د. حيدر مهدي باقر عبيدة
نشر بحوث علمية عدد (7) في مجلات و مؤتمرات علمية و عالمية أخرها عام 2019 كان في (ASME) (Journal of Turbomachinery) المدرجة في قاعدة بيانات سكوبس ضمن فئة (Q1)
ساهم بأعداد دليل الأعتماد لمؤسسات التعليم و التدريب التقني و المهني في العراق (TVET) عام 2019
المملكة المتحدة ليستر
تم الحصول على شهادة الدكتوراه باختصاص الهندسة الميكانيكية /حراريات من جامعة ليستر /المملكة المتحدة. تناولت دراسة الدكتوراه دراسة تأثير خفض التيارات الدوامة وتقليل تأثيرها على الضغط الأستاتيكي أثناء جريان غازات العادم خلال ريش التوربين ورفع كفاءة التوربين من خلال تقليل هذه الخسائر التي انعكست أيجابا على تقليل انبعاثات غاز ثنائي أوكسيد الكربون وتقليل أستهلاك الوقود في التوبينات الغازية المستخدمة في عملية تسييل الغاز الطبيعي.
تم الحصول على شهادة الماجستير من كلية الهندسة /جامعة النهرين باختصاص الهندسة الميكانيكية/طاقة حرارية.
حصل على شهادة البكلوريوس من قسم الهندسة الميكانيكية التابع الى كلية الهندسة جامعة النهرين في الهندسة الميكانيكية /المواد المركبة
Loss Reduction in a 1.5 Stage Axial Turbine by Computer- Driven Stator Hub Contouring
29 Jan 2019
Improvements in stage isentropic efficiency and reductions in total pressure loss are
sought in a 1.5 stage axial turbine. This is representative of power generation equipment
used in thermal power cycles, which delivers about 80% of the 201012 kWh worldwide
electricity. Component-level improvements are therefore timely and important
toward achieving carbon dioxide global emission targets. Secondary flow loss reduction
is sought by applying a nonaxisymmetric endwall design to the turbine stator hub. A
guide groove directs the pressure side branch of the horseshoe vortex away from the airfoil
suction side, using a parametric endwall hub surface, which is defined as to obtain
first-order smooth boundary connections to the remainder of the passage geometry. This
delays the onset of the passage vortex and reduces its associated loss. The Automatic
Process and Optimization WORKBENCH (APOW) generates a Kriging surrogate model from a
set of Reynolds-averaged Navier–Stokes simulations, which is used to optimize the hub
surface. The three-dimensional steady Reynolds-averaged Navier–Stokes model with an
axisymmetric hub is validated against reference experimental measurements from the
Rheinisch-Westf€alische Technische Hochschule (RWTH) Aachen. Comparative computational
fluid dynamics (CFD) predictions with an optimized nonaxisymmetric hub show a
decrease in the total pressure loss coefficient and an increase in the isentropic stage
efficiency at and off design conditions.
SOME PERSPECTIVES ON THE TREATMENT OF THREE-DIMENSIONAL FLOWS ON AXIAL COMPRESSOR BLADING
17 Jun 2016
The unsteady and three-dimensional nature of the flow past
axial compressor blading poses substantial challenges to the
design of the main flow passage. High aspect ratio blading is
amenable to the approach of splitting the design task between
the cascade and the meridional planes. However, the threedimensional
flows increasingly affect the stage aerodynamic
performance with decreasing blade aspect ratios. At very high
load conditions, corner vortices can grow to two-thirds of the
blade span, under the influence of the pitchwise pressure
gradient, causing significant blockage and loss. A survey of
treatments for three-dimensional flows highlights a variety of
approaches, including longitudinal and tangential slots for
suction and blowing, fences, turning vanes, fillets, and
grooves. The merits and issues exposed by past
implementations of these end-wall treatments are summarized.
