-Modern spark-ignited internal combustion engines have intake ports designed to introduce high levels of so-called "tumble" charge motion. Correspondingly high shear rates can lead to high fluctuations and turbulence within the combustion chamber. A suitable test case to characterize the intake flow is a steady-state flow bench. Although routinely used in the engine development process to determine the global discharge coefficients, only a few detailed numerical and experimental studies use this test case to analyze the flow in the vicinity of the valve with high spatial and temporal resolution. In this paper, we combined highly resolved two-dimensional, two-component Particle Image Velocimetry (PIV) measurements and numerical simulations using a Detached-Eddy Simulation (DES) model to characterize engine-relevant flow features on a flow bench. The spatial resolution of numerical simulations on two different grids is assessed and compared to that of the PIV measurement. The results of simulations and experiment are then compared in terms of their mean and fluctuation velocity fields and the jet orientation. A detailed study of the area around the valve seats investigates the validity of wall functions in this region. Finally, we examine structures induced by vortex-shedding at the valve stem and if they are transported into the combustion chamber.Résumé -Étude numérique et expérimentale résolue dans l'espace de l'écoulement à travers le conduit d'admission d'un moteur à combustion interne -Les moteurs à combustion interne modernes à allumage commandé disposent de conduits d'admission conçus pour générer des niveaux importants de mouvements de charge dits « tumble ». Les niveaux importants de taux de cisaillement qui en résultent peuvent conduire à de fortes fluctuations et turbulences dans la chambre de combustion. Un cas test adapté pour caractériser l'écoulement d'admission est un banc volute. Bien que son utilisation durant les phases de conception moteur pour déterminer les coefficients de perte de charge globaux soit très répandue, seules quelques études numériques et expérimentales détaillées utilisent ce test pour étudier l'écoulement au voisinage de la soupape avec des résolutions spatiales et temporelles élevées. Dans le présent article, nous avons combiné des mesures PIV bi-composants, bidimensionnelles hautement résolues et des simulations numériques utilisant une approche de type « Detached-Eddy Simulation » pour caractériser des structures d'écoulement d'importance pour le moteur sur un banc volute. La résolution spatiale des simulations numériques est évaluée sur deux maillages et comparée à celle de la mesure « Particle Image Velocimetry », PIV. Les résultats numériques et expérimentaux sont ensuite comparés en termes de champ de vitesse moyen et
The consensual assessment technique (CAT) is a reliable and valid method to measure (product) creativity and often considered the gold standard of creativity assessment. The reliability measure traditionally applied in CAT studies—inter‐rater reliability—cannot capture time‐sampling error, which is a particular relevant source of error for specific applications of the CAT. Therefore, the present study intended to investigate the test–retest reliability of CAT ratings. We asked raters (N = 61) for their creativity assessment of the same set of 90 fashion outfits at an initial rating session and a follow‐up session either 2 or 4 weeks later. We found that mean product ratings—the actual focus of interest in the CAT—were highly stable over time, as evidenced by consistency and agreement ICCs clearly exceeding levels of .90. However, individual raters (partially) lacked temporal stability, indicating a drift in rater tendencies over time. Our findings support the CAT’s reputation as a highly reliable measurement method, but question the temporal rating stability of the CAT’s actual “measurement instrument,” namely individual judges.
Rationale: Creativity assessment can be influenced by rater characteristics, including social group membership, such as gender. As raters are often male, the gender composition of rater panels in the Consensual Assessment Technique (CAT) could introduce unintended implicit biases into this measurement methodology. The present study analyzed such biases by examining gender differences in creativity assessment. Method: We applied the CAT and asked male (n = 26) and female (n = 39) judges to rate the creativity of fashion outfits presented on Instagram. We then examined gender differences in mean creativity ratings and rater consistency (inter-rater reliability). In an additional qualitative analysis, we analyzed implicit theories of creativity of female and male raters by comparing the criteria that these raters applied when assessing creativity. Results: We found no systematic support for gender differences in the level of creativity ratings, but observed that rating consistency was significantly higher for female than for male judges. Additional content analysis suggested that female and male raters attached different relative importance to various assessment criteria, indicating gender differences in rating criteria. Discussion: Our study suggests that rater panel composition can indeed affect aspects of creativity assessment, although we do not obtain strong support for a gender-related bias in the CAT methodology.
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