Prediction of the steady and non-steady flow performance of a highly loaded mixed flow turbine

Abidat, M.; Hachemi, Messaoud; Hamidou, M.; Baines, N. C.

doi:10.1243/0957650981536844

Cited by 42 publications

(24 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The impacts on different kinds of single stage turbine including double-entry turbine [4], waste-gated turbine [5,6], nozzled turbine [7] and variable geometry turbine [8] were studied. The characteristics of radial and mixed-flow turbines under pulsating flow conditions were disclosed in the investigations of Baines [9,10]. Under pulsating flow condition, the curve of mass flow rate versus expansion ratio is a hysteresis loop, which moves around the steady state performance curve.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Flow Loss Mechanism and Aerodynamic Improvement of Two-Stage Turbine under Pulsating Conditions

Zhao

Zhuge

et al. 2019

Entropy

View full text Add to dashboard Cite

The developments of two-stage turbocharging and turbocompounding promote the application of the two-stage turbine system in internal combustion engines. Since the turbine suffers from the pulsating exhaust, the performance deteriorates significantly from steady conditions. In the paper, the pulsating flow losses in the two-stage turbine are analyzed and a control method is proposed to improve the turbine performance. ANSYS CFX, which is a commercial software for computational fluid dynamic, is applied to resolve the three-dimensional unsteady flow problem. The accuracy of the simulation method is verified by the experimental data from each turbine. Firstly, the impacts of pulse amplitudes on transient loss of each component of the two-stage turbine are studied. Then flow field analysis is carried out to understand details of the unsteady flows. It is found that the variation of incidence angle at the low-pressure turbine (LPT) rotor tip is significantly larger than that at rotor hub, which causes severe flow loss near leading edge. As a result, the LPT performance drops down significantly. To improve the LPT performance, the blade shape at tip is modified. The aerodynamic performances of turbines with three different shapes under high- and low-load pulsating flow conditions are evaluated. It is found that increased inlet blade angle and medium thickness achieves good aerodynamic performance. The rotor averaged efficiency is improved by 2.27% under high-load pulsating condition.

show abstract

Section: Introductionmentioning

confidence: 99%

Unsteady Flow Loss Mechanism and Aerodynamic Improvement of Two-Stage Turbine under Pulsating Conditions

Zhao

Zhuge

et al. 2019

Entropy

View full text Add to dashboard Cite

show abstract

“…3 against a steady flow characteristic, deviation of the orbit from the characteristic line indicates that the QSF assumption tends to break down under certain pulse conditions. 7,8,17,21,22,26,27,28,29 Reduced…”

Section: The Quasi-steadiness Assumption and Other Modeling Apprmentioning

confidence: 99%

“…15,40,41 Some researchers indicated that pulse frequency was not as important as pulse amplitude in the performance of the system. 17,23,42 A recent simulation showed that for fixed amplitude of mass flow variation over a pulse, increasing pulse frequency increased the range of incidence, increasing the unsteadiness, thus lowering the efficiency. 21 Given the qualitative trends of increasing orbit variation with increases in frequency for fixed amplitude of oscillations 17,28 , frequency is seen to enhance unsteadiness, which leads to higher off-design losses and contradicts the claim for increased efficiency.…”

Section: Parametric Variations In Pulsed Flow Turbinesmentioning

confidence: 99%

Trends in Pulsating Turbine Performance: Pulse-Detonation Driven Axial Flow Turbine

