarding its ability for further extrapolation. Beyond scroll pressure ratio variations, unequal temperature admission conditions were studied. A way of characterizing the representative turbine inlet temperature, regarding the reduced turbine speed, is presented. The different scroll parameter ratios are evaluated regarding their capability of describing flow similarity under different unequal turbine admission conditions. In this content, turbine scroll Mach number ratio, velocity ratio and mass flow ratio are assessed. Furthermore, a generic representation of the turbine flow conditions at the engine is presented, based on standard turbine performance maps.

scholarly journals Heat Transfer Effect on Micro Gas Turbine Performance for Solar Power Applications

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6745
Author(s):  
Mahmoud A. Khader ◽  
Mohsen Ghavami ◽  
Jafar Al-Zaili ◽  
Abdulnaser I. Sayma
Keyword(s):  
Heat Transfer ◽  
Power Systems ◽  
Gas Turbine ◽  
Computational Study ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Micro Gas Turbine ◽  
Turbine Performance ◽  
Wide Range ◽  
The Cost

This paper presents an experimentally validated computational study of heat transfer within a compact recuperated Brayton cycle microturbine. Compact microturbine designs are necessary for certain applications, such as solar dish concentrated power systems, to ensure a robust rotodynamic behaviour over the wide operating envelope. This study aims at studying the heat transfer within a 6 kWe micro gas turbine to provide a better understanding of the effect of heat transfer on its components’ performance. This paper also investigates the effect of thermal losses on the gas turbine performance as a part of a solar dish micro gas turbine system and its implications on increasing the size and the cost of such system. Steady-state conjugate heat transfer analyses were performed at different speeds and expansion ratios to include a wide range of operating conditions. The analyses were extended to examine the effects of insulating the microturbine on its thermodynamic cycle efficiency and rated power output. The results show that insulating the microturbine reduces the thermal losses from the turbine side by approximately 11% without affecting the compressor’s performance. Nonetheless, the heat losses still impose a significant impact on the microturbine performance, where these losses lead to an efficiency drop of 7.1% and a net output power drop of 6.6% at the design point conditions.

scholarly journals Investigation of Transient Technique for Turbine Vane Heat Transfer Using a Shock Tube

1985 ◽  
Author(s):  
William C. Elrod ◽  
John E. Gochenaur ◽  
James E. Hitchcock ◽  
Richard B. Rivir
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Shock Tube ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Turbulent Heat Transfer ◽  
Flow Conditions ◽  
Transient Technique ◽  
Turbine Vane

An investigation was made of a transient technique for determining heat transfer and flow conditions in a cascade of turbine vanes. A shock tube was used to establish, behind a reflected shock, temperature ratios between the gas the vanes simulating the severe operating conditions of modern gas turbines. Heat transfer and flow conditions at five locations (leading edge and 1/4 and 1/2 chord positions on suction and pressure surfaces) were determined by a heat flux gage and by flow visualization with a Mach-Zehnder interferometer. The heat flux gage was a thin-film semiconductor type thermocouple used to measure the surface temperature of a semi-infinite solid as a function of time. Then a transient analysis using a finite difference scheme was used to calculate the heat transfer. The validity of the transient technique was established by measurements with the thin-film gage mounted on the shock tube wall. Analytical results for steady, turbulent heat transfer to a flat plate are somewhat less than the measured results, the difference decreasing with increased shock strength. Analysis of the transient flow conditions in the shock tube provides an explanation of this behavior. The heat transfer conditions for the turbine vane are believed to be established rapidly enough to represent valid steady state measurements for the simulated turbine vane flow conditions.

Understanding the Twin Scroll Turbine: Flow Similarity

2011 ◽  
Author(s):  
Nils Brinkert ◽  
Siegfried Sumser ◽  
Achmed Schulz ◽  
Siegfried Weber ◽  
Klaus Fieweger ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Velocity Ratio ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Flow Conditions ◽  
Hot Gas ◽  
Turbine Performance ◽  
Turbine Inlet ◽  
Gas Measurements ◽  
Flow Similarity

The current study investigates the flow conditions of a twin scroll asymmetric turbine. This is motivated by the operating conditions of the turbine at a heavy-duty reciprocating internal combustion engine with exhaust gas recirculation. The flow conditions of the turbine at the engine can be described best with the turbine scroll interaction map. Standard hot gas measurements of a turbocharger turbine are presented and discussed. Due to the strong interaction of the turbine scrolls, further hot gas measurements are performed at partial admission conditions. The turbine inlet conditions are analysed experimentally, in order to characterize the turbine performance. The turbine scroll pressure ratio is varied, leading to unequal twin turbine admission conditions. The flow behaviour is analysed regarding its ability for further extrapolation. Beyond scroll pressure ratio variations, unequal temperature admission conditions were studied. A way of characterizing the representative turbine inlet temperature, regarding the reduced turbine speed, is presented. The different scroll parameter ratios are evaluated regarding their capability of describing flow similarity under different unequal turbine admission conditions. In this content, turbine scroll Mach number ratio, velocity ratio and mass flow ratio are assessed. Furthermore, a generic representation of the turbine flow conditions at the engine is presented, based on standard turbine performance maps.

Flow Field and Wall Temperature Measurements for Reacting Flow in a Lean Premixed Swirl Stabilized Can Combustor

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Suhyeon Park ◽  
David Gomez-Ramirez ◽  
Siddhartha Gadiraju ◽  
Sandeep Kedukodi ◽  
Srinath V. Ekkad ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Gas Turbine ◽  
Swirling Flow ◽  
Single Case ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Flow Conditions ◽  
Gas Turbine Combustor ◽  
Lean Premixed

In this study, we provide detailed wall heat flux measurements and flow details for reacting flow conditions in a model combustor. Heat transfer measurements inside a gas turbine combustor provide one of the most serious challenges for gas turbine researchers. Gas turbine combustor improvements require accurate measurement and prediction of reacting flows. Flow and heat transfer measurements inside combustors under reacting flow conditions remain a challenge. The mechanisms of thermal energy transfer must be investigated by studying the flow characteristics and associated heat load. This paper experimentally investigates the effects of combustor operating conditions on the reacting flow in an optical single can combustor. The swirling flow was generated by an industrial lean premixed, axial swirl fuel nozzle. Planar particle image velocimetry (PIV) data were analyzed to understand the characteristics of the flow field. Liner surface temperatures were measured in reacting condition with an infrared camera for a single case. Experiments were conducted at Reynolds numbers ranging between 50,000 and 110,000 (with respect to the nozzle diameter, DN); equivalence ratios between 0.55 and 0.78; and pilot fuel split ratios of 0 to 6%. Characterizing the impingement location on the liner, and the turbulent kinetic energy (TKE) distribution were a fundamental part of the investigation. Self-similar characteristics were observed at different reacting conditions. Swirling exit flow from the nozzle was found to be unaffected by the operating conditions with little effect on the liner. Comparison between reacting and nonreacting flows (NR) yielded very interesting and striking differences.

Sign in / Sign up

Export Citation Format

Share Document