Effect of Kerosene Dual-Jet Spacing on the Mixing and Combustion Characteristics of a Scramjet Combustor.

As the core of a hypersonic propulsion system, the effective mixing efficiency of fuel and air in a supersonic combustor is crucial for its performance. This study focuses on a cold supersonic flow and employs computational fluid dynamics (CFD) techniques combined with Euler-Lagrange method's discrete-phase model (DPM) for multiphase flows, K-H and R-T (Kelvin-Helmholtz and Rayleigh-Taylor) mixing and atomization models, turbulence models, and surface evaporation models to investigate the injection, atomization, and mixing characteristics of kerosene in supersonic airflow. In order to enhance the mixing efficiency between kerosene and air while reducing flow losses, this study examines a staggered dual-jet injection scheme, with the dual jets arranged at the center of the cavity and having a dual-jet spacing of 10 and 20 mm, respectively. Starting from the interaction mechanism between jets, the impact of different staggered dual-jet spacings on the kerosene jet penetration height, span expansion area, angle of the shock wave, and Sauter mean diameter distribution was analyzed. The results show that a short dual-jet spacing (10 mm) leads to greater penetration height, wider span expansion, and a larger angle of the shock wave. When the dual-jet spacing is shorter, the interaction between the fuel jet and the cavity shear layer is stronger, resulting in an improved fuel mixing efficiency. The achievements of this study are consistent with previous experimental measurements and the literature, demonstrating a strong theoretical foundation for optimizing the design of hypersonic engines by deepening the understanding of the fundamental atomization mechanisms of kerosene jets in cold-state supersonic flows. Moreover, these results hold practical significance in improving the efficiency of kerosene combustion and enhancing the performance of flame stabilization devices.

Evaluation of Influences of Changed Lower Cover Geometry on Kerosene-Air Interaction in a Scramjet Combustor.

The fuel in a scramjet combustor must be injected into a high-speed crossflow and mixed with supersonic air in a very short period of time in order for the scramjet jet to operate reliably. More generally, the supersonic air is produced by the lower cover, similar to a Laval type nozzle, of the scramjet combustor. However, significant variation in lower cover geometry is prone to produce unstable vortexes. The unstable vortexes are accompanied by nonuniform stress and strain and are detrimental to the lower cover, even to the combustor. Inspired by mechanical design, this study proposes to change lower cover geometry by decreasing its sizes and then evaluates effects of these changes on kerosene fuel-air interaction in the combustor. The evaluation is based on three-dimensional computational fluid dynamics with couple level set and volume of fluids, which characterizes the penetration height, span expansion area, shock wave angle, and Sauter mean diameter of kerosene jets for three different injection diameters (0.5, 1.0, and 1.5 mm). The simulated air-kerosene interactions reasonably agree with the past numerical findings at identical working conditions. This result demonstrates the effectiveness of the changed lower cover geometry for the scramjet combustor.

Examination of the role of the rotating nursing department in the training of nursing staff based on SWOT analysis.

BACKGROUND: The implementation of the rotation system in the Chinese medical industry has achieved significant results. OBJECTIVES: The present study aims to 1) explore the strengths, weaknesses, opportunities and challenges of rotational nursing department implementation and 2) provide references for developing nursing staff's competencies in leadership, performance evaluation, quality of care, communication in relationships and human resources. METHODS: A total of 16 rotational nursing department staff members from a tertiary tuberculosis specialist hospital in Beijing were interviewed, and the interview data were analysed using a strengths, weaknesses, opportunities and threats analysis and class analysis. RESULTS: The advantages of the rotational nursing department included: (1) stimulating the nursing staff's enthusiasm and creativity; (2) strengthening the communication and collaboration between departments; (3) improving the detailed management of nursing quality; and (4) enhancing the nursing staff's comprehensive abilities. The disadvantages included: (1) the design of the rotation programme focusing on practice; (2) a lack of personalisation; and (3) imperfect performance assessment of the rotating staff. Opportunities included: (1) deepening the connotation of nursing job management and (2) developing the construction of nursing discipline and the need for personal career development and value realisation. Threats included the lack of a sound rotation management model to draw on. CONCLUSION: A rotational nursing department is conducive to enhancing the competence of nursing staff in management positions and providing new ideas for hospitals to select and train nursing management talents. By taking full advantage of the benefits of vertical nursing management, designing personalised rotation training programmes, building a diversified learning and training platform and developing a positive performance incentive mechanism is recommended to fully engage the role of rotation in nursing management talent training.

Right siting of complex acute wound management---preliminary study of teleconsultation wound services between acute and primary care in Singapore.

This study aimed to provide preliminary evidence on feasibility of the inaugural use of teleconsultation between acute hospitals and primary care for acute wound management in Singapore. Post-surgical patients with carbuncle wounds, perianal abscess wounds or surgical abdominal dehiscence wounds were recruited from an acute hospital. Instead of receiving their follow up care at the acute care tertiary hospital, patients were given the option to receive their care at primary care facilities instead, supported by teleconsultation wound services provided by wound care nurses from the hospital. The following outcome measures were collected: number of care sessions required (until wound healed), readmissions or referrals back to hospital, cost (patient's and healthcare provider's perspective), patients' and nurses' satisfaction. In total, 18 patients were recruited and completed the study (teleconsult group = 5; tertiary care clinic group = 13). The mean age (SD) of patients were 63.2 (SD 11.5) years old in the teleconsult group and 47.9 years old (SD 11.5) in the tertiary care clinic group. There were 7 female (54%), and 6 male (46%) in the tertiary care clinic group whereas teleconsult group consisted of male only (n = 5). Most had carbuncle wounds (teleconsult group: n = 4; 80%); tertiary care clinic group: (n = 10; 77%). For patients with carbuncle wounds, the average number of care sessions required were 21 and 33 for the tertiary care clinic and teleconsult respectively. None of the patients in the teleconsult group were referred back to the tertiary care hospital. All 16 nurses (n = 6 from acute care hospital, n = 10 from polyclinics) who participated in the feedback survey cited convenience, ease of tracking wound sizes, and closer collaboration between the acute care and primary care nurses as advantages of the service. Wound teleconsultation is feasible and potentially cost savings for patients with acute complex wounds.