Rib Tip Research Articles

V-spline design for enhanced performance in turbine blade internal cooling

Abstract Past experiments have consistently shown that V-shaped rib turbulators are among the best in heat transfer performance. While there is literature on the V rib design in various experimental studies, there is no literature that shows the V rib design applied on any current turbine blades. Instead, the straight and angled rib design are used. The V rib only offers a marginally better heat transfer performance over the angled rib, but it has a severe stress concentration at the rib tip. In this research, multiple design augmentations were analyzed, with the addition of a spline at the center of the V exhibiting alleviation of the tip stress concentration. The results show that the presence of the spline not only resolves the fatigue issues but also increases the heat transfer performance by 4.3% and 8.2% against the V rib and angled rib design respectively. With a better heat transfer performance, the creep analysis shows that the turbine blade with a V-spline rib design can operate at temperatures 203°C hotter than an angled rib at the same fluid power. Given the dependence of engine thermal efficiency on turbine inlet temperature, this simple design shows good potential for heat transfer augmentation.

EFFECT OF GEOMETRICAL PARAMETERS ON THE THERMAL-HYDRAULIC PERFORMANCE OF INTERNAL HELICALLY RIBBED TUBES

In this paper, single-phase heat transfer characteristics of water inside internal enhanced tubes were investigated. Refrigerants are boiling or condensing outside the tube. The experimental tubes have internal helical rib heights of 0.25-0.36 mm, helix angles of 40-60°, rib base thicknesses of 0.40-0.79 mm, rib tip thicknesses of 0.078-0.283 mm, and N<sub>s</sub> (starts number per circle) of 40-50. It shows that the heat transfer enhanced ratios usually range from 2.3 to 3.64. The friction factors relative to the smooth tube are about 1.8 to 3.3 times higher. Analyzing the effect of rib geometry on flow and heat transfer, it was found that the higher the height of the internal rib, the better the enhancement of convective heat transfer in the tube. Also, the greater the thickness of the rib tip and base, the more detrimental to the friction factor in the tube. There was no noticeable influence on the heat transfer performance as the helix angle increased from 45° to 50°. For the increase of N<sub>s</sub>, it appears that 45 ribs per circle is the best value in the present study when considering the increase in pressure loss. The thermal-hydraulic performance of 11 tubes was also evaluated. It shows that Tube-1 had the best performance in the condensing tubes and Tube-7 had the best performance in the boiling tubes.

Rib tip technique (RTT) to nhomboid block: A novel approach.

Rib tip technique (RTT) to nhomboid block: A novel approach.

Refined simulation of bond-slip behavior between ribbed steel and concrete: Effects of initial stress and temperature

The bond performance between steel and concrete exposed to fire is influenced by many factors, including the presence of an initial load before the temperature increase. To investigate such effect, a 3-D refined simulation model is presented accounting for the heterogeneity of concrete at the mesoscopic level and the external geometry of ribbed steel bars. The rationality and validity of the refined simulation model and of the multi-step analysis were verified by comparison with existing experimental data. Subsequently, the effects of aggregate gradation and distribution, initial loading level and temperature on the bond behavior were analyzed. The load transfer mechanism at the steel–concrete interface as a function of temperature under different loading levels is captured and discussed. It is found that the influence of aggregate grading and distribution on the bond-slip curve can be ignored under the aggregate volume fraction set in this work. Additionally, results show that the damage initially concentrates at the rib tip of the deformed steel bars, with an increase across the concrete section as the slip increases, as it could be expected. However, the bond stress and both stress and strain of steel at the same position decrease as the temperature increases. Finally and most importantly, it is found that the heating and loading sequence induce a different damage evolution inside the specimen, with a significant effect on the bond stiffness, the plateau portion of the bond stress-slip curve and the bond strength associated to a given critical temperature.

Anatomy of the anterior ribs and the composition of the costal margin: A cadaver study.

