Fuel injector: Air swirl characterization aerothermal modeling, phase 2, volume 1

A well integrated experimental/analytical investigation was conducted to provide benchmark quality relevant to a prefilming type airblast fuel nozzle and its interaction with the combustor dome air swirler. The experimental investigation included a systematic study of both single-phase flows that involved single and twin co-axial jets with and without swirl. A two-component Phase Doppler Particle Analyzer (PDPA) was used to document the interaction of single and co-axial air jets with glass beads that simulate nonevaporating spray and simultaneously avoid the complexities associated with fuel atomization processes and attendant issues about the specification of relevant boundary conditions. The interaction of jets with methanol spray produced by practical airblast nozzle was also documented in the spatial domain of practical interest. Model assessment activities included the use of three turbulence models (k-epsilon, algebraic second moment (ASM), and differential second moment (DSM)) for the carrier phase, deterministic or stochastic Lagrangian treatment of the dispersed phase, and advanced numerical schemes. Although qualitatively good comparison with data was obtained for most of the cases investigated, the model deficiencies in regard to modeled dissipation rate transport equation, single length scale, pressure-strain correlation, and other critical closure issues need to be resolved before one can achieve the degree of accuracy required to analytically design combustion systems

Fuel Injector: Air swirl characterization aerothermal modeling, phase 2, volume 2

A well integrated experimental/analytical investigation was conducted to provide benchmark quality data relevant to prefilming type airblast fuel nozzle and its interaction with combustor dome air swirler. The experimental investigation included a systematic study of both single-phase flows that involved single and twin co-axial jets with and without swirl. A two-component Phase Doppler Particle Analyzer (PDPA) equipment was used to document the interaction of single and co-axial air jets with glass beads that simulate nonevaporating spray and simultaneously avoid the complexities associated with fuel atomization processes and attendant issues about the specification of relevant boundary conditions. The interaction of jets with methanol spray produced by practical airblast nozzle was also documented in the spatial domain of practical interest. Model assessment activities included the use of three turbulence models (k-epsilon, algebraic second moment (ASM) and differential second moment (DSM)) for the carrier phase, deterministic or stochastic Lagrangian treatment of the dispersed phase, and advanced numerical schemes. Although qualitatively good comparison with data was obtained for most of the cases investigated, the model deficiencies in regard to modeled dissipation rate transport equation, single length scale, pressure-strain correlation, and other critical closure issues need to be resolved before one can achieve the degree of accuracy required to analytically design combustion systems

Aerothermal modeling program. Phase 2, element B: Flow interaction experiment

NASA has instituted an extensive effort to improve the design process and data base for the hot section components of gas turbine engines. The purpose of element B is to establish a benchmark quality data set that consists of measurements of the interaction of circular jets with swirling flow. Such flows are typical of those that occur in the primary zone of modern annular combustion liners. Extensive computations of the swirling flows are to be compared with the measurements for the purpose of assessing the accuracy of current physical models used to predict such flows

Modeling of Fluctuating Mass Flux in Variable Density Flows

The approach solves for both Reynolds and Favre averaged quantities and calculates the scalar pdf. Turbulent models used to close the governing equations are formulated to account for complex mixing and variable density effects. In addition, turbulent mass diffusivities are not assumed to be in constant proportion to turbulent momentum diffusivities. The governing equations are solved by a combination of finite-difference technique and Monte-Carlo simulation. Some preliminary results on simple variable density shear flows are presented. The differences between these results and those obtained using conventional models are discussed

MR defecography: A diagnostic test for the evaluation of pelvic floor motion in patients with dyssynergic defecation after biofeedback therapy

