Turbocharger-Design Effects on Gasoline-Engine Performance

2005 ◽  
Vol 127 (3) ◽  
pp. 525-530 ◽  
Author(s):  
Theodosios Korakianitis ◽  
T. Sadoi
Keyword(s):  
Steady Flow ◽  
Mass Flow ◽  
Gasoline Engine ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Final Choice ◽  
Design Point ◽  
Theoretical Considerations ◽  
Flow Experiments

Specification of a turbocharger for a given engine involves matching the turbocharger performance characteristics with those of the piston engine. Theoretical considerations of matching turbocharger pressure ratio and mass flow with engine mass flow and power permits designers to approach a series of potential turbochargers suitable for the engine. Ultimately, the final choice among several candidate turbochargers is made by tests. In this paper two types of steady-flow experiments are used to match three different turbochargers to an automotive turbocharged-intercooled gasoline engine. The first set of tests measures the steady-flow performance of the compressors and turbines of the three turbochargers. The second set of tests measures the steady-flow design-point and off-design-point engine performance with each turbocharger. The test results show the design-point and off-design-point performance of the overall thermodynamic cycle, and this is used to identify which turbocharger is suitable for different types of engine duties.

Turbocharger-Design Effects on Gasoline-Engine Performance

1997 ◽  
Author(s):  
T. Korakianitis ◽  
T. Sadoi
Keyword(s):  
Steady Flow ◽  
Mass Flow ◽  
Gasoline Engine ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Final Choice ◽  
Design Point ◽  
Theoretical Considerations ◽  
Flow Experiments

Specification of a turbocharger for a given engine involves matching the turbocharger performance characteristics with those of the piston engine. Theoretical considerations of matching turbocharger pressure ratio and mass flow with engine mass flow and power permits designers to approach a series of potential turbochargers suitable for the engine. Ultimately, the final choice among several candidate turbochargers is made by tests. In this paper two types of steady-flow experiments are used to match three different turbochargers to an automotive turbocharged-intercooled gasoline engine. The first set of tests measures the steady-flow performance of the compressors and turbines of the three turbochargers. The second set of tests measures the steady-flow design-point and off-design-point engine performance with each turbocharger. The test results show the design-point and off-design-point performance of the over-all thermodynamic cycle, and this is used to identify which turbocharger is suitable for different types of engine duties.

scholarly journals Development of a Flexible Turbine Cooling Prediction Tool for Preliminary Design of Gas Turbines

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Feijia Yin ◽  
Floris S. Tiemstra ◽  
Arvind G. Rao
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Specific Power ◽  
Inlet Temperature ◽  
Turbine Cooling ◽  
Engine Efficiency ◽  
Semi Empirical ◽  
Cooling Air

As the overall pressure ratio (OPR) and turbine inlet temperature (TIT) of modern gas turbines are constantly being increased in the pursuit of increasing efficiency and specific power, the effect of bleed cooling air on the engine performance is increasingly becoming important. During the thermodynamic cycle analysis and optimization phase, the cooling bleed air requirement is either neglected or is modeled by simplified correlations, which can lead to erroneous results. In this current research, a physics-based turbine cooling prediction model, based on semi-empirical correlations for heat transfer and pressure drop, is developed and verified with turbine cooling data available in the open literature. Based on the validated model, a parametric analysis is performed to understand the variation of turbine cooling requirement with variation in TIT and OPR of future advanced engine cycles. It is found that the existing method of calculating turbine cooling air mass flow with simplified correlation underpredicts the amount of turbine cooling air for higher OPR and TIT, thus overpredicting the estimated engine efficiency.

scholarly journals Turbine Map Extension - Theoretical Considerations and Practical Advice

2020 ◽  
Vol 4 ◽  
pp. 176-189
Author(s):  
Kurzke Joachim
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Flow Region ◽  
Aircraft Engine ◽  
Special Role ◽  
Power Simulation ◽  
Business Jet ◽  
Flow Limit ◽  
Geometrical Data

Physically sound compressor and turbine maps are the key to accurate aircraft engine performance simulations. Usually, maps only cover the speed range between idle and full power. Simulation of starting, windmilling and re-light requires maps with sub-idle speeds as well as pressure ratios less than unity. Engineers outside industry, universities and research facilities may not have access to the measured rig data or the geometrical data needed for CFD calculations. Whilst research has been made into low speed behavior of turbines, little has been published and no advice is available on how to extrapolate maps. Incompressible theory helps with the extrapolation down to zero flow as in this region the Mach numbers are low. The zero-mass flow limit plays a special role; its shape follows from turbine velocity triangle analysis. Another helpful correlation is how mass flow at a pressure ratio of unity changes with speed. The consideration of velocity triangles together with the enthalpy-entropy diagram leads to the conclusion that in these circumstances flow increases linearly with speed. In the incompressible flow region, a linear relationship exists between torque/flow and flow. The slope is independent of speed and can be found from the speed lines for which data are available. This knowledge helps in extending turbine maps into the regions where pressure ratio is less than unity. The application of the map extension method is demonstrated with an example of a three-stage low pressure turbine designed for a business jet engine.

