Download or read book Low Reynold Number Turbine Blade Cascade Calculations written by Richard Byram Rivir and published by . This book was released on 1996 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Reynolds Number Turbine Blade Cascade Calculations written by and published by . This book was released on 1996 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computations of the velocity fields for Langston turbine blade cascades with solidities of 1.075 and 0.84 have been carried out at Reynolds numbers of 50K, 100K, 200K, 441K, 1000K, and 2000K. A second cascade investigated at Reynolds numbers of 50K and 100K uses the Langston airfoil which has been modified by extending the trailing edge, resulting in a solidity of 0.786. The computations were performed with Allison's Blade Vanc Interaction code. Computational results are presented for transition, separation, and reattachment.
Download or read book Transonic Viscous Flow Calculations for a Turbine Cascade with a Two Equation Turbulence Model written by and published by . This book was released on 1989 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition on Turbine Blades and Cascades at Low Reynolds Numbers written by and published by . This book was released on 1996 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unpredicted losses in the low pressure turbine during operation at high altitudes has stimulated current interest in transition, and separation at low Reynolds numbers. In the turbine, free stream turbulence levels or unsteadiness resulting from vane wakes, passage vorticies, and end wall horseshoe vorticies exceeds the unsteadiness levels associated with a fully turbulent boundary layer. Transition and transition length are found to be a function of both turbulence intensity and length scale although there are no empirical relationships to be found in the literature which include both. An experimental and computation effort was undertaken to investigate the effect of turbulence intensity, and turbulence length scale on transition location, and transition length scale on transition location, and transition length in a Langston turbine cascade for solidities of 1.075 and 0.84 at Reynolds numbers of 50K to 2000K. Experimental observations of transition at turbulence levels of 1 and 10% for three integral turbulence scales indicate a relative lack of sensitivity to turbulence level and scale for the momentum thickness transition location, but a sensitivity to both for transition length.
Download or read book Flow Separation Prevention on a Turbine Blade in Cascade at Low Reynolds Number written by James P. Lake (CAPT, USAF.) and published by . This book was released on 1999 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design of a Three passage Low Reynolds Number Turbine Cascade with Periodic Flow Conditions written by Daniel R. Rogers and published by . This book was released on 2008 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical method for modeling a low Reynolds number turbine blade, the L1M, is presented along with the pitfalls encountered. A laminar solution was confirmed to not accurately predict the flow features known in low Reynolds number turbine blade flow. Three fully turbulent models were then used to try to predict the separation and reattachment of the flow. These models were also found to be insufficient for transitioning flows. A domain was created to manually trip the laminar flow to turbulent flow using a predictive turbulence transition model. The trip in the domain introduced an instability in the flow field that appears to be dependent on the discretization order, turbulence model, and transition location. The method was repeated using the Pack B blade and the same obstacles were apparent. The numerical method developed was then used in an optimization technique developed to design a wind tunnel simulating periodic flow conditions using only 2 blades. The method was first used to predict a cp distribution for the aft loaded L1A research blade provided by the U.S. Air Force. The method was then extended to a larger domain emulating the 2 blade, 2D wind tunnel. The end-wall geometry of the tunnel was then changed using previously defined control points to alter the distribution of cp along the suction surface of the interior blades. The tunnel cp's were compared to the computationally acquired periodic solution. The processed was repeated until an acceptable threshold was reached. The optimization was performed using the commercially available software iSIGHT by Engineous Solutions. The optimization algorithms used were the gradient based Successive Approximation Method, the Hooke Jeeves, and Simulated Annealing.
Download or read book Two equation Low Reynolds number Turbulence Modeling of Transitional Boundary Layer Flows Characteristic of Gas Turbine Blades written by Rodney C. Schmidt and published by . This book was released on 1988 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characteristics of a Turbine Cascade at Low Reynolds Numbers written by Koji Murata and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Orlando, FL, Jun 2-Jun 5, 1997.
Download or read book Transport Phenomena In Thermal Control written by Guang-Jyh Hwang and published by CRC Press. This book was released on 1989-08-01 with total page 822 pages. Available in PDF, EPUB and Kindle. Book excerpt: A collection of research papers into transport phenomena in thermal control, closely related to several important aspects of cooling technology. Articles provide overviews of current advances and details of individual technologies including electronic and turbine cooling and Marangoni convection.
