The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
Christian H. Roduner - One of the best experts on this subject based on the ideXlab platform.
-
Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor
Journal of Turbomachinery, 2009Co-Authors: Zoltán S. Spakovszky, Christian H. RodunerAbstract:In turbocharger applications, bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bear- ings. There is experimental evidence that the performance and operability of highly- loaded centrifugal Compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the Compressor Dynamic behavior, a research program was carried out on a preproduction, 5.0 pressure ratio, high-speed centrifugal Compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Com- pressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without the bleed flow, the prestall behavior is dominated by short-wavelength disturbances, or so called “spikes,” in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at the impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long- wavelength modal prestall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured in agreement with calculations obtained from a previously developed Dynamic Compressor model. In addition, a self-contained endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to the bleed flow and yielding a one point increase in adiabatic Compressor efficiency
-
spike and modal stall inception in an advanced turbocharger centrifugal Compressor
ASME Turbo Expo 2007: Power for Land Sea and Air, 2007Co-Authors: Zoltán S. Spakovszky, Christian H. RodunerAbstract:In turbocharger applications bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bearings. There is experimental evidence that the performance and operability of highly loaded centrifugal Compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the Compressor Dynamic behavior, a research program was carried out on a pre-production, 5.0 pressure ratio, high-speed centrifugal Compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Compressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without bleed flow, the pre-stall behavior is dominated by short wavelength disturbances, or so called ‘spikes’, in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long wavelength, modal pre-stall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured, in agreement with calculations obtained from a previously developed Dynamic Compressor model. In addition, a self-contained, endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to bleed flow and yielding a 1 point increase in adiabiatic Compressor efficiency.Copyright © 2007 by ASME
Zoltán S. Spakovszky - One of the best experts on this subject based on the ideXlab platform.
-
Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor
Journal of Turbomachinery, 2009Co-Authors: Zoltán S. Spakovszky, Christian H. RodunerAbstract:In turbocharger applications, bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bear- ings. There is experimental evidence that the performance and operability of highly- loaded centrifugal Compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the Compressor Dynamic behavior, a research program was carried out on a preproduction, 5.0 pressure ratio, high-speed centrifugal Compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Com- pressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without the bleed flow, the prestall behavior is dominated by short-wavelength disturbances, or so called “spikes,” in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at the impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long- wavelength modal prestall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured in agreement with calculations obtained from a previously developed Dynamic Compressor model. In addition, a self-contained endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to the bleed flow and yielding a one point increase in adiabatic Compressor efficiency
-
spike and modal stall inception in an advanced turbocharger centrifugal Compressor
ASME Turbo Expo 2007: Power for Land Sea and Air, 2007Co-Authors: Zoltán S. Spakovszky, Christian H. RodunerAbstract:In turbocharger applications bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bearings. There is experimental evidence that the performance and operability of highly loaded centrifugal Compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the Compressor Dynamic behavior, a research program was carried out on a pre-production, 5.0 pressure ratio, high-speed centrifugal Compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Compressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without bleed flow, the pre-stall behavior is dominated by short wavelength disturbances, or so called ‘spikes’, in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long wavelength, modal pre-stall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured, in agreement with calculations obtained from a previously developed Dynamic Compressor model. In addition, a self-contained, endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to bleed flow and yielding a 1 point increase in adiabiatic Compressor efficiency.Copyright © 2007 by ASME
Russell Bent - One of the best experts on this subject based on the ideXlab platform.
-
Dynamic Compressor optimization in natural gas pipeline systems
Informs Journal on Computing, 2019Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Russell BentAbstract:The growing dependence of electric power systems on gas-fired generators to balance fluctuating and intermittent production by renewable energy sources has increased the variation and volume of flo...