Background: Dyssynergic defecation is a major cause of chronic functional constipation as a common digestive complaint. We clinically evaluated the effects of biofeedback therapy on the pelvic floor motion indices through magnetic resonance (MR) defecography, quality of life and depression in patients with dyssynergic defecation. Methods: In this clinical trial study, among patients referring to the Colorectal Clinic of Hazrat Rasoul Hospital, 22 subjects were randomly assigned into two equal groups (n= 11) to receive either standard only or biofeedback and standard therapy. Dynamic changes of the pelvic floor were measured by MR defecography. During the simulated defecation, two MR defecography dynamic indices including abnormal anorectal angle change and perineal descent were measured before and after treatment. The effects of biofeedback therapy on patients' symptoms, quality of life and severity of depression were assessed and compared with the standard therapy. Statistical analysis was carried out using independent t-test and Mann-Whitney test. Results: Paradox index (p< 0.001), perineal descent index (p< 0.001), depression (p< 0.1), physical function (p< 0.001), vitality (p< 0.001) and role emotion (p< 0.001) significantly improved in the biofeedback therapy group in contrast to the standard therapy SDT group. Conclusion: Biofeedback therapy appears to be effective in improving symptoms of functional constipation and dysfunction of pelvic floor motion as well as patient's quality of life and depression state. MR defecography is able to show the changes in dynamic indices of the pelvic floor through biofeedback therapy

Patient assessment of constipation quality of life questionnaire: Translation, cultural adaptation, reliability, and validity of the persian version

Background: The Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaire is the most validated and the most specific tool for measuring the quality of life of patients with constipation. Over 120 million people live in countries whose official language is Persian. There is no reported Persian version of the PAC-QOL questionnaire yet. The aim of this study was to translate and culturally adapt the PAC-QOL questionnaire and to assess its reliability and validity among Persian patients with chronic constipation. Methods: Following the translation and cultural adaptation of the PAC-QOL questionnaire to Persian, 100 patients (mean±SD age=40.51±13.67) with constipation were recruited for validity measurement and 20 patients were re-examined for reliability. Content validity was assessed based on the opinions of an expert committee and the floor/ceiling effect. Construct validity was evaluated according to the hypothesis test. The SF-36 questionnaire was used for concurrent criterion validity, intraclass correlation coefficient for reliability, and Cronbach�s alpha for internal consistency. Results: The content validity of the PAC-QOL questionnaire was proven, and there was no floor/ceiling effect. Construct validity also was confirmed based on the hypothesis test. The overall Cronbach�s alpha of the PAC-QOL questionnaire was 0.92 (range=0.72�0.92), and the overall intra-class correlation coefficient of the questionnaire was 0.88 (range=0.69�0.87). The correlation between the SF-36 and PAC-QOL questionnaires was moderate. Conclusion: The Persian version of the PAC-QOL questionnaire demonstrated good validity and reliability properties in chronic constipation. Accordingly, Persian researchers and clinicians can benefit from this questionnaire in further research and assessment of treatment outcomes. © 2018, Shiraz University of Medical Sciences. All rights reserved

Patient assessment of constipation quality of life questionnaire: Translation, cultural adaptation, reliability, and validity of the persian version

Background: The Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaire is the most validated and the most specific tool for measuring the quality of life of patients with constipation. Over 120 million people live in countries whose official language is Persian. There is no reported Persian version of the PAC-QOL questionnaire yet. The aim of this study was to translate and culturally adapt the PAC-QOL questionnaire and to assess its reliability and validity among Persian patients with chronic constipation. Methods: Following the translation and cultural adaptation of the PAC-QOL questionnaire to Persian, 100 patients (mean±SD age=40.51±13.67) with constipation were recruited for validity measurement and 20 patients were re-examined for reliability. Content validity was assessed based on the opinions of an expert committee and the floor/ceiling effect. Construct validity was evaluated according to the hypothesis test. The SF-36 questionnaire was used for concurrent criterion validity, intraclass correlation coefficient for reliability, and Cronbach�s alpha for internal consistency. Results: The content validity of the PAC-QOL questionnaire was proven, and there was no floor/ceiling effect. Construct validity also was confirmed based on the hypothesis test. The overall Cronbach�s alpha of the PAC-QOL questionnaire was 0.92 (range=0.72�0.92), and the overall intra-class correlation coefficient of the questionnaire was 0.88 (range=0.69�0.87). The correlation between the SF-36 and PAC-QOL questionnaires was moderate. Conclusion: The Persian version of the PAC-QOL questionnaire demonstrated good validity and reliability properties in chronic constipation. Accordingly, Persian researchers and clinicians can benefit from this questionnaire in further research and assessment of treatment outcomes. © 2018, Shiraz University of Medical Sciences. All rights reserved