Bio-Inspired High Pressure Turbine Optimization Strategy for Hybrid-Electric Engines Operating at Off-Design

2020 ◽  
Author(s):  
Paht Juangphanich ◽  
Guillermo Paniagua ◽  
Vikram Shyam
Keyword(s):  
High Pressure ◽  
Separation Bubble ◽  
Leading Edge ◽  
Suction Side ◽  
Superior Performance ◽  
Optimization Strategy ◽  
High Pressure Turbine ◽  
Flow Angle ◽  
Diverse Range ◽  
Pressure Losses

Abstract Incident tolerant turbine design is a major challenge for any turbomachinery designer. High Pressure Turbines experience large aerodynamic losses when operating at reduced massflow and lower RPM. Turbine performance is adversely impacted at positive incidence angles due to shifting of the stagnation point towards the pressure side. This can cause a separation bubble in the aft suction side region. In marine life, a diverse range of animals have developed wavy surfaces along their fins and bodies to prevent stall or flow separation at engine-relevant Reynolds numbers, but for incompressible fluids. This paper describes a novel parameterization strategy for optimizing wavy-shaped airfoils to offer superior performance at off-design operation, in the present case, at positive incidence. The methodology can be applied to all types of aircraft engines: one, two, or three spool engine configurations. The parameterized geometries are compatible with existing gas turbine manufacturing processes including casting and additive manufacturing [1,2]. The objective of the optimization was to discover the appropriate waveform combinations at the airfoil leading edge, trailing edge, and suction side characterized by their amplitude, phase, and frequency, such that the airfoils offer the lowest possible pressure losses at 15 degrees positive incidence. The optimization was performed on a high pressure turbine passage, optimized for best efficiency at nominal conditions, while maintaining the same exit flow angle and massflow. The Reynolds number is 850,000. Based on 286 designs produced, the results of the optimization show a clear benefit at positive incidence, at the expense of a slightly lower performance at nominal conditions. A final comparison of the optimized rotor with stage is included in the analysis.

Heat Transfer and Aerodynamics of Over-Shroud Leakage Flows in a High-Pressure Turbine

2009 ◽  
Author(s):  
Knut Lehmann ◽  
Richard Thomas ◽  
Howard Hodson ◽  
Vassilis Stefanis
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Large Scale ◽  
Suction Side ◽  
Surface Flow ◽  
Tip Clearance ◽  
Flow Visualisation ◽  
Leakage Flow ◽  
High Pressure Turbine ◽  
High Heat Transfer

An experimental study has been conducted to investigate the distribution of the convective heat transfer on the shroud of a high pressure turbine blade in a large scale rotating rig. A continuous thin heater foil technique has been adapted and implemented on the turbine shroud. Thermochromic Liquid Crystals were employed for the surface temperature measurements to derive the experimental heat transfer data. The heat transfer is presented on the shroud top surfaces and the three fins. The experiments were conducted for a variety of Reynolds numbers and flow coefficients. The effects of different inter-shroud gap sizes and reduced fin tip clearance gaps were also investigated. Details of the shroud flow field were obtained using an advanced Ammonia-Diazo surface flow visualisation technique. CFD predictions are compared with the experimental data and used to aid interpretation. Contour maps of the Nusselt number reveal that regions of highest heat transfer are mostly confined to the suction side of the shroud. Peak values exceed the average by as much as 100 percent. It has been found that the interaction between leakage flow through the inter-shroud gaps and the fin tip leakage jets are responsible for this high heat transfer. The inter-shroud gap leakage flow causes a disruption of the boundary layer on the turbine shroud. Furthermore, the development of the large recirculating shroud cavity vortices is severely altered by this leakage flow.

scholarly journals Evaluation of High Pressure Turbine Blade Coatings on an LM2500 Rainbow Rotor

1995 ◽  
Author(s):  
B. Nagaraj ◽  
G. Katz ◽  
A. F. Maricocchi ◽  
M. Rosenzweig
Keyword(s):  
High Pressure ◽  
Turbine Blades ◽  
Leading Edge ◽  
Service Evaluation ◽  
High Pressure Turbine ◽  
Barrier Coating ◽  
Marine Propulsion ◽  
Corrosion Resistant Coatings ◽  
Stage 1 ◽  
Plasma Sprayed

Two LM2500 rainbow rotors with repaired stage 1 and stage 2 high pressure turbine blades are being assembled for marine propulsion service evaluation by the US Navy. The blades have seen between 5,000 and 15,000 hours of service in the Navy’s Fleets. A number of corrosion resistant coatings including plasma sprayed CoCrAlHf (bill of material), composite plated CoCrAlHf, platinum aluminide, aluminum silicide, and physical vapor deposited yttria stabilized zirconia thermal barrier coating (PVD TBC) will be evaluated in the rainbow rotor. This paper will discuss the advantages and microstructures of the various coatings. Composite plated CoCrAlHf, and PVD TBCs were recently service evaluated in an industrial LM2500 rainbow rotor for 10,500 hours. Both these coatings performed well, although the PVD TBC had local spallation at the leading edge. This paper will review the details of performance of these two coatings in the industrial LM2500 application.

