Navier-Stokes analysis of an oxidizer turbine blade with tip clearance with and without a mini-shroud

The Gas Generator Oxidizer Turbine (GGOT) Blade is being analyzed by various investigators under the NASA MSFC-sponsored Turbine Stage Technology Team design effort. The present work concentrates on the tip clearance region flow and associated losses; however, flow details for the passage region are also obtained in the simulations. The present calculations simulate the rotor blade row in a rotating reference frame with the appropriate coriolis and centrifugal acceleration term included in the momentum equations. The upstream computational boundary is located about one axial chord from the blade leading edge. The boundary conditions at this location have been determined by Pratt & Whitney using an Euler analysis without the vanes to obtain approximately the same flow profiles at the rotor as were obtained with the Euler stage analysis including the vanes. Inflow boundary layer profiles are then constructed assuming the skin friction coefficient at both the hub and the casing. The downstream computational boundary is located about one axial chord from the blade trailing edge, and the circumferentially averaged static pressure at this location was also obtained from the P&W Euler analysis. Results obtained for the 3-D baseline GGOT geometry at the full scale design Reynolds number show a region of high loss in the region near the casing. Particle traces in the near tip region show vortical flow behavior of the fluid which passes through the clearance region and exits at the downstream edge of the gap. In an effort to reduce clearance flow losses, the mini-shroud concept was proposed by the Pratt & Whitney design team. Calculations were performed on the GGO geometry with the mini-shroud. Results of these calculations indicate that the mini-shroud does not significantly affect the flow in the passage region, and although the tip clearance flow is different, the mini-shroud does not seem to prevent the above-mentioned vortical flow behavior. Since both flow distortion and total pressure losses are similar for both geometries, the addition of the mini-shroud does not seem to reduce the tip clearance flow effects

An Interactive Tool for Discrete Phase Analysis in Two-Phase Flows

Under a NASA MSFC SBIR Phase 1 effort an interactive software package has been developed for the analysis of discrete (particulate) phase dynamics in two-phase flows in which the discrete phase does not significantly affect the continuous phase. This package contains a Graphical User Interface (based on the X Window system and the Motif tool kit) coupled to a particle tracing program, which allows the user to interactively set up and run a case for which a continuous phase grid and flow field are available. The software has been applied to a solid rocket motor problem, to demonstrate its ease of use and its suitability for problems of engineering interest, and has been delivered to NASA Marshall Space Flight Center

Implementation and first results of a mandatory, nationwide audit on liver surgery

BACKGROUND: The Dutch Hepato Biliary Audit (DHBA) was initiated in 2013 to assess the national quality of liver surgery. This study aimed to describe the initiation and implementation of this audit along with an overview of the results and future perspectives. METHODS: Registry of patients undergoing liver surgery for all primary and secondary liver tumors in the DHBA is mandatory. Weekly, benchmarked information on process and outcome measures is reported to surgical teams. In this study, the first results of patients with colorectal liver metastases were presented, including results of data verification. RESULTS: Between 2014 and 2017, 6241 procedures were registered, including 4261 (68%) resections for colorectal liver metastases. For minor- and major liver resections for colorectal liver metastases, the median [interquartile range] hospital stay was 6 [4-8] and 8 [6-12] days, respectively. A postoperative complicated course (complication leading to >14 days of hospital stay, reintervention or death) occurred in 26% and 43% and the 30-day/in-hospital mortality was 1% and 4%, respectively. The completeness of data was 97%. In 3.6% of patients, a complicated postoperative course was erroneously omitted. CONCLUSION: Nationwide implementation of the DHBA has been successful. This was the first step in creating a complete evaluation of the quality of liver surgery

Reliability and Agreement of Radiological and Pathological Tumor Size in Patients with Multiple Endocrine Neoplasia Type 1-Related Pancreatic Neuroendocrine Tumors: Results from a Population-Based Cohort

