scholarly journals Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

2018 ◽  
Author(s):  
Jan Mihalyovics ◽  
Christian Brück ◽  
Dieter Peitsch ◽  
Ilias Vasilopoulos ◽  
Marcus Meyer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Experimental Studies ◽  
Total Pressure Loss ◽  
Design Parameters ◽  
Flow Conditions ◽  
Flow Angle ◽  
Flow Phenomena ◽  
The Impact ◽  
Stator Design

The objective of the presented work is to perform numerical and experimental studies on compressor stators. This paper presents the modification of a baseline stator design using numerical optimization resulting in a new 3D stator. The Rolls Royce in-house compressible flow solver HYDRA was employed to predict the 3D flow, solving the steady RANS equations with the Spalart-Allmaras turbulence model, and its corresponding discrete adjoint solver. The performance gradients with respect to the input design parameters were used to optimize the stator blade with respect to the total pressure loss over a prescribed incidence range, while additionally minimizing the flow deviation from the axial direction at the stator exit. Non-uniform profile boundary conditions, being derived from the experimental measurements, have been defined at the inlet of the CFD domain. The presented results show a remarkable decrease in the axial exit flow angle deviation and a minor decrease in the total pressure loss. Experiments were conducted on two compressor blade sets investigating the three-dimensional flow in an annular compressor stator cascade. Comparing the baseline flow of the 42° turning stator shows that the optimized stator design minimizes the secondary flow phenomena. The experimental investigation discusses the impact of steady flow conditions on each stator design while focusing on the comparison of the 3D optimized design to the baseline case. The flow conditions were investigated using five-hole probe pressure measurements in the wake of the blades. Furthermore, oil-flow visualization was applied to characterize flow phenomena. These experimental results are compared with the CFD calculations.

The Design, Analysis and Test of a Unique Gas Turbine Scroll for the F-35, Joint Strike Fighter

2006 ◽  
Author(s):  
Hakan Aksoy ◽  
Stony W. Kujala ◽  
Craig W. McKeever ◽  
Ly D. Nguyen
Keyword(s):  
Mach Number ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
Flow Distortion ◽  
Cfd Simulations ◽  
Flow Angle ◽  
Auxiliary Power Unit ◽  
Auxiliary Power ◽  
Stringent Performance

The design of the APU (Auxiliary Power Unit) for the F-35 JSF (Joint Strike Fighter) focused on minimizing size and weight while meeting stringent performance goals. To help realize that goal, a unique turbine scroll was designed. The scroll design delivers air from the combustor to the turbine inlet with minimal loss and flow distortion while minimizing design space. CFD (Computational Fluid Dynamics) results of scroll total pressure loss and exit peripheral distribution of total pressure, Mach number, and flow angle are presented. Rig tests were utilized for measuring and validating the computed total pressure and Mach number distributions around the periphery of the scroll exit. Comparisons of the CFD simulations and test data indicate strong correlation in values of average total pressure loss, local total pressure loss and Mach number around the exit periphery.

Impacts of tandem configurations on the aerodynamic performance of an axial supersonic through-flow fan cascade

2021 ◽  
pp. 1-25
Author(s):  
Shijun Sun ◽  
Jiaqi Hao ◽  
Jutao Yang ◽  
Ling Zhou ◽  
Lucheng Ji
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Threshold Value ◽  
Total Pressure Loss ◽  
System Structure ◽  
Pressure Loss Coefficient ◽  
Through Flow ◽  
Shock System ◽  
The Impact ◽  
Total Pressure Loss Coefficient

Abstract In the current study, the tandem blade technology is applied to an STFF tandem cascade for the first time, and a 2D STFF tandem cascade is preliminarily designed. Through the modification design of the tandem airfoils and their configuration (axial overlap, AO and percent pitch, PP), the coefficients of total pressure loss and loading are reduced by 4% and 8.58%, respectively. Furtherly, the impact of tandem configurations on the performance is parametrically investigated by numerical simulations. The results indicate that compared with AO, the performance under design incidence is more sensitive to PP except for the cases with PP exceeding a threshold value (1.15). PP dominates the loss and load by controlling the evolution of the FB wake and the shock structure of FB and RB, while AO mainly adjusts the entire shock system structure through the change of virtual shape, resulting in the variation in load distribution between FB and RB. It is worth noting that the overall loading and the total loss remain unchanged with increasing AO except for the tandem configurations (PP=1.05, AO≤−0.01), which make the flow structure in the gap region undergo a fundamental change. With the optimal tandem configuration (PP=1.05, AO=−0.01) and the modified tandem blades (The ratios of chord length and camber for FB over RB is 0.67 and 0.5, respectively), the total pressure loss coefficient is further reduced by 19.7% in comparison with the preliminary tandem design.