Clocking Effects of Inlet Non-Uniformities in a Fully Cooled High-Pressure Vane: A Conjugate Heat Transfer Analysis

2015 ◽  
Author(s):  
Duccio Griffini ◽  
Massimiliano Insinna ◽  
Simone Salvadori ◽  
Francesco Martelli
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Cooling System ◽  
Hot Spot ◽  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Heat Transfer Analysis

A high-pressure vane equipped with a realistic film-cooling configuration has been studied. The vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side while the leading edge is protected by a showerhead system of cylindrical holes. Steady three-dimensional Reynolds-Averaged Navier-Stokes (RANS) simulations have been performed. A preliminary grid sensitivity analysis with uniform inlet flow has been used to quantify the effect of spatial discretization. Turbulence model has been assessed in comparison with available experimental data. The effects of the relative alignment between combustion chamber and high-pressure vanes are then investigated considering realistic inflow conditions in terms of hot spot and swirl. The inlet profiles used are derived from the EU-funded project TATEF2. Two different clocking positions are considered: the first one where hot spot and swirl core are aligned with passage and the second one where they are aligned with the leading edge. Comparisons between metal temperature distributions obtained from conjugate heat transfer simulations are performed evidencing the role of swirl in determining both the hot streak trajectory within the passage and the coolant redistribution. The leading edge aligned configuration is resulted to be the most problematic in terms of thermal load, leading to increased average and local vane temperature peaks on both suction side and pressure side with respect to the passage aligned case. A strong sensitivity of both injected coolant mass flow and heat removed by heat sink effect has also been highlighted for the showerhead cooling system.

Acoustic and phase portrait analysis of leading-edge roughness element on laminar separation bubbles at low Reynolds number flow

2021 ◽  
pp. 095441002110443
Author(s):  
Hossein Jabbari ◽  
Esmaeili Ali ◽  
Mohammad Hasan Djavareshkian
Keyword(s):  
Reynolds Number ◽  
Phase Portrait ◽  
Separation Bubble ◽  
Roughness Element ◽  
Low Reynolds Number ◽  
Leading Edge ◽  
Suction Side ◽  
Laminar Separation ◽  
Roughness Elements ◽  
Edge Roughness

Since laminar separation bubbles are neutrally shaped on the suction side of full-span wings in low Reynolds number flows, a roughness element can be used to improve the performance of micro aerial vehicles. The purpose of this article was to investigate the leading-edge roughness element’s effect and its location on upstream of the laminar separation bubble from phase portrait point of view. Therefore, passive control might have an acoustic side effect, especially when the bubble might burst and increase noise. Consequently, the effect of the leading-edge roughness element features on the bubble’s behavior is considered on the acoustic pressure field and the vortices behind the NASA-LS0417 cross-section. The consequences express that the distribution of roughness in the appropriate dimensions and location could contribute to increasing the performance of the airfoil and the interaction of vortices produced by roughness elements with shear layers on the suction side has increased the sound frequency in the relevant sound pressure level (SPL). The results have demonstrated that vortex shedding frequency was increased in the presence of roughness compared to the smooth airfoil. Also, more complexity of the phase portrait circuits was found, retrieved from velocity gradient limitation. Likewise, the highest SPL is related to the state where the separation bubble phenomenon is on the surface versus placing roughness elements on the leading edge leads to a negative amount of SPL.

Using CFD to Reduce Resonant Stresses on a Single-Stage, High-Pressure Turbine Blade

2002 ◽  
Author(s):  
J. P. Clark ◽  
A. S. Aggarwala ◽  
M. A. Velonis ◽  
R. E. Gacek ◽  
S. S. Magge ◽  
...  
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Guide Vane ◽  
Turbine Blades ◽  
Suction Side ◽  
Lessons Learned ◽  
Single Stage ◽  
Navier Stokes ◽  
High Pressure Turbine ◽  
Time Resolved

The ability to predict levels of unsteady forcing on high-pressure turbine blades is critical to avoid high-cycle fatigue failures. In this study, 3D time-resolved computational fluid dynamics is used within the design cycle to predict accurately the levels of unsteady forcing on a single-stage high-pressure turbine blade. Further, nozzle-guide-vane geometry changes including asymmetric circumferential spacing and suction-side modification are considered and rigorously analyzed to reduce levels of unsteady blade forcing. The latter is ultimately implemented in a development engine, and it is shown successfully to reduce resonant stresses on the blade. This investigation builds upon data that was recently obtained in a full-scale, transonic turbine rig to validate a Reynolds-Averaged Navier-Stokes (RANS) flow solver for the prediction of both the magnitude and phase of unsteady forcing in a single-stage HPT and the lessons learned in that study.

scholarly journals Turbulence Amplification with Incidence at the Leading Edge of a Compressor Cascade

1999 ◽  
Vol 5 (2) ◽  
pp. 89-98 ◽  
Author(s):  
Garth V. Hobson ◽  
Bryce E. Wakefield ◽  
William B. Roberts
Keyword(s):  
Separation Bubble ◽  
Leading Edge ◽  
Laser Doppler Velocimeter ◽  
Free Shear Layer ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Flow Angle ◽  
Laminar Separation ◽  
High Incidence ◽  
High Turbulence