Traditional rib anatomy and costal margin teaching contends that the costal margin consists of a combined costal cartilage made up of ribs 7 to 10. Variations in 9th and 10th rib anatomy have been observed. We sought to evaluate the variability of interchondral joints and the make-up of the costal margin. Cadaveric dissections were performed to evaluate the anatomy of the anterior ribs and the composition of the costal margin. Experienced chest wall surgeons evaluated this anatomy through a standardized dissection and assessment. Dissection videos were performed to allow for further review/assessment. Bilateral chest wall anatomy of 30 cadavers was evaluated (15 male, 15 female). The average age was 78 ± 12 years, and all patients were Caucasian. In all patients, the first rib attached to the manubrium, the second rib attached to the manubriosternal junction, and ribs 3 to 6 attached directly to the sternum. Interchondral joints were present between ribs 4/5-3%, 5/6-68%, 6/7-83%, 7/8-72%. Ribs combining to form a common costal cartilage via cartilaginous unions were observed between 6/7-3%, 7/8-45%, 8/9-30%, and 9/10-20%.The 8th rib attached directly to the sternum without joining the 7th rib in 10% of cadavers. The 8th and 9th ribs had free tips in 45% and 60% of evaluations, respectively. The 10th rib was found to have a hooked tip in 25% of cases and was a floating rib without attachment to the 9th rib 52% of the time. Rib tip mobility was noted in ribs 8, 9, and 10 in 52%, 70%, and 90%, respectively. Interchondral joints are common between ribs 5 and 8. Significant variability exists in the chest wall and costal margin compared with traditional teaching. It is important for chest wall surgeons treating diseases of the costal margin to appreciate this anatomic variability.

Assessing the Variability of the Twelfth Rib as a Landmark for Percutaneous Nephrolithotomy Using Computed Tomography.

The variability in length of the twelfth rib is mentioned in the literature but has never been formally studied. The highly variable rib length provides a challenge for urologists seeking a consistent landmark for Percutaneous Nephrolithotomy (PCNL). We set out to determine whether the twelfth rib is safe to use as a consistent landmark for surgery. Single centre, cross-sectional retrospective observational study and analysis of CT scans of 100 adults who had imaging between 23rd March and 12th April 2020. The distance from the mid-sagittal line to the twelfth rib tip in the axial plane was measured as was the distance from the twelfth rib tip to the kidney, spleen and liver. Length from the mid-sagittal line to the right twelfth rib tip varied from 46 (percentile 95% CI 40 to 57) to 136mm (percentile 95% CI 133 to 138). On the left, the distances varied from 55 (percentile 95% CI 50 to 64) to 134mm (percentile 95% CI 131 to 135). Twenty-three percent of people had an organ lying between the tip of the twelfth rib and the kidney on the right and 11% on the left. The twelfth rib is highly variable in length. Similar variability was recorded in the distance from the tip to intra-abdominal organs. Due to the frequency of organs lying between the tip of the rib and the kidney it should not be used as a landmark for accessing the kidney without prior knowledge of an individual patient's anatomy as seen on imaging.

Experimental investigation on heat transfer characteristics in a ribbed leading edge channel of turbine blade

To investigate the structure of the leading edge of turbine blade with film outflow and its internal heat transfer law, the heat transfer characteristics of the triangular channel with half-ribbed structure at the leading edge with different Reynolds numbers (Re = 6000 ∼ 30000) and outflow ratios (OFR = 0 ∼ 0.8) are researched by using the transient liquid crystal (TLC) measurement technique. The results show that when the outflow ratio is 0, the high heat transfer area is mainly distributed in the region behind the ribs and the edge of the rib tip. The heat transfer is weaker in the area away from the ribs, and the high heat transfer area behind the ribs first weakens and then strengthens along the flow direction. With the increase of outflow ratio, the high heat transfer zone near the film holes increases. The heat transfer in the area near the stagnation point of the leading edge is enhanced, and the overall high heat transfer zone is more uniformly distributed. Under the large outflow ratio, more coolant flows out of the film holes, resulting in a small downstream flow rate and reduced velocity. The area of low heat transfer near the tip of the blade increased, and heat transfer decreased. With the increase in Reynolds number, the heat transfer of the internal cooling channel is significantly enhanced, and the area of the high heat transfer zone is expanded.

