Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512134
Naeem Khan, Muhammad Irfan Khattak, M. Khan, Faheem Khan, Latif Ullah Khan, S. Salam, D. Gu
Three different linear prediction coefficients (LPC) techniques are employed lo restore missing data in the process of state estimation. The conventional Normal Equation method has been found computationally expensive. Alternatively. Levinson Durbin Algorithm (LDA) considerably reduces this computational cost by avoiding the larger matrix inversions involved in the computation of LPC. However, LDA has been found suffering from a larger dynamic range in the values of LPC, An alternate method - Leroux Gueguen Algorithm (LGA) eliminates the problem associated with dynamic range in a stationary-point scenario by taking the application of Schwartz inequality in computation of this method. The main course of this work is to reduce the computational complexity of the Normal Equation when integrated with Kalman filter with that of LDA and LGA methods which do not require on matrix inversion in the computation of LPCs.
{"title":"Implementation of linear prediction techniques in state estimation","authors":"Naeem Khan, Muhammad Irfan Khattak, M. Khan, Faheem Khan, Latif Ullah Khan, S. Salam, D. Gu","doi":"10.1109/IBCAST.2013.6512134","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512134","url":null,"abstract":"Three different linear prediction coefficients (LPC) techniques are employed lo restore missing data in the process of state estimation. The conventional Normal Equation method has been found computationally expensive. Alternatively. Levinson Durbin Algorithm (LDA) considerably reduces this computational cost by avoiding the larger matrix inversions involved in the computation of LPC. However, LDA has been found suffering from a larger dynamic range in the values of LPC, An alternate method - Leroux Gueguen Algorithm (LGA) eliminates the problem associated with dynamic range in a stationary-point scenario by taking the application of Schwartz inequality in computation of this method. The main course of this work is to reduce the computational complexity of the Normal Equation when integrated with Kalman filter with that of LDA and LGA methods which do not require on matrix inversion in the computation of LPCs.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"235 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123039236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512186
K. Hayat, A. Kashif, S. Azam, T. Mehmood, M. Imran
This paper presents the design and characterization of a GaN HEMT based class-AB power amplifier (PA) for L-band radar applications at 1.3 GHz. The aim of this paper is to design and develop a 30 Watt PA together with high efficiency, small in size and low-cost solution. The source and load impedances have been extracted by performing source and load-pull for attaining an optimal performance of class-AB PA. The fabricated PA provides an RF power of 45.5 dBm at 1-dB compression point. The power added efficiency (PAE) of 63% is achieved together with power gain of 13.5 dB at desired frequency.
{"title":"High performance GaN HEMT class-AB RF power amplifier for L-band applications","authors":"K. Hayat, A. Kashif, S. Azam, T. Mehmood, M. Imran","doi":"10.1109/IBCAST.2013.6512186","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512186","url":null,"abstract":"This paper presents the design and characterization of a GaN HEMT based class-AB power amplifier (PA) for L-band radar applications at 1.3 GHz. The aim of this paper is to design and develop a 30 Watt PA together with high efficiency, small in size and low-cost solution. The source and load impedances have been extracted by performing source and load-pull for attaining an optimal performance of class-AB PA. The fabricated PA provides an RF power of 45.5 dBm at 1-dB compression point. The power added efficiency (PAE) of 63% is achieved together with power gain of 13.5 dB at desired frequency.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125059693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512145
Muhammad Ashraf, Z. Sajid, M. Sarim, Abdul Abdul Basit Shaikh
Face recognition is one of the most important computer vision problems. Its importance is largely due to the security issues the world is facing at the moment and also the requirement of a more robust system security standard. This work investigates the use of facial weighted distance transform to improve the face recognition rate. Weighted distance transform, also known as geodesic distance, not only considers the spatial distance among pixels but also takes into account the local intensity variations providing a distance transform in the spatiointensity domain. Geodesic distance transform of facial images is estimated using the “Fast Marching” [1, 2] technique which is based on Dijkstra's algorithm employed to identify the shortest network path. It is a single pass algorithm providing efficient geodesic distance feature vector, thereby reducing the recognition time. A standard Frontal Face Data Base [3] is used to validate the algorithm. The obtained results are comparable to the state-of-the-art face recognition techniques.
{"title":"Face recognition using weighted distance transform","authors":"Muhammad Ashraf, Z. Sajid, M. Sarim, Abdul Abdul Basit Shaikh","doi":"10.1109/IBCAST.2013.6512145","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512145","url":null,"abstract":"Face recognition is one of the most important computer vision problems. Its importance is largely due to the security issues the world is facing at the moment and also the requirement of a more robust system security standard. This work investigates the use of facial weighted distance transform to improve the face recognition rate. Weighted distance transform, also known as geodesic distance, not only considers the spatial distance among pixels but also takes into account the local intensity variations providing a distance transform in the spatiointensity domain. Geodesic distance transform of facial images is estimated using the “Fast Marching” [1, 2] technique which is based on Dijkstra's algorithm employed to identify the shortest network path. It is a single pass algorithm providing efficient geodesic distance feature vector, thereby reducing the recognition time. A standard Frontal Face Data Base [3] is used to validate the algorithm. The obtained results are comparable to the state-of-the-art face recognition techniques.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126640389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512153
A. Bakar, Zhang Ke-shi
This paper presents the importance of multidisciplinary optimization and its promising results. Evolutionary algorithm is applied which takes into account the aerodynamics and structure of transonic wing. Some classical and widely accepted principles are applied to predict the performance of the wing. Aerodynamic module calculates the induced drag of the wing using multiple lifting line theory. The friction/form drag is calculated by wetted area and using the prediction of skin friction models and form-factor estimation. Total drag is then calculated by summing the induced drag, friction drag and the wave drag, from Korn equation. To estimate the bending material weight, wing is modeled as double-plate wing box. Trade-off between minimum drag and minimum weight is studied. The dependency of the design space on specific wing parameters has also been studied. A significant improvement in the performance of a transonic transport aircraft wing can be achieved using the multidisciplinary optimization technique.
{"title":"Multidisciplinary optimization of transonic wing using evolutionary algorithm","authors":"A. Bakar, Zhang Ke-shi","doi":"10.1109/IBCAST.2013.6512153","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512153","url":null,"abstract":"This paper presents the importance of multidisciplinary optimization and its promising results. Evolutionary algorithm is applied which takes into account the aerodynamics and structure of transonic wing. Some classical and widely accepted principles are applied to predict the performance of the wing. Aerodynamic module calculates the induced drag of the wing using multiple lifting line theory. The friction/form drag is calculated by wetted area and using the prediction of skin friction models and form-factor estimation. Total drag is then calculated by summing the induced drag, friction drag and the wave drag, from Korn equation. To estimate the bending material weight, wing is modeled as double-plate wing box. Trade-off between minimum drag and minimum weight is studied. The dependency of the design space on specific wing parameters has also been studied. A significant improvement in the performance of a transonic transport aircraft wing can be achieved using the multidisciplinary optimization technique.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123009041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512181
S. K. Mustafa, S. Yasir
Dielectric rod antenna (DRA) has been used as an alternate feed system for the reflector antennas. Simulated and measured radiation characteristics for dielectric rod antenna have been discussed and compared. It is a cylindrical Teflon rod tapered from the radiating end and fed by a circular metallic waveguide. Such antennas are being used for their manufacturing simplicity, light weight, broadband characteristics and relatively higher gain and directivity as compared to horn antennas. Antenna discussed here was actually designed and measured for Ku band (12-14GHz) but simulated results reveal that it can exhibit broadband characteristics and can cover the range beyond 10-30GHz at either end.
{"title":"Design, development and testing of dielectric tapered rod feed for parabolic reflector antenna as an alternate to feed horns","authors":"S. K. Mustafa, S. Yasir","doi":"10.1109/IBCAST.2013.6512181","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512181","url":null,"abstract":"Dielectric rod antenna (DRA) has been used as an alternate feed system for the reflector antennas. Simulated and measured radiation characteristics for dielectric rod antenna have been discussed and compared. It is a cylindrical Teflon rod tapered from the radiating end and fed by a circular metallic waveguide. Such antennas are being used for their manufacturing simplicity, light weight, broadband characteristics and relatively higher gain and directivity as compared to horn antennas. Antenna discussed here was actually designed and measured for Ku band (12-14GHz) but simulated results reveal that it can exhibit broadband characteristics and can cover the range beyond 10-30GHz at either end.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122117951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512164
S. Manzoor, A. Islam, I. Chughtai, M. H. Inayat
This study investigates the flow visualization using PIV technique. It is tried to indigenously develop PIV technique with the help of low power laser, ordinary camera, and available tracer particles. PIV results are obtained with the help of some open software. Flow patterns of water containing tracer particles are studied. Flows are induced by magnetic stirrer and rotor. Flow visualization study is very useful in finding velocity profiles of different flows. Instantaneous vector maps of flow field and calibration of velocities are presented. Further studies are under consideration in PIEAS to develop the mature PIV technique.
{"title":"Low cost indigenous particle imaging velocimetry","authors":"S. Manzoor, A. Islam, I. Chughtai, M. H. Inayat","doi":"10.1109/IBCAST.2013.6512164","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512164","url":null,"abstract":"This study investigates the flow visualization using PIV technique. It is tried to indigenously develop PIV technique with the help of low power laser, ordinary camera, and available tracer particles. PIV results are obtained with the help of some open software. Flow patterns of water containing tracer particles are studied. Flows are induced by magnetic stirrer and rotor. Flow visualization study is very useful in finding velocity profiles of different flows. Instantaneous vector maps of flow field and calibration of velocities are presented. Further studies are under consideration in PIEAS to develop the mature PIV technique.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129100012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512173
K. Waqas, A. B. Tahir
When we talk about the underwater acoustic systems, noise comes in mind simultaneously. This noise deteriorates the amount of important information presented on different displays. This deterioration plays significant role in the quality of displays. Dynamic removal of noise plays significant role in this regard as noise levels are consistently changing with the change in the sea environment. We have already removed unwanted noise from broadband displays and presented our work previously. That removal of noise from broadband display significantly improved quality of displays. By looking at the previous achievement, we extended our approach and implemented it for the removal of noise from narrowband displays. The dynamic noise floor is being calculated from normalization process. This dynamic noise floor is being updated each time on arrival of new data. Hence it changes and optimizes itself on the go dynamically every single second. This dynamic noise floor is then used to put a threshold cut on the narrowband displays. This results in some extraordinary results and noise removal from narrowband displays. A complete comparison of non-noise removed narrowband displays and noise removed narrowband displays with calculation is being presented in this paper. This technique removed unwanted noise from narrowband displays making frequency lines crispier and accurate on narrowband displays.
{"title":"Dynamic threshold technique for noise removal in narrowband displays of underwater acoustic systems","authors":"K. Waqas, A. B. Tahir","doi":"10.1109/IBCAST.2013.6512173","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512173","url":null,"abstract":"When we talk about the underwater acoustic systems, noise comes in mind simultaneously. This noise deteriorates the amount of important information presented on different displays. This deterioration plays significant role in the quality of displays. Dynamic removal of noise plays significant role in this regard as noise levels are consistently changing with the change in the sea environment. We have already removed unwanted noise from broadband displays and presented our work previously. That removal of noise from broadband display significantly improved quality of displays. By looking at the previous achievement, we extended our approach and implemented it for the removal of noise from narrowband displays. The dynamic noise floor is being calculated from normalization process. This dynamic noise floor is being updated each time on arrival of new data. Hence it changes and optimizes itself on the go dynamically every single second. This dynamic noise floor is then used to put a threshold cut on the narrowband displays. This results in some extraordinary results and noise removal from narrowband displays. A complete comparison of non-noise removed narrowband displays and noise removed narrowband displays with calculation is being presented in this paper. This technique removed unwanted noise from narrowband displays making frequency lines crispier and accurate on narrowband displays.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126500238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512196
M. Kashif, M. Yasin, N. Ahsan, Z. Y. Malik
This paper presents the design and development of an X-band LFM sweep generator. The proposed waveform generator utilizes a fully synthesized hybrid architecture that combines the advantages of both DDS and PLL. The architecture consists of a synthesized PLL source with DDS as a reference generator. At start up, the PLL is programmed for a fixed frequency while DDS is programmed for a linear triangular sweep. The PLL follows the reference that results in a linear RF sweep. This paper also presents the linearity testing of the synthesized FMCW RF source. The test was performed on a down-converted signal using a high sampling oscilloscope. The measured results indicate that with the proposed scheme, a very linear chirp can be generated at X band that is very useful for radar applications.
{"title":"Design, development and linearity testing of synthesized FMCW RF source","authors":"M. Kashif, M. Yasin, N. Ahsan, Z. Y. Malik","doi":"10.1109/IBCAST.2013.6512196","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512196","url":null,"abstract":"This paper presents the design and development of an X-band LFM sweep generator. The proposed waveform generator utilizes a fully synthesized hybrid architecture that combines the advantages of both DDS and PLL. The architecture consists of a synthesized PLL source with DDS as a reference generator. At start up, the PLL is programmed for a fixed frequency while DDS is programmed for a linear triangular sweep. The PLL follows the reference that results in a linear RF sweep. This paper also presents the linearity testing of the synthesized FMCW RF source. The test was performed on a down-converted signal using a high sampling oscilloscope. The measured results indicate that with the proposed scheme, a very linear chirp can be generated at X band that is very useful for radar applications.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134258087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512197
M. Nazir, M. Kashif, N. Ahsan, Z. Y. Malik
This paper presents design and development of PIN diode based RF circuit blocks for radar applications. These RF blocks include a high power limiter, 5-bit digital phase shifter and a high isolation SPDT switch. PIN diode modelling technique along with design challenges and implementation schemes for these RF blocks have been discussed. For limiter, a loss reduction technique has been discussed that can reduce the noise figure of the receiver. For the intended application, the signal is limited from 1kW (60dBm) to 10 mW(10 dBm). Design philosophy and tradeoffs of a five bit digital phase shifter have been discussed in detail. The intended phase increments are 11.25, 22.5, 45, 90 and 180 degrees with tolerance of +/-1, 2, 3, 5, 7 degrees respectively. For PIN diode switch application, isolation improvement technique has also been presented. The targeted loss is 1 dB with isolation of 20 dB all over the band. Simulation and measured results of all three RF blocks are in good agreement, thus indicating the accuracy of proposed PIN diode modelling technique.
