Reliability optimal design is an integrated approach widely adopted in engineering. The fuze components are designed by a BP neural network combined with an optimal design approach based on their multi-failure modes. ...Reliability optimal design is an integrated approach widely adopted in engineering. The fuze components are designed by a BP neural network combined with an optimal design approach based on their multi-failure modes. Their reliability probabilities in multi-failure modes are transformed into deterministic design parameters. The designed results by an example of optimizing the fuze spring under a certain reliability show that the integrated approach is practical and efficient.展开更多
This paper studies the flow and heat transfer characteristics around a new type of egg-shaped tubes made up of a semicir- cle upstream and a semi-ellipse downstream, numerically and experimentally, for Reynolds number...This paper studies the flow and heat transfer characteristics around a new type of egg-shaped tubes made up of a semicir- cle upstream and a semi-ellipse downstream, numerically and experimentally, for Reynolds numbers varying from 4 000 to 5 0000 based on the hydraulic diameter. These tubes have axis ratios, 8 = 1, 1.5, 2, 3, 4, and 5 with the major axis parallel to the main- stream. When E = 1, the tube is a circular one and when 1/c = 0, it is a flat plate. Numerical results show that the minimum value of Cp occurs at an angular position, which decreases as c decreases, and the maximum value of Cf gradually increases with the increase of ~. Simulated results agree very well with those available in the existing literature. The egg-shaped tube has a higher favorable pressure gradient at its front and a lower adverse pressure gradient at its back, that helps the flow delay a separation from the tubes＇ surface. Empirical correlations for each tube are obtained by numerical simulations relating the dimensionless heat transfer coefficient with the Reynolds Number and the Prandtl Number. The performance evaluation criterion （PEC） is used to analyze the level of the heat transfer enhancement for egg-shaped tubes. It is found that an egg-shaped tube with c = 2 has the best overall heat transfer performance when Re 〉 11 952.展开更多
文摘Reliability optimal design is an integrated approach widely adopted in engineering. The fuze components are designed by a BP neural network combined with an optimal design approach based on their multi-failure modes. Their reliability probabilities in multi-failure modes are transformed into deterministic design parameters. The designed results by an example of optimizing the fuze spring under a certain reliability show that the integrated approach is practical and efficient.
基金supported by the Science and Technology Development Planning of Shandong Province(Grant No.2012GGX10421)
文摘This paper studies the flow and heat transfer characteristics around a new type of egg-shaped tubes made up of a semicir- cle upstream and a semi-ellipse downstream, numerically and experimentally, for Reynolds numbers varying from 4 000 to 5 0000 based on the hydraulic diameter. These tubes have axis ratios, 8 = 1, 1.5, 2, 3, 4, and 5 with the major axis parallel to the main- stream. When E = 1, the tube is a circular one and when 1/c = 0, it is a flat plate. Numerical results show that the minimum value of Cp occurs at an angular position, which decreases as c decreases, and the maximum value of Cf gradually increases with the increase of ~. Simulated results agree very well with those available in the existing literature. The egg-shaped tube has a higher favorable pressure gradient at its front and a lower adverse pressure gradient at its back, that helps the flow delay a separation from the tubes＇ surface. Empirical correlations for each tube are obtained by numerical simulations relating the dimensionless heat transfer coefficient with the Reynolds Number and the Prandtl Number. The performance evaluation criterion （PEC） is used to analyze the level of the heat transfer enhancement for egg-shaped tubes. It is found that an egg-shaped tube with c = 2 has the best overall heat transfer performance when Re 〉 11 952.
