Download or read book Turbulence Scale Effects on Heat Transfer in a Linear Turbine Cascade written by Lello Galassi (CAPT, USAF.) and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulence Scale Effects on Heat Transfer in a Linear Turbine Cascade written by and published by . This book was released on 1989 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer for a turbine cascade is examined for turbulence scale effects. The turbulence integral scale and microscale lengths of the free-stream flow are controlled by air-jet injection through a grid placed in the free- stream flow. Air is injected into the flow in three primary directions: co-flow, cross-flow, and counter-flow, at several injection pressures. Results are obtained for heat transfer on the blade without the jet-grid in the free-stream flow. Surface pressures on the turbine blade are examined for three injection directions. Surface heat transfer on the blade and turbulence intensity and turbulence scale results are obtained for two grid locations, three air injection orientations, and three injection orifice diameters over a range of injection pressures. Turbulence integral scale and microscale lengths are measured in two free-stream flow coordinates. Results show the integral scale length is primarily dependent on the diameter of the jet-grid tube, but may be controlled to a lesser degree by changing the orientation of the jet-grid injection to a co-flow or counter-flow direction; or by changing the secondary air-jet injection pressure. The turbulence microscale is primarily dependent on the location of the jet-grid within the flow, but, to a lesser degree, controlled by the orientation of the jet-grid injection, jet orifice diameter, and injection pressure.

Download or read book Turbulence Scales in the Passage of a Linear Turbine Cascade written by James L. Acree and published by . This book was released on 1990 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Convective heat transfer in a turbine cascade is examined for turbulence effects. Turbulence in the free stream is varied by injection of air through a jet-grid device upstream of the cascade. Pressure and flow patterns on the blade surface, and flow velocity in two components, are examined to determine the effect of the jet-grid. Velocity and velocity fluctuation in two components are measured. Local turbulence scales through the cascade passage are determined, and local turbulent energy dissipation rate is determined. Results indicate injection of air through the jet-grid changes the angle of incidence, and therefore changes the surface pressures and velocities on the blade. Heat transfer comparison is thereby invalidated. Variations in jet-grid plenum pressure change the turbulence microscale at the cascade entrance, but not the integral scale. Turbulence intensity is likewise relatively unaffected. Turbulence behavior in the passage indicates that velocity fluctuation and turbulence microscale are inversely related; turbulence intensity and microscale are not inversely related. With 6% freestream turbulence intensity, turbulence in the passage center is influenced first by events near the suction surface, then by events near the pressure surface. The primary vehicle for cross-stream diffusion is increased cross-stream velocity component fluctuations.

Download or read book Endwall Heat Transfer Measurements in a Transonic Turbine Cascade written by and published by . This book was released on 1996 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbine blade endwall heat transfer measurements are given for a range of Reynolds and Mach numbers. Data were obtained for Reynolds numbers based on inlet conditions of 0.5 and 1.0 x 10(exp 6), for isentropic exit Mach numbers of 1.0 and 1.3, and for freestream turbulence intensities of 0.25% and 7.0%. Tests were conducted in a linear cascade at the NASA Lewis Transonic Turbine Blade Cascade Facility. The test article was a turbine rotor with 136 deg of turning and an axial chord of 12.7 cm. The large scale allowed for very detailed measurements of both flow field and surface phenomena. The intent of the work is to provide benchmark quality data for CFD code and model verification. The flow field in the cascade is highly three-dimensional as a result of thick boundary layers at the test section inlet. Endwall heat transfer data were obtained using a steady-state liquid crystal technique.

Download or read book Effects of Inlet Turbulence Scale on Blade Surface Heat Transfer in a Linear Cascade written by Lello Galassi and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Angle of Incidence and Reynolds Number on Heat Transfer in a Linear Turbine Cascade written by and published by . This book was released on 1991 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The AFIT linear Turbine Cascade Test Facility was used to study the effect of the small changes in the angle of incidence on turbine blade convective heat transfer. Other parameters studied were the model Reynolds number and the freestream turbulence level. Characterization tests, performed to determine the feasibility of the study were followed by a series of tests designed to separate the effects of the angle of incidence, Reynolds number, and freestream turbulence level on convective heat transfer. For any given freestream turbulence level or angle of incidence, there is an increase in the heat transfer coefficient for an increase in the Reynolds number. For the low freestream turbulence (0.5%) configuration at a given Reynolds number, there is a decrease in the convective heat transfer coefficient with an increase in the angle of incidence, partially a result of the decrease in the cascade passage velocity and partially a result of the variation in boundary layer behavior. For the high freestream turbulence configuration (10%) at any Reynolds number, there is an obvious increase in the convective heat transfer coefficient over that for the low turbulence configuration; however, the transitional or fully turbulent boundary layer makes it difficult to observe any relation between the convective heat transfer coefficient and the angle of incidence.