Analysis of Non-uniform Local Strain in Corroded Reinforcing Bar in Concrete using Digital Image Correlation

Change in the mechanism of post corrosion bond behavior was investigated in a previous experimental study by analyzing the deformations in concrete using digital image correlation (DIC). Using their DIC data, this study focuses on the local strain non-uniformity in reinforcing bar during the uniaxial tensile test due to the effect of rib height reduction and corrosion layer. The results show that, the local strain below the rib tip is higher than that below the flat part between ribs, due to compressive stress resulting from mechanical interaction at the rib tip. Furthermore, the non-uniformity in local strain is less pronounced in highly corroded reinforcing bar because less compressive stress is transferred due to gentler rib slope. In highly corroded reinforcing bar, the appearance of non-uniformity in local strain is delayed since the accumulated corrosion product on the reinforcing bar surface delays the mechanical interaction and stress transfer between the concrete and the reinforcing bar.

Redefining the costal margin: A pilot study.

Classical teaching of rib anatomy contends that the false ribs (7th to 10th) fuse anteriorly to form the costal margin of the chest. Slipped rib syndrome consists of false rib subluxation into the thorax with symptomatic impingement of the intercostal nerve. We sought to determine the incidence of this anatomic finding through anatomic study of the costal margin. Cadavers were evaluated for mobility and attachment of the ninth and tenth ribs. Experienced anatomists and chest wall surgeons conducted a standardized dissection and assessed rib tip mobility using predefined criteria. Videos of dissections were submitted to a single investigator who reviewed the findings. Costal margins of 40 cadavers (45% male) were evaluated bilaterally. The average age was 83 years ± 11 years. The ninth rib was found to be attached to the eighth rib 100% of the time by an interchondral cartilaginous attachment along the body of the eighth and ninth ribs. Internal subluxation was noted in 19% (15 of 80), and the tip of the rib was mobile in 86% (69 of 80) evaluations. The tenth rib was attached to the ninth rib in 18%(14/80). A "floating" 10th rib was noted in 59% (47 of 80) of specimens. Subluxation was noted in 33% (26 of 60). Half of the ribs that subluxed moved medially to the ninth rib and half moved externally. An upwardly hooked tip was noted in 10% (8 of 80). Ribs with a hooked tip subluxed in 63% (5 of 8), and all of these ribs (5 of 5) moved to the interior of the chest ( p = 0.020). The ninth rib is commonly attached to the eighth rib, but the tenth rib is often not attached to the ninth rib. Most commonly, the tenth rib is a "floating" rib. Internal subluxation of the tenth rib as well as the presence of a hooked tip may predispose individuals to the development of "slipped rib syndrome." Diagnostic Tests or Criteria; Level III.

3D RBSM Analysis of Bond Degradation in Corroded Reinforced Concrete as Observed Using Digital Image Correlation.

The buildup of corrosion products over a reinforcing bar and associated reduction in rib height lead to degradation of the bond between reinforcement and concrete. The authors have previously used digital image correlation (DIC) to visualize and quantify load-induced cracking at the interface in specimens with varying degrees of corrosion. The results obtained in that study are used here to simulate the post-corrosion local bond behavior. A bond degradation model is incorporated into the discrete analysis tool, 3D Rigid Body Spring Model (RBSM) for the simulation. This analysis method allows the shape of the reinforcing bar to be directly modeled, and concrete cracking behavior is simulated by using a randomly shaped mesh. The magnitude of opening and sliding over the tips of ribs in the simulation, in which the reduction in rib height could not be modeled, is significantly lower than observed in the experiment. The results demonstrate that reduction in rib height is an important factor in post-corrosion behavior, and needs to be included in simulation models. It is also understood that in order to gain a better understanding of local post-corrosion bond behavior, de-bonding between reinforcement and concrete needs to be modeled in a discrete analysis framework.