Background: Pancreatic neuroendocrine tumors (pNETs) have a high prevalence in patients with multiple endocrine neoplasia type 1 (MEN1) and are the leading cause of death. Tumor size is still regarded as the main prognostic factor and therefore used for surgical decision-making. We assessed reliability and agreement of radiological and pathological tumor size in a population-based cohort of patients with MEN1-related pNETs. Methods: Patients were selected from the Dutch MEN1 database if they had undergone a resection for a pNET between 2003 and 2018. Radiological (MRI, CT, and endoscopic ultrasonography [EUS]) and pathological tumor size were collected from patient records. Measures of agreement (Bland-Altman plots with limits of agreement [LoA] and absolute agreement) and reliability (intraclass correlation coefficients [ICC] and unweighted kappa) were calculated for continuous and categorized (< or ≥2 cm) pNET size. Results: In 73 included patients, the median radiological and pathological tumor sizes measured were 22 (3-160) and 21 (4-200) mm, respectively. Mean bias between radiological and pathological tumor size was -0.2 mm and LoA ranged from -12.9 to 12.6 mm. For the subgroups of MRI, CT, and EUS, LoA of radiological and pathological tumor size ranged from -9.6 to 10.9, -15.9 to 15.8, and -13.9 to 11.0, respectively. ICCs for the overall cohort, MRI, CT, and EUS were 0.80, 0.86, 0.75, and 0.76, respectively. Based on the 2 cm criterion, agreement was 81.5%; hence, 12 patients (18.5%) were classified differently between imaging and pathology. Absolute agreement and kappa values of MRI, CT, and EUS were 88.6, 85.7, and 75.0%, and 0.77, 0.71, and 0.50, respectively. Conclusion: Within a population-based cohort, MEN1-related pNET size was not systematically over- or underestimated on preoperative imaging. Based on agreement and reliability measures, MRI is the preferred imaging modality

Reliability and Agreement of Radiological and Pathological Tumor Size in Patients with Multiple Endocrine Neoplasia Type 1-Related Pancreatic Neuroendocrine Tumors: Results from a Population-Based Cohort

Background: Pancreatic neuroendocrine tumors (pNETs) have a high prevalence in patients with multiple endocrine neoplasia type 1 (MEN1) and are the leading cause of death. Tumor size is still regarded as the main prognostic factor and therefore used for surgical decision-making. We assessed reliability and agreement of radiological and pathological tumor size in a population-based cohort of patients with MEN1-related pNETs. Methods: Patients were selected from the Dutch MEN1 database if they had undergone a resection for a pNET between 2003 and 2018. Radiological (MRI, CT, and endoscopic ultrasonography [EUS]) and pathological tumor size were collected from patient records. Measures of agreement (Bland-Altman plots with limits of agreement [LoA] and absolute agreement) and reliability (intraclass correlation coefficients [ICC] and unweighted kappa) were calculated for continuous and categorized (< or ≥2 cm) pNET size. Results: In 73 included patients, the median radiological and pathological tumor sizes measured were 22 (3-160) and 21 (4-200) mm, respectively. Mean bias between radiological and pathological tumor size was -0.2 mm and LoA ranged from -12.9 to 12.6 mm. For the subgroups of MRI, CT, and EUS, LoA of radiological and pathological tumor size ranged from -9.6 to 10.9, -15.9 to 15.8, and -13.9 to 11.0, respectively. ICCs for the overall cohort, MRI, CT, and EUS were 0.80, 0.86, 0.75, and 0.76, respectively. Based on the 2 cm criterion, agreement was 81.5%; hence, 12 patients (18.5%) were classified differently between imaging and pathology. Absolute agreement and kappa values of MRI, CT, and EUS were 88.6, 85.7, and 75.0%, and 0.77, 0.71, and 0.50, respectively. Conclusion: Within a population-based cohort, MEN1-related pNET size was not systematically over- or underestimated on preoperative imaging. Based on agreement and reliability measures, MRI is the preferred imaging modality

