Development of Two-Dimensional Wakes Within Curved Channels: Theoretical Framework and Experimental Investigation

Schobeiri, Meinhard T.; John, Jubi; Pappu, K.

doi:10.1115/1.2836697

Cited by 28 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore an increasing amount of research work has been focused on wake development and its evolution in the axial gap as well as within the blade row. Schobeiri et al (1996) studied the development of twodimensional wakes within curved channels and established a theoretical framework. Ames and Plesniak (1997) investigated the influence of combustor-like inlet turbulence on turbine vane wake characteristics, development and mixing.…”

mentioning

confidence: 99%

Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade

Sanz

Gehrer

Woisetschläger

et al. 1998

Volume 1: Turbomachinery

View full text Add to dashboard Cite

In turbomachinery the wake flow together with the inherent unsteadiness caused by interaction between stator and rotor has a significant impact on efficiency and performance. The prediction of the wake flow depends largely on the turbulence modeling. Therefore in this study the evolution of a viscous wake downstream of a linear turbine cascade is experimentally and computationally investigated. In a transonic cascade test stand Laser Doppler Velocimeter (LDV) measurements of velocity and turbulent kinetic energy are done in several axial planes downstream of the blade trailing edge. Two different turbulence models are then incorporated into a two-dimensional Navier-Stokes solver to calculate the turbulent wake flow and the results are compared with the experimental data to test the quality of the turbulence models. The large discrepancies between measurement and Calculation are assumed to be caused by the periodic vortex shedding from the blunt trailing edge which is not taken into account by the turbulence models. But further research is needed to resolve this issue.

show abstract

mentioning

confidence: 99%

Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade

Sanz

Gehrer

Woisetschläger

et al. 1998

Volume 1: Turbomachinery

View full text Add to dashboard Cite

show abstract

“…Two-dimensional periodic unsteady wakes are generated by a wake generator, consisting of a series of cylindrical rods mounted on two parallel timing belts driven by an electric motor and a frequency controller. The rod diameter, its distance from the blade leading edge, wake width, and corresponding drag coefficient are chosen according to the criteria outlined by Schobeiri et al 40 Main components of the research facility such as a large centrifugal compressor, diffuser, settling chamber, nozzle, and a turbine cascade test section are shown in Figure 1. The compressor with a volumetric flow rate of 15 m 3 /s is capable of generating a maximum mean velocity of 100 m=s at the test section inlet.…”

Section: Experimental Investigationmentioning

confidence: 99%

Combined numerical and experimental investigations of heat transfer of a highly loaded low-pressure turbine blade under periodic inlet flow condition

Nikparto

Schobeiri

2018

Proceedings of the Institution of Mechanical Engineers, Part A:

View full text Add to dashboard Cite

This paper experimentally and numerically investigates heat transfer characteristics of a low-pressure turbine blade under steady/unsteady flow conditions. Generally, the low-pressure turbine blades are not exposed to excessive temperatures that require detailed heat transfer predictions. In aircraft engines, they operate at low Re-numbers causing the inception of large separation bubbles on their suction surface. As documented in previous papers, the results of detailed aerodynamic simulations have shown significant discrepancies with experiments. It was the objective of the current investigation to determine the discrepancies between the experimental and numerical heat transfer results. It is shown that small errors in aero-calculation results in large deviations of heat transfer results. The characteristics of the blades mentioned above, make low-pressure turbine blades suitable candidates for evaluating the predictive capability of any numerical method. Documenting the scope of these discrepancies defines the framework of the current paper. The periodic flow inside the gas turbine engine was simulated using the cascade facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. In this study, the wakes that originate from stator blades were simulated by moving rods. The instrumented blade was covered with a liquid crystal sheet and it was used to measure heat transfer coefficient. Reynolds-averaged Navier-Stokes equations were used for numerical investigation purposes. Measurements and simulations were conducted at three different Reynolds numbers (110,000, 150,000, and 250,000). Furthermore, for unsteady flow condition, reduced frequencies of the incoming wakes were varied. The current paper includes a comprehensive heat transfer assessment of the predictive capability of Reynoldsaveraged Navier-Stokes based tools. The effect of the separation bubbles on heat transfer is thoroughly discussed in this paper. Comparisons of the experimental and numerical results detail the differences and identify the sources of error that leads to in accurate calculations in terms of predicting heat transfer calculation results.

show abstract

“…of steady and unsteady wake development under turbomachinery specific conditions. Schobeiri et al (1994) investigated the phenomenon of steady wake development and decay and established a comprehensive theoretical frame-work. Schobeiri and his co-workers also extended the theoretical work by Schobeiri et al (1995a) to a relative frame of reference to explain the development and decay of unsteady wakes.…”

Section: Background: Unsteady Boundary Layer Transitionmentioning

confidence: 99%

Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

Schobeiri¹,

Gilarranz²,

Johansen³

2004

The International Journal of Rotating Machinery

View full text Add to dashboard Cite

This article deals with the aerodynamic and performance behavior of a three-stage high pressure research turbine with 3-D curved blades at its design and off-design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circum-ferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory, TPFL, of Texas A&M University. Keywords Development in the field of turbomachinery computational fluid dynamics (CFD) has reached an advanced level that allows a detailed computation of the complex three-dimensional viscous flow field through a turbomachinery stage using Navier-Stokes codes. Numerous published cases demonstrate the capability of different CFD-methods to calculate various flow quantities in a remarkably detailed fashion. The efficiency and loss calculations, however, reveal noticeable disagreement between the experimental and computational results. The detailed 3-D flow pictures delivered by viscous flow solvers display the source and location of the total pressure losses and entropy distribution within the blade channel, particularly at the blade hub and tip regions. Based on these results, the turbine aerodynamicist is able to reconfigure the blade geometry to reduce the profile and the secondary flow losses. The latter is especially relevant for high pressure (HP) turbine design with relatively small aspect ratios where the secondary flow losses significantly contribute to the reduction of the stage efficiency. In recent years, the power generation turbine manufacturers have been increasingly focus-ing their efforts on reducing the secondary flow losses of HP-turbine blades by implementing the information obtained from the Navier-Stokes flow simulations. To account for the discrepancy mentioned above, the Navier-Stokes codes are frequently calibrated. The calibration process may provide a temporary matching solution for cases in which experimental results are available. However, it is not appropriate for a priori predicting of the efficiency of new designs. The disagreement between the Navier-Stokes based efficiency calculations and the measurements , however, does not allow the engine manufacturer to issue efficiency and performance guaranty without thoroughly testing their new design. Considering the physical aspects of the computation , among other things, two major issues may be considered primarily responsible for the above discrepancy, namely the turbulence modeling and the modeling of the laminar-turbulent boundary layer transition process. The latter directly impacts the a...

show abstract

Development of Two-Dimensional Wakes Within Curved Channels: Theoretical Framework and Experimental Investigation

Cited by 28 publications

References 17 publications

Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade

Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade

Combined numerical and experimental investigations of heat transfer of a highly loaded low-pressure turbine blade under periodic inlet flow condition

Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

Contact Info

Product

Resources

About