-
efficient Dynamic Compressor optimization in natural gas transmission systems
Advances in Computing and Communications, 2016Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Hassan Hijazi, Russell BentAbstract:The growing reliance of electric power systems on gas-fired generation to balance intermittent sources of renewable energy has increased the variation and volume of flows through natural gas transmission pipelines. Adapting pipeline operations to maintain efficiency and security under these new conditions requires optimization methods that account for transients and that can quickly compute solutions in reaction to generator re-dispatch. This paper presents an efficient scheme to minimize compression costs under Dynamic conditions where deliveries to customers are described by time-dependent mass flow. The optimization scheme relies on a compact representation of gas flow physics, a trapezoidal discretization in time and space, and a two-stage approach to minimize energy costs and maximize smoothness. The resulting large-scale nonlinear programs are solved using a modern interior-point method. The proposed optimization scheme is validated against an integration of Dynamic equations with adaptive time-stepping, as well as a recently proposed state-of-the-art optimal control method. The comparison shows that the solutions are feasible for the continuous problem and also practical from an operational standpoint. The results also indicate that our scheme scales to large gas transmission networks with more than 6000 kilometers of total pipeline.
-
efficient Dynamic Compressor optimization in natural gas transmission systems
arXiv: Optimization and Control, 2015Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Hassan Hijazi, Russell BentAbstract:The growing reliance of electric power systems on gas-fired generation to balance intermittent sources of renewable energy has increased the variation and volume of flows through natural gas transmission pipelines. Adapting pipeline operations to maintain efficiency and security under these new conditions requires optimization methods that account for transients and that can quickly compute solutions in reaction to generator re-dispatch. This paper presents an efficient scheme to minimize compression costs under Dynamic conditions where deliveries to customers are described by time-dependent mass flow. The optimization scheme relies on a compact representation of gas flow physics, a trapezoidal discretization in time and space, and a two-stage approach to minimize energy costs and maximize smoothness. The resulting large-scale nonlinear programs are solved using a modern interior-point method. The proposed optimization scheme is validated against an integration of Dynamic equations with adaptive time-stepping, as well as a recently proposed state-of-the-art optimal control method. The comparison shows that the solutions are feasible for the continuous problem and also practical from an operational standpoint. The results also indicate that our scheme provides at least an order of magnitude reduction in computation time relative to the state-of-the-art and scales to large gas transmission networks with more than 6000 kilometers of total pipeline.
Terrence W K Mak - One of the best experts on this subject based on the ideXlab platform.
-
Dynamic Compressor optimization in natural gas pipeline systems
Informs Journal on Computing, 2019Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Russell BentAbstract:The growing dependence of electric power systems on gas-fired generators to balance fluctuating and intermittent production by renewable energy sources has increased the variation and volume of flo...
-
efficient Dynamic Compressor optimization in natural gas transmission systems
Advances in Computing and Communications, 2016Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Hassan Hijazi, Russell BentAbstract:The growing reliance of electric power systems on gas-fired generation to balance intermittent sources of renewable energy has increased the variation and volume of flows through natural gas transmission pipelines. Adapting pipeline operations to maintain efficiency and security under these new conditions requires optimization methods that account for transients and that can quickly compute solutions in reaction to generator re-dispatch. This paper presents an efficient scheme to minimize compression costs under Dynamic conditions where deliveries to customers are described by time-dependent mass flow. The optimization scheme relies on a compact representation of gas flow physics, a trapezoidal discretization in time and space, and a two-stage approach to minimize energy costs and maximize smoothness. The resulting large-scale nonlinear programs are solved using a modern interior-point method. The proposed optimization scheme is validated against an integration of Dynamic equations with adaptive time-stepping, as well as a recently proposed state-of-the-art optimal control method. The comparison shows that the solutions are feasible for the continuous problem and also practical from an operational standpoint. The results also indicate that our scheme scales to large gas transmission networks with more than 6000 kilometers of total pipeline.