Download or read book Reynolds Averaged Navier Stokes Studies of Low Reynolds Number Effects on the Losses in a Low Pressure Turbine written by and published by . This book was released on 1996 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book An Experimental Investigation of Heat Transfer Transition and Separation on Turbine Blades at Low Reynolds Number and High Turbulence Intensity written by and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of turbulence intensity on the heat transfer distribution, transition and flow separation on a turbine blade was investigated at low Reynolds numbers. Measurements were performed in linear cascades (at both UCDavis and the USAF Academy) at low Reynolds number (67,000 to 144,000) representative of low pressure turbine stages at high altitude. Nominal turbulence intensities of 1% and 10% (generated with biplane lattice grids) were used. The heat transfer was measured with the uniform heat flux (UHF) or heated-coating method. The heated-coating was a gold-film and liquid crystals were used for the surface temperature measurement. A novel laser-tuft surface flow visualization method was also used. For low turbulence levels (1%) the pressure side of the blade exhibited streaks of varying heat transfer possibly associated with Taylor-Gortler vortices. With grid turbulence (10%) these streaks disappeared on the pressure side and the heat transfer nearly doubled. Gird turbulence also increased the heat transfer on the leading edge and suction surface, while advancing the location of boundary layer transition. Good agreement was generally found between the UCDavis and USAFA data. These cascade results compare favorably to those that have been reported with rotation.
Download or read book Control of Flow Separation on a Turbine Blade by Utilizing Tail Extensions written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted in a two-dimensional linear cascade, focusing on the suction surface of a low pressure turbine blade. Flow Reynolds numbers, based on exit velocity and suction surface length were varied from 50,000 to 300,000. The axial chord of the blades was varied using tail extenders from 0% to 15% beyond design. The effects of Reynolds number on a low pressure turbine cascade blade with tail extensions was investigated. This study has shown that for certain cases, changing the axial chord of a low pressure turbine blade by utilizing tail extensions provided a clear improvement in boundary layer behavior which results in better overall performance. There was no additional advantage when the tail extensions were longer than 6.1% of the axial chord. The shortest tail extension resulted in the greatest zone of performance enhancement. The longer tail extension resulted in a smaller region of performance enhancement.
Download or read book Flow Separation Prevention on a Turbine Blade in Cascade at Low ReynoldsNumber written by James Lake and published by . This book was released on 1999-06-01 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: The problem of flow separation from a low pressure turbine blade was investigated. The operating conditions under which the separation occurred were documented through measurement of surface pressure coefficients, boundary layer velocity and turbulence profiles, total pressure loss coefficient and wake velocity momentum deficit. Three different means for reducing the losses associated with the flow separation were also investigated. A boundary layer trip, dimples, and V-grooves were studied as passive means requiring no additional energy to reduce the separation losses. The boundary layer trip was only successful for an inlet and axial chord Reynolds number of 50k with a reduction in loss coefficient of 58.2%. Three sets of dimples were tested with the placement of each at axial chord locations of 50%, 55%, and 65%. The dimplesprovided reductions in the loss coefficient for Reynolds numbers of 50k, 100k, and 200k ranging from 5.1% (Re = 100k, freestream turbulence level of 4%) to 51.7% (Re = 50k, freestream turbulence level of 4%). Two sets of V-grooves were tested with axial chord start locations of 55% and 60%. The V-grooves provided smaller reductions in loss coefficient than the dimples. Boundary layer profiles, total pressure loss coefficients, and wake velocity momentum deficits are presented for the three passive modifications.
Download or read book Fluid Mechanics and Thermodynamics of Turbomachinery written by Sydney Lawrence Dixon and published by Elsevier. This book was released on 1998 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the intervening 20 years since the 3rd edition of this textbook many advances have been made in the design of turbines and greater understanding of the processes involved have been gained. This 4th edition brings the book up to date.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1971 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Procedure for Calculating Turbine Blade Temperatures and Comparison of Calculated with Observed Values for Two Stationary Air cooled Blades written by W. Byron Brown and published by . This book was released on 1952 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Local and average blade temperatures were calculated for two stationary air-cooled turbine blades with 10 tubes and 13 fins forming the internal heat-transfer surfaces. These temperatures were calculated using previously published NACA temperature-distribution equations and the most recent theories for determining heat-transfer coefficients, including for the first time the allowance for effects of variable wall temperature on gas-to-blade heat-transfer coefficients at the leading and trailing sections of turbine blades. Comparison of calculated and experimental blade temperatures, for gas temperatures of 300° and 1000°F, resulted in good agreement.
