Design and Parametric Analysis of a Supersonic Turbine for Rotating Detonation Engine Applications

Pressure gain combustion is a promising alternative to conventional gas turbine technologies and within this class the Rotating Detonation Engine has the greatest potential. The Fickett–Jacobs cycle can theoretically increase the efficiency by 15% for medium pressure ratios, but the combustion chamber delivers a strongly non-uniform flow; in these conditions, conventionally designed turbines are inadequate with an efficiency below 30%. In this paper, an original mean-line code was developed to perform an advanced preliminary design of a supersonic turbine; self-starting capability of the supersonic channel has been verified through Kantrowitz and Donaldson theory; the design of the supersonic profile was carried out employing the Method of Characteristics; an accurate evaluation of the aerodynamic losses has been achieved by considering shock waves, profile, and mixing losses. Afterwards, an automated Computational Fluid Dynamics (CFD) based optimization process was developed to find the optimal loading condition that minimizes losses while delivering a sufficiently uniform flow at outlet. Finally, a novel parametric analysis was performed considering the effect of inlet angle, Mach number, reaction degree, peripheral velocity, and blade height ratio on the turbine stage performance. This analysis has revealed for the first time, in authors knowledge, that this type of machines can achieve efficiencies over 70%.

Comparison of Cervical Sagittal Parameters Between Radiographs and Magnetic Resonance Images in Patients With Cervical Spondylotic Myelopathy

Study Design Observational study Objective As an important consideration of surgery, cervical sagittal balance is believed to be better assessed using standing radiograph than supine magnetic resonance imaging (MRI). However, few studies have researched this. Our study aimed to observe the correlations and differences in cervical sagittal parameters between radiograph and MRI in patients with cervical spondylotic myelopathy (CSM), and evaluate whether the change of position affects them. Methods We analyzed 84 patients, measuring Cobb angle (CA), T1 slope (T1S), neck tilt (NT), and thoracic inlet angle (TIA). Inter- and intra-parameter analyses were performed to identify any difference between standing radiograph and supine MRI. Statistical correlations and differences between the parameters were compared. Results There were excellent inter-observer agreement for each parameter (interclass correlation coefficient >.75), and significant differences were observed in each parameter between radiograph and magnetic resonance imaging ( P < .05). Strong correlations were noted between the same parameters in radiograph and MRI. Cobb angle, T1S, and neck tilt were significantly correlated with thoracic inlet angle on both radiograph and MRI, and CA was significantly correlated with T1S on both radiograph and MRI ( r: −1.0 to −.5 or .5 to 1.0). Conclusion Supine MRI obviously underestimated the value of CA, T1S, and TIA. Therefore, standing cervical radiographs should be obtained in CSM patients to assess and determine surgical strategy, not only supine MRI. Moreover, we observed that NT and TIA were not constant morphological parameters.

Effects of Particle Size and Mainstream Inlet Angle on Deposition in a Turbine Cascade

Based on the critical velocity model, impact and capture efficiencies in an AGTB turbine cascade are investigated numerically under various inlet angles of mainstream, blowing ratios, particle sizes, and particle densities. The effect of hole configuration on deposition is analyzed based on comparisons of results from combined hole and cylindrical hole. The impact efficiency increases with the increase of particle size. Impact area on pressure side of blade surface expands with increasing of the mainstream inlet angle from 123 deg to 143 deg. The capture efficiency decreases with the increase of blowing ratio for 10 µm particles. For particles with densities of 1485 kg/m3, 1980 kg/m3, and 2475 kg/m3, the maximum capture efficiency is reached when the particle size is 5 µm. The particle capture efficiency for the combined hole is up to 3.9% lower than that for cylindrical hole when the mainstream inlet angle is 123 deg.

