Numerical investigation on sealing performance of non-contact finger seal with herringbone groove surface topography

Since the last decade, the non-contact finger seal (NCFS) has attracted an increasing number of researchers due to its inherent flexibility and non-contact features, which can significantly improve the service life and reduce the leakage rate of the finger seals. In this paper, to enhance the NCFS sealing performance, lifting pads with twenty (20) different herringbone groove surface topographies are proposed based on the uniform design method. Numerical analysis is carried out based on the two-way fluid-structure interaction (FSI) method to better mimic the actual working conditions. The analysis of results using statistical tools reveals that the herringbone groove topographies placed on the bottom surface of low-pressure lifting pads can significantly improve the load-carrying capacity and sealing performance. In addition, the correlation analysis of the sealing performance and geometric parameters of the herringbone groove demonstrate that reducing the groove width or increasing the groove internal angle can improve the lifting and leakage capacities. Finally, the optimal herringbone groove and general structure (no groove) are comparatively analysed under variable working conditions, and the results show that the former has much better sealing performance.

Using Uniform Design Methodology of Turning Parameters Study of Nickel Alloy

The nickel alloy has good mechanical strength and corrosion resistance at high temperature, it is extensively used in aerospace, biomedical and energy industries, as well as alloy designs of different chemical compositions to achieve different mechanical properties. However, for high mechanical strength, low thermal conductivity and surface hardening property, the nickel alloy has worse cutting tool life and machining efficiency than general materials. Therefore, how to select the optimum machining parameters will influence the workpiece quality, cost and machining time. For the selection of nickel alloy turning parameters, this paper uses uniform design method to design cutting test to reduce the number of experiments. Three independent variable parameters are set up, including cutting speed, feed motion and cutting depth, and four dependent variable parameters are set up, including cutting tool wear, surface roughness, machining time and cutting force. A nickel alloy turning parameter model is built by using regression analysis to further predict the I/O relationship among various combinations of variables. The errors between actual values and prediction values are validated. When the cutting tool wear (VB) is 2.72~6.18%, the surface roughness (Ra) is 4.10~7.72%, the machining time (T) is 3.75~8.82%, and the cutting force (N) is 1.54~7.42%, the errors of various dependent variables are approximately less than 10%, so a high precision estimation model is obtained through a few experiments of uniform design method.

Micromotion Analysis of a Dental Implant System

The objective of project is to reduce the micromotion of novel implant under the static loads using function of uniform design for FE analysis. Integrating the features of regular implant, a new implant model has been done. Micromotion of the novel implant was obtained using static structural FE analysis. Compared to the existing International team for implantology implants, the micromotion of the novel implant model was considerably decreased by static structural analysis. Six control factors were taken for achieving minimizes the micromotion of novel dental implant system. In the present work, uniform design technique was used to create a set of finite element analysis simulation: according to the uniform design method, all FE analysis simulation; compared to the original model, the micromotion is 0.01944mm and micromotion of improved design version is 0.01244mm. The improvement rate for the micromotion is 35.02%.

Thermal-hydraulic performance prediction of two new heat exchangers using RBF based on different DOE

Thermal performance prediction with high precision and low cost is always the need for designers of heat exchangers. Three typical design of experiments (DOE) known as Taguchi design method (TDM), Uniform design method (UDM), and Response surface method (RSM) are commonly used to reduce experimental cost. The radial basis function artificial neural network (RBF) based on different DOE is used to predict the thermal performance of two new parallel-flow shell and tube heat exchangers. The applicability and expense of ten different prediction methods (RBF + TDML9, RBF + TDML18, RBF + UDM, RBF + TDML9 + UDM, RBF + TDML18 + UDM, RBF + RSM, RBF + RSM + TDML9, RBF + RSM + TDML18, RBF + RSM + UDM, RSM) are discussed. The results show that the RBF + RSM is a very efficient method for the precise prediction of thermal-hydraulic performance: the minimum error is 2.17% for Nu and 5.30% for f. For RBF, it is not true that the more of train data, the more precision of the prediction. The parameter “spread” of RBF should be adjusted to optimize the prediction results. The prediction using RSM only can also obtain a good balance between precision and time cost with a maximum prediction error of 14.52%.

Effect of Mixed Commercial Cold Flow Improvers on Flow Properties of Biodiesel from Waste Cooking Oil

The uniform design method was used to screen the solidifying point depressing effects of 18 traditional diesel cold flow improvers on biodiesel derived from waste cooking oil. The cold flow improvers with good effects were selected for orthogonal optimization. Finally, the mixed cold flow improver (CFI) with the best depressing effect was selected to explore its depressing mechanism for biodiesel. The results show that the typical CFIs such as A132, A146, 10-320, 10-330, A-4, CS-1, AH-BSFH, Haote, T1804D, and HL21 all have a certain solidifying point depressing effect on biodiesel, while other cold flow improvers had no obvious effect. Amongst them, 10-330 (PMA polymer) and AH-BSFH (EVA polymer) had better solidifying point depressing effects over others, both of which reduced the solidifying point (SP) of biodiesel by 4 °C and the cold filter plugging point (CFPP) by 2 °C and 3 °C, respectively. From the orthogonal mixing experiment, it can be seen that the combination of 10-330 and AH-BSFH at a mass ratio of 1:8 had the best depressing effect, reducing the solidifying point and cold filter plugging point of biodiesel by 5 °C and 3 °C, respectively. Orthogonal analysis showed that when used in combination, AH-BSFH had a greater impact on the solidifying point, while the ratio of the combination had a greater impact on the cold filter plugging point.

Micromotion Analysis of a Dental Implant System

The objective of project is to reduce the micromotion of novel implant under the static loads using function of uniform design for FE analysis. Integrating the features of regular implant, a new implant model has been done. Micromotion of the novel implant was obtained using static structural FE analysis. Compared to the existing International team for implantology implants, the micromotion of the novel implant model was considerably decreased by static structural analysis. Six control factors were taken for achieving minimizes the micromotion of novel dental implant system. In the present work, uniform design technique was used to create a set of finite element analysis simulation: according to the uniform design method, all FE analysis simulation; compared to the original model, the micromotion is 0.01944mm and micromotion of improved design version is 0.01244mm. The improvement rate for the micromotion is 35.02%.