Analyses of Off-Design Point Performances of Simple and Intercooled Brayton Helium Recuperated Gas Turbine Cycles for Generation IV Nuclear Power Plants

2017 ◽  
Author(s):  
Arnold Gad-Briggs ◽  
Pericles Pilidis
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Nuclear Power ◽  
Power Plants ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Outlet Temperature ◽  
Design Point ◽  
Part Load

The Design Point (DP) performance of a Nuclear Power Plant (NPP) is fairly straightforward to establish for a given mass flow rate, turbomachinery compressor Pressure Ratio (PR) and reactor Core Outlet Temperature (COT). The plant components are optimum for that point but this is no longer the case if the plant’s operating conditions are changed for part-load performance. Data from tests or previous operating experiences are useful in determining typical part load performance of components based on characteristic maps. However, when individual components are linked in a plant, the range of operating points for part load performances are severely reduced. The main objective of this study is to derive Off-Design Points (ODPs) for the Simple Cycle Recuperated (SCR) and Intercooled Cycle Recuperated (ICR) when considering a temperature range of −35 to 50°C and COTs between 750 to 1000°C, using a modelling & performance simulation tool designed specifically for this study, which calculates the best operational equilibrium ODPs that are critical to the economics of the NPP. Results show that the recuperator High-Pressure (HP) side and reactor pressure losses alter the actual operating parameters (mass flow rate and compressor PR). The SCR yielded a drop in plant cycle efficiency of 1% for a 4% pressure loss in comparison to the ICR (5%) for the same amount of recuperator HP losses. Other parameters such as the precooler and recuperator Low-Pressure (LP) losses still retain the same operating inlet PRs and mass flow rates regardless of the magnitude of the losses. In the absence of characteristic maps in the public domain, the ODPs have been used to produce characteristic trend maps for first order ODP calculations. The analyses intend to aid the development of cycles for Generation IV NPPs specifically Gas Cooled Fast Reactors (GFRs) and Very High Temperature Reactors (VHTRs), where helium is the coolant.

On-Line Compressor Cascade Washing for Gas Turbine Performance Investigation

2011 ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Ken Ramsden ◽  
Paul Lambart
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Flow ◽  
Engine Performance ◽  
Compressor Cascade ◽  
Design Point ◽  
Washing Process ◽  
On Line ◽  
Flow Compressor

On-line compressor washing for industrial gas turbine application is a promising method of mitigating the effects of compressor fouling degradation; however there are still few studies from actual engine experience that are inconclusive. In some cases the authors attribute this uncertainty as a result of other existing forms of degradation. The experimental approach applied here is one of the first of its kind, employing on-line washing on a compressor cascade and then relating the characteristics to a three-dimensional axial flow compressor. The overall performance of a 226MW engine model for the different cases of a clean, fouled and washed engine is obtained based on the changing compressor behavior. Investigating the effects of fouling on the clean engine exposed to blade roughness of 102μm caused 8.7% reduction in power at design point. This is equivalent, typically to 12 months degradation in fouling conditions. Decreases in mass flow, compressor efficiency, pressure ratio and unattainable design point speed are also observed. An optimistic recovery of 50% of the lost power is obtained after washing which lasts up to 10mins. Similarly, a recovery of all the key parameters is achieved. The study provides an insight into compressor cascade blade washing, which facilitates a reliable estimation of compressor overall efficiency penalties based on well established assumptions. Adopting Howell’s theory as well as constant polytropic efficiency, a general understanding of turbomachinery would judge that 50% of lost power recovered is likely to be the high end of what is achievable for the existing high pressure wash. This investigation highlights the obvious benefits of power recovery with on-line washing and the potential to maintain optimum engine performance with frequent washes. Clearly, the greatest benefits accrue when the washing process is initiated immediately following overhaul.

Re-Sizing of a Natural Gas Fired Two-Shaft Gas Turbine for Low Calorific Gas Operation

2009 ◽  
Author(s):  
Pontus Eriksson ◽  
Klas Jonshagen ◽  
Jens Klingmann ◽  
Magnus Genrup
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Mass Flow ◽  
Firing Temperature ◽  
Pressure Ratio ◽  
Gas Generator ◽  
Dimensional Parameter ◽  
Design Point ◽  
Component Size ◽  
Compressor Map