Implementation and first results of a mandatory, nationwide audit on liver surgery

Background: The Dutch Hepato Biliary Audit (DHBA) was initiated in 2013 to assess the national quality of liver surgery. This study aimed to describe the initiation and implementation of this audit along with an overview of the results and future perspectives. Methods: Registry of patients undergoing liver surgery for all primary and secondary liver tumors in the DHBA is mandatory. Weekly, benchmarked information on process and outcome measures is reported to surgical teams. In this study, the first results of patients with colorectal liver metastases were presented, including results of data verification. Results: Between 2014 and 2017, 6241 procedures were registered, including 4261 (68%) resections for colorectal liver metastases. For minor- and major liver resections for colorectal liver metastases, the median [interquartile range] hospital stay was 6 [4–8] and 8 [6–12] days, respectively. A postoperative complicated course (complication leading to >14 days of hospital stay, reintervention or death) occurred in 26% and 43% and the 30-day/in-hospital mortality was 1% and 4%, respectively. The completeness of data was 97%. In 3.6% of patients, a complicated postoperative course was erroneously omitted. Conclusion: Nationwide implementation of the DHBA has been successful. This was the first step in creating a complete evaluation of the quality of liver surgery

Hospital variation in combined liver resection and thermal ablation for colorectal liver metastases and impact on short-term postoperative outcomes: a nationwide population-based study

Background: Combining resection and thermal ablation can improve short-term postoperative outcomes in patients with colorectal liver metastases (CRLM). This study assessed nationwide hospital variation and short-term postoperative outcomes after combined resection and ablation. Methods: In this population-based study, all CRLM patients who underwent resection in the Netherlands between 2014 and 2018 were included. After propensity score matching for age, ASA-score, Charlson-score, diameter of largest CRLM, number of CRLM and earlier resection, postoperative outcomes were compared. Postoperative complicated course (PCC) was defined as discharge after 14 days or a major complication or death within 30 days of surgery. Results: Of 4639 included patients, 3697 (80%) underwent resection and 942 (20%) resection and ablation. Unadjusted percentage of patients who underwent resection and ablation per hospital ranged between 4 and 44%. Hospital variation persisted after case-mix correction. After matching, 734 patients remained in each group. Hospital stay (median 6 vs. 7 days, p = 0.011), PCC (11% vs. 14.7%, p = 0.043) and 30-day mortality (0.7% vs. 2.3%, p = 0.018) were lower in the resection and ablation group. Differences faded in multivariable logistic regression due to inclusion of major hepatectomy. Conclusion: Significant hospital variation was observed in the Netherlands. Short-term postoperative outcomes were better after combined resection and ablation, attributed to avoiding complications associated with major hepatectomy

Implementation and first results of a mandatory, nationwide audit on liver surgery

Background: The Dutch Hepato Biliary Audit (DHBA) was initiated in 2013 to assess the national quality of liver surgery. This study aimed to describe the initiation and implementation of this audit along with an overview of the results and future perspectives. Methods: Registry of patients undergoing liver surgery for all primary and secondary liver tumors in the DHBA is mandatory. Weekly, benchmarked information on process and outcome measures is reported to surgical teams. In this study, the first results of patients with colorectal liver metastases were presented, including results of data verification. Results: Between 2014 and 2017, 6241 procedures were registered, including 4261 (68%) resections for colorectal liver metastases. For minor- and major liver resections for colorectal liver metastases, the median [interquartile range] hospital stay was 6 [4–8] and 8 [6–12] days, respectively. A postoperative complicated course (complication leading to >14 days of hospital stay, reintervention or death) occurred in 26% and 43% and the 30-day/in-hospital mortality was 1% and 4%, respectively. The completeness of data was 97%. In 3.6% of patients, a complicated postoperative course was erroneously omitted. Conclusion: Nationwide implementation of the DHBA has been successful. This was the first step in creating a complete evaluation of the quality of liver surgery