Considered together, these arrangements display a variable
and open approach, which points towards an opportunity for
considering a more common framework, led by a greater
understanding of the flow physics. Preliminary work on the
parametrization of end-wall grooves has highlighted some
promising topological features of end walls generated by using
the Beta distribution function as the guide curve. This
seemingly unexplored application of the Beta function to axial
compressor end wall design promises a better fit with the
pitchwise periodic axial compressor geometry than other guide
curve functions considered herein and used in the past.
Numerical Study of the Flow Past an Axial Turbine Stator Casing and Perspectives for its Management
17 Aug 2017
The interaction of secondary flow with the main passage flow results in entropy generation; this accounts for considerable losses in turbomachines. Low aspect ratio blades in an axial turbine lead to a high degree of secondary flow losses. A particular interest is the reduction in secondary flow strength at the turbine casing, which adversely affects the turbine performance. This paper presents a selective review of effective techniques for improving the performance of axial turbines by turbine end wall modifications. This encompasses the use of axisymmetric and non-axisymmetric end wall contouring and the use of fences. Specific attention is given to non-axisymmetric end walls and to their effect on secondary flow losses. A baseline three-dimensional steady RANS k-ω SST model, with axisymmetric walls, is validated against experimental measurements from the Institute of Jet Propulsion and Turbomachinery at the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen, Germany, with comparative solutions generated by ANSYS Fluent and OpenFOAM. The predicted performance of the stator passage with an axisymmetric casing is compared with that from using a contoured casing with a groove designed using the Beta distribution function for guiding the groove shape. The prediction of a reduced total pressure loss coefficient with the application of the contoured casing supports the groove design approach based on the natural path of the secondary flow features. This work also provided an automated workflow process, linking surface definition in MATLAB, meshing in ICEM CFD, and flow solving and post-processing OpenFOAM. This has generated a casing contouring design tool with a good portability to industry, to design and optimize new turbine blade passages.
A Numerical Study of Secondary Flows in a 1.5 Stage Axial Turbine Guiding the Design of a Non-Axisymmetric Hub
17 Aug 2017
The performance of axial flow turbines is affected by losses from secondary flows that result in entropy generation. Reducing these secondary flow losses improves the turbine performance. This paper investigates the effect of applying a non-axisymmetric contour to the hub of a representative one-and-half stage axial turbine on the turbine performance. An analytical end-wall hub surface definition with a guide groove is used to direct the pressure side branch of the horseshoe vortex away from the blade suction side, so to retard its interaction with the suction side secondary flow and thus decrease the losses. This groove design is a development of the concept outlined in Obaida et al. (2016). A baseline three-dimensional steady RANS k-ω SST model, with axisymmetric walls, is validated against reference experimental measurements from a one-and-half stage turbine at the Institute of Jet Propulsion and Turbomachinery at RWTH Aachen, Germany. The CFD predictions of the non-axisymmetric hub with the guide groove show a decrease in the total pressure loss coefficient. The design work-flow is generated using the Alstom Process and Optimisation Workbench (APOW), which sensibly reduced the designer workload. The implementation of the guide groove has excellent portability to the turbomachinery industry and this makes this method promising for delivering the UK energy agenda through more efficient power turbines.
The Performance of a 1.5 stage Axial Turbine with a Non-Axisymmetric Casing at Off-Design Conditions
24 Dec 2017
Advances in manufacturing techniques allow greater freedom in designing axial turbine stage passages, including non-axisymmetric end walls. A non-axisymmetric end wall design method for the stator casing is implemented through a novel surface definition, towards mitigating secondary flow losses. The new design is compared with a diffusion design from the literature. Off-design operations are considered. Numerical predictions of a 1.5 stage axial turbine show a reduction in the rotor row total pressure loss of 1.69 % against the benchmark axisymmetric stage from RTWH Aachen, which is validated against experiment. Flow analysis gives an insight into the effectiveness of the new surface definition approach, which is implemented using Alstom Process and Optimization Workbench (APOW) software at design conditions. The numerical predictions show that performance is retained at off-design conditions.