Influence of Pulsating Flow on Turbine Performance Investigated by DES and PIV

2018 ◽  
Author(s):  
Yohei Nakamura ◽  
Manato Chinen ◽  
Masamichi Sakakibara ◽  
Kazuyoshi Miyagawa
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Internal Flow ◽  
Pulsating Flow ◽  
Total Pressure Loss ◽  
Operating Point ◽  
Pulsation Frequency ◽  
Flow Conditions ◽  
Experimental Apparatus ◽  
Loss Mechanisms

Recently, the downsizing of engine using turbocharger attracts more and more attention. Generally speaking, a turbocharger is usually designed based on its steady performance curve. However, the operating point of a turbocharger turbine does not match the steady operating point: instead it shows hysteresis behavior because of the pulsating flow generated by the engine valves. Unfortunately, turbine efficiency drops under pulsating flow conditions, but the loss mechanisms of the turbine under these conditions are not understood. Internal flow measurements under pulsating flow are actually very difficult. In this study, the internal flow under pulsating conditions was measured using a high speed PIV (Particle Image Velocimetry) system. The loss mechanisms were investigated by experimental investigation and computational fluid dynamics (CFD). The instantaneous pressure, velocity and torque were measured using a turbine experimental apparatus at WASEDA University. To generate the pulsating flow, a pulse generator was placed upstream of the turbine: a rotational disk with holes that only lets the flow through periodically. The pulsating frequency could be changed freely by changing the rotational speed of the disk. The visualization using PIV was performed at a frequency of 1 kHz at the turbine outlet. Many fine vortices which rotate in various directions were observed under pulsating flow. Such vortices mix in the exhaust diffuser and under low frequency flow, mixing of vortices took a long time. It was observed that one loss mechanism under unsteady conditions is the mixing of vortices at the turbine outlet. CFD was performed using ANSYS-CFX, with approximately 10 million nodes. Turbulent flows were treated by using the Reynolds-averaged Navier-Stokes (RANS) and Detached Eddy Simulation (DES) with the SST k-ω turbulence model. It was confirmed that the wheel and exhaust diffuser total pressure loss under pulsating flow was higher under steady flow conditions. In addition, the total pressure loss is proportional to the flow pulsation frequency. The analysis with DES agreed with the PIV results qualitatively. On the other hand, the analysis with RANS could not simulate the flow pattern at the turbine outlet.

Different Effects of Cantilevered and Shrouded Stators on Axial Compressor Performance

2017 ◽  
Author(s):  
Xiayi Si ◽  
Jinfang Teng ◽  
Xiaoqing Qiang ◽  
Jinzhang Feng
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Axial Position ◽  
Leakage Flow ◽  
Flow Angle ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Total Pressure Loss Coefficient

Numerical simulations with the steady 3D RANS were performed on the rear stage of a modern high pressure compressor. The labyrinth seal cavity model of the shrouded stator was simplified according to the actual stator structure, which the seal cavity gap is 1% of blade height. Several typical configurations (shrouded stator, idealized stator and cantilevered stators) were designed and carried out, and cantilevered stators contained no gap, small gap (CS1%), design gap (CS2.5%) and large gap (CS4%/CS5%). The results indicate due to the effect of leakage flow from 1% span seal cavity gap, the total pressure loss of SS is larger than IS, while IS instead of SS in the process of the compressor design, the stall margin will be enlarged nearly 6% numerically. At the design point, when the hub gap is 3.5% span clearance CS has the same loss with IS, and when the hub gap is 4.5% span clearance CS has almost the same loss with SS. Among all operation range, the total pressure loss of S1 increases with the increase of the hub clearance. When the hub gap is 0 (CS0), there is no leakage flow and the loss is the least. At the design point, comparing with SS, the total pressure loss coefficient of CS0 decreases 18.34%, CS2.5% decreases 8.46% and IS decreases 6.45%. It means if the cantilevered stator with 2.5% span hub clearance were adopted in the HPC, the performance would be better than the shrouded stator. However, because of the matching condition, the rotor that follows after cantilevered stator should be redesigned according to blade loading and inlet flow angle changed. The performance of cantilevered stator is impacted of various hub clearance, the loss below 25% span increases significantly with hub clearance, the maximum value of outlet flow angle deviation is 2.3 degree. The stator hub peak loading is shifted upstream toward the leading edge when hub clearance size is increased. The total pressure loss coefficient and pressure coefficient at different axial position had the function relation. When the hub clearance increases, the position of double leakage flow start backwards, in the rear part of stator the secondary flow becomes stronger leading to more mixing loss and lower total pressure.

