The effect of rectangulargurney flap on wells turbine performance

Wells turbine is very adept at converting pneumatic power from ocean waves into mechanical energy. However, such turbines incur from low performance, limited operating range and low efficiency. The present study introduces a method to enhance the power produced from Wells turbine by implementing rectangular Gurney flap (GF). The Gurney flap is placed on both pressure and suction sides of the trailing edge (TE) and perpendicular to the chord line without change chord length. GF increases the lift coefficient by altering the Kutta condition at the TE. The turbine performance is herein evaluated by solving numerically 3D incompressible Reynolds Averaged Navier–Stokes equations (RANS) by using ANSYS Fluent 19.0. The performance is demonstrated according to the flow coefficient, torque coefficient, total pressure loss coefficient, and the turbine efficiency, as well as the velocity and pressure fields around the turbine blades. The validation of the present work was achieved using previous experimental work and CFD work by using SST k – ω turbulence model. The present work showed that the Wells turbine augmented with GF increases the torque coefficient by 41.98%. Besides, the stall has been delayed compared with the conventional Wells turbine.

Cyclooxygenase-2 inhibitor treatment improves left ventricular function and mortality in a murine model of doxorubicin-induced heart failure

BACKGROUND

Progression of heart failure after initial myocardial injury is mediated in part by various redundant inflammatory mediators, including the widely expressed cyclooxygenase-2 (COX-2). Because COX-2 inhibitors are useful in treating many inflammation-mediated diseases, we asked whether COX-2 inhibition can attenuate heart failure progression.

METHODS AND RESULTS

Heart failure was experimentally induced in 100 mice by administration of doxorubicin (4 mg. kg(-1). wk(-1) for 6 weeks). Beginning at day 42, mice were fed daily with either COX-2 inhibitor-containing mice chow (n=50) or plain mice chow (controls; n=50). Left ventricular ejection fraction was evaluated as a measure of heart failure by a novel method of transthoracic echocardiography (with intravascular ultrasound catheters) at baseline and on days 42, 56, and 70. From baseline to study termination, left ventricular ejection fraction in COX-2 inhibitor-treated mice decreased significantly less than in control mice (9% versus 29%, P<0.01). Mortality was significantly lower for COX-2 inhibitor-treated mice than for control mice (18% versus 38%, P<0.01). These results were confirmed in a revalidation study in COX-2 inhibitor-treated mice (n=25) and controls (n=25). That study revealed that the hearts from control mice weighed roughly the same as hearts from COX-2 inhibitor-treated mice but showed more extensive signs of cardiomyopathy (as determined by pathological analysis by an independent, blinded observer) and higher levels of COX-2 proteins (as determined by immunoblotting [6442+/-1635 versus 4300+/-2408 arbitrary units, P<0.022]).

CONCLUSIONS

COX-2 inhibitors can attenuate the progression of heart failure in a murine model of doxorubicin-induced heart failure.

Hemodynamic support with a percutaneous left ventricular assist device during stenting of an unprotected left main coronary artery

Coronary artery bypass grafting prolongs survival in patients with left main coronary artery stenosis. However, this benefit is denied to patients who refuse the procedure or who are poor surgical candidates due to comorbid conditions. We describe a novel technique for the percutaneous revascularization of stenosis in an unprotected left main coronary artery in high-risk patients. The TandemHeart, a percutaneously inserted left ventricular assist device, was used to provide periprocedural hemodynamic support during angioplasty and stenting of an unprotected left main coronary artery for stenosis in a 70-year-old woman. The device was removed immediately after the procedure, and the patient was discharged from the hospital on the 2nd postprocedural day. The potential advantages of angioplasty with the support of percutaneous left ventricular assist devices in high-risk patients are discussed.