Influence of grooved rib tip structure on tip loss and heat transfer in a gas turbine blade

This study focuses on the effects of three groove tip structures (full rib groove tip, partial rib tip on the suction side, and partial rib tip on the pressure side) on tip leakage flow, aerodynamic characteristics of a cascade, and heat transfer in a gas turbine blade. The groove’s width B = 1.6 mm, while the tip clearance is τ = 1.2 mm. Results of the flow parameters, fluid flow, and heat transfer in the recessed channel are discussed. The results show that all ribbed tips obtain more uniform outlet flow angle distribution and higher aerodynamic performance than the plane tips. The total aerodynamic pressure loss of the ribbed tips on the pressure side is the same as that of complete ribbed tips. The evolution mechanisms are different, although both can improve the turbine efficiency. Although the partial rib tip on the pressure side weakens the mixing of the channel vortex and leakage vortex near the trailing edge and has the best control effect on the leakage vortex, the lack of the suction side rib will make it easier for the low-energy fluid to flow into the gap from the front of the suction side, which is not conducive to reducing the leakage flow inside the gap; the full rib tip not only minimizes the tip relative leakage flow and leakage loss but also increases the channel vortex loss. With the complex vortex system in the groove and the rib blocking effect at the leakage outlet, the suction-side rib tip becomes the tip structure with the best leakage flow control effect under the same clearance, but the leakage vortex loss is the highest.

Skin wound healing assessment via an optimized wound array model in miniature pigs

An appropriate animal wound model is urgently needed to assess wound dressings, cell therapies, and pharmaceutical agents. Minipig was selected owing to similarities with humans in body size, weight, and physiological status. Different wound sizes (0.07–100 cm2) were created at varying distances but fail to adequately distinguish the efficacy of various interventions. We aimed to resolve potential drawbacks by developing a systematic wound healing system. No significant variations in dorsal wound closure and contraction were observed within the thoracolumbar region between boundaries of both armpits and the paravertebral region above rib tips; therefore, Lanyu pigs appear suitable for constructing a reliable dorsal wound array. Blood flow signals interfered with inter-wound distances ˂ 4 cm; a distance > 4 cm is therefore recommended. Wound sizes ≥ 4 cm × 4 cm allowed optimal differentiation of interventions. Partial- (0.23 cm) and full-thickness (0.6 cm) wounds showed complete re-epithelialization on days 13 and 18 and strongest blood flow signals at days 4 and 11, respectively. Given histological and tensile strength assessments, tissue healing resembling normal skin was observed at least after 6 months. We established some golden standards for minimum wound size and distance between adjacent wounds for effectively differentiating interventions in considering 3R principles.

Direct observation of the local bond behavior between corroded reinforcing bars and concrete using digital image correlation

Corrosion induced rebar deterioration and concrete cracking alter the local bond interactions in reinforced concrete. An experimental methodology for investigating changes in the local deformation at the interface, caused by rib height reduction and corrosion layer is proposed. The effect of concrete cracking is eliminated by re-casting corroded rebars into new specimens. Local bond interaction is examined using uniaxial tensile tests and recorded through an observation window. The recorded interaction was analysed using Digital Image Correlation (DIC). Prior to visible crack formation, strain distribution maps revealed diagonal cracks indicating that the bond failure is associated with mechanical anchorage until a degree of corrosion of around 12%. Measurements of local opening and sliding behavior at the interface confirm that the slipping interactions become dominant with increase in corrosion. Differences in the shape of individual rib tips and flat lengths in specimens with higher corrosion cause significant variation in local bond interaction.

Research on the influence of ultrasonic on the inner rib’s surface morphology of ribbed cylindrical parts in flow spinning process