Experimental Investigation of the Clocking Effect in a 1.5-Stage Axial Turbine—Part I: Time-Averaged Results

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Sven König ◽  
Bernd Stoffel ◽  
M. Taher Schobeiri
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Separation Bubble ◽  
Measurement Techniques ◽  
Suction Side ◽  
Total Pressure Loss ◽  
Experimental Investigations ◽  
Flow Angle ◽  
Factors Affecting ◽  
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 static pressure tappings and five-hole probes as well as the time-averaged results of unsteady x-wire measurements. The probes were traversed in different measuring planes for ten clocking positions. Depending on the clocking position, a variation in total pressure loss for Stator 2, a change of the rotor exit flow angle, and a dependency of the Stator 2 exit flow angle were found. The influence of these parameters on turbine efficiency was studied. Three main factors affecting the total pressure loss could be separated: the size of the separation bubble, the production of turbulent kinetic energy, and the strength of the periodic fluctuations downstream of Stator 2.

scholarly journals Optimization Study of the Dump Diffuser in Gas Turbine to Reduce Pressure Loss

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Fei Xing ◽  
Hao Su ◽  
Shining Chan ◽  
Leilei Xu ◽  
Xinyi Yu
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Vortex Method ◽  
Total Pressure Loss ◽  
Pressure Recovery ◽  
Test Model ◽  
Gap Ratio ◽  
Efficient Combustion ◽  
The Impact

As a key component-connecting compressor and the entrance of combustion chamber, the diffuser is able to increase the pressure and slow down the airflow in order to promote efficient combustion as well as avoid a large amount of pressure loss. In this paper, experimental investigation and numerical studies have been carried out to understand the effects of air bleeding from dump region and dump gap ratio on the total pressure loss and static pressure recovery of the dump diffusers. The ultimate objective is optimizing the dump diffuser design to get the maximum static pressure recovery and minimum total pressure loss. A simplified test model is used to study the effect of the air bleeding from the outer dump region and the dump gap ratio on the total pressure loss and static pressure recovery in the dump diffuser. The impact of the dump gap ratio in the performance of the dump diffusers has also been discussed. Nearly all the pressure raise occurs in the prediffuser, and most of the total pressure loss occurs in the dump region. For the recirculating area in the dump region, the controllable vortex can be introduced. Bleeding air from the outer dump region can improve the velocity distribution near the flame tube. The results show that when 0.4% of the air is bled from outer dump region, the performance of the dump diffuser is optimal. Hence, the controllable vortex method is effective for improving the performance of the dump diffuser.

scholarly journals Investigation of Wash Fluid Preheating on the Effectiveness of Online Compressor Washing in Industrial Gas Turbines

2020 ◽  
Author(s):  
Roupa Agbadede ◽  
Biweri Kainga
Keyword(s):  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Flow Angle ◽  
Pressure Loss Coefficient ◽  
Industrial Gas Turbines ◽  
Total Pressure Loss Coefficient

Abstract This study presents an investigation of wash fluid preheating on the effectiveness of online compressor washing in industrial gas turbines. Crude oil was uniformly applied on the compressor cascade blades surfaces using a roller brush, and carborundum particles were ingested into the tunnel to create accelerated fouled blades. Demineralized water was preheated to 500C using the heat coil provided in the tank. When fouled blades washed with preheated demineralized and the one without preheating were compared, it was observed that there was little or no difference in terms of total pressure loss coefficient and exit flow angle. However, when the fouled and washed cases were compared, there was a significant different in total pressure loss coefficient and exit flow angle.

