Performance of a low-pressure-ratio centrifugal compressor with four diffuser designs

A low-pressure-ratio centrifugal compressor was tested with four different diffuser configurations. One diffuser had airfoil vanes. Two were pipe diffusers. One pipe diffuser had 7.5 deg cone diffusing passages. The other had trumpet-shaped passages designed for linear static-pressure rise from throat to exit. The fourth configuration had flat vanes with elliptical leading edges similar to those of pipe diffusers. The side walls were contoured to produce a linear pressure rise. Peak compressor efficiencies were 0.82 with the airfoil vane and conical pipe diffusers, 0.80 with the trumpet, and 0.74 with the flat-vane design. Surge margin and useful range were greater for the airfoil-vane diffuser than for the other three

Effect of inducer inlet and diffuser throat areas on performance of a low pressure ratio sweptback centrifugal compressor

A low-pressure-ratio centrifugal compressor was tested with nine combinations of three diffuser throat areas and three impeller inducer inlet areas which were 75, 100, and 125 percent of design values. For a given inducer inlet area, increases in diffuser area within the range investigated resulted in increased mass flow and higher peak efficiency. Changes in both diffuser and inducer areas indicated that efficiencies within one point of the maximum efficiency were obtained over a compressor specific speed range of 27 percent. The performance was analyzed of an assumed two-spool open-cycle engine using the 75 percent area inducer with a variable area diffuser

Electronic visualization of gas bearing behavior

Visualization technique produces a visual simulation of gas bearing operation by electronically combining the outputs from the clearance probes used to monitor bearing component motion. Computerized recordings of the probes output are processed, displayed on an oscilloscope screen and recorded with a high-speed motion picture camera

Satisfaction and quality of life in women who undergo breast surgery: a qualitative study to develop conceptual model

Background: In cosmetic and reconstructive breast surgery, measurement of patient-reported outcomes has become increasingly important to research efforts and clinical care. We aimed to describe how breast conditions and breast surgery impact on patient satisfaction and quality of life. Methods: We conducted qualitative, in-depth interviews with 48 women who had undergone either breast reduction (n = 15), breast augmentation (n = 12), or breast reconstruction (n = 21) surgery in order to begin to build a theoretical understanding of patient satisfaction and quality of life in breast surgery patients. Interviews were audio-taped, transcribed verbatim and analyzed thematically. Results: The patient interviews revealed that breast conditions and breast surgery impact women in the following six main areas: satisfaction with breasts; satisfaction with overall outcome; psychosocial well-being; sexual well-being; physical well-being; and satisfaction with the process of care. We used these six themes to form the basis of a conceptual framework of patient satisfaction and quality of life in women who undergo breast surgery. Conclusion: Our conceptual framework establishes the main issues of concern for breast surgery patients. This new framework can be used to help develop local guidelines for future clinical assessment, management and measurement, establish the validity of the current management strategies, and develop evidence-based guidance for the development of new patient reported outcome measures for future outcomes research

An Examination of Risk Factors for Adolescent Engagement in Directly and Indirectly Self-Injurious Behaviours

Research identifying similar and dissimilar risk factors for directly and indirectly self-injurious behaviours among adolescents is scarce. Due to the wide range of physical and mental health difficulties that may result from self-injurious behaviours, understanding differential risks is important to support at-risk adolescents. To address this gap in the literature, 541 clinically referred children and youth (ages 11-18 years old) were assessed using the interRAI Child and Youth Mental Health Assessment (ChYMH) and Adolescent Supplement. Logistic regression analyses revealed that older adolescents were at an increased risk for both direct and indirect self-injury. Moreover, adolescents who experienced high levels of depressive symptoms, caregiver distress, and neighbourhood violence were at an increased risk for direct self-injury (i.e., nonsuicidal self-injury, suicidal self-injury). In contrast, adolescents who experienced high levels of aggressive behaviour were at an increased risk for indirect self-injury (i.e., substance use). Implications for targetted preventative and intervention strategies are discussed

A Note on ADE-Spectra in Conformal Field Theory

We demonstrate that certain Virasoro characters (and their linear combinations) in minimal and non-minimal conformal models which admit factorized forms are manifestly related to the ADE series. This permits to extract quasi-particle spectra of a Lie algebraic nature which resembles the features of Toda field theory. These spectra possibly admit a construction in terms of the $W_n$-generators. In the course of our analysis we establish interrelations between the factorized characters related to the parafermionic models, the compactified boson and the minimal models.Comment: 7 pages Late

Experimental performance of a 16.10-centimeter-tip-diameter sweptback centrifugal compressor designed for a 6:1 pressure ratio

A backswept impeller with design mass flow rate of 1.033 kg/sec was tested with both a vaned diffuser and a vaneless diffuser to establish stage and impeller characteristics. Design stage pressure ratio of 5.9:1 was attained at a flow slightly lower than the design value. Flow range at design speed was 6 percent of choking flow. Impeller axial tip clearance at design speed was varied to determine effect on stage and impeller performance

A New Family of Diagonal Ade-Related Scattering Theories

We propose the factorizable S-matrices of the massive excitations of the non-unitary minimal model $M_{2,11}$ perturbed by the operator $\Phi_{1,4}$. The massive excitations and the whole set of two particle S-matrices of the theory is simply related to the $E_8$ unitary minimal scattering theory. The counting argument and the Thermodynamic Bethe Ansatz (TBA) are applied to this scattering theory in order to support this interpretation. Generalizing this result, we describe a new family of NON UNITARY and DIAGONAL $ADE$-related scattering theories. A further generalization suggests the magnonic TBA for a large class of non-unitary \G\otimes\G/\G coset models (\G=A_{odd},D_n,E_{6,7,8}) perturbed by $\Phi_{id,id,adj}$, described by non-diagonal S-matrices.Comment: 13 pages, Latex (no macros), DFUB-92-12, DFTT/30-9

Experimental performance of a 13.65-centimeter-tip-diameter tandem-bladed sweptback centrifugal compressor designed for a pressure ratio of 6

A 13.65 cm tip diameter backswept centrifugal impeller having a tandem inducer and a design mass flow rate of 0.907 kg/sec was experimentally investigated to establish stage and impeller characteristics. Tests were conducted with both a cascade diffuser and a vaneless diffuser. A pressure ratio of 5.9 was obtained near surge for the smallest clearance tested. Flow range at design speed was 6.3 percent for the smallest clearance test. Impeller exit to shroud axial clearance at design speed was varied to determine the effect on stage and impeller performance