• Ultrasonic-assisted flow spinning platform is established. • Ultrasonic reduces the deformation and friction resistance. • Application of ultrasonic benefits the material flow in spinning. • Rib tip surface morphology is more uniform with ultrasonic. • Quality of the inner longitudinal ribs is enhanced with ultrasonic. Thin-walled shell with inner ribs is the main load bearing structure for aerospace products, which decides the products overall performance. Flow spinning process is an effective method to realize the integrated manufacturing of thin-walled shells with inner ribs. However, this process still has defects of insufficient filling at the rib groove and fracture at the rib root. A novel process is proposed to fabricate the thin-walled shell with inner ribs by introducing ultrasonic energy into flow spinning process based on the softening effect and friction-reducing effect of the ultrasonic energy. This paper focuses on the forming quality of the inner longitudinal ribs. The longitudinal ribs are designed along the axial direction of the cylindrical parts. The rheological characteristics of material forming with ultrasonic is studied and the local cumulative deformation law of the inner rib material at the rib groove is revealed. The ultrasonic-assisted flow spinning platform was established and ultrasonic energy was introduced in the radial direction of the initial cylindrical parts. The experiment results with different ultrasonic amplitudes showed that the rib tip’s surface morphology and rib height were improved with ultrasonic. The finite element models were established to analyze the deformation characteristics of the inner ribs. The constitutive equation was established to reflect the material flowing property with ultrasonic. The simulation results showed that the material flowed into the groove more at the screw-in end and flowed out more at the screw-out end with ultrasonic. This flow state reduced the material accumulation phenomenon at the screw-out end. The tip’s surface morphology of inner longitudinal ribs were more uniform with ultrasonic. The displacement vectors of the nodes at rib groove were also extracted to explore the flow difference. Additionally, the rib height increased with ultrasonic. In conclusion, it is productive to apply ultrasonic into the ribbed cylindrical parts flow spinning process to enhance the forming quality of the inner longitudinal ribs.

Keraphyton gen. nov., a new Late Devonian fern-like plant from Australia.

The first plants related to the ferns are represented by several extinct groups that emerged during the Devonian. Among them, the iridopterids are closely allied to the sphenopsids, a group represented today by the genus Equisetum. They have been documented in Middle to early Late Devonian deposits of Laurussia and the Kazakhstan plate. Their Gondwanan record is poor, with occurrences limited to Venezuela and Morocco. Here we describe a new genus from a late Late Devonian locality of New South Wales. It is represented by a single anatomically preserved large stem characterized by a star-shaped vascular system with protoxylem strands located at rib tips, and by a lack of secondary tissues. Within the first fern-like plants, this stem shares the largest number of characters with iridopterid axes but differs by the pattern of its vascular system. Keraphyton mawsoniae gen. et sp. nov. adds a new record of early fern-like plants in eastern Gondwana. It provides new insights into the anatomical diversity within this key group of plants and supports the distinctiveness of the Australian flora in the latest Devonian.

Performance Evaluation of a Solar Air Heater Roughened with Conic-Curve Profile Ribs Based on Efficiencies and Entropy Generation

First and second laws of thermodynamics are well-established benchmarks to assess a thermal system. The literature revealed that efficiencies of a solar air heater are still low because the transport properties and heat transfer coefficient of the air are not superior. In the previous study, the heat and fluid flow characteristics and thermohydraulic performance of the solar air heater roughened conic-curve profile ribs were numerically examined. In the present extended work, the thermal efficiency, effective efficiency, and exergy efficiency were analytically evaluated. The entropy generation in the vicinity of the rib and the Bejan number along the length of the absorber plate were numerically analysed. These considerations aimed to provide a comprehensive evaluation and subsequent minimization of entropy generation. The impacts of the conic constant and Reynolds number on the above parameters were considered. The results indicated that decreasing the conic constant induced an increase in all efficiencies and a decrease in the entropy generation number. The maximum effective efficiency of 0.6719 occurred at a Reynolds number of 20,122, whereas the exergy efficiency of 0.01527 was obtained at a Reynolds number of 2786. The highest entropy generation due to heat transfer was found at the upstream and downstream corners of a rib and at the position just behind the detachment point. The largest entropy generation due to viscous dissipation was identified at the position in front of the rib tip. The entropy generation due to heat transfer was much higher than the entropy generation due to viscous dissipation.

Diagnosis and Treatment of Slipping Rib Syndrome.