-
efficient Dynamic Compressor optimization in natural gas transmission systems
arXiv: Optimization and Control, 2015Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Hassan Hijazi, Russell BentAbstract:The growing reliance of electric power systems on gas-fired generation to balance intermittent sources of renewable energy has increased the variation and volume of flows through natural gas transmission pipelines. Adapting pipeline operations to maintain efficiency and security under these new conditions requires optimization methods that account for transients and that can quickly compute solutions in reaction to generator re-dispatch. This paper presents an efficient scheme to minimize compression costs under Dynamic conditions where deliveries to customers are described by time-dependent mass flow. The optimization scheme relies on a compact representation of gas flow physics, a trapezoidal discretization in time and space, and a two-stage approach to minimize energy costs and maximize smoothness. The resulting large-scale nonlinear programs are solved using a modern interior-point method. The proposed optimization scheme is validated against an integration of Dynamic equations with adaptive time-stepping, as well as a recently proposed state-of-the-art optimal control method. The comparison shows that the solutions are feasible for the continuous problem and also practical from an operational standpoint. The results also indicate that our scheme provides at least an order of magnitude reduction in computation time relative to the state-of-the-art and scales to large gas transmission networks with more than 6000 kilometers of total pipeline.
Anatoly Zlotnik - One of the best experts on this subject based on the ideXlab platform.
-
Dynamic Compressor optimization in natural gas pipeline systems
Informs Journal on Computing, 2019Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Russell BentAbstract:The growing dependence of electric power systems on gas-fired generators to balance fluctuating and intermittent production by renewable energy sources has increased the variation and volume of flo...
-
efficient Dynamic Compressor optimization in natural gas transmission systems
Advances in Computing and Communications, 2016Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Hassan Hijazi, Russell BentAbstract:The growing reliance of electric power systems on gas-fired generation to balance intermittent sources of renewable energy has increased the variation and volume of flows through natural gas transmission pipelines. Adapting pipeline operations to maintain efficiency and security under these new conditions requires optimization methods that account for transients and that can quickly compute solutions in reaction to generator re-dispatch. This paper presents an efficient scheme to minimize compression costs under Dynamic conditions where deliveries to customers are described by time-dependent mass flow. The optimization scheme relies on a compact representation of gas flow physics, a trapezoidal discretization in time and space, and a two-stage approach to minimize energy costs and maximize smoothness. The resulting large-scale nonlinear programs are solved using a modern interior-point method. The proposed optimization scheme is validated against an integration of Dynamic equations with adaptive time-stepping, as well as a recently proposed state-of-the-art optimal control method. The comparison shows that the solutions are feasible for the continuous problem and also practical from an operational standpoint. The results also indicate that our scheme scales to large gas transmission networks with more than 6000 kilometers of total pipeline.
-
efficient Dynamic Compressor optimization in natural gas transmission systems
arXiv: Optimization and Control, 2015Co-Authors: Terrence W K Mak, Pascal Van Hentenryck, Anatoly Zlotnik, Hassan Hijazi, Russell BentAbstract:The growing reliance of electric power systems on gas-fired generation to balance intermittent sources of renewable energy has increased the variation and volume of flows through natural gas transmission pipelines. Adapting pipeline operations to maintain efficiency and security under these new conditions requires optimization methods that account for transients and that can quickly compute solutions in reaction to generator re-dispatch. This paper presents an efficient scheme to minimize compression costs under Dynamic conditions where deliveries to customers are described by time-dependent mass flow. The optimization scheme relies on a compact representation of gas flow physics, a trapezoidal discretization in time and space, and a two-stage approach to minimize energy costs and maximize smoothness. The resulting large-scale nonlinear programs are solved using a modern interior-point method. The proposed optimization scheme is validated against an integration of Dynamic equations with adaptive time-stepping, as well as a recently proposed state-of-the-art optimal control method. The comparison shows that the solutions are feasible for the continuous problem and also practical from an operational standpoint. The results also indicate that our scheme provides at least an order of magnitude reduction in computation time relative to the state-of-the-art and scales to large gas transmission networks with more than 6000 kilometers of total pipeline.
