SOURCE

<div class="fan-wrapper">
    <div class="fan"></div>
</div>

@keyframes rotateAnimate{
    from{
        transform: rotate(0deg) skew(-30deg);
    }
    to {
        transform:rotate(360deg) skew(-30deg);
    }
}

.fan-wrapper{
    overflow: hidden;
    position: relative;
    margin:100px;
    width:200px;
    height:200px;
    border-radius:50%;
    background: red;
}

.fan{
    position: absolute;
    right:0;
    animation: rotateAnimate 2s linear infinite;
    transform-origin: 0% 100%;
    width:100px;
    height:100px;
    background: blue;
}