(1) To investigate the clinical presentation, diagnosis, and treatment of slipping rib syndrome in athletes; (2) to investigate the hooking maneuver for diagnosis of slipping rib syndrome. Retrospective chart review of 362 athletes with rib pain. Pediatric-based sports medicine clinic between January 1, 1999, and March 1, 2014. Costochondritis, Tietze, fractures, rib tip syndrome, and unclear diagnoses were excluded. Athletes were included who had a palpable rib subluxation, mechanical rib symptom, positive hooking maneuver, or resolution of pain after the resection of a slipping rib segment. Slipping rib syndrome is associated with athletic performance. Fifty-four athletes were diagnosed with slipping rib syndrome, of which 38 (70%) were females. Mean age at presentation was 19.1 years (range 4-40 years). Mean number of previous specialist consultations per athlete was 2.3 and mean time from symptom onset to diagnosis was 15.4 months. The hooking maneuver was attempted 21 times (38.9%). Unilateral symptoms presented in 49 athletes (90.7%). The most symptomatic rib was the 10th, affecting 24 athletes (44.4%), eighth and ninth were affected in 17 athletes (31.5%) each. Most, 39 (72.2%), reported insidious onset of symptoms. Running, rowing, lacrosse, and field hockey were frequently associated activities. Twelve athletes had psychiatric diagnoses (22.2%), 10 (19.2%) were hypermobile. Sixty-six total imaging studies were performed. The most successful treatment options included: osteopathic manipulative treatment (71.4%), surgical resection (70%), and diclofenac gel (60%). Most athletes with slipping rib syndrome were active females with insidious onset of unilateral pain, a high prevalence of hypermobility and prolonged pain. The hooking maneuver was underused.

Slipping Rib Syndrome: A review of evaluation, diagnosis and treatment

Slipping rib syndrome (SRS) is an under-diagnosed cause of intermittent, yet often debilitating lower rib and abdominal pain. SRS is caused by a hypermobility of the anterior false ribs that allows the 8th–10th ribs to slip or click as the cartilaginous rib tip abuts or slips under the rib above. Pain occurs from impingement of the intercostal nerve passing along the undersurface of the adjacent rib. Studies consistently find patients reporting months to years of typical pain symptoms, unnecessary tests and procedures prior to diagnosis. SRS is a clinical diagnosis, but dynamic ultrasound can be helpful for confirmation or diagnosis in difficult cases. Resection of the slipping rib cartilages is the mainstay of treatment, with good results for pain relief. Rib stabilization is an emerging option for recurrent symptoms.

Vitamin D deficiency: an unrecognized cause of flank pain.

Loin pain is frequently not associated with any urinary abnormality. Musculoskeletal abnormalities are not uncommon as alternative cause of flank pain. Osteomalacia of the ribs was infrequently encountered as the cause of flank pain. Vitamin D deficiency has been reported as a common problem worldwide with special predilection to the Middle East area. In this study, we looked for vitamin D deficiency in patients with flank pain associated with tenderness over the tips of the lowermost ribs. Out of 783 patients presenting with unilateral or bilateral flank pain to a single center over a period of 3years, 316 did not have a definite urologic cause (group B). One hundred and eighty-seven of these patients had distinct tenderness over the costal margin (group B1) that could not be explained by history and radiology. All patients of group B were tested for serum levels of 25(OH) vitamin D. Very low serum levels of 25(OH) vitamin D was detected in all cases of group B1 and in only in only 26.4% of the remaining cases of group B (group B2). Relief of flank pain was noticed within 2months in 55.1% of vitamin D deficient cases. In patients presenting with flank pain, the existence of tenderness of the last ribs instead of the renal angle proper should alert to a possible cause in the rib cage. Estimation of serum vitamin D level should be performed in these cases.

A general optimized geometry of angled ribs for enhancing the thermo-hydraulic behavior of a solar air heater channel – A Taguchi approach

The thermo-hydraulic behavior of the air flow through a solar air heater is numerically simulated and then optimized by use of Taguchi method. An innovative general geometry is introduced for the rib that variation in its parameters can generate triangular, trapezoidal and rectangular geometries simultaneously. A L16 (44) orthogonal array is used to optimize the geometry factors accounts for the maximum thermal performance of the ribbed channel. Thermal performance concept includes maximization of heat transfer coefficient and minimization of friction factor. Maximization of thermal enhancement factor is taken as the criteria of optimization. At a constant flow Reynolds number of 10,000, rib relative pitch (P/H), rib relative height (e/H), rib relative tip width (a/H) and rib front projection (s) are employed as the design factors. Results show that rib pitch, rib height, rib tip width and rib front projection have the greatest influences on the thermo-hydraulic performance, respectively. A triangular rib geometry with rib height of 0.2H and P = 2H in which the rib front is normal to the flow direction (i.e. s = 0) is recognized as the optimum configuration.