Download or read book Effects of Incidence Angle Freestream Turbulence and Reynolds Number on Heat Transfer in a Linear Turbine Cascade written by S. G. Meschwitz and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Reynolds Number and Turbulence Effects on Aerodynamics and Heat Transfer in a Turbine Cascade written by Frederick C. Yeh and published by . This book was released on 1993 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of High Intensity Large Scale Freestream Combustor Turbulence on Heat Transfer in Transonic Turbine Blades written by and published by . This book was released on 2003 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of freestream turbulence representative of the flow downstream of a modem gas turbine combustor and the first stage vane on turbine blade heat transfer has been measured and analytically modeled in a linear, transonic turbine cascade. Measurements were performed on a high turning, transonic turbine blade. The facility is capable of heated flow with inlet total temperature of 120 degrees C and inlet total pressure of 10 psig. The Reynolds number based on blade chord and exit conditions (5x10(exp 6)) and the inlet and exit Mach numbers (0.4 and 1.2, respectively) are representative of conditions in a modem gas turbine engine. High intensity, large length-scale freestream turbulence was generated using a passive turbulence-generating grid to simulate the turbulence generated in modem combustors after it has passed through the first stage vane row. The grid produced freestream turbulence with intensity of approximately 10-12% and an integral length scale of 2 cm near the entrance of the cascade passages, which is believed to be representative of the core flow entering a first stage gas turbine rotor blade row. Mean heat transfer results showed an increase in heat transfer coefficient of approximately 8% on the suction surface of the blade, with increases on the pressure surface on the order of two times higher than on the suction surface (approximately 17%). This corresponds to increases in blade surface temperature of 5- 10%, which can significantly reduce the life of a turbine blade. The heat transfer data were compared with correlations from published literature with good agreement.

Download or read book The Effects of Inlet Turbulence and Rotor stator Interactions on the Aerodynamics and Heat Transfer of a Large scale Rotating Turbine Model Volume 1 written by Robert P. Dring and published by . This book was released on 1987 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Frequency Domain Analysis of Surface Heat Transfer Free Stream Turbulence Interactions in a Transonic Turbine Cascade written by David G. Holmberg and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The relationship of time resolved surface heat flux to the turbulent free stream flow over a turbine blade is investigated. Measurements are made in a transonic linear cascade with a modern high pressure turbine blade profile. Time resolved direct heat transfer measurements are made with Heat Flux Microsensor (HFM) inserts along the pressure side, and with one HFM directly deposited on the suction surface near the leading edge. Simultaneous velocity measurements are made above the heat flux sensors using miniature hot wire probes. Grids are used to produce two turbulence fields of constant inlet turbulence intensity, Tu=5%, but significantly different integral length scales (Ax). Results are compared with a low free stream turbulence baseline condition. Special emphasis is given to frequency domain analysis of the data via coherence function magnitude and phase, energy spectra, and time auto and cross correlations.

Download or read book Turbulent Heat Transfer Investigation Turbulence Length Scales and Turbine Heat Transfer written by and published by . This book was released on 1996 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experiment was designed to study the effects of turbulent length scales on turbine blade heat transfer in a steady state cascade wind tunnel. Turbine blade heat transfer is of interest due to the beneficial effects engine performance that can arise from improvements in turbine blade cooling and design. Turbulence in this experiment was generated by means of passive grids in the upstream flow. This experiment uses a steady state liquid crystal in combination with resistance heating to measure heat transfer. The liquid crystals provide surface temperature data and the resistance heating in the blade can be computed from measured currents to determine heat transfer. When combined with flow data taken with a hot film this allows for conclusions on the effects of length scales on heat transfer to be made. This experiment showed that the turbine blade heat transfer exhibited the trends already investigated for turbulence intensity, namely an increase in heat transfer with increased turbulence, the forward movement of boundary layer transition and the elimination of pressure side spanwise variations. Comparison of the two different length scales at the same turbulence intensity showed that the length scale evidenced no affect on transition location or post-transition heat transfer. However, pre-transition heat transfer was significantly increased as the integral length scale decreased from 2.78 to 0.51. This demonstrates that smaller more compact eddies in the turbulent flow have a more significant impact on increasing heat transfer than do larger eddies of the same intensity.

Download or read book Blade Heat Transfer Measurements and Prediction in a Transonic Turbine Cascade written by and published by . This book was released on 1999 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Frequency Domain Analysis of Surface Heat Transfer free stream Turbulence Interactions in a Transonic Turbine Cascade written by David G. Holmberg and published by . This book was released on 1996 with total page 438 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 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of the Effects of Wake Passage on Heat Transfer in a Linear Turbine Cascade written by and published by . This book was released on 1993 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigated the effect of wake passage On the heat transfer in a linear turbine cascade. The apparatus used was the Air-Force Institute of Technology linear Turbine Cascade Test Facility (TCTF). The TCTF was fitted with a be Pulley system to facilitate a series of translating bars. The bars, when passed d upstream of the cascade, created a series of wakes. The parameters varied were freestream model Reynolds number and bar conditions, i.e., bars in, bars out, and bar passing frequency. One blade in the TCTF was instrumented to allow pressure and temperature measurements at discrete points on the blade's surface. From the pressure and temperature data the convective heat transfer coefficient at these discrete locations was calculated. Results were compared to previous TCTF heat transfer data, empirical solutions, and other wake passage experiments. For all tests with closely spaced bars, the effect of wake passing on the heat transfer of the blade was similar to the effect of grid-generated 10% freestream turbulence on the cascade.

Download or read book The Effects of Free steam Turbulence Quantities on Heat Transfer to Turbine Blading written by W. J. Priddy and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: