Liu K.,Nanjing University of Science and Technology |
Yu Y.,Nanjing University of Science and Technology |
Zhao N.,Northwest Institute of Mechanical & Electrical Engineering
Journal of Harbin Institute of Technology (New Series) | Year: 2016
To investigate the spray characteristics of a new-type air-assist nozzle, three-dimensional laser phase Dopper analyzer (PDA) was used to measure the spray parameters. The external flow fields of the nozzle were simulated by means of computational fluid dynamics (CFD). The distributions of the diameter and the axial velocity for the droplets were analyzed respectively. The results indicate that, the mean diameter of the droplets fluctuates along the center axis. The distance between the measurement point and the nozzle increases, the axial velocity of the droplets decreases. The further the measurement point from the center axis is, the smaller the axial velocity of the droplets is. With the increase of the nozzle pressure drop, the axial velocity of the droplets improves while the mean diameter of the droplets is reduced, and the distribution uniformity of the droplets is better for the diameter. The simulation result agrees well with the experimental data. The average deviation ranges from 3.9% to 7.7%. © 2016, The Editorial Department of Journal of Harbin Institute of Technology. All right reserved.
Wang G.,University of Science and Technology of China |
Li K.,Northwest Institute of Mechanical & Electrical Engineering |
Li R.,Northwest Institute of Mechanical & Electrical Engineering
Bandaoti Guangdian/Semiconductor Optoelectronics | Year: 2016
Starting from the equations describing the relationship between the intracavity Iav, the incident Iin and the output beam Iout of a FPSOA, it is demonstrated that Iin is a single valued function of Iav. After expanding Iin into a third-order Taylor's series in terms of Iav approximately, the derivative of Iin with respect to Iav can be expressed as a quadratic equation in terms of Iav. Furthermore, it is verified that only when the quadratic equation owns two real roots, the FPSOA enters into bistable operation region. In other words, the discriminant of the quadratic equation being positive can be described as the necessary condition of bistability in FPSOAs. Numerical results agree well with the analytical formula. The results will afford a novel way for studying the bistability in other devices owning similar structures. © 2016, Editorial Office of Semiconductor Optoelectronics. All right reserved.
Liu K.,Nanjing University of Science and Technology |
Yu Y.-G.,Nanjing University of Science and Technology |
Zhao N.,Northwest Institute of Mechanical & Electrical Engineering |
Wang S.-S.,China Ship Development And Design Center
Hanneng Cailiao/Chinese Journal of Energetic Materials | Year: 2015
An impinging nozzle was designed to investigate the motion properties of spray particles from impinging nozzle at atmospheric environment. Phase doppler particle analyzer(PDPA) was used to record the effects of the nozzle pressure on the motion properties of spray particles. The distributions of axial velocity and radial velocity for particles were analyzed emphatically. Results indicate that as the distance between the measurement section and the nozzle increases from 25 mm to 100 mm, the mean diameter (D30) of the particles at the pressure drop of 2.2 MPa increases from 44.26 μm to 61.26 μm and from 42.88 μm to 55.49 μm at the pressure drop of 2.6 MPa. The further away from the nozzle, the smaller the axial velocity and the radial velocity of the particles. The axial velocity of the particles decreases and the radial velocity fluctuation increases with distance between the measuring points and the center axis increasing. The D30 of the particles decreases when the nozzle pressure increases, and the distribution uniformity of the particles is better for the axial velocity but worse for the radial velocity. ©, 2015, Institute of Chemical Materials, China Academy of Engineering Physics. All right reserved.
Chen C.,PLA Air Force Aviation University |
Xie J.,PLA Air Force Aviation University |
Zhang C.,Northwest Institute of Mechanical & Electrical Engineering |
Li C.,PLA Air Force Aviation University |
Wu T.,PLA Air Force Aviation University
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2016
The composability of simulation models is the core of research of the theory and method of composable simulation. Based on the composition-oriented M&S framework, the significance of the "context" to composability evaluation was described. Through the formal definitions of the application context, the model context and their relationship with the composability, the validity of composability is to determine whether the model context of simulation models and their composition is true under the restriction of the application context, therefore, based on the interface pruning and behavior pruning in the model context, the conditions of model composition which meet the application requirements were put forward, and then the criteria for the four IO levels were induced. The criteria not only help to clearly describe the research level and content of composability evaluation, but also help to carry out the engineering practice of composable design and simulation models' maturity. © 2016, Systems Engineering Society of China. All right reserved.
PubMed | Northwest Institute of Mechanical & Electrical Engineering, China Aerospace Science and Technology Corporation and Northwestern Polytechnical University
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2014
A dynamic attitude measurement system (DAMS) is developed based on a laser inertial navigation system (LINS). Three factors of the dynamic attitude measurement error using LINS are analyzed: dynamic error, time synchronization and phase lag. An optimal coning errors compensation algorithm is used to reduce coning errors, and two-axis wobbling verification experiments are presented in the paper. The tests indicate that the attitude accuracy is improved 2-fold by the algorithm. In order to decrease coning errors further, the attitude updating frequency is improved from 200 Hz to 2000 Hz. At the same time, a novel finite impulse response (FIR) filter with three notches is designed to filter the dither frequency of the ring laser gyro (RLG). The comparison tests suggest that the new filter is five times more effective than the old one. The paper indicates that phase-frequency characteristics of FIR filter and first-order holder of navigation computer constitute the main sources of phase lag in LINS. A formula to calculate the LINS attitude phase lag is introduced in the paper. The expressions of dynamic attitude errors induced by phase lag are derived. The paper proposes a novel synchronization mechanism that is able to simultaneously solve the problems of dynamic test synchronization and phase compensation. A single-axis turntable and a laser interferometer are applied to verify the synchronization mechanism. The experiments results show that the theoretically calculated values of phase lag and attitude error induced by phase lag can both match perfectly with testing data. The block diagram of DAMS and physical photos are presented in the paper. The final experiments demonstrate that the real-time attitude measurement accuracy of DAMS can reach up to 20 (1) and the synchronization error is less than 0.2 ms on the condition of three axes wobbling for 10 min.
Hu Z.-T.,Nanjing University of Science and Technology |
Yu Y.-G.,Nanjing University of Science and Technology |
Cao Y.-J.,Northwest Institute of Mechanical & Electrical Engineering
Hanneng Cailiao/Chinese Journal of Energetic Materials | Year: 2016
To explore the expansion characteristics of multiple wall combustion-gas jets which uniformly distributed along the circumferential direction under high temperature and high pressure in confined liquid working medium, the combustion gas generator and cylindrical filling liquid chamber were designed. The expansion processes of multiple wall jets were recorded by high-speed digital photographic system. The average axial displacements of multiple wall jets at different time were achieved by disposing the expansion sequence diagrams. It shows that the irregular interface induced by the Kelvin-Helmholtz instability exists in the entire jets expansion process. The effects of the number of orifices and the blasting injection pressure on expansion characteristics of multiple wall jets are discussed. The experimental results indicate that, as the number of orifices increase from four to eight, the axial expansion displacements of multiple jets decrease, at t=5 ms, the number of orifices increase from four to six, the axial expansion displacements decrease 8.3 percent, and it decrease 3.1 percent when the number of orifices increase from six to eight. The larger the blasting injection pressure, the greater the axial expansion velocity, the earlier jets get to the top of liquid filling chamber, at t=5 ms, the blasting injection pressure increase from 12 MPa to 20 MPa, the axial expansion velocity increase 20.1 percent, and it increase 19.9 percent when the blasting injection pressure increase from 20 MPa to 28 MPa. © 2016, Editorial Board of Chinese Chinese Journal of Energetic Materials. All right reserved.
