Download or read book Friction Factor for Smooth and Honeycomb Annular Gas Seals and Prediction of Rotordynamic Coefficients written by Amro M. Al-Qutub and published by . This book was released on 1996 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Comparison of Rotordynamic coefficient Predictions for Annular Honeycomb Gas Seals Using Different Friction factor Models written by Rohan Joseph D'Sousa and published by . This book was released on 2000 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rotordynamic Analysis of Annular Honeycomb stator Turbulent Gas Seals Using a New Friction factor Model Based on Flat Plate Tests written by Tae Woong Ha and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Annular Gas Seal Analysis Using Empirical Entrance and Exit Region Friction Factors written by David Alan Elrod and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wall shear stress results from stationary-rotor flow tests of five annular gas seals are used to develop entrance and exit region friction factor models. The friction factor models are used in a bulk-flow seal analysis which predicts leakage and rotor-dynamic coefficients. The predictions of the analysis are compared to experimental results and to the predictions of Nelson's analysis (1985). The comparisons are for smooth-rotor seals with smooth and honeycomb-stators. The present analysis predicts the destabilizing cross-coupled stiffness of a seal better than Nelson's analysis. Both analyses predict direct damping well and direct stiffness poorly.
Download or read book Test Versus Predictions for Rotordynamic and Leakage Characteristics of a Convergent tapered Honeycomb stator smooth rotor Annular Gas Seal written by Daniel Eduardo Van Der Velde Alvarez and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the results for measured and predicted rotordynamic coefficients and leakage for a convergent-tapered honeycomb seal (CTHC). The test seals had a diameter of 114.968 mm (4.5263 in) at the entrance, and a diameter of 114.709 mm (4.5161 in) at the exit. The honeycomb cell depth was 3.175 mm (0.125 in), and the cell width was 0.79 mm (0.0311 in). Measurements are reported with air as the test fluid at three different speeds: 10,200, 15,200, and 20,200 rpm; with a supply pressure of 69 bar (1,000 psi), with exit-to-inlet pressure ratios from 20% to 50%, and using two rotors that are 114.3 mm (4.500 in) and 114.5 mm (4.508 in) respectively; this enables the same seals to be tested under two different conditions. The q factor, which is just a simple way to quantify taper is defined as the taperangle seal parameter and is calculated using the inlet and exit radial clearance. Two taper-angles parameters were calculated; q = 0.24 for the 114.3 mm (4.500 in) rotor, and q = 0.386 for the 114.5 mm (4.508 in) rotor. The q = 0.24 condition was compared to a constant clearance honeycomb seal (CCHC q = 0) because both sets of data were taken with the same rotor diameter. The direct stiffness, effective stiffness, and direct damping coefficients were larger for q = 0.24. The CTHC q = 0.24 eliminates the direct negative static stiffness obtained with CCHC (q = 0). The cross-coupled stiffness and damping also were larger for q = 0.24, especially at low frequencies. Effective damping is one of the best indicators in determining the stability of a roughened stator annular gas seal. The frequency at which it changes sign is called the cross-over frequency. In applications, this frequency needs to be lower than the rotorsystem0́9s first natural frequency. Otherwise, the seal will be highly destabilizing instead of highly stabilizing. The magnitude of effective damping and the cross-over frequency also increases with q for all frequencies. Constant clearance honeycomb seals have less leakage than convergenttapered honeycomb seals. CTHC (q = 0.24), has approximately 20 percent more leakage than CCHC (q = 0). The experimental results for rotordynamic characteristics and leakage were compared to theoretical predictions by the two-control-volume developed by Kleynhans and Childs. All rotordynamic coefficients were reasonably predicted for all cases. The model does a better job predicting the cross-coupled stiffness and damping coefficients rather than the direct stiffness and damping coefficients. Also, the two-control-volume model predicts the dynamic characteristics of CCHC (q = 0) better, and does not predict well the effective stiffness and damping for CTHC q = 0.386.
Download or read book Entrance and Exit Region Friction Factor Models for Annular Seal Analysis written by David Alan Elrod and published by . This book was released on 1988 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Eccentric Annular Pressure Seals written by Dung Thanh Nguyen and published by . This book was released on 1988 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbomachinery Rotordynamics written by Dara Childs and published by John Wiley & Sons. This book was released on 1993-04-16 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imparts the theory and analysis regarding the dynamics of rotating machinery in order to design such rotating devices as turbines, jet engines, pumps and power-transmission shafts. Takes into account the forces acting upon machine structures, bearings and related components. Provides numerical techniques for analyzing and understanding rotor systems with examples of actual designs. Features an excellent treatment of numerical methods available to obtain computer solutions for authentic design problems.
