Theoretical Basis for Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles

1991 ◽  
Vol 113 (2) ◽  
pp. 228-232 ◽  
Author(s):  
J. W. Murdock ◽  
D. R. Keyser
Keyword(s):  
Boundary Layer ◽  
Theoretical Basis ◽  
Reynolds Numbers ◽  
Boundary Layer Theory ◽  
Calibration Data ◽  
Maximum Difference ◽  
Calibration Laboratory

Equations for the extrapolation of calibration data for ASME/PTC 6 throat tap nozzles are derived from boundary layer theory. The results match published coefficients with a maximum difference of +0.03 percent. It is also shown that the effects of transition in the boundary layer extend to throat Reynolds numbers in excess of 10,000,000, far beyond the capacity of any known calibration laboratory. The present PTC 6 requirement that calibration data must be in the fully turbulent range cannot be met with current facilities.

The steady streaming induced by a vibrating cylinder

1975 ◽  
Vol 68 (4) ◽  
pp. 801-812 ◽  
Author(s):  
N. Riley
Keyword(s):  
Boundary Layer ◽  
Reynolds Numbers ◽  
Higher Order ◽  
Boundary Layer Theory ◽  
Steady Streaming ◽  
Theoretical Predictions ◽  
Unbounded Fluid ◽  
Theory And Experiment

In this paper we apply the techniques of higher-order boundary-layer theory to study the steady streaming induced in the neighbourhood of a cylinder which vibrates harmonically, perpendicular to its generators, in an unbounded fluid. The theoretical predictions are compared with the results of experiments performed at high streaming Reynolds numbers. Improved agreement between theory and experiment is achieved although unresolved discrepancies remain.

A Method for the Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles

1991 ◽  
Vol 113 (2) ◽  
pp. 233-239 ◽  
Author(s):  
J. W. Murdock ◽  
D. R. Keyser
Keyword(s):  
Theoretical Basis ◽  
Single Point ◽  
Reynolds Numbers ◽  
Calibration Data ◽  
Precise Method ◽  
Numerical Examples ◽  
Coefficient Of Discharge

This paper describes a precise method for extrapolating the coefficient of discharge of PTC 6 throat tap nozzles using all or most of the calibration data. The theoretical basis for this method is described in a parallel paper [3]. Numerical examples are given using actual calibration data to describe this method. Because this method permits the use of all calibration data at or above Reynolds numbers of 1,000,000, it is a clear improvement over the PTC 6-1976 method, which permits only the highest single point.

Effect of Tube Diameter on Wall Shear Stress Measurements Using Preston Tubes

2000 ◽  
Author(s):  
Sutardi ◽  
C. Y. Ching
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Reynolds Numbers ◽  
Tube Diameter ◽  
Momentum Thickness ◽  
Maximum Difference ◽  
Calibration Equation ◽  
Wall Shear ◽  
Outside Diameter

Abstract The effect of tube diameter (d) on wall shear stress (τw) measurements using Preston tubes has been investigated in a zero pressure gradient turbulent boundary layer. Five different outside diameter tubes of 1.46, 1.82, 3.23, 4.76 and 5.54 mm, corresponding to (d/δ) of 0.022, 0.027, 0.048, 0.071 and 0.082 were used to measure τw at Reynolds numbers based on momentum thickness (Rθ) of 2800 to 4100. The calibration curves of Patel (1965) and Bechert (1995) are both dependent on the tube diameter. The maximum difference in the τw measurements from the different tubes using Patel’s calibration is about 8%, while Bechert’s calibration gives a maximum difference of approximately 18%. Based on the present measurements, a new Preston tube calibration equation that is less sensitive to the tube diameter is proposed.

A numerical study of laminar separation bubbles using the Navier-Stokes equations

1971 ◽  
Vol 47 (4) ◽  
pp. 713-736 ◽  
Author(s):  
W. Roger Briley
Keyword(s):  
Boundary Layer ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Separation Bubble ◽  
Reynolds Numbers ◽  
Boundary Layer Theory ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Laminar Separation ◽  
Boundary Layer Equations

The flow in a two-dimensional laminar separation bubble is analyzed by means of finite-difference solutions to the Navier-Stokes equations for incompressible flow. The study was motivated by the need to analyze high-Reynolds-number flow fields having viscous regions in which the boundary-layer assumptions are questionable. The approach adopted in the present study is to analyze the flow in the immediate vicinity of the separation bubble using the Navier-Stokes equations. It is assumed that the resulting solutions can then be patched to the remainder of the flow field, which is analyzed using boundary-layer theory and inviscid-flow analysis. Some of the difficulties associated with patching the numerical solutions to the remainder of the flow field are discussed, and a suggestion for treating boundary conditions is made which would permit a separation bubble to be computed from the Navier-Stokes equations using boundary conditions from inviscid and boundary-layer solutions without accounting for interaction between individual flow regions. Numerical solutions are presented for separation bubbles having Reynolds numbers (based on momentum thickness) of the order of 50. In these numerical solutions, separation was found to occur without any evidence of the singular behaviour at separation found in solutions to the boundary-layer equations. The numerical solutions indicate that predictions of separation by boundary-layer theory are not reliable for this range of Reynolds number. The accuracy and validity of the numerical solutions are briefly examined. Included in this examination are comparisons between the Howarth solution of the boundary-layer equations for a linearly retarded freestream velocity and the corresponding numerical solutions of the Navier-Stokes equations for various Reynolds numbers.

INVERSE PROBLEMS OF BOUNDARY LAYER THEORY

2018 ◽  
Vol 49 (8) ◽  
pp. 793-807
Author(s):  
Vladimir Efimovich Kovalev
Keyword(s):  
Boundary Layer ◽  
Inverse Problems ◽  
Boundary Layer Theory

The Effect of Pulsed Blowing on the Boundary Layer of a Highly Loaded Low Pressure Turbine Blade

2013 ◽  
Author(s):  
Marion Mack ◽  
Roland Brachmanski ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Mach Number ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Trailing Edge ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Highly Loaded

The performance of the low pressure turbine (LPT) can vary appreciably, because this component operates under a wide range of Reynolds numbers. At higher Reynolds numbers, mid and aft loaded profiles have the advantage that transition of suction side boundary layer happens further downstream than at front loaded profiles, resulting in lower profile loss. At lower Reynolds numbers, aft loading of the blade can mean that if a suction side separation exists, it may remain open up to the trailing edge. This is especially the case when blade lift is increased via increased pitch to chord ratio. There is a trend in research towards exploring the effect of coupling boundary layer control with highly loaded turbine blades, in order to maximize performance over the full relevant Reynolds number range. In an earlier work, pulsed blowing with fluidic oscillators was shown to be effective in reducing the extent of the separated flow region and to significantly decrease the profile losses caused by separation over a wide range of Reynolds numbers. These experiments were carried out in the High-Speed Cascade Wind Tunnel of the German Federal Armed Forces University Munich, Germany, which allows to capture the effects of pulsed blowing at engine relevant conditions. The assumed control mechanism was the triggering of boundary layer transition by excitation of the Tollmien-Schlichting waves. The current work aims to gain further insight into the effects of pulsed blowing. It investigates the effect of a highly efficient configuration of pulsed blowing at a frequency of 9.5 kHz on the boundary layer at a Reynolds number of 70000 and exit Mach number of 0.6. The boundary layer profiles were measured at five positions between peak Mach number and the trailing edge with hot wire anemometry and pneumatic probes. Experiments were conducted with and without actuation under steady as well as periodically unsteady inflow conditions. The results show the development of the boundary layer and its interaction with incoming wakes. It is shown that pulsed blowing accelerates transition over the separation bubble and drastically reduces the boundary layer thickness.

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