Investigation of Air Distribution in Mosque Rooms with Different Angles of Supply and Inlet Velocity

The HVAC (heating, ventilation, and air conditioning) systems utilization has increased in the last decade. It conducts global warming which has an impact on the rising of global temperatures. An excellent air conditioning system will make the room comfortable conditions. This paper aims to investigate the mosque space with a cooling model of wall-mounted air conditioning and the difference in inlet angle and air inlet velocity. The room design was constructed using SolidWorks software. Air distribution observations were created using ANSYS Workbench simulation software. The use of a supply angle of 90° results in an even distribution of air with a low inlet velocity, whereas in conditions of a supply angle of 60° requires a higher inlet speed. Thus, the uniform air distribution is able to be realized by the proper configuration which results an appropriately room temperature and saves energy usage.

Effect of Top Ventilation on Cooling Characteristics of Passenger Cabin

In order to solve the hot soak effect of car during summer parking, the CFD numerical method was used to simulate the cooling law of passenger cabin under different inlet area, inlet velocity and inlet angle at the top vent. From the two dimensions of cooling rate and cooling effect, the influence of top natural ventilation and top forced ventilation on the cooling characteristics of passenger cabin were studied. The results show that under the condition of top natural ventilation, the cabin can reach thermal balance at about 10 min under different vent area conditions, and the cooling rate is the largest when the vent is fully opened, and the minimum temperature can reach about 45 °C within 4 min, which is 10 °C higher than the ambient temperature. Under forced ventilation, the inlet velocity has a great influence on the cooling rate and cooling effect of cabin. When the inlet angle is 90° and the inlet velocity is 5 m / s, the cooling rate is the largest and the cooling effect is the best.

Analysis of Sagittal Thoracic Inlet Measures in Relation to Anterior Access to the Cervicothoracic Junction

Study Design: Retrospective radiographic study. Objective: The aim of this study was to define the association between thoracic inlet measures in relation to anterior access to the cervicothoracic junction. Methods: Trauma CT scans in patients >16 years were analyzed. The projection angle (PA), defined as the angle subtended by a line along the superior endplate of the vertebral body and the line from the anterosuperior corner of the vertebral body to the manubrium, was measured at C7, T1 and T2; angles were positive if the projection was above the manubrium. Thoracic inlet angle (TIA), thoracic inlet distance (TID) and pelvic incidence (PI) were measured. Results: 65 scans were assessed (33 males; mean age 47.7 years (s.d. 8.7)). The mean TIA 79.9° (s.d. 13.4°; range 52.6° – 112.2°), mean TID 66.1 mm (s.d. 6.6 mm) and mean PI was 50.5° (s.d. 10.2°). Mean values for the projection angles at C7, T1 and T2 were 24.2°, 7.6° and −8.3° respectively. PA were positive in 95% at C7, 73% at T1 and 30% at T2. PA at each level correlated significantly with age (mean r=−0.371; P = .015) and TIA (mean r=−0.916; P < .001) but neither TID nor PI. TIA correlated with age (r = 0.328; P = .008). Conclusions: The projection angles of the CTJ vertebrae are influenced by thoracic inlet angle and a lesser degree age. Understanding sagittal spinal parameters in the CTJ can aid in planning surgical strategy and approach.

Ventilation Diagnosis of Angle Grinder Using Thermal Imaging

The paper presents an analysis and classification method to evaluate the working condition of angle grinders by means of infrared (IR) thermography and IR image processing. An innovative method called BCAoMID-F (Binarized Common Areas of Maximum Image Differences—Fusion) is proposed in this paper. This method is used to extract features of thermal images of three angle grinders. The computed features are 1-element or 256-element vectors. Feature vectors are the sum of pixels of matrix V or PCA of matrix V or histogram of matrix V. Three different cases of thermal images were considered: healthy angle grinder, angle grinder with 1 blocked air inlet, angle grinder with 2 blocked air inlets. The classification of feature vectors was carried out using two classifiers: Support Vector Machine and Nearest Neighbor. Total recognition efficiency for 3 classes (TRAG) was in the range of 98.5–100%. The presented technique is efficient for fault diagnosis of electrical devices and electric power tools.