Cao Y.-J.,Northwest Institute of Mechanical & Electrical Engineering |
Zhang X.-M.,Northwest Institute of Mechanical & Electrical Engineering |
Li Z.-F.,Northwest Institute of Mechanical & Electrical Engineering
Dandao Xuebao/Journal of Ballistics | Year: 2016
In order to achieve the safety launch of recoilless guns in the confined space,a new charge structure containing liquid balance body was designed.The interior ballistic experiment was carried out based on the new charge structure,and the interior ballistic model was established.The calculated results are in good agreement with the experimental results.On this basis,the effects of the initial liquid balance body mass,the liquid density,the propellant web size,the nozzle throat diameter and the engraving pressure on the interior ballistic performance were analyzed.Results show that the balance body mass has remarkable effect on the maximum chamber pressure and the muzzle velocity,while the effect of the liquid density is little.Larger propellant web size,smaller nozzle throat diameter and lower engraving pressure are in favor of improving the overall interior ballistic performance.The results can offer theoretical guidance for the interior ballistics and charge-structure design of new recoilless gun based on the liquid balance body. © 2016, Editorial Board of Journal of Ballistics. All right reserved.
Dong Z.,Northwest Institute of Mechanical & Electrical Engineering |
Huang K.,Northwest Institute of Mechanical & Electrical Engineering |
Chen Y.,Northwest Institute of Mechanical & Electrical Engineering |
Ren R.,Northwest Institute of Mechanical & Electrical Engineering |
And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2016
In order to discuss the necessity of the research on the large pulse current rotary joint technology of the electromagnetic gun, referring to the structure and parameters of the USA ‘Blitzer’ electromagnetic gun, we established the geometric model of air defense electromagnetic gun A. The calculated results show that the maximum torque of the coaxial system is 6 026.4 N·m, this will seriously interfere with the servo system and this shows that it is necessary to research the technology of large pulse current rotary joint. Moreover, we put forward a scheme of structure and working principle of the pitching type rotary joint device with a ring brush for electromagnetic gun.According to this scheme,the current-carrying capacity of the test device will be developed to 400 kA. This can provide the experimental basis for the use of large pulse current rotary joint technology to solve the problem of the electromagnetic gun pitch power supply. © 2016, High Voltage Engineering Editorial Department of CEPRI. All right reserved.
Li C.,Northwest Institute of Mechanical & Electrical Engineering |
Chen M.,Northwest Institute of Mechanical & Electrical Engineering |
Han Y.,Northwest Institute of Mechanical & Electrical Engineering
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2015
For those position servo systems having time delay element, a design method is presented that the system possesses maximum phase margin under the same length of mid-frequency interval. Open loop gain crossover frequency is determined by letting the derivative of phase to angular frequency to zero. As a result, characteristics of phase margin and gain crossover frequency versus mid-frequency interval width are obtained. A new design method of position controller parameters is given and the designed system dynamic performance can be within the expected range. The robustness to open loop gain variation can be improved significantly. Moreover, in order to guarantee the servo system tracking precision, feedforward compensation to the servo system with time delay is executed. Through establishing position differential observer, numerical feedforward compensation with high signal to noise ratio is achieved. At last, a control platform based on permanent magnet synchronous motor (PMSM) position servo system is developed. Simulation and experimental results verify the effectiveness of the proposed approach, which can also apply to industry process control. © 2015, The editorial office of Transaction of China Electrotechnical Society. All right reserved.
Yongshou L.,Northwestern Polytechnical University |
Xindang H.,Northwestern Polytechnical University |
Xiaojun S.,Northwest Institute of Mechanical Electrical Engineering |
Jun L.,Northwestern Polytechnical University |
Zhufeng Y.,Northwestern Polytechnical University
Engineering Failure Analysis | Year: 2010
Load-transferred experiments and fatigue tests of the anti-double dog-bone riveted joints were carried out, and the fracture surfaces were observed by scanning electron microscopy (SEM) in this paper. Based on the finite element analysis (FEA), the multi-axial fatigue life of the anti-double dog-bone riveted joints has been predicted by Smith-Watson-Topper (S-W-T) method and Wang-Brown (W-B) method respectively. And the results of FEA were compared with the experiment results. The results show that because of the deformation of the rivets and the holes, the load transferred by the rivets decreases with external load increase. The fracture of joints all occur at rivet holes, and the crack initiates at the dog-bone specimen closed to the rivet head. Compared with the result of W-B method, the result of S-W-T method is more conservative and reliable. © 2010 Elsevier Ltd.