Improvement of Aerodynamic Performance of a Combustor Dump Diffuser Using Inclined Walls

2000 ◽  
Author(s):  
Shinji Honami ◽  
Eiichi Yamazaki ◽  
Takaaki Shizawa
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Aerodynamic Performance ◽  
Total Pressure Loss ◽  
Flow Conditions ◽  
Mean Velocity ◽  
Cold Flow ◽  
Inlet Distortion ◽  
Flow Experiment ◽  
The Mean

The combustor diffuser with the deep flame dome in the recent engine results in the large total pressure loss. It is important to obtain both better aerodynamic performance by reduction of total pressure loss and reduced NOx in the exhaust from the combustor, regardless of the inlet flow conditions such as inlet distortion. Installation of an inclined wall within the combustor dump diffuser is suggested in order to improve the aerodynamic performance. A cold flow experiment using Pitot probe surveys in a model of a combustor diffuser shows that the inclined wall is effective in improvement of the total pressure loss, even if the velocity profile at the diffuser inlet is distorted. Furthermore, the flow rate distributions into the branched channels are also improved. The flow mechanism in the inclined wall configuration is clarified from the measurements of the mean velocity and turbulent Reynolds stress by a Laser Doppler Velocimetry (LDV) system.

scholarly journals Correlation between total pressure losses of highly loaded annular diffusers and integral stage design parameters

2018 ◽  
Vol 2 ◽  
pp. I9AB30 ◽  
Author(s):  
Dajan Mimic ◽  
Christoph Jätz ◽  
Florian Herbst
Keyword(s):  
Boundary Layer ◽  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
Pressure Recovery ◽  
Design Parameters ◽  
Pressure Losses ◽  
Tip Leakage ◽  
Highly Loaded

Diffusers convert kinetic flow energy into a rise in static pressure. This pressure recovery is the primary aerodynamic design objective for exhaust gas diffusers in power-generating steam and gas turbines. The total pressure loss is an equally important diffuser design parameter. It is strongly linked to the pressure recovery and the residual kinetic energy of the diffuser outlet flow. A reduction benefits the overall thermodynamic cycle, which requires the adjacent components of a diffuser to be included in the design process. This paper focuses on the total pressure losses in the boundary layer of a highly loaded annular diffuser. Due to its large opening angle the diffuser is susceptible to flow separation under uniform inlet conditions, which is a major source for total pressure losses. However, the unsteady tip leakage vortices of the upstream rotor, which are a source of losses, stabilise the boundary layer and prevent separation. Experiments and unsteady numerical simulation conducted show that the total pressure loss reduction caused by the delayed boundary layer separation exceed the vortex-induced losses by far. This flow interaction between the rotor and diffuser consequently decreases the overall total pressure losses. The intensity of the tip leakage vortex is linked to three rotor design parameters, namely work coefficient, flow coefficient and reduced blade-passing frequency. Based on these parameters, we propose a semi-empiric correlation to predict and evaluate the change in total pressure losses with regards to design operating conditions.

Characterization of a Supersonic Turbine Downstream of a Rotating Detonation Combustor

2018 ◽  
Author(s):  
Zhe Liu ◽  
James Braun ◽  
Guillermo Paniagua
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Oblique Shock ◽  
Total Pressure Loss ◽  
Flow Angle ◽  
Pressure Losses ◽  
Power Extraction ◽  
Inlet Conditions ◽  
Rotating Detonation

Rotating detonation combustors offer theoretically a significant total pressure increase, which may result in enhanced cycle efficiency. The fluctuating exhaust of rotating detonation combustors, however, induces low supersonic flow and large flow angle fluctuations at several kHz which affects the performance of the downstream turbine. For such flows, power extraction can be achieved by either integrating a diffuser with a conventional subsonic turbine or a nozzle with a supersonic turbine. In this paper, a numerical methodology is proposed to characterize a supersonic turbine exposed to fluctuations from rotating detonation combustors without any dilution. The inlet conditions of the turbine were extracted from a three dimensional unsteady Reynolds-Averaged Navier-Stokes simulation of a nozzle attached to a rotating detonation combustor, optimized for minimum flow fluctuations and a mass-flow averaged Mach number of 2 at the nozzle outlet. In a first step, a supersonic turbine able to handle steady Mach 2 inflow was designed based on a method of characteristics solver and total pressure loss was assessed. Afterwards unsteady simulations of eight stator passages exposed to periodic oblique shocks were performed. Total pressure loss was evaluated for several oblique shock frequencies and amplitudes. The unsteady stator outlet profile was extracted and used as inlet condition for the unsteady rotor simulations. Finally, a full stage unsteady simulation was performed to characterize the flow field across the entire turbine stage. Power extraction, airfoil base pressure, and total pressure losses were were assessed, which enabled the estimation of the loss mechanisms in supersonic turbine exposed to large unsteady inlet conditions. Frequency analysis of the pressure field across the turbine rows was used to evaluate the damping of the oblique shock waves.

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