Detailed measurements, with a two-component laser-Doppler velocimeter and a thermal anemometer were made near the suction surface leading edge of controlled-diffusion airfoils in cascade. The Reynolds number was near 700,000, Mach number equal to 0.25, and freestream turbulence was at 1.5% ahead of the cascade.It was found that there was a localized region of high turbulence near the suction surface leading edge at high incidence. This turbulence amplification is thought to be due to the interaction of the free-shear layer with the freestream inlet turbulence. The presence of the local high turbulence affects the development of the short laminar separation bubble that forms very near the suction side leading edge of these blades. Calculations indicate that the local high levels of turbulence can cause rapid transition in the laminar bubble allowing it to reattach as a short “non-burst” type.The high turbulence, which can reach point values greater than 25% at high incidence, is the reason that leading edge laminar separation bubbles can reattach in the high pressure gradient regions near the leading edge. Two variations for inlet turbulence intensity were measured for this cascade. The first is the variation ofmaximum inlet turbulence with respect to inlet-flow angle; and the second is the variation of leading edge turbulence with respect to upstream distance from the leading edge of the blades.

Experimental Study of Leakage Flow on Flow Field and Film Cooling of High Pressure Turbine Blade Platform

2015 ◽  
Author(s):  
Kenichiro Takeishi ◽  
Yutaka Oda ◽  
Shintaro Kozono
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Turbine Blades ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Temperature Fields ◽  
Leakage Flow ◽  
High Pressure Turbine ◽  
Film Cooling Effectiveness ◽  
Injection Angle

An experiment has been conducted to study stator/rotor disc cavity leakage flow on the platform of a highly loaded stationary linear blade cascade. The linear cascade consists of a scaled-up model of the high-pressure turbine blades of an E3 (Energy efficient engine) and leakage slot models installed under the platform. Experiments have been conducted to investigate the effect of the slot injection angle, leakage flow rates, distance between the leading edge of the blade and the slot, and spacing of the blades. The film-cooling effectiveness was measured by pressure sensitive paint (PSP), and the temperature fields and flow fields were investigated using laser-induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. It was observed from the experiments that the leakage flow covered the surface of the blade platform when the distance between the leading edge and the slot was zero; however, with increasing distance, the horseshoe vortex dominates near the junction of the blade leading edge, and the leakage flow could not cover the region. It was also found that the leakage flow has an effect that promotes the formation of the horseshoe vortex for some experimental conditions.

The Influence of Upstream Flow Angle Variation on Intermediate Turbine Duct

2014 ◽  
Vol 670-671 ◽  
pp. 705-708
Author(s):  
Yang Wang
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Flow Condition ◽  
Quantitative Result ◽  
Complex Flow ◽  
High Pressure Turbine ◽  
Angle Variation ◽  
Flow Angle ◽  
Intermediate Turbine Duct ◽  
Upstream Flow

Intermediate turbine duct represent the flow path between the high pressure and low pressure turbine. Caused by the complex flow mechanism, the outlet flow condition of the high pressure turbine is easily changed. Since the upstream flow condition from the high pressure turbine has a significant effect on the internal flow field of intermediate turbine duct, the study in the upstream condition is of high value. Through numerical simulation, the influence of upstream flow angle variation on intermediate turbine duct is observed. It is found that the main influence of the flow angle variation is near the hub side of the duct, and the quantitative result shows that a larger flow angle has a positive effect on the flow field and can reduce loss.

Experimental Investigation of the Clocking Effect in a 1.5-Stage Axial Turbine—Part II: Unsteady Results and Boundary Layer Behavior

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Sven König ◽  
Bernd Stoffel ◽  
M. Taher Schobeiri
Keyword(s):  
Boundary Layer ◽  
Separation Bubble ◽  
Measurement Techniques ◽  
Leading Edge ◽  
Suction Side ◽  
Experimental Investigations ◽  
Stress Signal ◽  
Upstream Direction ◽  
Loss Parameter ◽  
Lp Turbine

Comprehensive experimental investigations were conducted to get deeper insight into the physics of stator clocking in turbomachines. Different measurement techniques were used to investigate the influence of varying clocking positions on the highly unsteady flow field in a 1.5-stage axial low-pressure (LP) turbine. A Reynolds number typical for LP turbines as well as a two-dimensional blade design were chosen. Stator 2 was developed as a high-lift profile with a separation bubble on the suction side. This paper presents the results that were obtained by means of unsteady x-wire measurements upstream and downstream of Stator 2 and surface mounted hot-film measurements on the Stator 2 suction side. It was found that for the case when the Stator 1 wakes impinge close to the leading edge of Stator 2 the interaction between the Stator 1 and the rotor vortical structures takes place in proximity of the Stator 2 boundary layer, which leads to a shift of the transition point in the upstream direction. The major loss parameter concerning the Stator 2 aerodynamic performance could be attributed to the strength of the periodic fluctuations within the Stator 2 suction side boundary layer. A phase shift in the quasiwall shear stress signal in the front region of the Stator 2 vane was observed for different clocking positions.

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