Download or read book Friction Factor Measurement Analysis and Modeling for Flat plates with 12 15 Mm Diameter Hole pattern Tested with Air at Different Clearances Inlet Pressures and Pressure Ratios written by Thanesh Deva Asirvatham and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Friction factor data are important for better prediction of leakage and rotordynamic coefficients of gas annular seals. A flat-plate test rig is used to determine friction factor of hole-pattern/honeycomb flat-plate surfaces representing annular seals. Three flat-plates, having a hole-pattern with hole diameter of 12.15 mm and hole depths of 0.9 mm, 1.9 mm, and 2.9 mm, are tested with air as the working medium. Air flow is produced between two surfaces, one having the hole-pattern roughness representing the hole-pattern seal and the other smooth, at the following three clearances of 0.254, 0.381, and 0.635 mm and three inlet pressures of 56, 70, and 84 bar with all possible pressure ratios at each configuration. The friction factor data are presented for all tested configurations, with description of the test rig and theory behind the calculations. The effect of hole diameter, hole depth, clearance, Reynolds number, and inlet pressure are analyzed, and friction factor models based on these parameters are calculated. Friction factor upset (an undesirable phenomenon making the test data non repeatable) is also explained. Dynamic pressure data are presented, measured from dynamic pressure probes located at both the hole-pattern plate and the smooth plates at different locations.
Download or read book ASME Technical Papers written by and published by . This book was released on 2001 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Test Results for Turbulent Annular Seals Using Smooth Rotors and Helically Grooved Stators written by Dara W. Childs and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Test results, consisting of leakage data, friction factors, and rotordynamic force coefficients, are presented for seven annular seals using smooth rotors and helically-grooved stators. All seals have the same nominal clearances and groove depths. The helix angles vary from zero (circumferential grooving) to 70 deg. The number of grooves and the leakage rates increase steadily with increasing helix angles. Helically-grooved stators leak more than smooth seals for helix angles greater than 30 deg. The effective direct stiffness of the seals first decreases and then increases with increasing helix angles. Contrary to theoretical predictions (Kim and Childs 1987), the effective net damping was relatively insensitive to changes in the helix angles.
Download or read book Journal of Tribology written by and published by . This book was released on 2005 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rotordynamic Instability Problems in High Performance Turbomachinery 1996 written by and published by . This book was released on 1997 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Shock and Vibration Digest written by and published by . This book was released on 1989 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paper written by and published by . This book was released on 2001 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Effects of Inlet Preswirl on the Dynamic Coefficients of a Straight bore Honeycomb Gas Damper Seal written by Tony Brandon Sprowl and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In high-pressure centrifugal compressors, honeycomb seals are often used as replacements for labyrinth seals to enhance dynamic stability. A concern exists with the loss of this enhanced stability if the honeycomb cavities become clogged with debris over time. So, as a first objective, static and dynamic tests were conducted on a constant-clearance honeycomb and a constant-clearance smooth-bore seal under three inlet preswirl conditions to determine the effects of inlet preswirl. The resulting leakage flowrate and dynamic parameters, effective stiffness and damping of the seal, were measured for each seal and then compared, with the smooth-bore seal representing the honeycomb seal with completely clogged cells. The second objective was to evaluate a two-control volume theory by Kleynhans and Childs with the measured data under the influence of preswirl. Both seals have a 114.7mm bore with a radial clearance of 0.2mm from the test rotor. The honeycomb seal has a cell width of 0.79mm and cell depth of 3.2mm. The target test matrix for each preswirl setting consisted of three exit-to-inlet pressure ratios of 15%, 35%, and 50%, and three rotor speeds out to 20,200 rpm. The target inlet air pressure was 70 bar-a. Experimental results show that, for a clean honeycomb seal, preswirl has little effect on effective stiffness, Keff*, and decreases effective damping, Ceff*, by about 20% at the high inlet preswirl ratio (%7E0.6). However, comparing smooth and honeycomb seal results at higher inlet preswirl shows a potential reduction in Keff* by up to 68%, and a large drop and shift in positive Ceff* values, which could cause an instability in the lower frequency range. Measured leakage shows a potential increase of about 80%, regardless of test conditions. A swirl brake at the seal entrance would fix this loss in stability by significantly reducing inlet preswirl. The two-control-volume theory model by Kleynhans and Childs seems to follow the frequency-dependent experimental data well for the honeycomb seal. Theory predicts conservatively (under-predicts) for stability parameters such as k* and Ceff* and for leakage. Predictions for K and Keff may possibly be improved with better measured friction factor coefficients for each seal.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 1518 pages. Available in PDF, EPUB and Kindle. Book excerpt:
