Combustion of hydrogen in a two-dimensional duct with step fuel injectors

An investigation of the combustion of hydrogen perpendicularly injected from step fuel injectors into a Mach 2.72, 2100 K vitiated test gas was conducted. The model simulated the flow between the center and side struts of an integrated scramjet module at Mach 7 flight and an altitude of 29 km. Parametric variation included equivalence ratio, fuel dynamic pressure ratio, and area distribution of the model. The overall area ratio of the model was held constant at 2.87. The data analysis indicated that no measurable improvement in mixing or combustion efficiency was obtained by varying the fuel dynamic pressure ratio from 0.79 to 2.45. Computations indicated approximately 80 percent of the fuel was mixed so that it could react; however, only approximately 50 percent of the mixed fuel actually reacted in two test configurations, and 74 percent in later tests where less area expansion of the flow occurred

Experimental investigation of a swept-strut fuel-injector concept for scramjet application

Results are presented of an experiment to investigate the behavior at Mach 4 flight conditions of the swept-strut fuel-injector concept employed in the Langley integrated modular scramjet engine design. Autoignition of the hydrogen fuel was not achieved at stagnation temperatures corresponding to a flight Mach number of 4; however, once ignition was achieved, stable combustion was maintained. Pressure disturbances upstream of the injector location, which were caused by fuel injection and combustion, were generally not observed; this indicates the absence of serious adverse combustor-inlet interactions. Mixing performance and reaction performance determined from probe surveys and wall pressure data indicate that high combustion efficiency should be obtained with the combustor length provided in the scramjet engine design. No adverse interaction between the perpendicular and parallel fuel-injection modes was observed

Quality of cause of death certification at an academic hospital in Cape Town, South Africa

Objectives. To investigate the quality of cause of deathcertification and assess the level of under-reporting of HIV/AIDS as a cause of death at an academic hospital.Design. Cross-sectional descriptive retrospective review ofdeath notification forms (DNFs) of deaths due to naturalcauses in an academic hospital in Cape Town during 2004.Errors in cause of death certification and ability to code causesof death according to the 10th revision of the InternationalStatistical Classification of Diseases and Related Health Problems(ICD-10) were assessed. The association between seriouserrors and age, gender, cause of death and hospital ward wasanalysed. A sample of DNFs (N=243) was assessed for level ofunder-reporting of HIV/AIDS.Results. A total of 983 death certificates were evaluated.Almost every DNF had a minor error; serious errors werefound in 32.2% (95% confidence interval (CI) 29.3 - 35.1%).Errors increased with patient age, and cause of death wasthe most important factor associated with serious errors.Compared with neoplasms, which had the lowest error rate,the odds ratios for errors in endocrine and metabolic diseasesand genito-urinary diseases were 17.2 (95% CI 8.7 - 34.0) and17.3 (95% CI 7.8 - 38.2), respectively. Based on the sub-sample,the minimum prevalence of HIV among the deceased patientswas 15.7% (95% CI 11.1 - 20.3%) and the under-reporting ofdeaths due to AIDS was 53.1% (95% CI 35.8 - 70.4%).Conclusion. Errors were sufficiently serious to affectidentification of underlying cause of death in almost a thirdof the DNFs, confirming the need to improve the quality ofmedical certification

Research to action to address inequities: the experience of the Cape Town Equity Gauge

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