{"title":"PIN diode modelling for simulation and development of high power limiter, digitally controlled phase shifter and high isolation SPDT switch","authors":"M. Nazir, M. Kashif, N. Ahsan, Z. Y. Malik","doi":"10.1109/IBCAST.2013.6512197","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512197","url":null,"abstract":"This paper presents design and development of PIN diode based RF circuit blocks for radar applications. These RF blocks include a high power limiter, 5-bit digital phase shifter and a high isolation SPDT switch. PIN diode modelling technique along with design challenges and implementation schemes for these RF blocks have been discussed. For limiter, a loss reduction technique has been discussed that can reduce the noise figure of the receiver. For the intended application, the signal is limited from 1kW (60dBm) to 10 mW(10 dBm). Design philosophy and tradeoffs of a five bit digital phase shifter have been discussed in detail. The intended phase increments are 11.25, 22.5, 45, 90 and 180 degrees with tolerance of +/-1, 2, 3, 5, 7 degrees respectively. For PIN diode switch application, isolation improvement technique has also been presented. The targeted loss is 1 dB with isolation of 20 dB all over the band. Simulation and measured results of all three RF blocks are in good agreement, thus indicating the accuracy of proposed PIN diode modelling technique.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"331 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133463878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-02DOI: 10.1109/IBCAST.2013.6512166
S. Hashmi, Q. W. Yang, Chen Ping Ping
Modern day research is striving towards the improvement of stability margin of Fans and Compressors. Flow control techniques are implemented to enhance the performance and increase the stability margin however the control mechanism complexity can be reduced if performance enhancement is built into design of turbomachinery with minimum possible design variables. In this paper numerical investigation on single stage low speed fan has been presented with effect of blade lean angle variation to be the design variable. The said fan has been designed for test rig to be installed at School of Power and Energy, Northwestern Polytechnic University (NWPU). Recent numerical investigations on stall mechanism have revealed that the single stage low speed fan stalls due stator hub-corner stall. The details of flow mechanism (specifically at hub corner region of stator) with the variation of rotor blade lean angle at near stall conditions are presented in this paper. Commercial CFD code NUMECA FINE/TURBO has been used to carry out all simulations. Two approaches have been adopted for blade lean angle modification: one is to modify the blade lean angle with linear stacking line secondly with simple Bezier Curve. The maximum variation of ±10° has been kept for lean angle variation for both approaches. Steady state simulations are run for shorter number of iterations to get the best lean angle including the base line angle. Harmonic method has been used to compute the unsteady near stall and just stall operating points. Positive lean angle (in the direction of rotation) has been found to slightly suppress the hub corner stall for both approaches. Linear stacking line has proven to be more effective than simple Bezier curve for both near and just stall operating conditions.
{"title":"Numerical investigation on effect of rotor blade lean angle variation on single stage fan stability","authors":"S. Hashmi, Q. W. Yang, Chen Ping Ping","doi":"10.1109/IBCAST.2013.6512166","DOIUrl":"https://doi.org/10.1109/IBCAST.2013.6512166","url":null,"abstract":"Modern day research is striving towards the improvement of stability margin of Fans and Compressors. Flow control techniques are implemented to enhance the performance and increase the stability margin however the control mechanism complexity can be reduced if performance enhancement is built into design of turbomachinery with minimum possible design variables. In this paper numerical investigation on single stage low speed fan has been presented with effect of blade lean angle variation to be the design variable. The said fan has been designed for test rig to be installed at School of Power and Energy, Northwestern Polytechnic University (NWPU). Recent numerical investigations on stall mechanism have revealed that the single stage low speed fan stalls due stator hub-corner stall. The details of flow mechanism (specifically at hub corner region of stator) with the variation of rotor blade lean angle at near stall conditions are presented in this paper. Commercial CFD code NUMECA FINE/TURBO has been used to carry out all simulations. Two approaches have been adopted for blade lean angle modification: one is to modify the blade lean angle with linear stacking line secondly with simple Bezier Curve. The maximum variation of ±10° has been kept for lean angle variation for both approaches. Steady state simulations are run for shorter number of iterations to get the best lean angle including the base line angle. Harmonic method has been used to compute the unsteady near stall and just stall operating points. Positive lean angle (in the direction of rotation) has been found to slightly suppress the hub corner stall for both approaches. Linear stacking line has proven to be more effective than simple Bezier curve for both near and just stall operating conditions.","PeriodicalId":276834,"journal":{"name":"Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124161931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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