George

Gutmark

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

View full text Add to dashboard Cite

An investigation of previous studies involving turbines driven by pulsating, unsteady flows is conducted. The suitability of conventional steady flow performance metrics for application to the case of pulsating flow is discussed, with a focus on the observed deviation from quasi-steady behavior. This deviation is found to be a strong function of upstream geometry, pulse form and amplitude, and disparity between the time scales of the pulse and of the rotor dynamics. Existing studies exhibit controversy as to the effects of parametric variation of pulsating flow quantities on the turbine performance as well as suitable metrics to describe this performance. These studies are used to predict qualitative trends for the performance of an integrated pulse-detonation driven axial turbine. Trends from current experimental studies of pulse-detonation driven flows are examined to assess these hypotheses. Nomenclaturea = Sonic Velocity (m/s) PDC = Pulse Detonation Combustion AF = Amplitude Factor PDE = Pulse Detonation Engine BSR = Blade Speed Ratio, Velocity Ratio PMSt = Pressure Modified Strouhal Number C = Absolute Flow Velocity (m/s) PR = Pressure Ratio c p = Specific Heat at Constant Pressure (J/kg·K) QSF = Quasi-Steady Flow CVC = Constant Volume Combustion St = Strouhal Number d = Diameter (m) T = Temperature (K) f = Frequency of Pulsation (Hz) U = Rotor Tip (Blade) Speed (m/s) h = Specific Enthalpy (J/kg) v = Mean Flow Velocity (m/s) L = Characteristic Length (m) W = Relative Flow Velocity (m/s) ṁ = Mass Flow Rate (kg/s) x = Arbitrary Spatial Location MFP = Mass Flow Parameter (K ½ ·s/m) β = Reduced Frequency MSt = Modified Strouhal Number γ = Ratio of Specific Heats N = Turbine Speed (rad/s) η = Efficiency T N / = Normalized Turbine Speed (rad/K ½ s) φ = Duty Cycle P = Power (W), Pressure (Pa) τ = Torque (N·m) ω = Frequency of Pulsation (rad/s)

show abstract

“…This length selection was done supposing that half the mass flow enters the rotor at this point. This method is further refined and used in other works, such as in the work by Abidat et al [7] and by Costall et al [8]. The accuracy of this one-dimensional approach is limited for frequencies higher than 1000 Hz, and it is expected that a more realistic simulation of the volute, taking into account its lateral window flow, should provide better results.…”

Section: Introductionmentioning

confidence: 99%

Effect of the numerical scheme resolution on quasi-2D simulation of an automotive radial turbine under highly pulsating flow

Galindo

Climent

Tiseira

et al. 2016

Journal of Computational and Applied Mathematics

View full text Add to dashboard Cite

Elsevier Galindo, J.; Climent, H.; Tiseira Izaguirre, AO.; García-Cuevas González, LM. (2016). Effect of the numerical scheme resolution on quasi-2D simulation of an automotive radial turbine under highly pulsating flow. AbstractAutomotive turbocharger turbines usually work under pulsating flow because of the sequential nature of engine breathing. However, existing turbine models are typically based on quasi-steady assumptions. In the paper a model where the volute is calculated in a quasi-2D scheme is presented. The objective of the work is to quantify and analyse the effect of the numerical resolution scheme used in the volute model. The conditions imposed upstream are isentropic pressure pulsations with different amplitude and frequency. The volute is computed using a finite volume approach considering the tangential and radial velocity components. The stator and rotor are assumed to be quasi-steady. In the paper, different integration and spatial reconstruction schemes are explored. The spatial reconstruction is based on the MUSCL method with different slope limiters fulfilling the TVD criterion. The model results are assessed against 3D U-RANS calculations. The results show that under low frequency pressure pulses all the schemes lead to similar solutions. But, for high frequency pulsation the results can be very different depending upon the selected scheme. This may have an impact in noise emission predictions.

show abstract

Prediction of the steady and non-steady flow performance of a highly loaded mixed flow turbine

Cited by 42 publications

References 3 publications

Unsteady Flow Loss Mechanism and Aerodynamic Improvement of Two-Stage Turbine under Pulsating Conditions

Unsteady Flow Loss Mechanism and Aerodynamic Improvement of Two-Stage Turbine under Pulsating Conditions

Trends in Pulsating Turbine Performance: Pulse-Detonation Driven Axial Flow Turbine

Effect of the numerical scheme resolution on quasi-2D simulation of an automotive radial turbine under highly pulsating flow

Contact Info

Product

Resources

About