Numerical Investigation of Airfoil Clocking in a Three-Stage Low Pressure Turbine

2001 ◽  
Author(s):  
Andrea Arnone ◽  
Michele Marconcini ◽  
Roberto Pacciani ◽  
Claudia Schipani ◽  
Ennio Spano
Keyword(s):  
Reynolds Number ◽  
Numerical Investigation ◽  
Relative Position ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Low Pressure Turbine ◽  
Wake Interaction ◽  
Low Reynolds ◽  
Lp Turbine

A quasi–three–dimensional, blade–to–blade, time–accurate, viscous solver w as used for a three–stage LP turbine study Due to the low Reynolds number, transitional computations were performed. Unsteady analyses were then carried out by varying the circumferential relative position of consecutive vanes and blade rows to study the effects of clocking on the turbine’s performance. A clocking strategy developed in order to limit the number of configurations to be analyzed is discussed. The optimum analytically–determined clocking position is illustrated for two different operating conditions, referred to as cruise and takeoff. The effects of clocking on wake interaction mechanisms and unsteady blade loadings is presented and discussed. For low Reynolds number turbine flows, the importance of taking transition into account in clocking analysis is demonstrated by a comparison with a fully turbulent approach.

Numerical Investigation of Airfoil Clocking in a Three-Stage Low-Pressure Turbine

2001 ◽  
Vol 124 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Andrea Arnone ◽  
Michele Marconcini ◽  
Roberto Pacciani ◽  
Claudia Schipani ◽  
Ennio Spano
Keyword(s):  
Reynolds Number ◽  
Numerical Investigation ◽  
Relative Position ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Low Pressure Turbine ◽  
Wake Interaction ◽  
Low Reynolds ◽  
Lp Turbine

A quasi-three-dimensional, blade-to-blade, time-accurate, viscous solver was used for a three-stage LP turbine study. Due to the low Reynolds number, transitional computations were performed. Unsteady analyses were then carried out by varying the circumferential relative position of consecutive vanes and blade rows to study the effects of clocking on the turbine’s performance. A clocking strategy developed in order to limit the number of configurations to be analyzed is discussed. The optimum analytically-determined clocking position is illustrated for two different operating conditions, referred to as cruise and takeoff. The effects of clocking on wake interaction mechanisms and unsteady blade loadings is presented and discussed. For low Reynolds number turbine flows, the importance of taking transition into account in clocking analysis is demonstrated by a comparison with a fully turbulent approach.

Numerical Investigation of Three-Dimensional Clocking Effects in a Low Pressure Turbine

2003 ◽  
Author(s):  
Andrea Arnone ◽  
Michele Marconcini ◽  
Alberto Scotti Del Greco ◽  
Ennio Spano
Keyword(s):  
Numerical Investigation ◽  
Dimensional Analysis ◽  
Relative Position ◽  
Three Dimensional ◽  
Low Pressure ◽  
Blade Height ◽  
Interaction Mechanisms ◽  
Low Pressure Turbine ◽  
Wake Interaction

One and a half stages of a low pressure turbine were investigated using a three-dimensional, time-accurate, viscous solver. Unsteady analyses were carried out by varying the circumferential relative position of consecutive vanes to study the effects of clocking on performance. Assuming that efficiency improvements by clocking are linked to the wake tangential position with respect to the successive blade, a certain circumferential shift in this position can be observed along the blade height due to blade twist and non-radial stacking, giving different contributions. In order to assess this phenomenon, results from three-dimensional computations were compared with a quasi three-dimensional analysis at mid-span. The effects of clocking on wake interaction mechanisms and unsteady blade loadings are presented and discussed.

Numerical Investigation of Three-Dimensional Clocking Effects in a Low Pressure Turbine

2004 ◽  
Vol 126 (3) ◽  
pp. 375-384 ◽  
Author(s):  
Andrea Arnone ◽  
Michele Marconcini ◽  
Alberto Scotti Del Greco ◽  
Ennio Spano
Keyword(s):  
Numerical Investigation ◽  
Dimensional Analysis ◽  
Relative Position ◽  
Three Dimensional ◽  
Low Pressure ◽  
Blade Height ◽  
Interaction Mechanisms ◽  
Low Pressure Turbine ◽  
Wake Interaction

One and a half stages of a low pressure turbine were investigated using a three-dimensional time-accurate viscous solver. Unsteady analyses were carried out by varying the circumferential relative position of consecutive vanes to study the effects of clocking on performance. Assuming that efficiency improvements by clocking are linked to the wake tangential position with respect to the successive blade, a certain circumferential shift in this position can be observed along the blade height due to blade twist and nonradial stacking, giving different contributions. In order to assess this phenomenon, results from three-dimensional computations were compared with a quasi-three-dimensional analysis at mid-span. The effects of clocking on wake interaction mechanisms and unsteady blade loadings are presented and discussed.