Gas turbine systems are predominantly designed to be fuelled with gaseous fuels within a limited Wobbe index range (typically HHV = 45–55 MJ/Nm3 or 1200–1480 Btu/scf). When low calorific fuel gases are fired, the engine will be forced to operate outside its design envelope. The added mass flow will typically raise the cycle pressure ratio and in two-shaft designs also raise the gas generator shaft speed. In this study, the response of a natural gas fired simple cycle two-shaft gas turbine operating at full firing temperature is investigated. A model based on the Volvo Aero Corp. VT4400 gas turbine (originally Dresser Rand DR990) characterized by one compressor and two expander maps is considered. The free turbine is operated at fixed physical speed. Different amounts of N2 or CO2 are added to the fuel path. These two inerts are typically found in large quantities in medium and low calorific fuels. The fuels lower heating value is thus gradually changed from 50 MJ/kg (21.5 kBtu/lb) to 5MJ/kg (2.15 kBtu/lb). Emphasis has been put on predicting the compressor behavior in different resizing scenarios. The full ‘firing temperature’ operating point in the compressor map is tracked as the compressor size is reduced up to 7.5%, high pressure turbine size is increased up to 20%, low pressure turbine size is changed ±7.5% or up to 10% of steam (c.f. design point compressor air mass flow) is injected between the turbines. Different re-matching schemes are discussed where one turbomachinery component size is fixed and the two other component sizes are changed such that the compressor design point is restored. Finally a re-optimized turbine flow path is computed in a fixed compressor size scenario. Results are, as far as possible, given as non-dimensional parameter groups for easy comparison with other machines.

The One-Dimensional Meanline Design of Radial Turbines for Small Scale Low Temperature Organic Rankine Cycles

2015 ◽  
Author(s):  
M. White ◽  
A. I. Sayma
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Design Methodology ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Small Scale ◽  
Design Point ◽  
Turbine Design ◽  
Isentropic Efficiency

This paper presents a complete radial turbine design methodology intended for the design of a small scale organic Rankine cycle (ORC) turbo expander. The design methodology is comprised of 1D meanline design, coupled with REFPROP for real fluid properties, and 3D geometrical construction of the turbine rotor, stator and volute. A novel method to predict the rotor passage velocity distribution also enables the rotor passage to be effectively designed to ensure a smooth expansion without requiring CFD analysis. The design method is used to construct two test turbines with target isentropic total-to-static efficiencies of 85%. The first expands air from 282.3kPa and 1073K with a total-to-static pressure ratio of 3 and mass flow rate of 0.1kg/s. The ORC turbine expands R245fa from 350K and 623kPa, with a pressure ratio of 2.5 and mass flow of 0.7kg/s. Comparison with design point CFD validates the turbine design program, predicting a mass flow rate of 0.104kg/s for the air turbine at the design point with a total-to-static isentropic efficiency of 84.73%. At the design mass flow rate and rotational speed, the ORC turbine achieves a total-to-static pressure ratio of 2.51 and a total-to-static isentropic efficiency of 84.87%.

Impact of Air System Bleeding on Aircraft Engine Performance

2011 ◽  
Author(s):  
Bin Zhao ◽  
Shaobin Li ◽  
Qiushi Li ◽  
Sheng Zhou
Keyword(s):  
Fuel Consumption ◽  
Negative Impact ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Aircraft Engine ◽  
Engine Model ◽  
Engine Thrust ◽  
Air System ◽  
Compressor Performance

Air system bleeding is indispensable to aircraft engines despite its negative impact on the engine thrust and the fuel consumption. However, the compressor performance can be improved if the bleeding design is optimized. The model in this paper is a one-dimensional engine model based on air system bleeding. The relation between the compressor performance and the engine thermodynamic cycle caused by bleeding is analyzed to explore the potential of air system bleeding in improving compressor and engine performance. The results show that if bleeding brings an increase the pressure ratio of compressor, the negative impact on engine specific fuel consumption can be inhibited. If the efficiency of compressor is increased after bleeding, the negative impact on engine thrust can be alleviated. With proper bleeding flow rates, if both the pressure ratio and the efficiency increase at the same time, the negative impact on the engine performance can be eliminated.

Investigation of the Part-Load Performance of Two 1.12 MW Regenerative Marine Gas Turbines

1992 ◽  
Author(s):  
Theodosios Korakianitis ◽  
Kurt Beier
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Thermodynamic Cycle ◽  
Operating Regime ◽  
Gas Generator ◽  
Turbine Engine ◽  
Design Point ◽  
Electric Bus ◽  
Power Turbine ◽  
Commercial Applications

Regenerative and intercooled-regenerative shaft-power gas turbine engines of low pressure ratio have significant efficiency advantages over traditional aero-derivative engines of higher pressure ratios, and can compete with modern diesel engines for marine propulsion. The design-point performance is extremely sensitive to thermodynamic-cycle parameter choices. The type of components chosen affects power and efficiency significantly. The design-point and off-design-point performance of two 1.12 MW (1500 hp) regenerative gas turbines are predicted with computer simulations. One engine has single-shaft configuration, and the other has a gas-generator / power-turbine combination. The gas-generator / power-turbine engine arrangement is essential for wide off-design operating regime. The performance of each engine driving fixed-pitch and controllable-pitch propellers, or an AC electric bus (for electric-motor-driven propellers) is investigated. For commercial applications the controllable-pitch propeller may have efficiency advantages (depending on engine type and shaft arrangements). For military applications the electric drive provides better operational flexibility.

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