Low Pressure Turbine Lapse Rate Study: CFD Model vs. Rig Data

2002 ◽  
Author(s):  
J.-S. Liu ◽  
M. L. Celestina ◽  
G. B. Heitland ◽  
D. B. Bush ◽  
M. L. Mansour ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Fluid Dynamic ◽  
Low Reynolds Number ◽  
Low Pressure ◽  
Lapse Rate ◽  
Bypass Transition ◽  
Blade Row ◽  
Low Reynolds ◽  
Lp Turbine

As an aircraft engine operates from sea level take-off (SLTO) to altitude cruise, the low pressure (LP) turbine Reynolds number decreases. As Reynolds number is reduced the condition of the airfoil boundary layer shifts from bypass transition to separated flow transition. This can result in a significant loss. The LP turbine performance fall-off from SLTO to altitude cruise, due to the loss increase with reduction in Reynolds number, is referred to as a lapse rate. A considerable amount of research in recent years has been focused on understanding and reducing the loss associated with the low Reynolds number operation. A recent 3-1/2 stage LP turbine design completed a component rig test program at Honeywell. The turbine rig test included Reynolds number variation from SLTO to altitude cruise conditions. While the rig test provides detailed inlet and exit condition measurements, the individual blade row effects are not available. Multi-blade row computational fluid dynamics (CFD) analysis is used to complement the rig data by providing detailed flow field information through each blade row. A multi-blade row APNASA model was developed and solutions were obtained at the SLTO and altitude cruise rig conditions. The APNASA model predicts the SLTO to altitude lapse rate within 0.2 point compared to the rig data. The global agreement verifies the modeling approach and provides a high confidence level in the blade row flow field predictions. Additional Reynolds number investigation with APNASA will provide guidance in the LP turbine Reynolds number research areas to reduce lapse rate. To accurately predict the low Reynolds number flow in the LP turbine is a challenging task for any computational fluid dynamic (CFD) code. The purpose of this study is to evaluate the capability of a CFD code, APNASA, to predict the sensitivity of the Reynolds number in LP turbines.

Non-Spheric Colloidal Suspensions in Three-Dimensional Space

1997 ◽  
Vol 08 (04) ◽  
pp. 985-997 ◽  
Author(s):  
Dewei Qi
Keyword(s):  
Reynolds Number ◽  
Dimensional Space ◽  
Low Reynolds Number ◽  
Paper Industry ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Solid Particles ◽  
Spherical Particles ◽  
Dynamic Simulations ◽  
Low Reynolds

The translation and rotation of non-spherical particles, such as ellipsoidal, cylindric or disk-like pigment particles, in a Couette flow system similar to a blade coating system in the paper industry6 have been successfully simulated by using the lattice-Boltzmann method combined with Newtonian dynamic simulations. Hydrodynamic forces and torques are obtained by the use of boundary conditions which match the moving surface of solid particles. Then Euler equations have been integrated to include three-dimensional rotations of the suspensions by using four quaternion parameters as generalized coordinates. The three-dimensional rotations have been clearly observed. Consequently, the motion of the particles suspended in fluids of both low-Reynolds-number and finite-Reynolds-number, up to several hundreds, has been studied. It appears that the 3D translation and rotation of the non-spherical particles are more clearly observed in a high-Reynolds-number fluid than in a low-Reynolds-number fluid.

The motion of rigid particles in a shear flow at low Reynolds number

1962 ◽  
Vol 14 (2) ◽  
pp. 284-304 ◽  
Author(s):  
F. P. Bretherton
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Body Of Revolution ◽  
Rigid Particles ◽  
Unidirectional Flow ◽  
Uniform Shear ◽  
Ellipsoid Of Revolution ◽  
Low Reynolds ◽  
Bounding Surfaces

According to Jeffery (1923) the axis of an isolated rigid neutrally buoyant ellipsoid of revolution in a uniform simple shear at low Reynolds number moves in one of a family of closed periodic orbits, the centre of the particle moving with the velocity of the undisturbed fluid at that point. The present work is a theoretical investigation of how far the orbit of a particle of more general shape in a non-uniform shear in the presence of rigid boundaries may be expected to be qualitatively similar. Inertial and non-Newtonian effects are entirely neglected.The orientation of the axis of almost any body of revolution is a periodic function of time in any unidirectional flow, and also in a Couette viscometer. This is also true if there is a gravitational force on the particle in the direction of the streamlines. There is no lateral drift. On the other hand, certain extreme shapes, including some bodies of revolution, will assume one of two orientations and migrate to the bounding surfaces or to the centre of the flow. In any constant slightly three-dimensional uniform shear any body of revolution will ultimately assume a preferred orientation.

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